BOOK - IBM zOS V1R10 communications server TCP / IP implementation volume 1 base functions, connectivity, and routing

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Front cover
IBM z/OS V1R10 Communications Server
TCP/IP Implementation Volume 1:
Base Functions, Connectivity, and Routing
Bill White
Mike Ebbers
Valirio de Souza Braga Jr.
WenHong Chen
Gwen Dente
Octavio L. Ferreira
Marco Giudici
Joel Porterie
Micky Reichenberg
Andi Wijaya
Discusses important z/OS Communications
Server TCP/IP base function capabilities
Includes z/OS Communications Server
base function implementation examples
Provides useful verification
techniques

International Technical Support Organization
IBM z/OS V1R10 Communications Server TCP/IP
Implementation Volume 1: Base Functions,
Connectivity, and Routing
April 2009
SG24-7696-00

© Copyright International Business Machines Corporation 2009. All rights reserved.
Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule
Contract with IBM Corp.
First Edition (April 2009)
This edition applies to Version 1, Release 10 of z/OS Communications Server.
Note: Before using this information and the product it supports, read the information in “Notices” on
page ix.

© Copyright IBM Corp. 2009. All rights reserved. iii
Contents
Notices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Trademarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .x
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
The team that wrote this book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii
Become a published author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv
Comments welcome. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv
Chapter 1. Introduction to z/OS Communications Server IP. . . . . . . . . . . . . . . . . . . . . . 1
1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.1 Basic concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Featured functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 z/OS Communications Server IP implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3.1 Functional overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3.2 Operating environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3.3 Reusable address space ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3.4 Protocols and devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3.5 Supported routing applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.6 Application programming interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.7 z/OS Communications Server applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.3.8 UNIX Systems Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.4 Additional information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Chapter 2. The Resolver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.1 Basic concepts of the Resolver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.2 The Resolver address space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.2.1 The Resolver SETUP data set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.2.2 The Resolver configuration file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.2.3 Local hosts file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.2.4 Affinity servers and generic servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.2.5 Resolving an IPv6 address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.2.6 Resolver support for EDNS0. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.2.7 Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.3 Implementing the Resolver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.3.1 Implementation tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.3.2 Activation and verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2.4 Problem determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.5 Additional information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Chapter 3. Base functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.1 The base functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.1.1 Basic concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.2 Common design scenarios for base functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.2.1 Single stack environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
3.2.2 Multiple stack environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3.2.3 Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.2.4 Recommendations for MTU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.3 z/OS UNIX System Services setup for TCP/IP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.3.1 RACF actions for UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

iv IBM z/OS V1R10 Communications Server TCP/IP Implementation Volume 1: Base Functions, Connectivity, and Routing
3.3.2 APF authorization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3.3.3 Changes to SYS1.PARMLIB members. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
3.3.4 Changes to SYS1.PROCLIB members. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
3.3.5 Additional z/OS customization for UNIX System Services . . . . . . . . . . . . . . . . . . 66
3.3.6 TCP/IP server functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
3.3.7 TCP/IP client functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
3.3.8 UNIX client functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
3.3.9 Verification checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
3.4 Configuring z/OS TCP/IP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
3.4.1 TCP/IP configuration data set names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
3.4.2 PROFILE.TCPIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
3.4.3 VTAM Resource . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
3.4.4 TCPIP.DATA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
3.4.5 Configuring the local hosts file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
3.5 Implementing the TCP/IP stack. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
3.5.1 Create TCPIP.DATA file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.5.2 Create the PROFILE.TCPIP file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.5.3 Check BPXPRMxx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
3.5.4 Create TCP/IP cataloged procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
3.5.5 Add RACF definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
3.5.6 Create a VTAM TRL major node for MPCIPA OSA . . . . . . . . . . . . . . . . . . . . . . . 85
3.6 Activating the TCP/IP stack. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
3.6.1 UNIX System Services verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
3.6.2 Verifying TCP/IP configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
3.7 Reconfiguring the system with z/OS commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
3.7.1 Deleting a device and adding or changing a device . . . . . . . . . . . . . . . . . . . . . . 102
3.7.2 Modifying a device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
3.8 Job log versus syslog as diagnosis tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
3.9 Message types: Where to find them . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
3.10 Additional information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Chapter 4. Connectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
4.1 What is connectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
4.1.1 System z network connectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
4.2 Recommended interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
4.2.1 High-bandwidth and high-speed networking technologies . . . . . . . . . . . . . . . . . 112
4.2.2 OSA-Express (MPCIPA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
4.2.3 HiperSockets (MPCIPA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
4.2.4 Dynamic XCF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
4.3 Connectivity for the z/OS environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
4.3.1 IOCP definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
4.3.2 VTAM definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
4.4 OSA-Express connectivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
4.4.1 Dependencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
4.4.2 Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
4.4.3 Configuring OSA-Express with VLAN ID. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
4.4.4 Verifying the connectivity status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
4.5 HiperSockets connectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
4.5.1 Dependencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
4.5.2 Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
4.5.3 Configuring HiperSockets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
4.5.4 Verifying the connectivity status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
4.6 Dynamic XCF connectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

Contents v
4.6.1 Dependencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
4.6.2 Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
4.6.3 Configuring DYNAMICXCF. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
4.6.4 Verifying connectivity status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
4.7 Controlling and activating devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
4.7.1 Starting a device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
4.7.2 Stopping a device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
4.7.3 Activating modified device definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
4.8 Problem determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
4.9 Additional information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Chapter 5. Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
5.1 Basic concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
5.1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
5.1.2 Direct routes, indirect routes, and default route . . . . . . . . . . . . . . . . . . . . . . . . . 155
5.1.3 Route selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
5.1.4 Static routing and dynamic routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
5.1.5 Choosing the routing method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
5.2 Routing in the z/OS environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
5.2.1 Static routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
5.2.2 Dynamic routing using OMPROUTE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
5.2.3 Policy-based routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
5.3 Dynamic routing protocols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
5.3.1 Open Shortest Path First . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
5.3.2 Routing Information Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
5.3.3 IPv6 dynamic routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
5.4 Implementing static routing in z/OS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
5.4.1 Dependencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
5.4.2 Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
5.4.3 Implementation tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
5.4.4 Activation and verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
5.5 Implementing OSPF routing in z/OS with OMPROUTE . . . . . . . . . . . . . . . . . . . . . . . 179
5.5.1 Dependencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
5.5.2 Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
5.5.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
5.5.4 Implementation tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
5.5.5 Configure routers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
5.5.6 Activation and verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
5.5.7 Managing OMPROUTE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
5.6 Problem determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
5.6.1 Commands to diagnose networking connectivity problems . . . . . . . . . . . . . . . . 200
5.6.2 Diagnosing an OMPROUTE problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
Chapter 6. VLAN and Virtual MAC support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
6.1 Virtual MAC overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
6.1.1 Why use virtual MACs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
6.1.2 Virtual MAC concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
6.1.3 Virtual MAC address assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
6.2 Virtual MAC implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
6.2.1 IP routing when using VMAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
6.2.2 Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
6.3 Virtual LAN overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

vi IBM z/OS V1R10 Communications Server TCP/IP Implementation Volume 1: Base Functions, Connectivity, and Routing
6.3.1 Types of connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
6.4 VLAN Implementation on z/OS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
6.4.1 Single VLAN per OSA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
6.4.2 Multiple VLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
6.4.3 Multiple VLANs configuration guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
6.4.4 Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
6.5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
Chapter 7. Sysplex subplexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
7.2 Subplex environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
7.3 Load Balancing Advisor and subplexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
7.4 Subplex implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
7.4.1 XCF group names. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
7.4.2 TCP/IP structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
7.4.3 Subplex 11: Internal subplex. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
7.4.4 Subplex 22: External subplex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
7.4.5 Access verifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
7.4.6 LBA connected to a subplex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
7.5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
Chapter 8. Diagnosis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
8.1 Debugging a problem in a z/OS TCP/IP environment. . . . . . . . . . . . . . . . . . . . . . . . . 240
8.1.1 An approach to problem analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
8.2 Logs to diagnose CS for z/OS IP problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
8.3 Useful commands to diagnose CS for z/OS IP problems . . . . . . . . . . . . . . . . . . . . . . 243
8.3.1 PING command (TSO or z/OS UNIX). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
8.3.2 TRACEROUTE command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
8.3.3 The netstat command (console, TSO, or z/OS UNIX) . . . . . . . . . . . . . . . . . . . . 246
8.4 Gathering traces in CS for z/OS IP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
8.4.1 Taking a component trace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
8.4.2 Event trace for TCP/IP stacks (SYSTCPIP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
8.4.3 Packet trace (SYSTCPDA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
8.4.4 OMPROUTE trace (SYSTCPRT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
8.4.5 Resolver trace (SYSTCPRE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
8.4.6 IKE daemon trace (SYSTCPIK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
8.4.7 Intrusion detection services trace (SYSTCPIS) . . . . . . . . . . . . . . . . . . . . . . . . . 264
8.4.8 OSAENTA trace (SYSTCPOT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
8.4.9 Queued Direct I/O Diagnostic Synchronization. . . . . . . . . . . . . . . . . . . . . . . . . . 265
8.4.10 Network security services server trace (SYSTCPNS). . . . . . . . . . . . . . . . . . . . 266
8.4.11 Obtaining component trace data with a dump. . . . . . . . . . . . . . . . . . . . . . . . . . 266
8.4.12 Analyzing a trace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
8.4.13 Configuration profile trace. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
8.5 OSA-Express2 Network Traffic Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
8.5.1 Determining the microcode level for OSA-Express2. . . . . . . . . . . . . . . . . . . . . . 268
8.5.2 Defining TRLE definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
8.5.3 Checking TCPIP definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
8.5.4 Customizing OSA-Express Network Traffic Analyzer . . . . . . . . . . . . . . . . . . . . . 270
8.5.5 Defining a resource profile in RACF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
8.5.6 Allocating a VSAM linear data set. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
8.5.7 Starting the OSAENTA trace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
8.6 Additional tools for diagnosing CS for z/OS IP problems . . . . . . . . . . . . . . . . . . . . . . 285
8.6.1 Network Management Interface API . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285

Contents vii
8.6.2 Systems Management Facilities accounting records . . . . . . . . . . . . . . . . . . . . . 286
Appendix A. IPv6 support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
Overview of IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
Importance of IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
Common design scenarios for IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
Tunneling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
Dedicated data links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
MPLS backbones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294
Dual-stack backbones. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294
Dual-mode stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294
Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
How IPv6 is implemented in z/OS Communications Server. . . . . . . . . . . . . . . . . . . . . . . . 295
IPv6 addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
IPv6 TCP/IP Network part (prefix). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297
IPv6 implementation in z/OS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
Appendix B. Additional parameters and functions . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
MVS System symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
Reusable Address Space ID (REUSASID) function examples . . . . . . . . . . . . . . . . . . . . . 319
PROFILE.TCPIP statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
IPCONFIG statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
GLOBALCONFIG statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
PORT statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
IDYNAMICXCF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
SACONFIG (SNMP subagent) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
SMFCONFIG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332
INTERFACE statement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333
DEVICE AND LINK statements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338
SRCIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339
TCP/IP built-in security functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
Appendix C. Examples used in our environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343
Resolver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
TCP/IP stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346
OMPROUTE dynamic routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352
Appendix D. Our implementation environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
The environment used for all four books . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
Our focus for this book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360
Related publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
IBM Redbooks publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
Other publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
Online resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363
How to get IBM Redbooks publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363
Help from IBM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365

viii IBM z/OS V1R10 Communications Server TCP/IP Implementation Volume 1: Base Functions, Connectivity, and Routing

© Copyright IBM Corp. 2009. All rights reserved. ix
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x IBM z/OS V1R10 Communications Server TCP/IP Implementation Volume 1: Base Functions, Connectivity, and Routing
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© Copyright IBM Corp. 2009. All rights reserved. xi
Preface
For more than 40 years, IBM® mainframes have supported an extraordinary portion of the
world’s computing work, providing centralized corporate databases and mission-critical
enterprise-wide applications. The IBM System z®, the latest generation of the IBM
distinguished family of mainframe systems, has come a long way from its IBM System/360
heritage. Likewise, its IBM z/OS® operating system is far superior to its predecessors in
providing, among many other capabilities, world class and state-of-the-art support for the
TCP/IP Internet protocol suite.
TCP/IP is a large and evolving collection of communication protocols managed by the Internet
Engineering Task Force (IETF), an open, volunteer organization. Because of its openness,
the TCP/IP protocol suite has become the foundation for the set of technologies that form the
basis of the Internet. The convergence of IBM mainframe capabilities with Internet
technology, connectivity, and standards (particularly TCP/IP) is dramatically changing the
face of information technology and driving requirements for even more secure, scalable, and
highly available mainframe TCP/IP implementations.
The z/OS Communications Server TCP/IP Implementation series provides understandable,
step-by-step guidance about how to enable the most commonly used and important functions
of z/OS Communications Server TCP/IP.
In this IBM Redbooks® publication, we provide an introduction to z/OS Communications
Server TCP/IP. We then discuss the System Resolver, showing the implementation of global
and local settings for single and multi-stack environments. Next, we present implementation
scenarios for TCP/IP Base functions, Connectivity, Routing, Virtual MAC support, and sysplex
subplexing.
For more specific information about z/OS Communications Server standard applications, high
availability, and security, refer to the other volumes in the series:
Communications Server for z/OS V1R9 TCP/IP Implementation Volume 2: Standard
Applications, SG24-7533
Communications Server for z/OS V1R9 TCP/IP Implementation Volume 3: High
Availability, Scalability, and Performance, SG24-7534
Communications Server for z/OS V1R9 TCP/IP Implementation Volume 4: Security and
Policy-Based Networking, SG24-7535
For comprehensive descriptions of the individual parameters for setting up and using the
functions described in this book, along with step-by-step checklists and supporting examples,
refer to the following publications:
z/OS Communications Server: IP Configuration Guide, SC31-8775
z/OS Communications Server: IP Configuration Reference, SC31-8776
z/OS Communications Server: IP User’s Guide and Commands, SC31-8780
This book does not duplicate the information in those publications. Instead, it complements
them with practical implementation scenarios that can be useful in your environment. To
determine at what level a specific function was introduced, refer to z/OS Communications
Server: New Function Summary, GC31-8771. For complete details, we encourage you to
review the documents referred to in the additional resources section at the end of each
chapter.

xii IBM z/OS V1R10 Communications Server TCP/IP Implementation Volume 1: Base Functions, Connectivity, and Routing
The team that wrote this book
This book was produced by a team of specialists from around the world working at the
International Technical Support Organization (ITSO), Poughkeepsie Center.
Bill White is a Project Leader and Senior Networking Specialist at the ITSO, Poughkeepsie
Center.
Mike Ebbers is a Project Leader and Consulting IT Specialist at the ITSO, Poughkeepsie
Center. He has worked for IBM for 35 years, and at one time he was an SNA Specialist.
Valirio de Souza Braga Jr. is a Senior IT Specialist in Brazil working for the IBM Support
Center. He has 10 years of experience in networking with areas of expertise, including
VTAM®, TCP/IP, z/OS Communications Server, and OSA. His current responsibilities include
architecting mainframe IP connectivity solutions, designing inter-company Enterprise
Extender configurations, and assisting customers with high availability data center
implementations. Valirio has also co-authored other IBM Redbooks publications.
WenHong Chen is a Senior IT Specialist in IBM Global Services, China. For 11 years
WenHong has provided technical support to mainframe customers in southern China for
system architecture design, implementation, and performance tuning for z/OS, as well as
major subsystems (z/OS Communications Server, WLM, RACF®, DFSMS) and BCRS
services. Her areas of expertise in z/OS Communications Server include VTAM/APPN,
TCP/IP, and Enterprise Extender.
Gwen Dente is a Consulting IT Specialist with IBM Advanced Technical Support at the
Washington Systems Center in Gaithersburg, Maryland, U. S. She focuses on System z
networking and security, assisting customers and the IBM technical community with
cross-platform integration and network design. Gwen presents frequently at SHARE and
other IBM technical conferences and has shared authorship of multiple IBM Redbooks
publications.
Octavio L. Ferreira is a Senior IT Specialist in IBM Brazil. He has 28 years of experience in
IBM software support. His areas of expertise include z/OS Communications Server, SNA and
TCP/IP, and Communications Server on all platforms. For the last 10 years, Octavio has
worked at the Area Program Support Group, providing guidance and support to clients and
designing networking solutions such as SNA/TCP/IP Integration, z/OS Connectivity,
Enterprise Extender design and implementation, and SNA-to-APPN migration. He has also
co-authored other IBM Redbooks publications.
Marco Giudici is an IT Architect in IBM Australia. He has 20 years experience in supporting
IBM mainframes in different areas and different countries, including ten years in networking.
His current responsibilities include designing mainframe and non-mainframe solutions for IBM
Australia Strategic Outsourcing customers, mainly in the financial and government sectors.
Joel Porterie is a Senior IT Specialist who has been with IBM France for over 30 years. He
works for Network and Channel Connectivity Services in the EMEA Product Support Group.
His areas of expertise include z/OS, TCP/IP, VTAM, OSA-Express, and Parallel Sysplex®.
Joel has taught OSA-Express and FICON® problem determination classes and has provided
onsite assistance in these areas in numerous countries. He has also co-authored many other
IBM Redbooks publications.

Preface xiii
Micky Reichenberg is an independent consultant with more than 35 years of experience in
mainframe networking. He specializes in mainframe TCP/IP, SNA, open systems connectivity
to the mainframe, Enterprise Extender design and implementation. Prior to becoming a
consultant, Micky was a systems programmer with IBM in Israel for 17 years. During his
assignment with the ITSO at the Raleigh Center, he published five networking-related IBM
Redbooks publications. He holds a Bachelor’s degree in Aeronautical Engineering from the
Techion Israel Institute of Technology. Micky has also co-authored other IBM Redbooks
publications.
Andi Wijaya is a Senior Systems Engineer in IBM-JTI Indonesia. His areas of expertise are
IT infrastructure management, networking, security, and open source based system. He is a
trainer, consultant, and subject matter expert in Indonesia and also a public quality assurance
reviewer for other international books. For more than 10 years, Andi has been working with
networking solutions such as fault tolerant infrastructure, high performance enterprise
network, and end-to-end integrated security in network infrastructure.
Thanks to the following people from the ITSO, Poughkeepsie Center for their contributions to
this project: David Bennin, Emma Jacobs, Rich Conway, and Bob Haimowitz.
Thanks to the following people for their technical advice and support:
As is always the case with any complex technical effort, success would not have been
possible without the advice, support, and review of many outstanding technical professionals.
We are especially grateful for the significant expertise and contributions of content to this
book from the z/OS Communications Server development team and other Communications
Server experts:
Bebe Isrel (Raleigh CS)
Jeff Haggar (Raleigh CS)
Thomas McSweeney (Raleigh CS)
Mike Fox (Raleigh CS)
Todd Lopez (Raleigh CS)
Angelo Macchiano (Poughkeepsie/Endicott zVM)
Stephen Valley (Poughkeepsie OSA)
Joyce Anne Porter (Raleigh CS)
Curtis M. Gearhart (Raleigh CS)
Pamela S. Ross (Raleigh CS)
Srinivasan Muralidharan (Raleigh CS)
Gus Kassimis (Raleigh CS)
Daniel Vargas (IBM Tampa)
Finally, we want to thank the authors of the previous z/OS Communications Server TCP/IP
Implementation series for creating the groundwork for this series: Rama Ayyar, Valirio Braga,
Gwen Dente, Gilson Cesar de Oliveira, Octavio Ferreira, Adi Horowitz, Michael Jensen,
Shizuka Katoh, Sherwin Lake, Bob Louden, Garth Madella, Yukihiko Miyamoto, Shuo Ni,
Yohko Ojima, Roland Peschke, Joel Porterie, Marc Price, Larry Templeton, Rudi van Niekerk,
Bill White, and Thomas Wienert.

xiv IBM z/OS V1R10 Communications Server TCP/IP Implementation Volume 1: Base Functions, Connectivity, and Routing
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© Copyright IBM Corp. 2009. All rights reserved. 1
Chapter 1. Introduction to z/OS
Communications Server IP
z/OS Communications Server is the IBM implementation of the standard TCP/IP protocol
suite on the z/OS platform. TCP/IP is a component product of the z/OS Communications
Server, and it provides a multitude of technologies. Collectively, those technologies provide
an Open Systems environment for the development, establishment, and maintenance of
applications and systems.
The z/OS Communications Server product includes ACF/VTAM, in addition to TCP/IP.
This chapter presents a basic overview of z/OS Communications Server IP as it is
implemented in the z/OS environment. You can find a more complete and comprehensive
explanation of z/OS Communications Server IP from the publications that are listed in 1.4,
“Additional information” on page 18.
This chapter discusses the following topics.
1
Section Topic
1.1, “Overview” on page 2 Basic concepts of z/OS Communications Server IP
1.2, “Featured functions” on page 3 Key characteristics of z/OS Communications Server IP
and why they might be important in your environment
1.3, “z/OS Communications Server IP
implementation” on page 4
Functional overview of how z/OS Communications
Server IP is implemented

2 IBM z/OS V1R10 Communications Server TCP/IP Implementation Volume 1: Base Functions, Connectivity, and Routing
1.1 Overview
z/OS Communications Server provides the industry-standard TCP/IP protocol suite, allowing
z/OS environments to share data and computing resources with other TCP/IP computing
environments, when authorized. z/OS Communications Server IP enables anyone in a
non-z/OS TCP/IP environment to access resources in the z/OS environment and perform
tasks and functions provided by the TCP/IP protocol suite.
It provides the computer platform with the freedom desired by organizations to distribute
workload to environments best suited to their needs. z/OS Communications Server IP,
therefore, adds the z/OS environment to the list of environments in which an organization can
share data and computer processing resources in a TCP/IP network.
z/OS Communications Server IP supports two environments:
It provides a native MVS (z/OS) environment in which users can exploit the TCP/IP
protocols in the z/OS applications environment, including batch jobs, started tasks, TSO,
CICS® applications, and IMS applications.
It also provides native TCP/IP support in the UNIX® Systems Services environment in
which users can create and use applications that conform to the POSIX or XPG4 standard
(a UNIX specification). The UNIX environment and services can also be exploited from the
z/OS environment, and vice versa.
1.1.1 Basic concepts
The TCP/IP address space is where the TCP/IP protocol suite is implemented for z/OS
Communications Server IP. The TCP/IP address space is commonly referred to as a stack.
z/OS Communications Server IP has highly efficient direct communication between the UNIX
System Services address space (OMVS) and a TCP/IP stack that was integrated in UNIX
System Services. This communication path includes the UNIX System Services Physical File
System (PFS) component for AF_INET and AF_INET6 (Addressing Family-Internet) sockets
communication.
The z/OS Communications Server has the following features:
A process model that provides a full multiprocessing capability. It includes full duplex data
paths of reduced lengths.
An I/O process model that allows VTAM to provide the I/O device drivers. MultiPath
Channel (MPC) Data Link Control (DLC) is shared between VTAM and TCP/IP. It executes
multiple dispatchable units of work and is tightly integrated with the Common Storage
Manager support.
A storage management model handles expansion and contraction of storage resources,
as well as requests of varying sizes and types of buffers. Common Storage Manager
(CSM) manages communication between the Sockets PFS through the transport provider
and network protocols to the network interface layer of z/OS Communications Server IP
stack. The data that is placed in the buffers can be accessed by any function all the way
down to the protocol stack.
z/OS Communications Server IP runs as a single stack that serves both the traditional MVS
(z/OS) environment and the z/OS UNIX (UNIX Systems Services) environment.

Chapter 1. Introduction to z/OS Communications Server IP 3
z/OS Communications Server IP offers two variants of the UNIX shell environment:
The OMVS shell, which is much like a native UNIX environment
The ISHELL, which is an ISPF interface with access to menu-driven command interfaces
The TCP/IP protocol suite is implemented by an MVS started task within the TCP/IP address
space in conjunction with z/OS UNIX (UNIX System Services).
A z/OS Communications Server IP environment requires a Data Facility Storage
Management Subsystem (DFSMS), a z/OS UNIX file system, and a security product such as
Resource Access Control Facility (RACF). These resources must be defined and functional
before the z/OS Communications Server can be started successfully and establish the
TCP/IP environment. We later mention the manner in which these products impact a z/OS
Communications Server IP environment.
1.2 Featured functions
z/OS Communications Server provides a high-performance, highly secure, scalable, and
reliable platform on which to build and deploy networking applications.
z/OS Communications Server IP offers an environment that is accessible to the enterprise IP
network and the Internet if so desired. It defines the z/OS environment as a viable platform by
making z/OS applications and systems available to the non-z/OS environment, which are
typically UNIX/Windows®-centric. Consequently, it eliminates the issues and challenges of
many large corporations to migrate or integrate with a more accessible platform and newer
technologies.
The following list includes many of the technologies that have been implemented in the z/OS
environment to complement TCP/IP.
High-speed connectivity, such as:
– OSA-Express Gigabit Ethernet or 1000BASE-T in QDIO mode
– High-speed communication between TCP/IP stacks running in logical partitions using
HiperSockets™
High availability for applications using Parallel Sysplex technology in conjunction with:
– Dynamic Virtual IP Address (VIPA), which provides TCP/IP application availability
across z/OS systems in a sysplex and allows participating TCP/IP stacks to provide
backup and recovery for each other, for planned and unplanned TCP/IP outages
– Sysplex Distributor, which provides intelligent load balancing for TCP/IP application
servers in a sysplex, and along with Dynamic VIPA provides a single system image for
client applications connecting to those servers
– The Load Balancing Advisor (LBA), which provides z/OS Sysplex server application
availability and performance data to outboard load balancers through the Server
Application State Protocol (SASP)
Enterprise connectivity support is offered through many features, such as:
– TN3270 Server, which provides workstation connectivity over TCP/IP networks to
access z/OS and enterprise SNA applications.
– Enterprise Extender, which allows SNA Enterprise applications to communicate
reliably over an IP network, using SNA HPR and UDP transport layer protocols.

– IPv4 and IPv6 networking functions are provided by the TCP/IP stack operating in a
standard dual-mode setup where IPv4 and IPv6 connectivity and applications are
supported concurrently by a single TCP/IP stack instance.
– Sockets programming interface support for traditional z/OS workloads provide IP
connectivity to applications written in REXX, COBOL, PL/I. Sockets programming
interfaces are supported in various environments, such as TSO, batch, CICS, and IMS.
Network Security protects sensitive data and the operation of the TCP/IP stack on z/OS,
by using:
– IPsec/VPN functions that enable the secure transfer of data over a network using
standards for encryption, authentication, and data integrity.
– Intrusion Detection Services (IDS), which evaluates the stack for attacks that would
undermine the integrity of its operation. Events to examine and actions to take (such as
logging) at event occurrence are defined by the IDS policy.
– Transport Layer Security (TLS) enablement ensures data is protected as it flows across
the network.
– Kerberos and GSSAPI support is provided for selected applications.
– Defensive filtering provides an infrastructure to add, delete and modify short-term
TCP/IP filters in real time to counter specific attacks.
– Network Security Services provides a centralized security infrastructure to extend
System z security to NSS clients such as IKE daemons and XML appliances.
Network Management support collects network topology, status, and performance
information and makes it available to network management tools, including:
– Local management applications that can access management data using a specialized
high-performing network management programming interface that is known as NMI.
– Support of remote management applications through the SNMP protocol.
Communications Server z/OS supports the latest SNMP standard, SNMPv3.
Communications Server z/OS also supports standard TCP/IP-based Management
Information Base (MIB) data.
– Additional MIB support is also provided by Enterprise-specific MIB, which supports
management data for Communications Server TCP/IP stack-specific functions.
1.3 z/OS Communications Server IP implementation
z/OS Communications Server IP provides TCP/IP support for the native MVS and UNIX
System Services environment. It is implemented within a z/OS address space and runs within
the native MVS environment, and consequently it has RACF, DFSMS, and z/OS UNIX file
system dependencies.
1.3.1 Functional overview
CS for z/OS IP takes advantage of Communications Storage Manager (CSM) and of VTAM’s
Multipath Channel (MPC) and Queued Direct I/O (QDIO) capabilities in its TCP/IP protocol
implementation. This tight coupling with VTAM provides enhanced performance and
serviceability.

As illustrated in Figure 1-1, many data link control (DLC) protocols are provided with the z/OS
Communications Server by the VTAM component.
Figure 1-1 Functional overview
With CS for z/OS IP, two worlds converge, providing access to the z/OS UNIX environment
and the traditional MVS environment.
1.3.2 Operating environment
Because the z/OS UNIX environment is supported in the MVS environment, there is no need
to discuss the creation of an MVS environment here. However, there are customization
requirements on the UNIX Systems Services side of the environment that are needed in order
to start z/OS Communications Server IP successfully. This dependence on UNIX, of course,
implies that z/OS UNIX administrators must also be familiar with both traditional MVS
commands and interfaces.
I/O flow process
Another feature of the operating environment is the storage and I/O designs. The operating
environment design features a tightly integrated storage and I/O model, known as Common
Storage Manager (CSM). The CSM facility is used by authorized programs to manage
subsystem storage pools. It provides a flat storage model that is accessible by multiple layers
of the process model, as Figure 1-1 illustrates. It is also accessible across z/OS address
space boundaries, thereby reducing the data moves between processes and tasks that
exchange data as they perform work. VTAM and TCP/IP tasks are typical examples. The
IP and ICMP (Network Protocols and Interface Layer)
TCP, UDP, and Raw Sockets (Transport Protocol Layer)
Physical File System
Bind 4.9.3 (DNS/WLM server), Bind 9 (DNS server), DHCP
server, TN3270 server, FTP server, FTP client, Telnet
server, X-Windows client, SNMP Agent, OMPROUTE,
DPI library and SNMP Command: Netstat, Ping, Tracerte,
R-commands, RPC, REXEC, RSH, Sendmail
NDB, NICS, RPC, Kerberos,
MISC server, NCPRoute,
Portmapper, NPF, SNMP query,
X-Windows client, DPI library
LPD client,
LPD server,
SMTP server,
Telnet client
IMS CICS
Pascal
API
Sockets Extended
Callable ASM, COBOL, PL/1
Assembler
C-Sockets
REXX
Sockets
MPC+
SAMEHOST
(SNALINK,
X.25)
CDLC CLAW CTC HYPER LCS XCF ATM
TCP/IP Exclusive
DLCs
Shared DLCs
C
S
M
C-Sockets
BPX
ASM
Callable
API
z/OS UNIX Sockets
Logical File System

CSM facility also manages storage as it automates the addition and subtraction of the
different types and sizes of storage requests.
1.3.3 Reusable address space ID
The z/OS system assigns an address space identifier (ASID) to an address space when the
address space is created. A limited number of ASIDs are available for the system to assign.
When all ASIDs are assigned to existing address spaces, the system cannot start a new
address space. This condition can cause lost ASIDs in the system, which are address spaces
that have terminated but which the system does not reuse because of the address space’s
residual cross memory connections.
ASIDs used for the TCP/IP stack, the Resolver, VTAM, and TN3270 are non-reusable,
because they provide PC-entered services that must be accessible to other address spaces.
If these address spaces are terminated enough times, all available ASIDs can be exhausted,
preventing the creation of a new address space on the system. That situation might require
an IPL.
With the reusable address space support, ASIDs that would otherwise be unusable after
termination of the started task are made available for reuse. The reusable ASID function is
available for the TCP/IP, Resolver, VTAM, and TN3270 started tasks; however, it is not
available to TNF, VMCF, and all the products and applications that use their services (such as
TSO TELNET, HOMETEST, and so forth).
To enable the reuse ASID function, you must:
Specify REUSASID(YES) in member DIAGxx of your PARMLIB
Specify REUSASID=YES on the start command when starting the address space
The REUSASID parameter cannot be coded in the JCL of the started task because the
Master Scheduler needs to know this information before the JCL is read and the ASID is
assigned.
The Resolver started task will always use a reusable ASID when started during z/OS UNIX
initialization through the BPXRMMxx statement RESOLVER_PROC but will use a
non-reusable ASID if stopped and started. You should, therefore, restart Resolver with the
REUSASID=YES parameter specified on the start command.
The REUSASID parameter is to be used only by address spaces such as TCP/IP, Resolver,
and TN3270 that are usually non-reusable when terminated, because unnecessary use of
REUSASID=YES can reduce the number of ASIDs that are available for satisfying ordinary
address space requests.
We include examples of REUSASID coding and its results in Appendix B, “Additional
parameters and functions” on page 315.

1.3.4 Protocols and devices
As illustrated in Figure 1-1 on page 5, the DLC is a protocol layer that manages and provides
communication between the file I/O subsystem and the I/O device driver of the particular
device. The figure also shows two categories of DLCs:
TCP/IP exclusive DLCs
Shared DLCs
TCP/IP exclusive DLCs
TCP/IP exclusive DLCs are those only available for TCP/IP usage and are not shared with
ACF/VTAM. Here are examples of TCP/IP exclusive DLCs that are supported by z/OS
Communications Server IP:
LAN Channel Station (LCS), which is a protocol is used by OSA-Express, some routers,
and the 3746-9x0 MAE.
SAMEHOST, which is another TCP/IP exclusive DLC protocol that exists, although it does
not make use of System z channels. In the past, this communication was provided by
IUCV. Currently, SNALINK LU0, SNALINK LU6.2, and X.25 exploit the SAMEHOST DLC.
Shared DLCs
Shared DLCs are those that can be simultaneously used by TCP/IP and ACF/VTAM.
Figure 1-1 on page 5 indicates the shared DLCs. The most commonly used DLCs include
those that we describe here.
Multipath Channel+
Multipath Channel+ (MPC+) is an enhanced version of VTAM’s MPC protocol. The MPC I/O
process defines the implementation of the MPC protocols and allows for the efficient use of
multiple read and write channels.
MPC handles protocol headers and data separately and executes multiple I/O dispatchable
units of work. This process, when used in conjunction with Communication Storage
Management, creates efficient I/O throughput. High Performance Data Transfer uses MPC+
together with CSM to decrease the number of data copies that are required to transmit data.
This type of connection can be used in two ways:
MPCPTP allows a z/OS Communications Server IP environment to connect to a peer IP
stack in a point-to-point configuration. With MPCPTP, a z/OS Communications Server IP
stack can be connected to:
– Another z/OS Communications Server IP stack
– An IP router with corresponding support
– A non-z/OS server
– 3746-9x0 MAE
PTP Samehost (MPCPTP), sometimes referred to IUTSAMEH: This connection type is
used to connect two or more z/OS Communications Server IP stacks running on the same
z/OS LPAR. In addition, it can be used to connect these z/OS Communications Server IP
stacks to z/OS VTAM for the use of Enterprise Extender.
MPCIPA allows an Open Systems Adapter-Express (OSA-Express) port to act as an
extension of the z/OS Communications Server TCP/IP stack and not as a peer TCP/IP
stack, as with MPCPTP.
– OSA-Express provides a mechanism for communication called Queued Direct I/O
(QDIO). Although it uses the MPC+ protocol for its control signals, the QDIO interface
is quite different from channel protocols. It uses Direct Memory Access (DMA) to avoid

the overhead associated with channel programs. A partnership between CS for z/OS
IP and the OSA-Express adapter provides compute-intensive functions from the
System z server to the adapter.
Segmentation offload is a feature of OSA-Express2. This interface is called IP Assist
(IPA). Offloading reduces System z server cycles required for network interfaces, and
provides an overall improvement in the OSA-Express environment compared to
existing OSA-2 interfaces. OSA-Express collaborates with z/OS Communications
Server TCP/IP to support Gigabit Ethernet, 1000BASE-T, Fast Ethernet, Fast
Token-Ring, and ATM LAN emulation.
– HiperSockets (Internal Queued Direct I/O, iQDIO) provides high-speed, low-latency IP
message passing between logical partitions (LPARs) within a single System z server.
The communication is through processor system memory through Direct Memory
Access (DMA). The virtual servers that are connected through HiperSockets form a
virtual LAN. HiperSockets uses internal QDIO at memory speeds to pass traffic
between virtual servers.
Cross-System Coupling Facility
Cross-System Coupling Facility (XCF) allows communication between multiple z/OS
Communications Server IP stacks within a Parallel Sysplex. The XCF DLC can be defined as
with traditional DLCs, but it also supports XCF Dynamics, in which the XCF links are
established automatically.
If DYNAMICXCF is coded, z/OS images within the same server will use the HiperSockets
DYNAMICXCF connectivity instead of the standard XCF connectivity for data transfer.
For more information about devices and connectivity options, refer to Chapter 4,
“Connectivity” on page 109.
1.3.5 Supported routing applications
z/OS Communications Server ships only one routing application, called OMPROUTE.
OMPROUTE implements the Open Shortest Path First protocols (OSPF and OSPFv4) and
Routing Information Protocols (RIPv1, RIPv2, RIPng). It enables the z/OS Communications
Server IP to function as an OSPF/RIP-capable router in a TCP/IP network. Either (or both) of
these two routing protocols can be used to dynamically maintain the host routing table.
Additionally, z/OS Communications Server IP provides an OMPROUTE subagent that
implements the OSPF MIB variable containing OSPF protocol and state information for
SNMP. This MIB variable is defined in RFC 1850. Refer to Chapter 5, “Routing” on page 153,
for a detailed discussion about OMPROUTE and its function within the z/OS Communications
Server IP environment.
1.3.6 Application programming interfaces
As Figure 1-1 on page 5 illustrates, all of the APIs provided by z/OS Communications Server
IP, with the exception of the Pascal API, interface with the Logical File System (LFS) layer.
The APIs are divided into the following categories:
Pascal
TCP/IP socket APIs
z/OS UNIX APIs
REXX sockets
We describe these items in more detail in the following sections.

Pascal API
The Pascal application programming interface enables you to develop TCP/IP applications in
Pascal language. Supported environments are normal MVS address spaces. Unlike the other
APIs, the Pascal API does not interface directly with the LFS. It uses an internal interface to
communicate with the TCP/IP protocol stack. The Pascal API only supports AF_INET.
TCP/IP socket APIs
The z/OS Communications Server provides several APIs to access TCP/IP sockets. These
APIs can be used in either or both integrated and common INET PFS configurations.
In a common INET PFS configuration, however, they function differently from z/OS UNIX
APIs. In this type of configuration, the z/OS Communications Server APIs always bind to a
single PFS transport provider, and the transport provider must be the TCP/IP stack provided
by the z/OS Communications Server.
The following TCP/IP socket APIs are included in the z/OS Communications Server:
The CICS socket interface enables you to write CICS applications that act as clients or
servers in a TCP/IP-based network. CICS sockets only support AF_INET.
The C sockets interface supports socket function calls that can be invoked from C
programs. However, note that for C application development, IBM recommends the use of
the UNIX C sockets interface. These programs can be ported between MVS and most
UNIX environments relatively easily if the program does not use any other MVS-specific
services. C sockets only support AF_INET.
The Information Management System (IMS) IPv4 socket interface supports client/server
applications in which one part of the application executes on a TCP/IP-connected host
and the other part executes as an IMS application program. The IMS sockets API supports
AF_INET.
The Sockets Extended macro API is a generalized assembler macro-based interface to
sockets programming. The Sockets Extended macro API supports AF_INET and
AF_INET6.
The Sockets Extended Call Instruction API is a generalized call-based, high-level
language interface to sockets programming. The Sockets Extended Call Instruction API
supports AF_INET and AF_INET6.
z/OS UNIX APIs
The following APIs are provided by the z/OS UNIX element of z/OS and are supported by the
TCP/IP stack in the z/OS Communications Server:
z/OS UNIX C sockets is used in the z/OS UNIX environment. It is the z/OS UNIX version
of the native MVS C sockets programming interface. Programmers use this API to create
applications that conform to the POSIX or XPG4 standard (a UNIX specification). The
z/OS UNIX C sockets support AF_INET and AF_INET6.
z/OS UNIX assembler callable services is a generalized call-based, high-level language
interface to z/OS UNIX sockets programming. The z/OS UNIX assembler callable services
support AF_INET and AF_INET6.
Refer to z/OS XL C/C++ Compiler and Run-Time Migration Guide for the Application
Programmer, GC09-4913, for complete documentation of the z/OS UNIX C sockets APIs. You
can also find further guidance in z/OS UNIX System Services Programming Tools,
SA22-7805.

REXX sockets
The REXX sockets programming interface implements facilities for socket communication
directly from REXX programs by using an address rxsocket function. REXX socket programs
can execute in TSO, online, or batch. The REXX sockets programming interface supports
AF_INET and AF_INET6.
Refer to z/OS Communications Server: IP Sockets Application Programming Interface Guide
and Reference, SC31-8788, for complete documentation of the TCP/IP Services APIs.
1.3.7 z/OS Communications Server applications
z/OS Communications Server TCP/IP provides a number of standard client and server
applications, including:
SNA 3270 Logon Services (TN3270)
z/OS UNIX logging services (syslogd)
File Transfer Services (FTP)
Network Management Services (SNMP Agents, Subagents, Trap forwarding)
IP Printing (LPR, LPD, Infoprint Server)
Internet Daemon Listener (INETD)
Mail Services (SMTP and sendmail)
z/OS UNIX logon services (otelnetd)
Remote Execution (REXECD, RSHD, REXEC, RSH, orexecd, orshd, orexec, orsh)
Domain Name Services (Caching DNS BIND9 server)
These applications are discussed in detail in Communications Server for z/OS V1R9 TCP/IP
Implementation Volume 2: Standard Applications, SG24-7533, and z/OS Communications
Server: IP Configuration Guide, SC31-8775.
z/OS Communications Server also provides a number of specialized applications, including:
Policy Agent for implementing networking and security policies in a z/OS environment
Centralized or Distributed Policy Services
Network Security Services (NSS)
Defense Manager
These applications are discussed in detail in the following publications:
Communications Server for z/OS V1R9 TCP/IP Implementation Volume 1: Base
Functions, Connectivity, and Routing, SG24-7532
1.3.8 UNIX Systems Services
UNIX System Services is the z/OS Communications Server implementation of UNIX as
defined by X/Open in XPG 4.2. UNIX System Services coexists with traditional MVS functions
and traditional MVS file types (partitioned data sets, sequential files, and so on). It
concurrently allows access to z/OS UNIX file system files and to UNIX utilities and commands
by means of application programming interfaces and the interactive shell environment.
z/OS Communications Server IP offers two variants of the UNIX shell environment:
The z/OS shell, which is the default shell
The tcsh shell (Ishell), which is an enhanced version of the Berkeley UNIX C shell
The Communications Server for z/OS IP requires that UNIX System Services be customized
in full-function mode before the TCP/IP stack will successfully initialize. For this reason we

present an overview of UNIX System Services to provide an overview of the coding and
security considerations that are involved with UNIX System Services.
Customization levels of UNIX System Services
There are two levels of z/OS UNIX services:
Minimum mode, indicating that although OMVS initializes, it provides few z/OS UNIX
services, and there is no support for TCP/IP and the z/OS shell. In this mode there is no
need for DFSMS or for a security product such as RACF.
Full-function mode, indicating that the complete array of z/OS UNIX services is available.
In this mode DFSMS, RACF, and the z/OS UNIX file system are required. TCP/IP and
z/OS UNIX file system interaction with UNIX System Services is defined within the
BPXPRMxx member of SYS1.PARMLIB.
See z/OS UNIX System Services Planning, SA22-7800 for a useful description of the UNIX
System Services customization process and TCP/IP.
UNIX System Services concepts
z/OS UNIX enables two open systems interfaces on the z/OS operating system:
An application program interface (API)
An interactive shell interface
With the APIs, programs can run in any environment (including batch jobs, in jobs submitted
by TSO/E interactive users, and in most other started tasks) or in any other MVS application
task environment. The programs can request:
Only MVS services
Only z/OS UNIX services
Both MVS and z/OS UNIX services
The shell interface is an execution environment similar to TSO/E, with a programming
language of shell commands like those in the Restructured Extended Executor (REXX)
language. The shell work consists of:
Programs that are run interactively by shell users
Shell commands and scripts that are run interactively by shell users
Shell commands and scripts that are run as batch jobs
In z/OS UNIX Systems Services, address spaces are provided by the fork() or spawn()
functions of the Open Edition callable services.
For a fork() function, the system copies one process, called the parent process, into a
new process, called the child process, and places the child process in a new address
space, the forked address space.
A spawn() functions also starts a new process in a new address space. Unlike a fork(), in
a spawn() call the parent process specifies a name of a program to be run in the child
process.

The types of processes can be:
User processes, which are associated with a user
Daemon processes, which perform continuous or periodic system-wide functions, such as
a Web server
Daemons (a UNIX concept) are programs that are typically started when the operating
system is initialized and remain active to perform standard services. Some programs are
considered daemons that initialize processes for users even though these daemons are
not long-running processes. Examples of daemons provided by z/OS UNIX are cron,
which starts applications at specific times, and inetd, which provides service management
for a network.
A process can have one or more threads. A thread is a single flow of control within a process.
Application programmers create multiple threads to structure an application in independent
sections that can run in parallel for more efficient use of system resources.
UNIX Hierarchical File System
Data sets and files are comparable terms. If you are familiar with MVS, you probably use the
term data set to describe a unit of data storage. If you are familiar with AIX® or UNIX, you
probably use the term file to describe a named set of records stored or processed as a unit.
In the UNIX System Services environment, the files are arranged in a z/OS UNIX file system.
The Hierarchical File System allows you to set up a file hierarchy that consists of:
Directories, which contain files, other directories, or both. Directories are arranged
hierarchically, in a structure that resembles an upside-down tree, with the root directory at
the top and branches at the bottom.
z/OS UNIX file system files, which contain data or programs. A file containing a load
module, shell script, or REXX program is called an executable file. Files are kept in
directories.
Additional local or remote file systems, which are mounted on directories of the root file
system or of additional file systems.
To the z/OS system, the UNIX file hierarchy appears as a collection of System z File System
data sets. Each z/OS UNIX file system data set is a mountable file system. The root file
system is the first file system mounted. Subsequent file systems can be mounted logically on
a directory within the root file system or on a directory within any mounted file system.
Each mountable file system resides in a z/OS UNIX file system data set on direct access
storage. DFSMS/MVS manages the z/OS UNIX file system data sets and the physical files.
For more information about the z/OS UNIX file system, refer to z/OS CS: IP Migration,
GC31-8773, and z/OS UNIX System Services Planning, SA22-7800.
z/OS UNIX file system definitions in BPXPRMxx
To get UNIX System Services active in full-function mode, you need to define the root file
system in the BPXPRMxx member of SYS1.PARMLIB. The root file system is usually loaded
or copied at z/OS installation time. The BPXPRMxx definition is detailed in z/OS UNIX
System Services Planning, SA22-7800.

An important part of your z/OS UNIX file system is located in the /etc directory. The /etc
directory contains some basic configuration files of UNIX System Services, and most
applications keep their configuration files in there as well. To avoid losing all of your
configuration when you upgrade your operating system, it is recommended that you put the
/etc directory in a separate z/OS UNIX file system data set and mount it at the /etc
mountpoint. Refer to z/OS UNIX System Services Planning, SA22-7800, for more information
about the /etc directory.
z/OS UNIX user identification
All users of an MVS system, including users of z/OS UNIX functions, must have a valid MVS
user ID and password. To use standard MVS functions, the user must have the standard MVS
identity based on the RACF user ID and group name.
If a unit of work in MVS uses z/OS UNIX functions, this unit of work must have, in addition to
a valid MVS identity, a z/OS UNIX identity. A z/OS UNIX identity is based on a UNIX user ID
(UID) and a UNIX group ID (GID). Both UID and GID are numeric values ranging from 0 to
2147483647 (231
-1).
In a z/OS UNIX system, the UID is defined in the OMVS segment in the user's RACF user
profile, and the GID is defined in an OMVS segment in the group's RACF group profile. What
we in an MVS environment call the user ID is in a UNIX environment normally termed the
user name or the login name. It is the name that users use to present themselves to the
operating system. In both a z/OS UNIX system and other UNIX systems, this user name is
correlated to a numeric user identification, the UID, which is used to represent this user
wherever such information has to be stored in the z/OS UNIX environment. One example of
this is in the Hierarchical File System, where the UID of the owning user is stored in the file
security portion of each individual file.
Access to resources in the traditional MVS environment is based on the MVS user ID, group
ID, and individual resource profiles that are stored in the RACF database.
Access to z/OS UNIX resources is granted only if the MVS user ID has a valid OMVS
segment with an OMVS UID, or if a default user is configured as explained next. Access to
resources in the Hierarchical File System is based on the UID, the GID, and file access
permission bits that are stored with each file. The permission bits are three groups of three
bits each. The groups describe:
The owner of the file itself
The users with the same GID as the owner
The rest of the world
The three bits are:
Read access
Write access
Search access if it is a directory or if it is a file that is executable
The superuser UID has a special meaning in all UNIX environments, including the z/OS UNIX
environment. This user has a UID of zero and can access every resource.
In lieu of or in addition to RACF definitions for individual users, you can define a default user.
The default user will be used to allow users without an OMVS segment defined to access
UNIX System Services. The default user concept should be used with caution, because it
could become a security exposure.

You will also find more information about the RACF security aspects of implementing the z/
Communications Server for z/OS IP in Communications Server for z/OS V1R9 TCP/IP
Implementation Volume 4: Security and Policy-Based Networking, SG24-7535.
Accessing the z/OS UNIX shells
You can access z/OS UNIX shells in the following ways:
The TSO/E OMVS command provides a 3270 interface in the z/OS UNIX shell.
The TSO/E ISHELL or ISH command provides a 3270 interface that uses ISPF dialogs.
The rlogin command provides an ASCII interface.
The Telnet command provides an ASCII interface. This Telnet is into the UNIX Telnet
daemon and not the TN3270 server in the z/OS system space.
From a TCP/IP network, the TN3270 command can be used, which provides a full-screen
3270 interface for executing the OMVS or ISHELL commands.
There are two shells, the z/OS shell and the Ishell. The login shell is determined by the
PROGRAM parameter in the RACF OMVS segment for each user. The default is the z/OS
shell.
You can find further information about the z/OS UNIX shells in z/OS UNIX System Services
User’s Guide, SA22-7801.
Operating mode
When a user first logs on to the z/OS UNIX shell, the user is operating in line mode.
Depending on the method of accessing the shell, the user can then use utilities that require
raw mode (such as vi) or run an X Window System application.
The different workstation operating modes are:
Line mode
Input is processed after you press Enter. This is also called canonical mode.
Raw mode
Each character is processed as it is typed. This is also called non-canonical mode.
Graphical mode
This is a graphical user interface for X Window System applications.
UNIX System Services communication
A socket is the endpoint of a communication path; it identifies the address of a specific
process at a specific computer using a specific transport protocol. The exact syntax of a
socket address depends on the protocol being used, that is, on its addressing family.
When you obtain a socket using the socket() system call, you pass a parameter that tells the
socket library to which addressing family the socket should belong. All socket addresses
within one addressing family use the same syntax to identify sockets.
Socket addressing families in UNIX System Services
In a z/OS UNIX environment, the most widely used addressing families are AF_INET and
AF_UNIX. There is IPv6 support (AF_INET6 addressing family) in Communications Server
for z/OS IP in a single transport driver environment configured in Dual-mode. Socket
applications written to the IPv6 APIs can use the z/OS TCP/IP stack for IPv6 network
connectivity.

The z/OS UNIX Systems Services implements support for a given addressing family through
different physical file systems. There is one physical file system for the AF_INET addressing
family, and there is another for the AF_UNIX addressing family. A PFS is the part of the z/OS
UNIX operating system that handles the storage of data and its manipulation on a storage
medium.
AF_UNIX addressing family
The UNIX addressing family is also referred to as the UNIX domain. If two socket applications
on the same MVS image want to communicate with each other, they can open a socket as an
AF_UNIX family socket. In that case, the z/OS UNIX address space will handle the full
communication between the two applications (see Figure 1-2). That is, the AF_UNIX physical
file system is self-contained within z/OS UNIX and does not rely on other products to
implement the required functions.
Figure 1-2 AF_UNIX sockets
AF_INET addressing family
This is the Internet addressing family, also referred to as the Internet domain. Socket
programs communicate with socket programs on other hosts in the IP network using
AF_INET family sockets which, in turn, use the AF_INET physical file system.
You can configure either AF_INET or both AF_INET and AF_INET6. You cannot define the
stack as IPv6 only. Although coding AF_INET6 alone is not prohibited, TCP/IP will not start
because the master socket is AF_INET and the call to open it will fail.
For more on this subject, refer to Chapter 3, “Base functions” on page 51 or z/OS UNIX
System Services Planning, SA22-7800.
The AF_INET physical file system relies on other products to provide the AF_INET transport
services to interact with UNIX System Services and its sockets programs.
Note: Throughout this discussion, information regarding AF_INET (IPv4) also applies to
AF_INET6 (IPv6).
UNIX Application UNIX Application
LFS
PFS = AF_UNIX = UDS

For AF_INET/AF_INET6 sockets, the z/OS UNIX address space routes the socket request to
the TCP/IP address space directly. As shown in Figure 1-3, the sockets/Physical File System
layer is a transform layer between z/OS UNIX and the TCP/IP stack.
Figure 1-3 AF_INET sockets
The sockets/PFS effectively transforms the sockets calls from the z/OS UNIX interface to the
TCP/IP stack regardless of the version of MVS or TCP/IP. The sockets/PFS handles the
communication between the TCP/IP address space and the z/OS UNIX address space in
much the same manner as High Performance Native Socket (HPNS) handles the
communication between the TCP/IP address space and the TCP/IP client and server address
spaces.
Physical File System transport providers
TCP/IP requires the use of the Physical File System (AF_INET) configured in two ways:
The Integrated Sockets File System type (INET)
The Common INET Physical File System type (CINET)
INET is used in a single-stack environment and CINET is used in a multiple-stack
environment.
A single Physical File System transport provider
If your background is in a UNIX environment, it might seem strange to have a choice of using
INET or CINET, because you are familiar with the TCP/IP protocol stack being an integral part
of the UNIX operating system. However, this is not the case in a z/OS environment; it is very
versatile. In this environment you can start multiple instances of a TCP/IP protocol stack,
each stack running on the same operating system, but each stack having a unique TCP/IP
identity in terms of network interfaces, IP addresses, host name, and sockets applications.
A simple example of a situation where you have more TCP/IP stacks running in your z/OS
system is if you have two separate IP networks, one production and one test (or one secure
and one not). You do not want routing between them, but you do want to give hosts on both IP
networks access to your z/OS environment. In this situation you could implement two TCP/IP
stacks, one connected to the production IP network and another connected to the test
network.
UNIX Application
CS for z/OS IP
LFS
PFS = AF_INET=Type(INET)

This multi-stack implementation in which you share the UNIX System Services across
multiple TCP/IP stacks provides challenges. Sockets applications that need to have an affinity
to a particular stack need special considerations, in some cases including the coordination of
port number assignments to avoid conflicts. For more information, see Chapter 3, “Base
functions” on page 51.
If a single AF_INET(6) transport provider is sufficient, then use the Integrated Sockets
physical file system (INET). If you need more than one AF_INET(6) transport provider
(multiple TCP/IP stacks), then you must use the Common INET physical file system (CINET).
You can customize z/OS to use the Common INET physical file system with just a single
transport provider (AF_INET(6), but it is generally not recommended due to a slight
performance decrease as compared to the Integrated Sockets Physical File System (INET).
However, you might consider doing this if you expect to run multiple stacks in the future.
The PFS is also known under the name INET, and this appears in UNIX System Services
definitions when a FILESYSTYPE and NETWORK TYPE need to be defined in the
BPXPRMxx member of SYS1.PARMLIB.
Common INET Physical File System (CINET)
If you have two or more AF_INET transport providers on an MVS image, such as a production
TCP/IP stack together with a test TCP/IP stack, you must use the Common INET Physical
File System. Figure 1-4 shows a multiple stack environment with Common INET (CINET).
Figure 1-4 Multiple INET transport providers: CINET PFS
OE Application
OE LFS
C-INET PFS
Stack TCPIPA Stack TCPIPB
CS for z/OS
TCP and UDP
IP and ICMP
Network Interfaces
CS for z/OS
TCP and UDP
IP and ICMP
Network Interfaces
IP Network

1.4 Additional information
The following IBM publications provide further details for implementing a z/OS environment
that supports the TCP/IP protocol suite:
This document explains the major concepts of, and provides implementation guidance for,
z/OS Communications Server functions.
This document details the parameters or statements that can be used to implement z/OS
Communications Server functions.
z/OS Communications Server: IP Programmer’s Guide and Reference, SC31-8787
This document provides the guidelines for programming the IP applications on the z/OS.
z/OS Communications Server: IP Sockets Application Programming Interface Guide and
Reference, SC31-8788
This document provides detailed information about the socket API for programming the IP
applications on the z/OS.
For migration, the following publications are also helpful:
z/OS Communications Server: New Function Summary, SC31-8771
This document includes function summary topics to describe all the functional
enhancements for the IP and SNA components of Communications Server, including task
tables that identify the actions necessary to exploit new function. Use this document as a
reference to using all the enhancements of z/OS Communications Server.
z/OS Planning for Installation, GA22-7504
This document helps you prepare to install z/OS by providing the information you need to
write an installation plan.
Recommendation: Although there are specialized cases where multiple stacks per LPAR
can provide value, in general we recommend that you implement only one TCP/IP stack
per LPAR for the following reasons:
A TCP/IP stack is capable of exploiting all available resources defined to the LPAR in
which it is running. Therefore, starting multiple stacks will not yield any increase in
throughput.
When running multiple TCP/IP stacks, additional system resources, such as memory,
CPU cycles, and storage, are required.
Multiple TCP/IP stacks add a significant level of complexity to TCP/IP system
administration tasks.
It is not necessary to start multiple stacks to support multiple instances of an application
on a given port number, such as a test HTTP server on port 80 and a production HTTP
server also on port 80. This type of support can instead be implemented using
BIND-specific support where the two HTTP server instances are each associated to
port 80 with their own IP address, using the BIND option on the PORT reservation
statement.

z/OS Migration, GA22-7499
This document describes how to migrate (convert) from release to release. Use this
document as a reference for keeping all z/OS applications working as they did in previous
releases.
z/OS Introduction and Release Guide, GA22-7502
This document provides an overview of z/OS and lists the enhancements in each release.
Use this document to determine whether to obtain a new release, and to decide which
new functions to implement.
z/OS Summary of Message and Interface Changes, SA22-7505
This document describes the changes to interfaces for individual elements and features of
z/OS. Use this document as a reference to the new and changed commands, macros,
panels, exit routines, data areas, messages, and other interfaces of individual elements
and features of z/OS.

Chapter 2. The Resolver
TCP/IP protocols rely upon IP addressing in order to reach other hosts in a network to
communicate. For ease of use, instead of using the IP addresses represented by numbers,
they are sometimes mapped to easy-to-remember names. Typically, the names are assigned
to the IP address of the servers that many users can access, such as Web servers, FTP
servers, and TN3270 servers.
The Resolver function allows applications to use names instead of IP addresses to connect to
other partners. The mapping of IP addresses and names is managed by name servers or
local definitions. The Resolver queries those name servers, or searches local definitions, in
order to convert the name to an IP address or the IP address to a name. Using the Resolver
relieves users of having to remember the decimal or hexadecimal IP addresses.
The Resolver is important for enabling TCP/IP stacks or TCP/IP applications to establish
connections to other hosts.
2
Section Topic
2.1, “Basic concepts of the Resolver” on
page 22
Basic concepts of the Resolver
2.2, “The Resolver address space” on
page 23
Key characteristics of the Resolver address space
2.3, “Implementing the Resolver” on
page 35
The configuration and verification tasks of Resolver
implementation
2.4, “Problem determination” on page 44 Problem determination techniques

2.1 Basic concepts of the Resolver
A Resolver is a set of routines that acts as a client on behalf of an application. It reads a local
host file or accesses one or more Domain Name System (DNS) for name-to-IP address or IP
address-to-name resolution.
In most systems, in order for an application to reach a remote partner, it uses two commands
to ask the Resolver what the IP address is for a host name, or vice versa. The commands are
gethostbyname(nnnnn) and gethostbyaddress(aaa.aaa.aaa.aaa).
Figure 2-1 illustrates the information request and response flows. The Resolver gets a
request and, based on its own configuration file, will either look at a local hosts file or send a
request to a DNS server. After the relationship between the host name and IP address is
established, the Resolver returns the response to the application.
Figure 2-1 How the Resolver works
As mentioned, the Resolver function allows applications to use names instead of IP
addresses to connect to other partners. Although using an IP address might seem to be an
easy way to establish such a connection, for applications that need to connect to numerous
partners, or for applications that are accessed by thousands of clients, using names is a much
easier and more reliable form of establishing access.
Another important reason to use names instead of IP addressing is that a user or an
application is not affected by the IP address changes to the underlying network.
--
--
gethostbyname(hostx)
--
connect(192.168.1.1)
--
--
DomainOrigin abc.com
NSInterAddr 10.1.1.1
--
Get resolver info
send UDP query
receive UDP reply
return IP address
DNS server
IP address
is 192.168.1.1
Client Application Resolver Routines
resolv.confv
Give me IP address
for hostx.abc.com
Find an IP address that
corresponds to the name

Chapter 2. The Resolver 23
Table 2-1 compares the benefits and drawbacks of the use of hard-coded IP addresses and
the two name resolution methods:
The local hosts file
The name server (DNS)
Table 2-1 Comparing the use of direct addressing with name resolution
2.2 The Resolver address space
In z/OS systems, the Resolver works as a procedure. The Resolver must be started before
TCP/IP stacks or any TCP/IP applications issue the resolver calls. It can be started in one of
the following ways:
Default z/OS UNIX RESOLVER
If no customized Resolver address space is configured, the z/OS UNIX System Services
starts the default Resolver. The default Resolver is named RESOLVER. To use the default
RESOLVER address space, specify the RESOLVER_PROC(DEFAULT) statement or do
not specify any RESOLVER_PROC statements in BPXPRMxx.
Customized Resolver address space
The customized Resolver address space can specify additional options to control the use
of the Resolver configuration file. To create the Customized Resolver address space,
create a Resolver started procedure and a SETUP data set to specify the additional
options. The customized Resolver address space can be started automatically with the
RESOLVER_PROC(procname) statement in BPXPRMxx.
Although the Resolver address space can be started manually, we recommend that you start
the Resolver address space automatically during initialization of the UNIX System Services
with the RESOLVER_PROC() statement within BPXPRMxx.
After the Resolver address space is activated, the global TCPIP.DATA statements cannot be
overridden unless the MODIFY command is issued.
Hard-coded IP
addresses
Local hosts file Domain Name System
(DNS)
Technology None - Use the entered
IP address directly on the
connect() or sendto()
socket call.
Use gethostbyname() and
let the Resolver find an
IP address in the locally
configured hosts file.
Use gethostbyname() and
let the Resolver contact
the configured name
server for an IP address.
Benefits Fast (no name resolution).
Good in some debugging
situations (you know
exactly which IP address
is being used).
Fast (local name
resolution).
IP address changes can
be done without any local
changes. All host names
(in the entire network) can
be resolved.
A hierarchical name
space.
Drawbacks Difficult to remember
IP addresses. Very
inconvenient if an
IP address change
occurs. Just think about
IPv6.
If an IP addressing
change is needed, all the
local hosts files have to be
updated. Only locally
configured host names
can be resolved.
Additional packets
(requests) flow to resolve
host name before
destination can be
reached.

2.2.1 The Resolver SETUP data set
The Resolver SETUP data set is used by the customized Resolver address space. The
default z/OS UNIX Resolver does not read this file. The SETUP data set can include the
following statements:
GLOBALTCPIPDATA
DEFAULTTCPIPDATA
GLOBALIPNODES
DEFAULTIPNODES
COMMONSEARCH or NOCOMMONSEARCH
The use of each statement is discussed in later sections.
2.2.2 The Resolver configuration file
The Resolver configuration file is often called TCPIP.DATA. In this file you can define how the
Resolver should query the name-to-address or address-to-name resolution to the name
servers or search the local hosts file.
The configuration file can be an MVS data set or a z/OS UNIX Hierarchical File System (HFS)
file.
TCPIP.DATA configuration statements
The following basic statements should be defined in the TCPIP.DATA file.
TCPIPJOBNAME (equivalent to TCPIPUSERID)
The name of the procedure used to start the TCP/IP address space. The default is TCPIP.
DOMAIN (equivalent to DOMAINORIGIN)
The domain origin that is appended to the host name to form the fully qualified domain
name of a host.
HOSTNAME
The TCP host name of the z/OS Communications Server server.
LOOKUP
The order in which the DNS or local host files are to be searched for name resolution. By
default, DNS is looked up first and if the resolution is unsuccessful, the local host files are
searched next.
NSINTERADDR (equivalent to NAMESERVER)
The IP address of a name server the Resolver should query to.
DATASETPREFIX
The high-level qualifier for the dynamic allocation of data sets. DATASETPREFIX is
referred to as the hlq of the TCP/IP stacks.
Note: The publication z/OS Communications Server: IP Configuration Guide, SC31-8775,
contains useful information about the characteristics that are required for the z/OS data
sets or file system files that contain resolver SETUP and configuration statements. The
guide also points out the security characteristics and file system permission settings that
are needed.

TCPIP.DATA search order
On z/OS, the configuration file is located based on the search order. You must be mindful of
this search order, to ensure that the Resolver works in the way you expect.
The TCP/IP applications execute a set of commands in the Sockets API Library to initiate a
request to the Resolver in z/OS. The Sockets API Library uses one of the following socket
environments:
Native MVS environment
z/OS UNIX environment
Table 2-2 lists some of the APIs, z/OS applications, and user commands that use the active
MVS environment and the z/OS UNIX environment.
Table 2-2 Socket APIs, applications, and commands in Native MVS or z/OS UNIX environment
Native MVS environment z/OS UNIX environment
Socket APIs TCP/IP C Sockets
TCP/IP Pascal Sockets
TCP/IP REXX Sockets
TCP/IP Sockets Extended
IMS Sockets
CICS Sockets
Language Environment® C Sockets
UNIX System Services
z/OS Applications TN3270 Telnet server
SMTP
CICS Listener
LPD
Miscellaneous server
PORTMAP
RSHD
FTP
OMPROUTE
SNMP
z/OS UNIX OPORTMAP
z/OS UNIX OREXECD
z/OS UNIX ORSHD
User commands TSO FTP (batch)
TSO NETSTAT
TSO NSLOOKUP
TSO PING
TSO TRACERTE
TSO DIG
TSO LPR
TSO REXEC
TSO RPCINFO
TSO RSH
TSO FTP (command)
netstat
nslookup
ping
traceroute
ftp
host
hostname
dnsdomainname
dig
rexec
rpcinfo
sendmail
snmp

Each socket environment uses a different search order of the Resolver configuration file, as
shown in Figure 2-2.
Figure 2-2 The Resolver configuration file search order for each socket environment
This provides the flexibility to control the Resolver lookup differently, depending on which
socket API the application uses. However, because of the difference in search orders, it could
sometimes cause an unexpected result in the address resolution.
For example, if you set up /etc/resolv.conf as your Resolver configuration file, the FTP server
application that uses the z/OS UNIX search order can resolve the name-to-address or
address-to-name successfully. However, the TN3270 server, which uses the native MVS
search order, would fail because /etc/resolv.conf is not included in its search list.
Using GLOBALTCPIPDATA
In order to deal with the complexity of the different search orders in the environments, the
GLOBALTCPIPDATA statement was introduced. Using the GLOBALTCPIPDATA statement,
you can use the same Resolver configuration file throughout the z/OS system, because it is
the first choice in all socket search orders. This consolidation allows for consistent name
resolution processing across all TCP/IP applications.
To specify the GLOBALTCPIPDATA statement, you need to create a Resolver started
procedure and its SETUP data set, instead of using the z/OS UNIX System Services default
RESOLVER address space. The use of the Resolver address space and
GLOBALTCPIPDATA statement simplifies the Resolver configuration on z/OS.
The TCPIP.DATA file specified by the GLOBALTCPIPDATA statement is often called the
global TCPIP.DATA file. If you define GLOBALTCPIPDATA, the following statements can be
included only in the global TCPIP.DATA file:
DomainOrigin/Domain or Search
NSInterAddr/NameServer
NSPortAddr
ResolveVia
ResolverTimeOut
ResolverUDPRetries
SortList
Other TCPIP.DATA statements can be optionally included in the global TCPIP.DATAfile, and
the definition in the global TCPIP.DATA always has precedence. If TCPIPJobname is specified
Note: UNIX System Services Callable sockets use the z/OS UNIX environment search
order but cannot use the RESOLVER_CONFIG environment variable.
1. GLOBALTCPIPDATA
2. //SYSTCPD DD statement
3. userid/jobname.TCPIP.DATA
4. SYS1.TCPPARMS(TCPDATA)
5. DEFAULTTCPIPDATA
6. TCPIP.TCPIP.DATA
1. GLOBALTCPIPDATA
2. RESOLVER_CONFIG
environment variable
3. /etc/resolv.conf
4. //SYSTCPD DD statement
5. userid/jobname.TCPIP.DATA
6. SYS1.TCPPARMS(TCPDATA)
7. DEFAULTTCPIPDATA
8. TCPIP.TCPIP.DATA

in both the global TCPIP.DATA file and the local (non-global) TCPIP.DATA file, then the one in
the global TCPIP.DATA file is used.
If other TCPIP.DATA statements, such as HostName and TCPIPJobname, cannot be found in
the global TCPIP.DATA file, then the Resolver continues its search according to the search
order of the each socket environment. The search stops when the file is found.
If statements such as HostName and TCPIPJobname cannot be found in that file either, the
defaults are applied. Note that it does not continue searching in the list. In other words, a
maximum of two files can be used (global TCPIP.DATA file and one TCPIP.DATA file in the
search order list).
Using GLOBALTCPIPDATA, the administrators can specify which statements should be
applied throughout the z/OS image, and decide which statements can be customized by each
socket environment by omitting those statements in the global TCPIP.DATA file.
Figure 2-3 depicts the relationship between global TCPIP.DATA and local TCPIP.DATA.
Figure 2-3 Using global TCPIP.DATA and Local TCPIP.DATA
Using DEFAULTTCPIPDATA
DEFAULTTCPIPDATA can be specified in the Resolver SETUP data set to define the last
choice of the TCPIP.DATA in the search order. The file specified by DEFAULTTCPIPDATA is
used when the application does not specify the local (non-global) TCPIP.DATA.
Note: In the Common INET (CINET) multi-stack environment, you should omit the
TCPIPJobname statement from the global TCPIP.DATA file so that each TCP/IP stack, or
the applications that have affinity to a stack, can specify a local TCP.DATA with its own
TCPIPJobname statement.
When using GLOBALTCPIPDATA in the CINET environment, the name server specified by
NSInterAddr or NameServer in the global TCPIP.DATA file must be accessible from all
TCP/IP stacks that issue Resolver calls.
Global TCPIP.DATA
DOMAINORIGIN ITSO.IBM.COM
NSINTERADDR 10.12.6.7
NSPORTADDR 53
RESOLVEVIA UDP
RESOLVERTIMEOUT 10
RESOLVERUDPRETRIES
LOOKUP LOCAL DNS
TCPIPA
Local TCPIP.DATA
TCPIPJOBNAME TCPIPA
HOSTNAME WTSC30A
DATASETPREFIX TCPIPA
MESSAGECASE MIXED
SC30
TN3270
server
TCPIPZ
FTPDZ
server
Local TCPIP.DATA
TCPIPJOBNAME TCPIPZ
HOSTNAME WTSC30Z
DATASETPREFIX TCPIPZ
MESSAGECASE MIXED

2.2.3 Local hosts file
The local hosts file lists the mapping of the IP addresses and the names just like the name
servers, but held locally on the server. The LOOKUP statement in the TCPIP.DATA
configuration file defines whether the Resolver address space performs the name resolution
only in the local files, or using the defined name server, or both, in any specified order.
Using COMMONSEARCH
When the local hosts file is searched, the search order for the native MVS environment and
the z/OS UNIX environment are different. The difference in the search orders adds complexity
to configuration tasks and can lead unexpected results of the name resolution.
The simpler approach is to utilize the COMMONSEARCH statement in the Resolver SETUP
data set. By specifying COMMONSEARCH, native MVS and z/OS UNIX environments use
the same search order as shown in Figure 2-4 (except the RESOLVER_IPNODES
environment variable, which is only supported by the z/OS UNIX environment). In both
environments, the first choice is the file specified by GLOBALIPNODES statement, which is
defined in the Resolver SETUP data set.
The local hosts files looked up in this search order are typically called ETC.IPNODES files.
When the COMMONSEARCH is specified in the Resolver SETUP data set, it uses the same
search order for both IPv4 and IPv6 queries. You can list both IPv4 and IPv6 addresses in the
ETC.IPNODES file.
Figure 2-4 Local hosts file search order with COMMONSEARCH specified
To determine which environment is used for a particular socket’s APIs, applications, or
commands, refer to Table 2-2 on page 25.
If COMMONSEARCH is not specified in the Resolver SETUP data set, then the default is
NOCOMMONSEARCH and the default search order shown in Figure 2-5 is used.
Using GLOBALIPNODES
The GLOBALIPNODES statement specifies the global local host file that is to be used in the
entire z/OS image, regardless of which environment (native MVS or z/OS UNIX) that the
applications or sockets API use. To put the GLOBALIPNODES statement into effect for the
name resolution of IPv4 addresses, also specify COMMONSEARCH in the Resolver SETUP
data set.
(COMMONSEARCH specified)
IPv4 or IPv6 host name or address
search:
1. GLOBALIPNODES
2. userid/jobname.ETC.IPNODES
3. hlq.ETC.IPNODES
4. DEFAULTIPNODES
5. /etc/ipnodes
(COMMONSEARCH specified)
IPv4 or IPv6 host name or address
search:
1. GLOBALIPNODES
2. RESOLVER_IPNODES
3. userid/jobname.ETC.IPNODES
4. hlq.ETC.IPNODES
5. DEFAULTIPNODES
6. /etc/ipnodes

Using DEFAULTIPNODES
The DEFAULTIPNODES statement specifies the last candidate of the local host file search.
To put the DEFAULTIPNODES statement into effect for the name resolution of IPv4
addresses, also specify COMMONSEARCH in the Resolver SETUP data set.
Default local hosts file search order
If NOCOMMONSEARCH (the default) is specified in the Resolver SETUP data set or default
z/OS UNIX Resolver is used, the default local hosts file search order shown in Figure 2-5 is
used. The default local hosts file search order only applies to the query of IPv4 addresses.
The query for IPv6 addresses always uses the search order listed in Figure 2-4.
Figure 2-5 Local hosts file search order with NOCOMMONSEARCH specified (default)
2.2.4 Affinity servers and generic servers
In the multiple stack environment, a TCP/IP application might have an affinity to a specific
TCP/IP stack. When designing a multiple stack system, it is important to check each
application that will be used and how it will be implemented in the environment.
Affinity server
An affinity server is an application that has affinity to a specific TCP/IP stack; it provides
service to the clients that are connected through the TCP/IP stack to the applications.
In this case, you need to code a TCP/IPJobname statement that represents the application in
order to direct traffic to a specific stack. So, when designing the global definitions in the
Resolver address space, do not code a TCPIPJobname statement in GLOBALTCPIPDATA.
Instead, allow it to be coded in the local TCPIP.DATA.
A native TCP/IP sockets program will always use one stack only, and by default, it will be the
stack that is identified in the TCPIPJOBNAME option in the chosen Resolver configuration
file. However, the stack can also be chosen through the program configuration and API calls
to associate the program with a chosen stack, as shown in Figure 2-6 on page 30.
(NOCOMMONSEARCH specified)
IPv4 host name or address search:
1. X_SITE or X_ADDR
2. /etc/hosts
3. userid.HOSTS.SITEINFO or
userid.HOSTS.ADDRINFO
4. hlq.HOSTS.SITEINFO or
hlq.HOSTS.ADDRINFO
(NOCOMMONSEARCH specified)
IPv4 host name or address search:
1. userid.HOSTS.SITEINFO or
userid.HOSTS.ADDRINFO
2. hlq.HOSTS.SITEINFO or
hlq.HOSTS.ADDRINFO

Figure 2-6 Native TCP/IP applications in a multiple stack environment
Applications using UNIX System Services callable APIs or Language Environment C/C++
sockets APIs can also use a specific bind to open a socket. A bind-specific server socket will
only receive connections from the stack that owns the IP address to which the socket is
bound. Outbound connections or UDP datagrams will be handled by the stack that offers the
best route to the destination IP address, as shown in Figure 2-7.
Figure 2-7 UNIX System Services callable APIs or Language Environment C/C++ sockets APIs,
bind-specific
Inbound Outbound
Native MVS
Socket
Program
X
TCPA TCPB TCPC
Y Z V
C-INET
BPX Callable Sockets
Pre-routing Table
TCPIPJobname
TCPB
Inbound Outbound
socket( )
bind(8001, Y)
listen( )
X
TCPA TCPB TCPC
Y Z V
C-INET
Pre-routing Table
Application-specific
Configuration Data

Generic server
A generic server is a server without an affinity to a specific stack, and it provides service to
any clients that are connected to any TCP/IP stacks on the system.
When using the generic bind, it does not matter if the chosen Resolver configuration file has a
TCPIPJobname; it is not used when the server is a pure generic server.
Applications using UNIX System Services callable APIs or Language Environment C/C++
sockets APIs can be implemented using a generic bind to open the same port in all TCP/IP
stacks. By doing so, the application will accept incoming connections or UDP datagrams over
any interface of all connected stacks, as shown in Figure 2-8.
Figure 2-8 UNIX System Services callable APIs or Language Environment C/C++ sockets APIs,
generic bind
Outbound connections or UDP datagrams are processed by the C-INET pre-router, and the
stack with the best route to the destination is chosen.
When using a generic bind, the server port number must be reserved in all stacks. If one
stack has it reserved to another address space, the bind() call fails.
2.2.5 Resolving an IPv6 address
IPv6 support introduces several changes to how host name and IP address resolution is
performed. These changes affect several areas of Resolver processing, including:
Resolver APIs were introduced for IPv6-enabled applications.
An algorithm is defined to describe how a Resolver needs to sort a list of IP addresses
returned for a multihomed host.
DNS resource records are defined to represent hosts with IPv6 addresses, and therefore
network flows between Resolvers and name servers (instead of DNS IPv4 A records).
IPv6 Resolver statements
ETC.IPNODES is a local host file (in the style of /etc/hosts), which can contain both IPv4 and
IPv6 addresses. IPv6 addresses can only be defined in ETC.IPNODES. This file allows the
Inbound Outbound
socket( )
bind(8001, 0)
listen( )
X
TCPA TCPB TCPC
Y Z V
C-INET
Pre-routing Table

administration of local host files to more closely resemble that of other TCP/IP platforms, and
eliminates the requirement of post-processing the files (specifically, MAKESITE).
The IPv6 search order is same as the COMMONSEARCH search order, as shown in
Figure 2-4 on page 28. If you do not want to use the COMMONSEARCH search order for
existing IPv4 local hosts files, you might need to maintain two different local host files (for
example, IPv4 addresses in HOSTS.LOCAL, and IPv6 and IPv4 addresses in
ETC.IPNODES).
Name and address resolution functions
The APIs such as getaddrinfo, getnameinfo, and freeaddrinfo allow applications to resolve
host names to IP addresses and vice versa for IPv6. The APIs are designed to work with both
IPv4 and IPv6 addressing. The use of these APIs should be considered if an application is
being designed for eventual use in an IPv6 environment.
The manner in which host name (getaddrinfo) or IP address (getnameinfo) resolution is
performed is dependent upon Resolver specifications contained in the Resolver SETUP data
sets and TCPIP.DATA configuration data sets, just like IPv4 address resolution. These
specifications determine whether the APIs will query a name server first and then search the
local host files, or whether the order will be reversed—or even if one of the steps will be
eliminated completely. The specifications also control whether local host files have to be
searched, and which local host file will be accessed.
Default destination address selection
Resolver APIs have the capability to return multiple IP addresses as a result of a host name
query. However, many applications only use the first address returned to attempt a
connection or to send a UDP datagram. Therefore, the sorting of these IP addresses is
performed by the default destination address selection algorithm.
Establishing connectivity might depend on whether an IPv6 address or an IPv4 address is
selected, thus making this sorting function even more important. Default destination address
selection only occurs when the system is enabled for IPv6 and the application is using the
getaddrinfo() API to retrieve IPv6 or IPv4 addresses.
The default destination address selection algorithm takes a list of destination addresses and
sorts them to generate a new list. The algorithm sorts together both IPv6 and IPv4 addresses
by a set of rules.
The following rules are applied, in order, to the first and second address, choosing a best
address. Rules are then applied to this best address and the third address. This process
continues until rules are applied to the entire list of addresses.
Rule 1 Avoid unusable destinations. If one address is reachable (the stack has a route
to the particular address) and the other is unreachable, then place the
reachable destination address prior to the unreachable address.
Rule 2 Prefer matching scope. If the scope of one address matches the scope of its
source address and the other address does not meet this criteria, then the
address with the matching scope is placed before the other destination
address.
Rule 3 Avoid deprecated addresses. If one address is deprecated and the other is
non-deprecated, then the non-deprecated address is placed prior to the other
address.

Rule 4 Prefer matching address formats. If one address format matches its associated
source address format and the other destination does not meet this criteria,
then place the destination with the matching format prior to the other address.
Rule 5 Prefer higher precedence. If the precedence of one address is higher than the
precedence of the other address, then the address with the higher precedence
is placed before the other destination address.
Rule 6 Use the longest matching prefix. If one destination address has a longer
CommonPrefixLength with its associated source address than the other
destination address has with its source address, then the address with the
longer CommonPrefixLength is placed before the other address.
Rule 7 Leave the order unchanged. No rule selected a better address of these two;
they are equally good. Choose the first address as the better address of these
two and the order is not changed.
2.2.6 Resolver support for EDNS0
Early implementation of DNS, as covered by RFC 1035, allows only a maximum of 512 bytes
for DNS packet send through UDP. This limitation inhibits DNS performance because, when a
DNS server or client needs to communicate with a large amount of data, it will have to use the
bulky TCP protocol (higher performance cost) instead of the simple UDP protocol (lower
performance cost).
Extension Mechanism for DNS (EDNS0) was introduced in RFC 2671 to address the
performance improvement limitation imposed by the traditional DNS implementation. The
EDNS0 standard allows DNS communication to up to 3072 bytes using UDP. This
implementation provides improvement for DNS communicating a large amount of data, such
as IP version 6 (IPv6).
z/OS Communications Server resolver supports the EDNS0 standard by default. No
additional steps are needed to enabled this feature. However, the following dependencies are
required for the resolver to support EDNS0 properly:
The DNS name server must also support EDNS0 protocols in order to use UDP packets
larger than 512 bytes.
Firewalls that exist between the DNS name server and the z/OS resolver must be
configured to accept DNS messages sent as UDP packets of greater than 512 bytes in
order to use EDNS0 protocols.
In rare situations where the DNS server was just upgraded to support EDNS0, a refresh of
the z/OS resolver is required so that it can relearn the DNS server EDNS0 capabilities. Issue
MODIFY RESOLVER,REFRESH to the resolver address space to refresh.
Terminology: Deprecated, in this context, means that the state of an IPv6 address has
changed from preferred state (the address was leased to an interface for a fixed, possibly
infinite, length of time) to deprecated state. (When a lifetime expires, the binding and
address can become invalid, and the address can be reassigned to another interface
elsewhere on the Internet.) While in a deprecated state, the use of an address is
discouraged but not strictly forbidden.

2.2.7 Considerations
To implement the Resolver address space, it is important to first determine whether your
environment requires a single TCP/IP stack or multiple TCP/IP stacks. In both cases the
Resolver is an independent address space and has to be up and running before the TCP/IP
stack is started.
The statements defined in the global TCPIP.DATA cannot be overridden by the local
TCPIP.DATA file of the each TCP/IP stack. The local TCPIP.DATA file can only specify the
statement if it is not already defined in the global TCPIP.DATA file.
The Resolver in a single stack environment
We recommend that you create a global TCPIP.DATA file for a single stack environment. The
TCPIPJobname statement can be coded in a global TCPIP.DATA file or in the local
(non-global) TCPIP.DATA file, because there is only one stack on the system. If some
applications have requirements to specify their own TCPIP.DATA statements, then omit them
from the global TCPIP.DATA so the applications can point to the local TCPIP.DATA file to be
used.
The Resolver in a multiple stack environment
When implementing for a multiple stack environment, each TCP/IP stack should use a local
TCPIP.DATA file specifying stack-specific statements, such as TCPIPJobname and
HostName. Optionally, you can merge some statements that can be applied to all TCP/IP
stacks and all TCP/IP applications to a global TCPIP.DATA file. You need to determine which
statements should be defined in the global TCPIP.DATA and used in the entire z/OS image.
This will depend on how much you want to allow each stack or application to define its own
definitions.
In the multiple stack environment, we recommend that you create a global TCPIP.DATA if all
the statements needed in the global TCPIP.DATA (see “Using GLOBALTCPIPDATA” on
page 26) can be applied to all the stacks as shown in Figure 2-3 on page 27. If not, do not use
the global TCPIP.DATA and only use local TCPIP.DATA for each stack.
Important: In some Resolver environments, the use of the trace functions (such as
SockDebug or TraceResolver) might affect performance. Therefore, we recommend using
the method that we describe in “CTRACE - RESOLVER (SYSTCPRE)” on page 48.

Figure 2-9 depicts the multiple stack environment without the use of a global TCPIP.DATA.
Figure 2-9 The multiple stack environment without global TCPIP.DATA
2.3 Implementing the Resolver
In this scenario, we use the customized Resolver address space and specify
GLOBALTCPIPDATA, DEFAULTTCPIPDATA, and GLOBALIPNODES in the Resolver SETUP
data set. We define a global TCPIP.DATA file and define a common set of parameters for
entire z/OS image. We leave some statements omitted from the global TCPIP.DATA file so the
can provide value, generally we recommend implementing only one TCP/IP stack per
LPAR. The reasons for this recommendation are as follows:
throughput.
BIND-specific support where the two HTTP server instances are each associated with
statement.
One example where multiple stacks can have value is when an LPAR needs to be
connected to multiple isolated security zones in such a way that there is no network level
connectivity between the security zones. In this case, a TCP/IP stack per security zone can
be used to provide that level of isolation, without any network connectivity between the
stacks.
Local TCPIP.DATA
TCPIPJOBNAME TCPIPA
HOSTNAME WTSC30A
MESSAGECASE MIXED
NSPORTADDR 53
RESOLVEVIA UDP
RESOLVERTIMEOUT 10
RESOLVERUDPRETRIES
LOOKUP LOCAL DNS
SC30
Local TCPIP.DATA
TCPIPJOBNAME TCPIPZ
HOSTNAME WTSC30Z
DATASETPREFIX TCPIPZ
MESSAGECASE MIXED
NSINTERADDR 10.2001.2
NSPORTADDR 53
RESOLVEVIA UDP
RESOLVERTIMEOUT 10
RESOLVERUDPRETRIES
LOOKUP DNS LOCAL
TCPIPA
TN3270
server TCPIPZ
FTPDZ
server

applications or TCP/IP stack can use their own local TCPIP.DATA file for the statements
undefined in the global TCPIP.DATA file.
Figure 2-10 depicts the environment that we use for this implementation.
Figure 2-10 Our Resolver environment on SC30
2.3.1 Implementation tasks
To implement the Resolver address space in our test environment, we followed these steps:
1. Set up the Resolver started procedure.
2. Customize BPXPRMxx.
3. Configure the Resolver SETUP data set.
4. Create the global TCPIP.DATA file.
5. Create the default TCPIP.DATA file.
6. Create the global ETC.IPNODES data set.
7. Create a TCPIP.DATA file for TCPIPA stack.
8. Create the TCPIPA stack started procedure.
We describe these steps in the sections that follow.
Set up the Resolver started procedure
We created the Resolver procedure to be started during the UNIX System Services
initialization.
RESOLV30
Global TCPIP.DATA
NSPORTADDR 53
RESOLVEVIA UDP
RESOLVERTIMEOUT 10
RESOLVERUDPRETRIES
LOOKUP LOCAL DNS
TCPIP stack
Local TCPIP.DATA
TCPIPJOBNAME TCPIPA
HOSTNAME WTSC30A
MESSAGECASE MIXED
SC30
Global ETC.IPNODES
10.1.1.10 WTSC30A
10.1.1.20 WTSC31B
10.1.1.30 WTSC32C
10.1.2.240 router1
10.1.2.220 router2 ...

To create the procedure, we copied the sample procedure hlq.SEZAINST(EZBREPRC) and
customized it to our environment, as shown in Example 2-1. The procedure has only one DD
card that must be configured, the SETUP DD card 1, which describes where the SETUP data
set is located.
Example 2-1 The Resolver started procedure
/*****************************************
/* SYS1.PROCLIB(RESOLV30)
/*****************************************
//RESOLV30 PROC PARMS='CTRACE(CTIRES00)' 1
//EZBREINI EXEC PGM=EZBREINI,REGION=0M,TIME=1440,PARM=&PARMS
//* SETUP contains Resolver setup parameters.
//* See the section on "Understanding Resolvers" in the
//* IP Configuration Guide for more information. A sample of
//* Resolver setup parameters is included in member RESSETUP
//* of the SEZAINST data set.
//*
//SETUP DD DSN=TCPIPA.TCPPARMS(RESOLV&SYSCLONE),DISP=SHR,FREE=CLOSE 2
In this example, the numbers correspond to the following information:
1. The name of the Resolver procedure is RESOLV30.
2. Specifies the Resolver SETUP data set. The &SYSCLONE MVS system symbol value on
this system is 30.
Customize BPXPRMxx
We customized the RESOLVER_PROC statement in BPXPRMxx, to specify the procedure
name that we used, which causes the Resolver to start automatically the next time z/OS
UNIX System Services initializes. Example 2-2 shows the partial contents of BPXPRMxx.
Example 2-2 Specifying the Resolver procedure to be started
/*****************************************
/* SYS1.PARMLIB(BPXPRM00)
/*****************************************
/* RESOLVER_PROC is used to specify how the resolver address space */
/* is processed during Unix System Services initialization. */
/* The resolver address space is used by Tcp/Ip applications */
/* for name-to-address or address-to-name resolution. */
/* In order to create a resolver address space, a system must be */
/* configured with an AF_INET or AF_INET6 domain. */
/* RESOLVER_PROC(procname|DEFAULT|NONE) */
/* procname - The name of the address space for the resolver. */
/* In this case, this is the name of the address */
/* space as well as the procedure member name */
/* in SYS1.PROCLIB. procname is 1 to 8 characters */
/* long. */
/* DEFAULT - An address space with the name RESOLVER will */
/* be started. This is the same result that will */
/* occur if the RESOLVER_PROC statement is not */
/* specified in the BPXPRMxx profile. */
/* */

/* NONE - Specifies that a RESOLVER address space is */
/* not to be started. */
/* @DAA*/
/********************************************************************/
RESOLVER_PROC(RESOLV30) 1
1. Specifies the name of the Resolver procedure we created in the previous step.
Configure the Resolver SETUP data set
We configured the Resolver SETUP data set which is specified with the SETUP DD definition
in the Resolver started procedure. This data set defines the location of the global and default
TCPIP.DATA files containing the parameters we wanted to be defined in the z/OS
environment.
In our test environment, we copied the SETUP sample data set hlq.SEZAINST(RESSETUP) and
changed its contents to meet our requirements, as shown in Example 2-3.
Example 2-3 Resolver address space SETUP data set
; *****************************************
; TCPIPA.TCPPARMS(RESOLV30)
; *****************************************
GLOBALTCPIPDATA('TCPIPA.TCPPARMS(GLOBAL)') 1
DEFAULTTCPIPDATA('TCPIPA.TCPPARMS(DEFAULT)') 2
GLOBALIPNODES('TCPIPA.TCPPARMS(IPNODES)') 3
COMMONSEARCH 4
1. Specifies the first choice of the TCPIP.DATA file.
2. Specifies the last choice of the TCPIP.DATA file.
3. Specifies the first choice of the local hosts file.
4. The COMMONSEARCH search order is used. This statement is needed to have
GLOBALIPNODES to be applied.
Important: When the Resolver is started by UNIX System Services, you must pay
attention to the following information:
The Resolver address space is started with SUB=MSTR. This means that JES services
are not available to the Resolver address space. Therefore, no DD cards with SYSOUT
can be used.
The Resolver start procedure needs to reside in a data set that is specified by the
MSTJCLxx PARMLIB member’s IEFPDSI DD card specification. Otherwise, the
procedure will not be found and the Resolver will not start. SYS1.PROCLIB is usually
one of the libraries specified there.
Important: Plan carefully to create these global parameters. The definitions in the
Resolver SETUP data set is applied to all TCP/IP stacks or applications.

Create the global TCPIP.DATA file
In this step, we provided the global statements that all TCP/IP stacks and applications used in
our z/OS environment. To define these statements we copied the sample TCPIP.DATA file
provided in hlq.SEZAINST(TCPDATA) and customized the statements, as shown in
Example 2-4.
Example 2-4 Global TCPIP.DATA file
; *****************************************
; TCPIPA.TCPPARMS(GLOBAL)
; *****************************************
DOMAINORIGIN ITSO.IBM.COM 1
NSINTERADDR 10.12.6.7 2
NSPORTADDR 53
RESOLVEVIA UDP
RESOLVERTIMEOUT 10
RESOLVERUDPRETRIES 1
LOOKUP LOCAL DNS 3
1. Specifies the list of domain names appended to the host name when the search is
performed.
2. Specifies the IP address of the DNS server.
3. The local hosts file is looked up first. If it fails, the DNS server is searched.
Create the default TCPIP.DATA file
We created a default TCPIP.DATA file, as shown in Example 2-5, to be the last choice of the
local TCPIP.DATA search order. It is used when the application does not specify the local
TCPIP.DATA explicitly.
Example 2-5 Default TCPIP.DATA file
; *****************************************
; TCPIPA.TCPPARMS(DEFAULT)
; *****************************************
TCPIPJOBNAME TCPIP 1
HOSTNAME WTSC30 2
1. Specifies the default TCP/IP procedure name.
2. Specifies the default host name.
Important: If GLOBALTCPIPDATA is specified:
Any statements contained in the global TCPIP.DATA file will take precedence over any
statements in local TCPIP.DATA file found by way of the appropriate environment’s
(Native z/OS or z/OS UNIX) search order.
The TCPIP.DATA statements in Example 2-4 marked with 1 can only be specified in
GLOBALTCPIPDATA. If the resolver statements are found in any of the other search
locations for TCPIP.DATA, they are ignored. If the resolver statements are not found in
GLOBALTCPIPDATA, their default value will be used.

Create the global ETC.IPNODES data set
We created the global ETC.IPNODES data set, which is referred as GLOBALIPNODES in the
Resolver SETUP data set. It contains name-to-address mappings. This data set is used for
the local search to resolve a name into an IP address or vice versa.
We chose to use the COMMONSEARCH, because it allowed us to have a common local
search environment with IPv4 or IPv6 hosts. Example 2-6 shows the contents of the
GLOBALIPNODES data set. When using COMMONSEARCH, only the IPNODES data set is
used.
Example 2-6 GLOBALIPNODES data set
; *****************************************
; TCPIPA.TCPPARMS(IPNODES)
; *****************************************
10.12.6.7 OURDNS 1
10.1.1.10 WTSC30A 1
10.1.1.20 WTSC31B 1
10.1.1.30 WTSC32C 1
10.1.2.240 router1 1
10.1.2.220 router2 1
1::2 TESTIPV6ADDRESS1 2
1:2:3:4:5:6:7:8 TESTIPV6ADDRESS2 2
1. The mapping of a name and a IPv4 address is listed.
2. The mapping of a name and a IPv6 address is listed.
Create a TCPIP.DATA file for TCPIPA stack
We created a local TCPIP.DATA file for the TCPIPA stack with file name DATAA30, as shown
in Example 2-7.
Example 2-7 TCPIP.DATA file DATAA30
; *****************************************
; TCPIPA.TCPPARMS(DATAA30)
; *****************************************
TCPIPJOBNAME TCPIPA 1
HOSTNAME WTSC30A 2
MESSAGECASE MIXED
1. Specifies the procedure name of TCPIPA stack.
2. Specifies the host name of the TCPIPA stack.
Important: Applications that use Language Environment services without a
TCPIPJOBNAME statement cause applications that issue __iptcpn() to receive a job
name of NULL, and some of these applications will use INET instead of TCP/IP. Although
this presents no problem when running in a single-stack environment, it can potentially
cause errors in a multi-stack environment.

Create the TCPIPA stack started procedure
We created the TCPIPA stack procedure (RESOLVER_CONFIG) and pointed to
TCPIPA.TCPPARMS(DATAA30), using the &sysclone variable to simplify our implementation
to allow for a single procedure to be used by any z/OS image in our sysplex environment, as
shown in Example 2-8.
Example 2-8 TCPIPA procedure
/*****************************************
/* SYS1.PROCLIB(TCPIPA)
/*****************************************
//TCPIPA PROC PARMS='CTRACE(CTIEZB00),IDS=00', 1
// PROFILE=PROFA&SYSCLONE.,TCPDATA=DATAA&SYSCLONE
//TCPIPA EXEC PGM=EZBTCPIP,REGION=0M,TIME=1440,
// PARM=('&PARMS',
// 'ENVAR("RESOLVER_CONFIG=//''TCPIPA.TCPPARMS(&TCPDATA)''")') 2
//SYSPRINT DD SYSOUT=*,DCB=(RECFM=VB,LRECL=132,BLKSIZE=136)
//ALGPRINT DD SYSOUT=*,DCB=(RECFM=VB,LRECL=132,BLKSIZE=136)
//CFGPRINT DD SYSOUT=*,DCB=(RECFM=VB,LRECL=132,BLKSIZE=136)
//SYSOUT DD SYSOUT=*,DCB=(RECFM=VB,LRECL=132,BLKSIZE=136)
//CEEDUMP DD SYSOUT=*,DCB=(RECFM=VB,LRECL=132,BLKSIZE=136)
//SYSERROR DD SYSOUT=*
//PROFILE DD DISP=SHR,DSN=TCPIPA.TCPPARMS(&PROFILE.) 3
1. The TCP/IP procedure name is TCPIPA.
2. The local TCPIP.DATA is specified.
3. The TCP/IP profile is specified (the TCP/IP configuration file example is not shown in this
chapter).
2.3.2 Activation and verification
To verify the Resolver address space was working as we expected, we followed these steps:
1. Stop the default z/OS UNIX Resolver.
2. Start the Resolver address space.
3. Display the Resolver address space configuration.
4. Use the ping command to verify the name resolution.
To implement our Resolver address space, we first halted the running Resolver using the
STOP command, as shown in Example 2-9.
Stop the default z/OS UNIX Resolver
In our current environment, the default z/OS UNIX Resolver was running. We stopped this
default Resolver, as shown in Example 2-9, to run the customized Resolver.
Example 2-9 Stopping the Resolver address space
P RESOLVER
EZZ9292I RESOLVER ENDING
IEF196I IEF142I IEESYSAS RESOLVER - STEP WAS EXECUTED - COND CODE 0000
Important: Stop and restart the resolver only if you install a new level of the Resolver
code.

IEF196I IEF373I STEP/IEFPROC /START 2005270.1315
IEF196I IEF374I STEP/IEFPROC /STOP 2005285.1723 CPU 0MIN 00.02SEC
IEF196I SRB 0MIN 00.12SEC VIRT 44K SYS 176K EXT 220K SYS
IEF196I 26984K
IEF196I IEF375I JOB/RESOLVER/START 2005270.1315
IEF196I IEF376I JOB/RESOLVER/STOP 2005285.1723 CPU 0MIN 00.02SEC
IEF196I SRB 0MIN 00.12SEC
IEF352I ADDRESS SPACE UNAVAILABLE
IEF196I IEF352I ADDRESS SPACE UNAVAILABLE
Start the Resolver address space
We started the customized Resolver address space using the procedure we created in the
previous step, as shown in Example 2-10.
Example 2-10 Starting a configured Resolver address space
S RESOLV30,SUB=MSTR
IRR812I PROFILE ** (G) IN THE STARTED CLASS WAS USED 366
TO START RESOLV30 WITH JOBNAME RESOLV30.
EZZ9298I DEFAULTTCPIPDATA - TCPIPA.TCPPARMS(DEFAULT) 1
EZZ9298I GLOBALTCPIPDATA - TCPIPA.TCPPARMS(GLOBAL) 2
EZZ9298I DEFAULTIPNODES - None
EZZ9298I GLOBALIPNODES - TCPIPA.TCPPARMS(IPNODES) 3
EZZ9304I COMMONSEARCH 4
EZZ9291I RESOLVER INITIALIZATION COMPLETE
$HASP395 BPXAS ENDED
1. The correct DEFAULTTCPIPDATA file is applied.
2. The correct GLOBALTCPIPDATA file is applied.
3. The correct GLOBALIPNODES file is applied.
If you want to reload the SETUP data set content changes, use the MODIFY command to
refresh the Resolver. To show how this is done, we created a new SETUP data set named
NEWSETUP, without GLOBALTCPIPDATA or DEFAULTTCPIPDATA definitions, and
refreshed the Resolver to reflect the changes, as shown in Example 2-11.
Example 2-11 Modifying the Resolver address space
F RESOLV30,REFRESH,SETUP=TCPIPA.TCPPARMS(NEWSETUP)
EZZ9298I DEFAULTTCPIPDATA - None
EZZ9298I GLOBALTCPIPDATA - None
EZZ9298I DEFAULTIPNODES - TCPIPA.TCPPARMS(IPNODES)
Note: If you want to start the default z/OS UNIX Resolver, use the following command
instead:
START IEESYSAS.RESOLVER,PROG=EZBREINI,SUB=MSTR
Note: The resolver utilizes non-reusable address spaces. To start Resolver using a
reusable address space ID (REUSASID), see 1.3.3, “Reusable address space ID” on
page 6.

EZZ9298I GLOBALIPNODES - None
EZZ9304I COMMONSEARCH
EZZ9293I REFRESH COMMAND PROCESSED
Display the Resolver address space configuration
To verify the correct configuration file is applied to the Resolver address space, use the
MODIFY command with the display option, as shown in Example 2-12.
Example 2-12 Modify Resolver with display option
F RESOLV30,DISPLAY
EZZ9298I DEFAULTTCPIPDATA - TCPIPA.TCPPARMS(DEFAULT) 1
EZZ9298I GLOBALTCPIPDATA - TCPIPA.TCPPARMS(GLOBAL) 2
EZZ9298I DEFAULTIPNODES - None
EZZ9298I GLOBALIPNODES - TCPIPA.TCPPARMS(IPNODES) 3
EZZ9304I COMMONSEARCH
EZZ9293I DISPLAY COMMAND PROCESSED
1. The correct DEFAULTTCPIPDATA file is applied.
2. The correct GLOBALTCPIPDATA file is applied.
3. The correct GLOBALIPNODES file is applied.
Use the ping command to verify the name resolution
Verify that the Resolver is able to perform the expected name-to-address resolution by using
the ping command, as shown in Example 2-14. As you can see, the name router1 has
resolved to address 10.1.2.240.
Example 2-13 UNIX ping command display
CS03 @ SC30:/u/cs03>ping router1
CS V1R10: Pinging host router1 (10.1.2.240)
Ping #1 response took 0.000 seconds.
The TSO PING command was also successful, as shown in Example 2-14.
Example 2-14 TSO PING command display
TSO PING ROUTER1
***
It is also possible to verify where the resolver is looking by using the TRACE RESOLVER
parameter in the stack’s or application’s TCPIP.DATA file. For an explanation of how this is
done and what the contents of this trace will be, refer to the next section, 2.4, “Problem
determination” on page 44.

2.4 Problem determination
To diagnose Resolver problems, you can use two kinds of trace tools:
Trace Resolver
This provides information that can be helpful in debugging problems that an application
program could have with using Resolver facilities (for example, GetHostByName or
GetHostByAddr).
Component Trace RESOLVER (SYSTCPRE)
This is useful for diagnosing Resolver problems that cannot be isolated to one particular
application.
In this section we provide a brief explanation of when to debug, which trace has to be used,
and how to use these trace facilities. For more information about Resolver diagnosis, refer to
z/OS Communications Server: IP Diagnosis Guide, GC31-8782.
Deciding which tool to use to diagnose a Resolver problem
The first thing to do when diagnosing a possible Resolver problem is to check the symptoms
to verify if it is indeed a Resolver problem (see Table 2-3).
Table 2-3 What to do if the host name cannot be reached
Trace Resolver
The Trace Resolver tells what the Resolver looked for (the questions) and where it looked
(name server’s IP addresses or local host file names).
The following situations can be checked in the trace output:
Check whether the correct Resolver data sets is in use. If an unexpected TCPIP.DATA file
is used, check the search orders of the data set.
Check whether the data sets defined to be used are authorized by RACF and can be read
by the application, TCP/IP stack, or user.
Check the TCPIP.DATA parameter values, especially Search, NameServer,
NSINTERADDR, and NsPortAddr.
When we ping a host name,
the ping command:
What is the problem? Solution
Succeeds, but another
application fails when
resolving the same host
name.
The problem is with the Resolver
configuration for the application in
the users environment.
Use the Trace Resolver
statement on the local
TCPIP.DATA used by the
application that has the
problem.
Fails, but the host name is
converted to an IP address.
The resolution is successful but
the host is not reachable or active.
This problem is related to
connectivity, not a Resolver
problem.
Fails to convert the name to
an IP address.
The problem might be with the
Resolver configuration, searching
local host files, or using DNS.
Use Trace Resolver to solve the
problem.
Tip: If the problem seems to be related to the DNS, use the LOOKUP LOCAL DNS
statement to check the local files first.

Check the questions posed by the Resolver to DNS or in searching the local host files. Are
these the queries you expected?
Look for errors or failures in the trace.
Did DNS respond (if you expected it to)? If not, see whether DNS is active at the IP
address you specified for NameServer and NSINTERADDR and what port it is listening
on. Also, DNS logs can be helpful, so ask the DNS administrator for help.
Trace Resolver can be activated in the following ways, in its precedence order:
1. The RESOLVER_TRACE environment variable (z/OS UNIX environment only).
2. SYSTCPT DD allocation.
3. TRACE RESOLVER or OPTIONS DEBUG statements (you must allocate STDOUT or
SYSPRINT to generate trace data).
4. The resDebug bit set to on in the _res structure option field (you must allocate STDOUT or
SYSPRINT to generate trace data).
Next, we illustrate using Trace Resolver in a z/OS UNIX environment, and in a TSO
environment.
Using Trace Resolver in z/OS UNIX environment
Example 2-15 shows how to enable and disable the Trace Resolver in z/OS UNIX
environment.
Example 2-15 Using Trace Resolver in a z/OS UNIX environment
CS06 @ SC30:/u/cs06>export RESOLVER_TRACE=/u/cs06/trace1.txt 1
CS06 @ SC30:/u/cs06>ping router1 2
CS06 @ SC30:/u/cs06>set -A RESOLVER_TRACE 3
CS06 @ SC30:/u/cs06>obrowse /u/cs06/trace1.txt
1. To enable the Trace Resolver, set the RESOLVER_TRACE environment variable. This
command directs the output to the /u/cs06/trace1.txt HFS file. You can also direct the
output to STDOUT by specifying RESOLVER_TRACE=STDOUT. If you want to direct it to a new
MVS data set, specify the following command:
RESOLVER_TRACE="//’SOME.MVS.DATASET’"
2. After enabling a Trace Resolver, perform a z/OS UNIX shell command that invokes a
resolver call.
3. This command disables the Trace Resolver.
Using Trace Resolver in a TSO environment with SYSTCPT DD
Example 2-16 shows how to enable and disable the Trace Resolver in a TSO environment
environment.
Example 2-16 Using Trace Resolver in a TSO environment
alloc dd(systcpt) da(*) 1
ping router1 2
free dd(systcpt) 3

1. To enable the Trace Resolver, allocate a SYSTCPT data set. If you specify da(*), the
Trace Resolver output to a TSO terminal. If you want to direct the output to a specific data
set, specify da(‘SOME.DATASET.NAME’).
2. After enabling the Trace Resolver, perform a TSO command that invokes a Resolver call.
3. To disable theTrace Resolver, free a SYSTCPT data set.
Using Trace Resolver for applications with TCPIP.DATA statements
Allocate STDOUT or SYSPRINT (as a DD statement in the procedure) as an output data set,
and define the statement TRACE RESOLVER or OPTIONS DEBUG in the first line of the
TCPIP.DATA file that is being used by the application, as shown in Example 2-17. Start the
application that invokes a Resolver call.
Example 2-17 Using the OPTIONS DEBUG to get a trace of the resolver
OPTIONS DEBUG 1
TCPIPJOBNAME TCPIPA
HOSTNAME WTSC30A
MESSAGECASE MIXED
NSPORTADDR 53
1. Specify OPTIONS DEBUG or TRACE RESOLVER to enable Trace Resolver.
Displaying the output of the Trace Resolver
Example 2-18 shows the output of the Trace Resolver in the z/OS UNIX environment (which
was taken from Example 2-15 on page 45). Note that the Trace Resolver taken in the TSO
environment (Example 2-16 on page 45) is almost identical.
Example 2-18 Trace Resolver output - z/OS UNIX shell environment
Resolver Trace Initialization Complete -> 2007/09/28 11:31:14.088323
res_init Resolver values:
Global Tcp/Ip Dataset = TCPIPA.TCPPARMS(GLOBAL) 1
Default Tcp/Ip Dataset = TCPIPA.TCPPARMS(DEFAULT)
Local Tcp/Ip Dataset = /etc/resolv.conf 2
Translation Table = Default
UserId/JobName = CS06
Caller API = LE C Sockets
Caller Mode = EBCDIC
(L) DataSetPrefix = TCP
(L) HostName = wtsc30
(L) TcpIpJobName = TCPIP
(G) Search = ITSO.IBM.COM
IBM.COM
(G) NameServer = 10.12.6.7
(G) NsPortAddr = 53 (G) ResolverTimeout = 10
(G) ResolveVia = UDP (G) ResolverUdpRetries = 1
Tip: When directing Trace Resolver output to a TSO terminal, define the screen size to
be only 80 columns wide. Otherwise, trace output is difficult to read.

(*) Options NDots = 1
(*) SockNoTestStor
(*) AlwaysWto = NO (L) MessageCase = MIXED
(G) LookUp = LOCAL DNS 3
res_init Succeeded
res_init Started: 2007/09/28 11:31:14.127535
res_init Ended: 2007/09/28 11:31:14.127540
***************************************************************************
GetAddrInfo Started: 2007/09/28 11:31:14.127575
GetAddrinfo Invoked with following inputs:
Host Name: router1 4
No Service operand specified
Hints parameter supplied with settings:
ai_family = 0, ai_flags = 0x00000062
ai_protocol = 0, ai_socktype = 0
GetAddrInfo Opening Socket for IOCTLs
BPX1SOC: RetVal = 0, RC = 0, Reason = 0x00000000
GetAddrInfo Opened Socket 0x00000004
GetAddrInfo Only IPv4 Interfaces Exist
GetAddrInfo Searching Local Tables for IPv4 Address
Global IpNodes Dataset = TCPIPA.TCPPARMS(IPNODES) 5
Default IpNodes Dataset = None
Search order = CommonSearch
SITETABLE from globalipnodes TCPIPA.TCPPARMS(IPNODES)
- Lookup for router1.ITSO.IBM.COM
- Lookup for router1.IBM.COM
- Lookup for router1 6
ADDRTABLE from globalipnodes TCPIPA.TCPPARMS(IPNODES)
- Lookup for 10.1.2.240 7
GetAddrInfo Returning Zero as Port Number
GetAddrInfo Built 1 Addrinfos
GetAddrInfo Closing IOCTL Socket 0x00000004
BPX1CLO: RetVal = 0, RC = 0, Reason = 0x00000000
GetAddrInfo Succeeded: IP Address(es) found:
IP Address(1) is 10.1.2.240
GetAddrInfo Ended: 2007/09/28 11:31:14.199817
***************************************************************************
FreeAddrInfo Started: 2007/09/28 11:31:14.199862
FreeAddrInfo Called to free addrinfo structures
FreeAddrInfo Succeeded, Freed 1 Addrinfos
FreeAddrInfo Ended: 2007/09/28 11:31:14.199874
***************************************************************************
1. Informs the global TCPIP.DATA in use.
2. Informs the local TCPIP.DATA in use.
3. The local hosts file is looked up first, followed by the DNS server if it fails.
4. router1 host name is looked up.
5. Informs the global ETC.IPNODE in use.
6. router1 entry is looked up in the global ETC.IPNODES file.
7. router1 is resolved to 10.1.2.240.

CTRACE - RESOLVER (SYSTCPRE)
Component Trace (CTRACE) is used for the RESOLVER component (SYSTCPRE) to collect
debug information. The TRACE RESOLVER traces information about a per-application basis
and directs the output to a unique file for each application. The CTRACE shows Resolver
actions for all applications (although it might be filtered).
The CTRACE support allows for JOBNAME, ASID filtering, or both. The trace buffer is located
in the Resolver private storage. The trace buffer minimum size is 128 KB. The maximum size
is 128 MB. The default size is 16 MB. Trace records can optionally be written to an external
writer.
The Resolver CTRACE can be started any time needed by using the TRACE CT command,
or it can be activated during Resolver procedure initialization.
Using CTRACE for RESOLVER
The Resolver CTRACE initialization PARMLIB member can be specified at Resolver start
time. To activate the Resolver CTRACE during resolver initialization, follow these steps:
1. Create a CTWTR procedure in your SYS1.PROCLIB, as shown in Example 2-19.
Example 2-19 CTWTR procedure
//CTWTR PROC
//IEFPROC EXEC PGM=ITTTRCWR
//TRCOUT01 DD DSNAME=CS03.CTRACE1,VOL=SER=COMST2,UNIT=3390,
// SPACE=(CYL,10),DISP=(NEW,KEEP),DSORG=PS
//*
2. Using the sample Resolver procedure shipped with the product, enter the following
console command:
S RESOLV30,PARMS='CTRACE(CTIRESxx)'
Where xx is the suffix of the CTIRESxx PARMLIB member to be used. To customize the
parameters used to initialize the trace, you can update the SYS1.PARMLIB member
CTIRES00, as shown in Example 2-20.
Example 2-20 Trace options
/*********************************************************************/
TRACEOPTS
/* ---------------------------------------------------------------- */
/* Optionally start external writer in this file (use both */
/* WTRSTART and WTR with same wtr_procedure) */
WTRSTART(CTWTR)
/* ---------------------------------------------------------------- */
/* ON OR OFF: PICK 1 */
/* ---------------------------------------------------------------- */
ON
/* OFF */
/* BUFSIZE: A VALUE IN RANGE 128K TO 128M */
BUFSIZE(16M)
/* JOBNAME(jobname1,...) */
/* ASID(Asid1,...) */
WTR(CTWTR)
/* ---------------------------------------------------------------- */

/* OPTIONS: NAMES OF FUNCTIONS TO BE TRACED, OR "ALL" */
/* ---------------------------------------------------------------- */
/* OPTIONS( */
/* 'ALL ' */
/* ,'MINIMUM ' */
/* ) */
3. Use the TRACE CT command to define the options; see Example 2-21.
Example 2-21 TRACE CT command flow
TRACE CT,ON,COMP=SYSTCPRE,SUB=(RESOLV30)
*189 ITT006A SPECIFY OPERAND(S) FOR TRACE CT COMMAND.
R 189,OPTIONS=(ALL),END
IEE600I REPLY TO 189 IS;OPTIONS=(ALL),END
ITT038I ALL OF THE TRANSACTIONS REQUESTED VIA THE TRACE CT COMMAND
WERE SUCCESSFULLY EXECUTED.
IEE839I ST=(ON,0256K,00512K) AS=ON BR=OFF EX=ON MT=(ON,024K) 497
ISSUE DISPLAY TRACE CMD FOR SYSTEM AND COMPONENT TRACE STATUS
ISSUE DISPLAY TRACE,TT CMD FOR TRANSACTION TRACE STATUS
4. Reproduce the problem.
5. Save the trace contents into the trace file created by the CTWRT procedure, executing the
the commands shown in Example 2-22.
Example 2-22 Saving the trace contents
R 190,WTR=DISCONNECT,END
IEE600I REPLY TO 190 IS;WTR=DISCONNECT,END
6. Stop the CTRACE by issuing the command shown in Example 2-23.
Example 2-23 Stopping CTRACE
TRACE CT,OFF,COMP=SYSTCPRE,SUB=(RESOLV30)
After these steps, we will have a trace file to be formatted using the IPCS command:
CTRACE COMP(SYSTCPRE) TALLY

Displaying the CTRACE result
The resulting display will show the Resolver process entries, as shown in Example 2-24.
Example 2-24 Resolver formatted trace entries
COMPONENT TRACE TALLY REPORT
SYSNAME(SC30)
COMP(SYSTCPRE)
TRACE ENTRY COUNTS AND AVERAGE INTERVALS (IN MICROSECONDS)
FMTID COUNT Interval MNEMONIC DESCRIBE
-------- ----------- ------------ -------- --------------------------------
00000001 0 CTRACE CTrace Initialized
00000002 0 CTRACE Status changed or displayed
00000003 0 CTRACE CTrace Terminated
00000004 0 CTRACE !CTrace has abended
00000005 0 CTRACE CTrace Stopped - Buffers Retain
00010001 0 API GetHostByAddr Entry Parameters
00010002 0 API GetHostByAddr Stack Affinity
00010003 0 API GetHostByAddr Failure
00010004 0 API GetHostByAddr Success
00010005 0 API GetHostByAddr GetLocalHostName
00010006 0 API GetHostByName Entry Parameters
00010007 0 API GetHostByName Stack Affinity
00010008 0 API GetHostByName Failure
00010009 0 API GetHostByName Success
For more specific information regarding the Resolver address space, refer to z/OS
Communications Server: IP Configuration Guide, SC31-8775 and z/OS Communications
Server: IP Configuration Reference, SC31-8776.
For more information about Resolver diagnosis, refer to z/OS Communications Server: IP
Diagnosis Guide, GC31-8782.

Chapter 3. Base functions
The term base functions in this case implies the minimum configuration required for the
proper operation of a z/OS TCP/IP environment. The base functions that we describe in this
chapter are considered necessary for any useful deployment of the TCP/IP stack and
commonly used applications.
3
SectioncSectionSection Topic
3.1, “The base functions” on page 52 Basic concepts of base functions
3.2, “Common design scenarios for base
functions” on page 52
Key characteristics of base functions and why they might
be important in your environment
3.3, “z/OS UNIX System Services setup
for TCP/IP” on page 56
Selected implementation scenarios, tasks, configuration
examples, and problem determination suggestions
3.4, “Configuring z/OS TCP/IP” on
page 70
Configuration details for the z/OS TCP/IP environment
3.5, “Implementing the TCP/IP stack” on
page 80
Implementation tasks for the TCP/IP stack
3.6, “Activating the TCP/IP stack” on
page 86
Messages used to verify the accuracy of the current
environment customization data sets used in z/OS UNIX
and TCP/IP initialization
3.7, “Reconfiguring the system with z/OS
commands” on page 101
z/OS commands used to reconfigure the system
3.8, “Job log versus syslog as diagnosis
tool” on page 106
Information about using job log versus syslog when
diagnosing issues
3.9, “Message types: Where to find
them” on page 106
Listing of message types

3.1 The base functions
Base functions are those functions considered to be standard in TCP/IP environments
regardless of the implementation. Base functions establish a functional working environment
that can be exploited by other features, or upon which many other functions can be
implemented or validated. When the base functions are implemented, they exercise the most
commonly used features of a TCP/IP environment, providing an effective way to perform
integrity tests and validate the TCP/IP environment before embarking on the more complex
features, configurations, and implementations of the stack.
Most of these functions are implemented at the lower layers. There are some base functions
that are implemented at the application layer (such as Telnet and FTP). The details of the
standard applications can be found in Communications Server for z/OS V1R9 TCP/IP
Implementation Volume 2: Standard Applications, SG24-7533. Here, we discuss the
configuration that provides the infrastructure of the TCP/IP protocol suite in the z/OS
Communications Server environment.
3.1.1 Basic concepts
The z/OS TCP/IP stack (a TCP/IP instance) is a full functional implementation of the standard
RFC protocols that are fully integrated and tightly coupled between z/OS and UNIX System
Services. It provides the environment that supports the base functions, as well as the many
traditional TCP/IP applications. The two environments that need to be created and
customized to support the z/OS Communications Server for TCP/IP are:
A native z/OS environment in which users can exploit the TCP/IP protocols in a standard
z/OS application environment such as batch jobs (with JES interface), started tasks, TSO,
CICS, and IMS applications.
A z/OS UNIX System Services environment that lets you develop and use applications
and services that conform to the POSIX or XPG4 standards (UNIX specifications). The
z/OS UNIX environment also provides some of the base functions to support the z/OS
environment and vice versa.
Because the z/OS Communications Server exploits z/OS UNIX services even for traditional
z/OS environments and applications, a full-function mode z/OS UNIX environment, including
a Data Facility Storage Management Subsystem (DFSMS), a z/OS UNIX file system, and a
security product (such as Resource Access Control Facility, or RACF), are required before the
z/OS Communications Server can be started successfully and the TCP/IP environment
initialized.
3.2 Common design scenarios for base functions
Because base functions are primarily setting up the primitives in the TCP/IP environment, we
deal with very basic scenarios, which can be built upon at a later time. For the base functions
we consider two scenarios:
Single stack environment
Multiple stack environment
Important: Although there are specialized cases where multiple stacks per LPAR can
provide value, in general we recommend implementing only one TCP/IP stack per LPAR.

Chapter 3. Base functions 53
3.2.1 Single stack environment
A single stack environment refers to the existence of one TCP/IP system address space in a
single z/OS image (LPAR) providing support for the functions and features of the TCP/IP
protocol suite.
Dependencies
In order to achieve a successful implementation of the z/OS Communications Server - TCP/IP
component, we identified certain dependencies, as explained here:
Implement a full-function UNIX System Services system on z/OS. Detailed information
about this topic is available in z/OS UNIX System Services Planning, GA22-7800, and in
and z/OS MVS Initialization and Tuning Reference, SA22-7592. Also refer to z/OS
Program Directory, GI10-0670, which is available at the following address:
http://publibz.boulder.ibm.com/epubs/pdf/i1006707.pdf
Define a RACF environment for the z/OS Communications Server - TCP/IP component.
This includes defining RACF groups to z/OS UNIX groups to manage resources, profiles,
user groups, and user IDs.
An OMVS UID must be defined with UID (0) and assigned to the started task name of the
CS for z/OS IP system address space. Detailed information is available in
Policy-Based Networking, SG24-7535; z/OS Security Server RACF Security
Administrator's Guide, SA22-7683; z/OS Security Server RACF System Programmer's
Guide, SA22-7681; and z/OS Security Server RACF Command Language Reference,
SA22-7687.
Customize SYS1.PARMLIB members with special reference to BPXPRMxx to use the
integrated sockets INET with the AF_INET and AF_INET6 physical file system. Detailed
information is available in z/OS MVS Initialization and Tuning Reference, SA22-7592;
z/OS UNIX System Services Planning, GA22-7800; and z/OS V1R7.0 Program Directory
GI10-0670.
Customize the TCP/IP configuration data sets:
– PROFILE.TCPIP
– TCPIP.DATA
– Other configuration data sets
Fully functional VTAM is required to support the interfaces used by TCP/IP.
Advantages
The advantages of a single stack are:
Fewer CPU cycles are spent processing TCP/IP traffic, because there is only one logical
instance of each physical interface in a single stack environment versus a multiple stack
environment.
Servers use fewer CPU cycles when certain periodic updates arrive (OMPROUTE
processing routing updates). Multiple stacks mean multiple copies of OMPROUTE.
Each stack requires a certain amount of storage, the most significant being virtual storage.
Considerations for a single stack environment
When creating a TCP/IP stack, you need to consider the other requirements upon which the
successful initialization of the stack depends. Very often the initial problems encountered are

related to the omission of tasks that were not performed by other disciplines such as RACF
administration.
CS for z/OS TCP/IP exploits the tightly coupled design of the z/OS Communications Server,
the integration of z/OS and UNIX System Services, and the provision of RACF services.
Coordination is the key to a successful implementation the TCP/IP stack.
3.2.2 Multiple stack environment
A multiple stack environment consists of more than one stack running concurrently in a single
LPAR. These stacks exist independent of each other, with the ability to be uniquely
configured. Each stack can support different features and provide different functions. Each
stack is configured in its own address space, and can communicate with the other stacks in
the LPAR if so desired.
Dependencies
The dependencies for the multiple stack environment are exactly the same as for the single
stack environment, as well as:
Additional storage, especially virtual storage
Additional CPU cycles for processing subsequent interfaces and services performing
periodic functions, such as OMPROUTE routing updates
Advantages
There are advantages for running a multiple stack environment, because it provides you with
the flexibility to partition your networking environment. Here are advantages to consider:
You might want to establish separate stacks to separate workloads based on availability
and security. For example, you might have different requirements for a production stack, a
system test stack, and a secure stack.
This approach could, for example, be used to establish a test TCP/IP stack, where new
socket applications are tested before they are moved into the production system. You
might also want to apply maintenance to a non-production stack so it can be tested before
you apply it to the production stack.
Your strategy might be to separate workload onto multiple stacks based on the functional
characteristics of applications, as with UNIX (OpenEdition) applications and non-UNIX
(z/OS) applications.
You might be running z/OS servers and UNIX (OpenEdition) servers on the same
well-known port (TN3270 and otelnet on port 23). An alternative to this is approach is the
BIND for INADDR_ANY function.
Whatever the reason, the ability to configure multiple stacks and have them fully functional,
independently and concurrently, can be exploited in many different ways.
Considerations for a multiple stack environment
The considerations for a multiple stack environment are primarily the same as they are for a
single stack environment. We therefore indicate here only the differences and the additional
considerations regarding the multiple stack environment.
Sharing Resolver between multiple stacks
The general recommendation is that you use separate DATASETPREFIX values per stack
and create separate copies of configuration data sets or at the very least Resolver data sets.
Refer to “The Resolver in a multiple stack environment” on page 34, for further details.

Selecting the correct configuration data sets
The Resolver needs access to all Resolver data sets if there are multiple stacks in multiple
z/OS LPARs. Refer to Chapter 2, “The Resolver” on page 21, for further details.
TSO clients
TSO client functions can be directed against any number of TCP/IP stacks. Keep in mind,
though, that the client must be able to find the TCPIP.DATA data set appropriate for the stack
of interest. You can modify your TSO logon procedure with a SYSTCPD DD statement, or use
a common TSO logon procedure without the SYSTCPD DD statement and allocate the
TCPIP.DATA data set to the appropriate stack of interest.
Stack affinity
Any server or client needs to reference the appropriate stack if the desired stack is not the
default stack defined in the BPXPRMxx member of SYS1.PARMLIB. Servers can use the
BPXK_SETIBMOPT_TRANSPORT environment variable to override the choice of the default
stack. There might also be applications that have affinity to the wrong stack and do not have
the option of establishing stack affinity. In those instances, you can execute BPXTCAFF prior
to the application execution step. For example:
//AFFINITY EXEC PGM=BPXTCAFF,PARM='TCPIPA'
This assumes TCPIPA is not the default stack.
Port management
When there is a single stack and the relationship of server to stack is 1:1, port management is
relatively simple. Using the PORT statement, the port number can be reserved for the server
in the PROFILE.TCPIP for that given stack.
Port management becomes more complex, however, in an environment where there are
multiple stacks and a potential for multiple combinations of the same server (for example,
UNIX System Services and TN3270). Therefore, in a multiple stack environment, you need to
answer some questions based on the following concepts:
Generic server
A generic server is a server without affinity for a specific stack, and it provides service to
any client on the network. FTP is an example, because the stack is merely a connection
linking client and server. The service File Transfer is not related to the internal functioning
of the stack, and the server can communicate concurrently over any number of stacks.
Servers with an affinity for a specific stack
There must be an explicit binding of the server application to the chosen stack when the
service (for example, UNIX System Services DNS, OSNMP, and ONETSTAT) is related to
the internal functioning of the stack.
This bind is made using the setibmopt() socket call (to specify the chosen stack) or using
the C function _iptcpn(), which allows applications to search in the TCPIP.DATA file to
find the name of a specific stack.
Ephemeral ports
In addition to synchronizing PORT reservations for specific applications across all stacks,
you have to synchronize reservations for port numbers that will be dynamically assigned
across all stacks when running with multiple stacks.
Those ports are called ephemeral ports, which are all above 1024, and are assigned by
the stack when none is specified on the application bind(). Use the PORTRANGE
statement in the PROFILE.TCPIP to reserve a group of ports, and specify the same port
range for every stack. You also need to let CINET know which ports are guaranteed to be

available on every stack, using the BPXPRMxx parmlib member through
INADDRANYPORT and INADDRANYCOUNT statements.
CPU resources
Provisions need to be made for additional CPU cycles and storage (especially virtual
storage). These increases in resources are just for the existence of the additional stacks
running concurrently.
3.2.3 Recommendation
In general, we recommend implementing only one TCP/IP stack per LPAR, for the following
reasons:
throughput.
When running multiple TCP/IP stacks additional system resources, such as memory, CPU
cycles, and storage, are required.
BIND-specific support where the two HTTP server instances are each associated to port
80 with their own IP address, using the BIND option on the PORT reservation statement.
3.2.4 Recommendations for MTU
The maximum transmission unit (MTU) is the largest packet size that can be sent using this
route. If the packet is larger than this size, the packet will have to be fragmented if
fragmentation is permitted. If fragmentation is not permitted, the packet is dropped and an
ICMP error is returned to the originator of the packet. If a route is inactive, the configured
MTU value that was defined using the MTU parameter in the ROUTE statement (or the
default MTU value for the specified interface type) is displayed. If a route is active, then the
actual MTU value is displayed.
For more information about MTU sizes for OSA-Express and HiperSockets, refer to
Communications Server for z/OS V1R9 TCP/IP Implementation Volume 3: High Availability,
Scalability, and Performance, SG24-7534.
3.3 z/OS UNIX System Services setup for TCP/IP
There are several areas that require your attention and action in order to implement a TCP/IP
stack successfully. In Chapter 1, “Introduction to z/OS Communications Server IP” on page 1,
we review the UNIX concepts in the z/OS environment. We make specific references to the
BPXPRMxx member in SYS1.PARMLIB. However, it is important to first understand the
security considerations for the UNIX environment.

3.3.1 RACF actions for UNIX
Security is an important consideration for most z/OS installations, and there are a few
features we need to mention here for the base functions of any TCP/IP environment. TCP/IP
has some built-in internal security mechanisms, and it relies on the services of a security
manager, such as the IBM Resource Access Control Facility (RACF).
A security manager is a requirement in the Communications Server for z/OS IP environment.
As an online application, it is important that TCP/IP undergo security checks to eliminate
possible security exposures. Some basic security concepts are included in the following
sections, but for a more detailed explanation refer to Communications Server for z/OS V1R9
TCP/IP Implementation Volume 4: Security and Policy-Based Networking, SG24-7535.
RACF environment
RACF is very flexible and can be set up and tailored to meet almost all security requirements
of large enterprises. All RACF implementations are based on the following key elements:
User IDs
Groups
RACF resources
RACF profiles
RACF facility classes
The hierarchical owner principle, which is applicable for all RACF definitions of user IDs,
groups, and RACF resources
RACF implementation
Each unit of work in the z/OS system that requires UNIX System Services must be
associated with a valid UNIX System Services identity. A valid identity refers to the presence
of a valid UNIX user ID (UID) and a valid UNIX group ID (GID) for each such user. The UID
and the GID are defined through the OMVS segment in the user’s RACF user profile and in
the group’s RACF group profile.
Each functional RACF access group must be authorized to access a specific TCP/IP RACF
resource with a specific access attribute. The details of this process are discussed in
Policy-Based Networking, SG24-7535.
Assigning user IDs to started tasks
In some cases, the user ID and started task must be associated with the UNIX superuser. In
other cases, you can associate the user ID and started task with the default user.
RACF offers you two techniques to assign user IDs and group IDs to started tasks:
The started procedure name table (ICHRIN03)
The RACF STARTED resource profiles
By using the STARTED resources, you can add new started tasks to RACF, and
immediately make those new definitions active.
IEF695I START T03DNS WITH JOBNAME T03DNS IS ASSIGNED TO USER TCPIP3, GROUP
OMVSGRP
The user ID and default group must be defined in RACF, which then treats the user ID as any
other RACF user ID for its resource access checking. RACF allows multiple started procedure

names to be assigned to the same RACF user ID. We used this method to assign RACF user
IDs to all TCP/IP started tasks.
Started task user IDs
The UNIX System Services tasks OMVS and BPXOINIT need to execute in an z/OS system
space and have the special user ID OMVSKERN assigned to them. OMVSKERN has to be
defined as superuser with UID 0, program /bin/sh, and home directory.
TCP/IP tasks need RACF user IDs with the OMVS segment defined. The user ID associated
with the main TCP/IP address space must be defined as a superuser; the requirements for
the individual servers vary, but most need to be a superuser as well.
z/OS VARY TCPIP commands
Access to VARY TCPIP commands can be controlled by RACF. This places restrictions on
this command, which can be used to alter and disrupt the TCP/IP environment.
NETSTAT command
Access to the TSO NETSTAT command, the UNIX shell command onetstat, and command
options can be controlled by RACF, by defining NETSTAT resources to the RACF generic
class SERVAUTH. This command might also need to be restricted, because it can be used to
alter or drop connections or to stop the TN3270 server.
Establish RACF security environment
The notes that follow are merely an overview of the steps in the process. Consult the
instructions in z/OS Security Server RACF Callable Services, SA22-7691, to accomplish
these tasks.
1. Defining commands for CS for z/OS IP in the RACF OPERCMDS class.
2. Establishing a group ID for a default OMVS group segment:
ADDGROUP OEDFLTG OMVS(GID(9999))
3. Defining a user ID for a default OMVS group segment:
RDEFINE FACILITY BPX.DEFAULT.USER APPLDATA('OEDFLTU/OEDFLTG')
ADDUSER OEDFLTU DFLTGRP(OEDFLTG) NAME('OE DEFAULT USER') PASSWORD(xg18ej)
OMVS(UID(999999) HOME('/') PROGRAM('/bin/sh'))
4. Activating or refreshing appropriate facility classes:
SETROPTS CLASSACT(FACILITY)
SETROPTS RACLIST(FACILITY)
SETROPTS RACLIST(FACILITY) REFRESH
5. Defining one or more superuser IDs to be associated with certain UNIX System Services
users and TCP/IP started tasks:
ADDGROUP OMVSGRP OMVS(GID(1))
ADDUSER TCPIP3 DFLTGRP(OMVSGRP) OMVS(UID(0) HOME('/') PROGRAM('/bin/sh'))
6. Defining other UNIX System Services users.
You might already have defined RACF groups and users. If this is the case, you can set up
a z/OS UNIX file system home directory for each user and add an OMVS identity by
altering the group to include a GID (ALTGROUP). Then, using the ISHELL utility, add OE
segments for UNIX System Services users (associating them with the altered group and
giving each user a distinct UID).

Otherwise, you will have to perform these tasks in a more painstaking manner, for
example:
ADDGROUP usergrp OMVS(GID(10))
ADDUSER user01 DFLTGRP(usrgrp) OMVS(UID(20) HOME('/u/user01')
PROGRAM('/bin/sh/'))
More information about RACF with z/OS Communications Server TCP/IP
RACF can be used to protect many TCP/IP resources, such as the TCP/IP stack itself and
ports. Further information about securing your TCP/IP implementation can be found in
Policy-Based Networking, SG24-7535.
3.3.2 APF authorization
The TCP/IP system program libraries must be APF authorized. Authorized Program Facility
(APF) means that z/OS built-in security can be bypassed by programs that are executed from
such libraries. CS for z/OS IP data sets have to be protected with RACF. Special attention has
to be given to the APF authorized libraries defined in PROGxx.
We used the LNKAUTH=LNKLST specification in SYSx.PARMLIB member IEASYSxx, which
means that all libraries in the LNKLST concatenation will be APF authorized. If these libraries
are accessed through STEPLIB or JOBLIB, they will not be APF authorized unless they have
been specifically defined in the IEAAPFxx or PROGxx member.
SEZALOAD is one library that must be made part of your LNKLST concatenation. Because of
the LNKAUTH=LNKLST specification, it will be APF authorized when it is accessed through
the LNKLST concatenation. The SEZALOAD library holds the TCP/IP system code used by
both servers and clients.
In addition to the LNKLST libraries, there are libraries that are not accessed through the
LNKLST concatenation, but have to be APF authorized. The SEZATCP library holds the
TCP/IP system code used by servers. This library is normally placed in the STEPLIB or
JOBLIB concatenation, which is part of the server JCL.
The following libraries might have to be APF authorized, depending on the choices that you
make during the installation of z/OS:
SEZALPA This library holds the TCP/IP modules that must be made part of your
system’s LPA. If you choose to add the library name to your LPALSTxx
member in SYSx.PARMLIB, you also have to make sure the library is
APF authorized. If you copy the load modules in the library to an
existing LPALSTxx data set, you do not need to authorize the
SEZALPA data set.
SEZADSIL This library holds the load modules used by the SNMP command
processor running in the NetView® address space. If you choose to
concatenate this library to STEPLIB in the NetView address space,
you might have to APF authorize it, if other libraries in the
concatenation are already APF authorized.

Every APF-authorized online application might have to be reviewed to ensure that it matches
the security standards of the installation. A program is a “well-behaved program” if:
Logged-on users cannot access or modify system resources for which they are not
authorized.
The program does not require any special credentials to be able to execute.
Or, in the case of RACF, the program does not need the RACF authorization attribute
OPERATIONS for execution.
3.3.3 Changes to SYS1.PARMLIB members
As we noted, the z/OS environment consists of the traditional MVS and UNIX Systems
Services environment. Because the UNIX Systems Services environment is implemented
within a z/OS system space, there are definitions in the z/OS environment upon which the
UNIX Systems Services environment depends.
SYS1.PARMLIB is the single most important data set in the z/OS environment. It contains
most of the parameters that define z/OS as well as many other subsystems. The
SYS1.PARMLIB data set definition parameters are critical to the proper initialization and
functioning of UNIX Systems Services and, therefore, to the TCP/IP implementation. Some of
the members of interest include:
IEASYS00
BPXPRMxx
Integrated Sockets PFS definitions
IEASYS00
Because the z/OS Communications Server exploits z/OS UNIX services even for traditional
MVS environments and applications, a full-function mode z/OS UNIX environment, including
a Data Facility Storage Management Subsystem (DFSMS) and z/OS File Systems (including
z/OS UNIX file system) is required before the z/OS Communications Server can be started
and the TCP/IP environment successfully established.
The IEASYS00 parmlib definitions we used that are relevant to TCP/IP are:
OMVS=7A,
SMS=00,
OMVS=7A specifies that BPXPRM7A is used to configure the z/OS UNIX environment at
system initialization time. SMS=00 specifies that IGDSMS00 is to be used for definitions of
the Data Facility Storage Management Subsystem at z/OS UNIX initialization time.
BPXPRMxx
All the parameters defined in BPXPRMxx should be reviewed and tailored to individual
installation specification and resource utilization. z/OS UNIX System Services Planning,
GA22-7800, and z/OS MVS Initialization and Tuning Guide, SA22-7591, explain the details
and significance of each parameter in the BPXPRMxx member.
z/OS UNIX System Services Planning, GA22-7800; z/OS UNIX System Services User's
Guide, SA22-7802; and z/OS Program Directory, GI10-0670, detail the structure, design,
installation, and implementation of the z/OS UNIX environment.
Note: User IDs with the RACF attribute OPERATIONS have ALTER access to all data
sets in the system. The access authority to single data sets can be specifically lowered
or excluded.

z/OS Program Directory, GI10-0670, is available at the following address:
http://publibz.boulder.ibm.com/epubs/pdf/i1006707.pdf
Concepts such as Logical and Physical File Systems (PFS) are design components of z/OS
UNIX and are not discussed here.
Integrated Sockets PFS definitions
We need to define the desired file systems to support the communication provided by the
stack. Example 3-1 illustrates how support for IPv4 and IPv6 (dual mode) is defined for a
single stack environment.
Specifying NETWORK definitions for both AF_NET and AF_INET6 provides dual support. If
IPv6 support is not desired, then you can omit the NETWORK DOMIAINNAME(AF_INET6)
statement and subsequent parameters.
Example 3-1 BPXPRMxx definitions for a single stack supporting dual mode
FILESYSTYPE TYPE(UDS)
ENTRYPOINT(BPXTUINT)
NETWORK DOMAINNAME(AF_UNIX)
DOMAINNUMBER(1)
MAXSOCKETS(10000)
TYPE(UDS)
/* IPv4 support
NETWORK DOMAINNAME(AF_INET) 1
DOMAINNUMBER(2)
MAXSOCKETS(25000)
TYPE(INET) 2
INADDRANYPORT(10000)
INADDRANYCOUNT(2000)
FILESYSTYPE TYPE(INET) 2
ENTRYPOINT(EZBPFINI) 3
/* IPv6 support
NETWORK DOMAINNAME(AF_INET6) 4
DOMAINNUMBER(19)
TYPE(INET)
INET specifies a single stack with TCP/IP (by default) as the stack name. In this example, the
numbers correspond to the following information:
1. AF_INET specifies IPv4 support for the physical file type for socket address used by this
stack (TCP/IP).
2. Specify TYPE(INET) for a single stack environment. If you specify INET, you cannot start
multiple TCP/IP stacks.
3. EZBPFINI identifies a TCP/IP stack (this is the only valid value).
4. AF_INET6 specifies IPv6 support for the physical file type for socket address used by this
stack (TCP/IP).
Example 3-2 shows BPXPRMxx definitions for a multiple stack environment.

Example 3-2 BPXPRMxx definitions for a multiple stack supporting dual mode
FILESYSTYPE TYPE(UDS) ENTRYPOINT(BPXTUINT)
NETWORK DOMAINNAME(AF_UNIX)
DOMAINNUMBER(1)
MAXSOCKETS(10000)
TYPE(UDS)
FILESYSTYPE TYPE(CINET)
ENTRYPOINT(BPXTCINT)
NETWORK DOMAINNAME(AF_INET) 1
DOMAINNUMBER(2)
MAXSOCKETS(10000)
TYPE(CINET) 2
INADDRANYPORT(10000)
INADDRANYCOUNT(2000)
NETWORK DOMAINNAME(AF_INET6) 3
DOMAINNUMBER(19)
MAXSOCKETS(10000)
TYPE(CINET)
SUBFILESYSTYPE NAME(TCPIPA) 4
TYPE(CINET) 2
DEFAULT
SUBFILESYSTYPE NAME(TCPIPB) 4
TYPE(CINET) 2
.....
1. AF_INET specifies IPv4 support for the physical file type for socket address used by this
stack (TCP/IP).
2. Specify TYPE(CINET) for a single stack environment. If you specify INET, you cannot start
3. AF_INET6 specifies IPv6 support for the physical file type for socket address used by this
stack (TCP/IP).
4. Specify the name of TCP/IP stack you want to configure.
5. EZBPFINI identifies a TCP/IP stack (this is the only valid value).
Additional SYS1.PARMLIB updates
The updates are:
1. LNKLSTxx
Add the following CS for z/OS IP link libraries to the z/OS system link list:
– hlq.SEZALOAD
– hlq.SEZALNK2
2. LPALSTxx
Add the following CS for z/OS IP LPA modules to the LPA during IPL of z/OS:
– hlq.SEZALPA

3. PROGnn or IEAAPFxx
Add the following TCP/IP libraries for APF authorization:
– hlq.SEZATCP
– hlq.SEZADSIL
– hlq.SEZALOAD
– hlq.SEZALNK2
– hlq.SEZALPA
– SYS1.MIGLIB
4. IEFSSNxx
TNF and VMCF are required for CS for z/OS IP. Add the subsystem definitions for the
MVS address spaces of TNF and VMCF as follows:
– If you choose to use restartable VMCF and TNF:
• TNF
• VMCF
– If you will not be using restartable VMCF and TNF:
• TNF,MVPTSSI
• VMCF,MVPXSSI,nodename
Set the nodename to the MVS NJE node name of this MVS system. It is defined in the
JES2 parameter member of SYSx.PARMLIB:
NJEDEF ....
OWNNODE=03,
....
N03 NAME=SC30,SNA,NETAUTH
Before you make this update, make sure that the hlq.SEZALOAD definition has been
added to LNKLSTxx and the library itself has been APF authorized. z/OS initializes the
address spaces of the TNF and VMCF subsystems during IPL as part of the master
scheduler initialization.
5. SCHEDxx
You need to specify certain CS for z/OS IP modules as privileged modules in MVS. The
following entries are present in the IBM-supplied program properties table (PPT); however,
if your installation has a customized version of the PPT, ensure these entries are present:
– For CS for z/OS IP:
PPT PGMNAME(EZBTCPIP) KEY(6) NOCANCEL PRIV NOSWAP SYST LPREF SPREF
– If you use restartable VMCF and TNF:
PPT PGMNAME(MVPTNF) KEY(0) NOCANCEL NOSWAP PRIV SYST
PPT PGMNAME(MVPXVMCF) KEY(0) NOCANCEL NOSWAP PRIV SYST
Note: hlq.SEZALPA must be cataloged into the MVS master catalog.
hlq.SEZALOAD and hlq.SEZALNK2 can be cataloged into the MVS master catalog.
You can omit them from the MVS master catalog if you identify them to include a
volume specification as in:
TCPIP.SEZALOAD(WTLTCP),
TCPIP.SEZALNK2(WTLTCP)
If the three data sets mentioned were renamed during the installation process, then
use these names instead.

– For NPF:
PPT PGMNAME(EZAPPFS) KEY(1) NOSWAP
PPT PGMNAME(EZAPPAAA) NOSWAP
– For SNALINK:
PPT PGMNAME(SNALINK) KEY(6) NOSWAP SYST
6. COMMNDxx
VMCF and TNF are required for CS for z/OS IP. If you use restartable VMCF and TNF,
procedure EZAZSSI must be run during your IPL sequence (EZAZSSI starts VMCF and
TNF).
Either use your operation's automation software to start EZAZSSI, or add a command to
your COMMNDxx member in SYSx.PARMLIB:
COM='S EZAZSSI,P=your_node_name'
The value of variable P defaults to the value of the MVS symbolic &SYSNAME. If your
node name is the same as the value of &SYSNAME, then you can use the following
command instead:
COM='S EZAZSSI'
When the EZAZSSI address space starts, a series of messages is written to the MVS log
indicating the status of VMCF and TNF. Then, the EZAZSSI address space terminates.
After VMCF and TNF initialize successfully, you can start your TCP/IP system address
spaces.
7. IKJTSOxx
You also need to specify CS for z/OS IP modules as authorized for TSO commands.
Update the IKJTSOxx member by adding the following to the AUTHCMD section:
MVPXDISP, NETSTAT, TRACERTE, RSH, LPQ, LPR, and LPRM.
8. IEASYSxx
Review your CSA and SQA specifications and verify that the numbers allocated are
sufficiently large enough to prevent getmain errors.
IEASYSxx: CSA(3000,250M)
IEASYSxx: SQA(8,448)
9. IVTPRMxx
Review the computed CSM requirements to reflect ACF/VTAM and CS for z/OS IP usage:
– IVTPRMxx: FIXED MAX(120M)
– IVTPRMxx: ECSA MAX(120M)
10.CTIEZBxx
Copy CTIEZB00 to SYSx.PARMLIB from hlq.SEZAINST for use with CTRACE.
This member can be customized to include a different size buffer. The default buffer size is
8 MB. This should be increased to 32 MB to allow the capture of debugging information.
We made a new member, CTIEZB01, with the buffer size change.
For more information about the use of component tracing (CTRACE), refer to z/OS CS: IP
Diagnosis, GC31-8782.and z/OS CS: IP Migration, GC31-8773. Also see Chapter 8,
“Diagnosis” on page 239.

11.BPXPRMxx
In addition to defining the UNIX Physical File Systems, you must ensure that the ports
enabled on the system are consistent with what is defined in the PROFILE.TCPIP data
set, as shown in Example 3-3.
Example 3-3 BPXPRMxx member with port range provided by a single stack environment
/* IPv4 support
NETWORK DOMAINNAME(AF_INET)
DOMAINNUMBER(2)
MAXSOCKETS(25000)
TYPE(INET)
INADDRANYPORT(10000) 8
INADDRANYCOUNT(2000) 8
* IPv6 support
NETWORK DOMAINNAME(AF_INET6)
DOMAINNUMBER(19)
TYPE(INET)
Ensure that the INADDRANYPORT 8 assignment does not conflict with PORT
assignments in the TCPIP.PROFILE data set.
Review the values specified in BPXPRMxx for MAXPROCSYS, MAXPROCUSER,
MAXUIDS, MAXFILEPROC, MAXPTYS, MAXTHREADTASKS, and MAXTHREADS.
12.IFAPRDxx or PROGxx
Use these to add product and feature information in a z/OS environment.
3.3.4 Changes to SYS1.PROCLIB members
This section explains changes that you can make to incorporate the new TCP/IP functions.
TCP/IP JCL procedures
If you choose to use restartable VMCF and TNF, add procedure EZAZSSI:
//EZAZSSI PROC P=''
//STARTVT EXEC PGM=EZAZSSI,PARM=&P
//STEPLIB DD DSN=hlq.SEZATCP,DISP=SHR
Update your TCP/IP startup JCL procedure. The sample for the CS for z/OS IP procedure is
in hlq.SEZAINST(TCPIPROC).
TSO logon procedures
Update your TSO logon procedures by adding the TCP/IP help data set SYS1.HELP to the
//SYSHELP DD concatenation. Optionally, add the //SYSTCPD DD statement to your logon
procedures.
Add hlq.SEZAMENU to the //ISPMLIB DD concatenation and hlq.SEZAPENU to the
//ISPPLIB DD and the //ISPTLIB DD concatenations.
Note: The OpenEdition ENTRYPOINT for CS for z/OS IP is EZBPFINI. If you have
the incorrect value in BPXPRMxx member, you might see messages such as
EZZ4203I or abend codes such as S806.

3.3.5 Additional z/OS customization for UNIX System Services
Updating the MVS system libraries must be done with great care. Follow the instructions in
z/OS Program Directory, Program Number 5694-A01, GI10-0670, and check the PSP bucket
to ensure that all required PTFs and modifications are done as required. You might need to
make changes to some or all of the following members, depending on the features you are
installing.
3.3.6 TCP/IP server functions
Each CS for z/OS IP server relies on the use of a security manager such as RACF. Several
servers provide some built-in security functions for additional security. These servers are
described in Communications Server for z/OS V1R9 TCP/IP Implementation Volume 2:
Standard Applications, SG24-7533.
3.3.7 TCP/IP client functions
The client functions of Communications Server for z/OS IP are executed in a TSO
environment or a UNIX shell environment. Some functions are also available in other
environments, such as batch or started task address spaces.
Any TSO user can execute any TCP/IP command and use a TCP/IP client function to access
any other TCP/IP server host through the attached TCP/IP network. If these TCP/IP servers
have not implemented adequate password protection, then any TSO client user can log on to
these servers and access all data.
3.3.8 UNIX client functions
Certain client functions executed from the UNIX shell environment require superuser
authority. The user ID accessing the shell must have an OMVS segment associated with it.
RACF considerations for UNIX Client functions in CS for z/OS IP are covered in detail in
Applications, SG24-7533, and Communications Server for z/OS V1R9 TCP/IP
Implementation Volume 4: Security and Policy-Based Networking, SG24-7535.
Common errors implementing UNIX System Services
In this section, we discuss implementation problems frequently encountered.
Superuser mode
Certain commands and operations from OMVS or from the ISHELL are authorized only for
superusers. There are two alternatives for running as a superuser:
The user ID can have permanent superuser status.
This means that the ID has been created with a UID value of zero (0). TCP/IP started
tasks and some of its servers are also defined with a UID of zero.
The user ID can have temporary authority for the superuser tasks.
The defined UID will have been set up as a non-zero value in RACF, but the user will have
been granted READ access to the RACF facility class of BPX.SUPERUSER. Also, RACF
provides superuser granularity enhancements to assign functions to users that need them.
If you need only temporary authority to enter superuser mode, then granting simple READ
permission to the BPX.SUPERUSER facility class will allow the user to switch back and forth

between superuser mode and standard mode. You can enter su from the OMVS shell, or you
can select SETUP OPTIONS from the ISHELL and specify Option #7 to obtain superuser
mode.
The user is then authorized to enter commands authorized for the superuser function from the
ISHELL, or switch to an OMVS shell the user has already signed onto. The basic prompt
level, indicated by the dollar sign ($) prompt, is changed when in superuser mode to a pound
sign (#). The exit command takes the user out of superuser mode as well as the OMVS
(UNIX) shell. Use of the whoami command shows the change of user IDs.
Problems with the home directory
In Figure 3-1, the TSO user attempted unsuccessfully to enter the OMVS shell interface from
ISPF. The user has an OMVS segment defined but another problem occurs. The user entered
the TSO OMVS command to enter the UNIX environment and received the response shown
in Figure 3-1.
Figure 3-1 Error executing the TSO OMVS command
This error occurred because the home directory that is associated with the user is not defined
or authorized in to the OMVS segment. You can determine the home directory with the RACF
listuser command (if you have the RACF authorization to use the command). However, you
still have access to the z/OS file, even though the message was displayed.
A similar problem occurs when trying to access the ISHELL environment, as shown in
Figure 3-2.
Figure 3-2 Error executing in the ISHELL
In both cases, the user had an OMVS segment defined in RACF. However, the home directory
that was associated with the user in the user’s OMVS segment was not defined or authorized.
(You can determine the home directory with the RACF listuser command.) Authorization is
provided with the permission bits.
The same symptom shows up for users without an OMVS segment defined if the
BPX.DEFAULTUSER facility has been activated with an inaccessible home directory.
UNIX permission bits
You have already read something about setting up appropriate UNIX permission bits.
Figure 3-3 shows an example of incorrect permission bits set for a user.
Figure 3-3 Error with UNIX permission bit settings
FSUM2078I No session was started. The home directory for this TSO/E
user does not exist or cannot be accessed, +
FSUM2079I Function = sigprocmask, return value = FFFFFFFF, return code
code = 9C reason code = 0507014D
Errno=9Cx Process Initialization error; Reason=0507014D The dub failed
due to an error with the initial home directory. Press Enter to continue.
ICH408I USER(CS01 ) GROUP(WTCRES ) NAME(CS RESIDENT ) 703
/u/CS01 CL(DIRSRCH) FID(01E2D7D3C5E7F34E2B0F000000000003)
INSUFFICIENT AUTHORITY TO LOOKUP
ACCESSINTENT(--X) ACCESS ALLOWED(OTHER ---)
ICH408I USER(CS01 ) GROUP(WTCRES ) NAME(CS RESIDENT ) 704

In this case, although the user has the UNIX permission bit settings of 755 on the /u/cs01/
directory, the permission bits are set at 600 for the /u/ directory. Thus, you must ensure that all
directories in the entire path are authorized with suitable permission bits. After the settings
are changed to 755 for the /u/ directory, access to the subdirectory is allowed.
You can display UNIX permission bits from the ISHELL environment or by issuing the ls -alF
command from the shell.
The ls -alF options indicate that all files should be listed (including hidden files), that the long
format should be displayed, and that the flags about the type of file (link, directory, and so on)
should be given.
Default search path and symbolic links
The directory search path is specified in the environment variable $PATH. Normally this
environment variable is set system-wide in the /etc/profile and can be further customized for
individual users in $home/.profile. The sample for /etc/profile sets $PATH to:
/bin:.
It should be expanded to:
/bin:/usr/sbin:.
or (depending on whether you want the current directory searched first or last):
.:/bin:/usr/sbin
The instructions for setting up this user profile are contained in z/OS UNIX System Services
User’s Guide, SA22-7801, and z/OS UNIX System Services Planning, SA22-7800.
A user might attempt to run a simple TCP/IP command, such as oping, and receive an error
that the command is not found, as shown in Figure 3-4.
Figure 3-4 Command not found error
In this case you must preface the command with the directory path necessary to locate it:
/usr/lpp/tcpip/bin/oping
If you experience such a problem, check that the symbolic links are correct. Part of the
installation is to run the UNIX MKDIR program to set up the symbolic links for the various
commands and programs from their real path to /bin or /usr/sbin, where they can be found
using the default search path.
Note: To view the search path that has been established for you, issue echo $PATH from
the shell environment.
BROWSE -- /tmp/cs01
Command ===>
********************************* Top of Data ***
oping: FSUM7351 not found

3.3.9 Verification checklist
The following checklist can help ensure that all z/OS and UNIX Systems Services related
setup tasks are complete for the base functions:
1. Have TNF and VMCF initialized successfully?
Check the console log for a successful start of EZAZSSI, TNF, VMCF.
2. Has the TCP/IP feature of z/OS been enabled or registered in IFAPRDxx?
3. Has a full-function OMVS (DFSMS, RACF, zFS) started successfully?
– Is OMVS active when you issue D OMVS?
– Is SMS active when you issue D SMS?
– Have z/OS UNIX file systems been mounted? Verify with D OMVS,F.
– Is RACF enabled on the system?
4. Have the definitions in BPXPRMxx of SYS1.PARMLIB been made to reflect:
– The correct stack for the stack (or stacks) you will be running?
– The support for dual-mode is defined to support IPv4 and IPv6 (AF_INET and
AF_INET6)?
– The correct CS for z/OS IP proc names?
– The correct use of INET versus CINET?
– The correct ENTRYPOINT name for Communications Server for z/OS IP versus earlier
versions of OE function in TCP/IP (z/OS IP ENTRYPOINT = EZBPFINI)?
– The mounting of file systems for users? (You can verify with D OMVS,F.)
– Appropriate values for MAXPROCSYS, MAXPROCUSER, MAXUIDS,
MAXFILEPROC, MAXPTYS, MAXTHREADTASKS, and MAXTHREADS?
5. Have z/OS UNIX file systems and directories been created and mounted for the users of
the system?
6. Have RACF definitions been put in place? For example:
– OMVS user IDs and group IDs for your CS for z/OS IP procedures
– OMVS user IDs and group IDs for your other users, for superusers, for a default user,
with definitions for appropriate Facility classes, like BPX.SUPERUSER
– TCP/IP VARY commands
– NETSTAT commands
7. Have you placed the correct definitions in the z/OS data sets? For example:
SYSx.LNKLSTxx
SYSx.LPALSTxx
SYSx.SCHEDxx
SYSx.PROGxx
SYSx.IEASYSxx
SYSx.IEFSSNxx
SYSx.IKJTSOxx
SYSx.IVTPRMxx
8. Raw sockets require authorization; they run from SEZALOAD and are usually already
authorized. If you have moved applications and functions to another library (which is not
recommended), ensure that this library is authorized.
9. The loopback address is now 127.0.0.1 for IPv4 and ::1 for IPv6. However, If you require
14.0.0.0, have you added this to the HOME list?

10.Have you computed CSA requirements to include not only ACF/VTAM, but also CS for
z/OS IP?
– IEASYSxx: CSA(3000,250M) (need to review)
– IEASYSxx: SQA(8,448) (need to review)
11.Have you computed CSM requirements to include not only ACF/VTAM, but also CS for
z/OS IP?
– IVTPRMxx: FIXED MAX(120M)
– IVTPRMxx: ECSA MAX(120M)
12.Have you modified the CTRACE initialization member (CTIEZB00) to reflect 32 MB of
buffer storage?
13.Have you created CTRACE Writer procedures for taking traces?
14.Have you updated your TCP/IP procedure?
15.Have you updated your other procedures, for example, the FTP server procedure?
16.Have you revamped your TCP/IP Profile to use the new statements and to comment out
the old?
– Have you made provisions to address device connections that are no longer
supported?
– Have you investigated all your connections to ensure to what extent they are still
supported? (In some cases, definitions will have changed.)
17.Have your applications that relied on VMCF and IUCV sockets been converted now that
those APIs are no longer supported?
18.If you are migrating from a previous release, have you reviewed the Planning and
Migration checklist in z/OS CS: IP Migration, GC31-8773, and made appropriate plans to
use the sample data sets?
19.Have you reviewed the list and location of configuration data set samples in z/OS
Communications Server: IP Configuration Reference, SC31-8776?
3.4 Configuring z/OS TCP/IP
A z/OS TCP/IP environment can be very complex. It is controlled using a large variety of
settings, including parmlib members, and /etc files for UNIX System Services. Each of these
has a different interface and requires special knowledge to configure.
z/OS Communications Server IP continues to be enhanced with new features,
enhancements, and defaults. So if you are migrating from a previous release, consult with the
migration guide for your particular release from which you are migrating. For further details,
refer to z/OS Communications Server: New Function Summary, GC31-8771.
3.4.1 TCP/IP configuration data set names
This topic is described in z/OS CS: IP Configuration Guide, SC31-8775. We strongly
recommend that you read the information about data set names in this book, before you
decide on your data set naming conventions.
The purpose here is to give an introduction to the data set naming and allocation techniques
that z/OS Communications Server uses. If you choose, you can allocate some of the

configuration data sets either implicitly or explicitly. In addition, you need to ensure that both
the MVS and the z/OS UNIX functions can find the data sets.
Implicit allocation
The name of the configuration data set is resolved at runtime based on a set of rules (the
search order) implemented in the various components of TCP/IP. When a data set name
has been resolved, the TCP/IP component uses the dynamic allocation services of MVS
or of UNIX System Services to allocate that configuration data set. See z/OS CS: IP
Configuration Guide, SC31-8775, for details.
These are some of the data sets (or files) that can only be implicitly allocated in an z/OS
Communications Server IP:
hlq.ETC.PROTO
hlq.ETC.RPC
hlq.HOSTS.ADDRINFO
hlq.HOSTS.SITEINFO
hlq.SRVRFTP.TCPCHBIN
hlq.SRVRFTP.TCPHGBIN
hlq.SRVRFTP.TCPKJBIN
hlq.SRVRFTP.TCPSCBIN
hlq.SRVRFTP.TCPXLBIN
hlq.STANDARD.TCPCHBIN
hlq.STANDARD.TCPHGBIN
hlq.STANDARD.TCPKJBIN
hlq.STANDARD.TCPSCBIN
hlq.STANDARD.TCPXLBIN
In these data set names, hlq is determined using the following search sequence:
– User ID or jobname
– DATASETPREFIX value (or its default of TCP/IP), defined in TCPIP.DATA
Dynamically allocated data sets can include a mid-level qualifier (MLQ), for example, a
node name, or a function name.
– For data sets containing a PROFILE configuration file:
xxxx.nodename.zzzz
– For data sets containing a translate table used by a particular TCP/IP server:
xxxx.function_name.zzzz (for the FTP server the function_name is SRVRFTP)
Data set SYS1.TCPPARMS(TCPDATA) can be dynamically allocated if it contains the
TCPIP.DATA configuration file.
Explicit allocation
For some of the configuration files, you can tell TCP/IP which files to use by coding DD
statements in JCL procedures, or by setting UNIX environment variables. The various data
sets used by TCP/IP functions and their resolution method are described in z/OS CS: IP
Configuration Guide, SC31-8775.
3.4.2 PROFILE.TCPIP
Before you start your TCP/IP stack, you must configure the operational and address space
characteristics. These definitions are defined in the configuration data set which is often
called PROFILE.TCPIP. The PROFILE.TCPIP data set is read by the TCP/IP address space
during initialization.

The PROFILE data set contains the following major groups of TCP/IP configuration
parameters:
Operating characteristics
Port number definitions
Network interface definitions
Network routing definitions
A sample PROFILE.TCPIP configuration file is provided in hlq.SEZAINST(SAMPPROF).
You can find detailed information about TCP/IP connectivity and routing definitions in
Chapter 4, “Connectivity” on page 109, and Chapter 5, “Routing” on page 153, respectively.
PROFILE.TCPIP statements
In this section we show some essential statements for configuring TCP/IP stack.
The syntax for the parameters in the PROFILE can be found in z/OS Communications Server:
IP Configuration Reference, SC31-8776. Additional profile statements and descriptions are
available in “PROFILE.TCPIP statements” on page 322.
Most PROFILE parameters required in a basic configuration have default values that will allow
the stack to be initialized and ready for operation. There are, however, a few parameters that
must be modified or must be unique to the stack.
Appendix D, “Our implementation environment” on page 357, describes the environment we
used to create this book.
DEVICE and LINK
Use DEVICE and LINK statements to define the physical or virtual interfaces, such as OSA,
HiperSockets, and VIPA. z/OS Communications Server can define multiple interfaces. You
need to define a pair of DEVICE and LINK statements for each interface you want to
configure for a TCP/IP stack.
Each device type has a different set of parameters that you can define. For details on each
device type and its definition, refer to Chapter 4, “Connectivity” on page 109.
The following is an example of DEVICE and LINK statements for defining one OSA in QDIO
mode.
DEVICE OSA20A0 MPCIPA
LINK OSA20A0I IPAQENET OSA20A0
The following is an example of DEVICE and LINK statements for defining one VIPA.
DEVICE VIPA1 VIRTUAL 0
LINK VIPA1L VIRTUAL 0 VIPA1
INTERFACE
The INTERFACE statement defines all IPv6 interfaces and is enhanced to define IPv4
IPAQENET devices. This statement combines the definitions of the DEVICE, LINK, and
HOME into a single statement for IPv4 and IPv6.
Note: You can instead define IPv4 OSA-Express devices (IPQAENET) with the
INTERFACE statement. We recommend this approach, as described in “INTERFACE” on
page 72.

The INTERFACE statement is set to reference the PORTNAME that is defined in the QDIO
TRLE definition statement as per DEVICE and LINK definitions and assigns an IP address to
it using the IPADDR operand, according to the HOME definition. Optional operands include
subnetmask settings using the /subnetmask bit number value in the IPADDR statement and
MTU size with the BEGINROTES or BSDROUTINGPARMS and SOURCEVIPAINT
statements, which associates a specific VIPA with this INTARFACE only.
You can define the VLANID and VMAC with the LINK statement, with the additional benefit
that you can use the INTERFACE statement to set multiple VLANs on the same OSA port.
You cannot, however, define multiple VLANs on the same OSA port with the LINK statement.
The devices that are defined through the INTERFACE statement return different displays than
devices that are defined through the DEVICE/LINK statements. See examples in Appendix B,
“INTERFACE statement” on page 333.
Example 3-4 shows a sample definition of the INTERFACE statement.
Example 3-4 INTERFACE statement in profile TCP/IP for IPv4 IPAQENET devices
INTERFACE OSA20A0I
DEFINE IPAQENET
PORTNAME OSA20A0
IPADDR 10.1.2.12/24
MTU 1492
VLANID 20
VMAC
SOURCEVIPAINT VIPA2L
You can delete a previously defined interface from the stack, after you stop it, with the
INTERFACE DELETE command using the OBEYFILE command, as shown in Example 3-5.
Example 3-5 INTERFACE delete statement
INTERFACE OSA20A0I
DELETE
More examples and displays are available in Appendix B, “INTERFACE statement” on
page 333.
Refer to z/OS Communications Server: IP Configuration Guide, SC31-8775, and z/OS
Communications Server: IP Configuration Reference, SC31-8776, for further details.
HOME
The HOME statement is used for assigning an IP address for each interface you defined with
DEVICE and LINK statements. The following is an example of a HOME statement.
HOME
10.1.1.10 VIPA1L
10.1.2.12 OSA20A0I
Note: If SOURCEVIPAINT is coded, you define the entire INTERFACE definition block in
PROFILE after the VIPA DEVICE and LINK statements are defined.
Note: The HOME statement (along with DEVICE and LINK) is mutually exclusive from the
INTERFACE statement. You must use one or the other. We recommend that you use
INTERFACE, as described in “INTERFACE” on page 72.

The TCP/IP stack uses an IP address of 127.0.0.1 for IPv4 and ::1 for IPv6 as the loopback
interfaces. If there is a requirement to represent the loopback IP address of 14.0.0.0 for
compatibility with earlier TCP/IP versions, you must code an entry in the HOME statement.
The link label specified is LOOPBACK and you can define multiple IP addresses with the
LOOPBACK interface. For example:
HOME
14.0.0.0 LOOPBACK
You can display the HOME IP address defined in a particular TCP/IP stack with a
D TCPIP,procname,Netstat HOME command, as shown in Example 3-6. You can also use the
z/OS UNIX shell command onetstat -h. There is an additional field, called the Flag field, that
indicates which interface is the primary interface. The primary interface is the first entry in the
HOME list in the PROFILE.TCPIP definitions unless the PRIMARYINTERFACE parameter is
specified.
The PRIMARYINTERFACE statement can be used to specify which link is to be designated
as the default local host address for the GETHOSTID() function.
Example 3-6 Netstat home display
D TCPIP,TCPIPA,N,HO
EZD0101I NETSTAT CS V1R10 TCPIPA 676
HOME ADDRESS LIST:
LINKNAME: VIPA1L
ADDRESS: 10.1.1.10
FLAGS: PRIMARY
LINKNAME: VIPA2L
ADDRESS: 10.1.2.10
FLAGS:
LINKNAME: IUTIQDF4L
ADDRESS: 10.1.4.11
FLAGS:
LINKNAME: IUTIQDF5L
ADDRESS: 10.1.5.11
FLAGS:
LINKNAME: IUTIQDF6L
ADDRESS: 10.1.6.11
FLAGS:
LINKNAME: EZASAMEMVS
ADDRESS: 10.1.7.11
FLAGS:
LINKNAME: IQDIOLNK0A01070B
ADDRESS: 10.1.7.11
FLAGS:
LINKNAME: VIPL0A01080A
ADDRESS: 10.1.8.10
FLAGS:
LINKNAME: LOOPBACK
ADDRESS: 127.0.0.1
FLAGS:
INTFNAME: OSA2080I
ADDRESS: 10.1.2.11
FLAGS:
INTFNAME: OSA20A0I
ADDRESS: 10.1.2.12
FLAGS:

INTFNAME: OSA20C0I
ADDRESS: 10.1.3.11
FLAGS:
INTFNAME: OSA20E0I
ADDRESS: 10.1.3.12
FLAGS:
INTFNAME: LOOPBACK6
ADDRESS: ::1
TYPE: LOOPBACK
FLAGS:
14 OF 14 RECORDS DISPLAYED
END OF THE REPORT
BEGINROUTES
Use this statement to define static routes for TCP/IP routing table. This statement is optional
when you use OMPROUTE dynamic routing daemon. However, if you do not configure
OMPROUTE dynamic routing daemon, BEGINROUTES is necessary for a TCP/IP stack to
communicate with other hosts. For details on static and dynamic routing, refer to Chapter 5,
“Routing” on page 153.
VIPADYNAMIC
This statement is not always necessary. Use this statement to define dynamic VIPA or the
functions related to dynamic VIPA, such as sysplex distributor and dynamic VIPA takeover.
Refer to Communications Server for z/OS V1R9 TCP/IP Implementation Volume 3: High
Availability, Scalability, and Performance, SG24-7534, for details about high availability and
load balancing functions using dynamic VIPA.
AUTOLOG
The procedures specified in AUTOLOG statement are initialized at TCP/IP startup, so you do
not have to start the TCP/IP applications manually after the TCP/IP startup. AUTOLOG also
monitors procedures started under its auspices, and will restart a procedure that terminates
for any reason unless NOAUTOLOG is specified on the PORT statement.
For UNIX servers, some special rules apply;
If the procedure name on the AUTOLOG statement is eight characters long, no jobname
needs be specified.
If the procedure name on the AUTOLOG statement is less than eight characters long and
the job spawns listener threads with different names, you might have to specify the
JOBNAME parameter and ensure that the jobname matches that coded on the PORT
statement. In the following example, jobname FTPDE1 on the PORT statement matches
JOBNAME on the AUTOLOG statement:
PORT
20 TCP * NOAUTOLOG ;OMVS
21 TCP FTPDA1 ;Contol Port
AUTOLOG 1
FTPDA JOBNAME FTPDA1 ; FTP Server
ENDAUTOLOG
START
Specify a device name on a START statement to initialize the interface at the TCP/IP stack
startup. The following is an example of START statement for an OSA and a HiperSockets
device. VIPA does not need to be started because it is virtual and always active.

If you do not specify a device name on a START statement, you can initialize the device with
the TCPIP,procname,START,devicename command after the TCP/IP stack startup.
START OSA20A0
START IUTIQDF4
IPCONFIG
IPv4 features are defined within IPCONFIG. There is a separate configuration section for IPv6
parameters. Refer to “PROFILE.TCPIP statements” on page 322 for commonly used
IPCONFIG statements.
TCPCONFIG
TCP features are defined within TCPCONFIG. Refer to “PROFILE.TCPIP statements” on
page 322 for commonly used TCPCONFIG statements.
UDPCONFIG
UDP features are defined within UDPCONFIG. Refer to “PROFILE.TCPIP statements” on
page 322 for commonly used UDPCONFIG statements.
GLOBALCONFIG
GLOBALCONFIG statement defines the parameters that are affective to the entire TCP/IP
stack. Refer to “PROFILE.TCPIP statements” on page 322 for commonly used
GLOBALCONFIG statements.
IPCONFIG6
All IPv6 features are defined within IPCONFIG6.
Locating PROFILE.TCPIP
The following search order is used to locate the PROFILE.TCPIP configuration file:
1. //PROFILE DD
//PROFILE DD DSN=TCPIPA.TCPPARMS(PROFA30)
2. jobname.nodename.TCPIP
3. hlq.nodename.TCPIP
4. jobname.PROFILE.TCPIP
5. hlq.PROFILE.TCPIP
The PROFILE must exist. Otherwise, the TCP/IP address space will terminate abnormally
with the following message:
EZZ0332I DD:PROFILE NOT FOUND. CONTINUING PROFILE SEARCH
EZZ0325I INITIAL PROFILE COULD NOT BE FOUND
We recommend using the //PROFILE DD statement in the TCP/IP address space JCL
procedure to explicitly allocate the PROFILE data set.
3.4.3 VTAM Resource
As mentioned in the introduction, VTAM provides the Data Link Control layer (Layer 2 of the
OSI model) for TCP/IP, including support of the Multi-Path Channel (MPC) interfaces. MPC
protocols are used to define the DLC layer for OSA-Express devices in QDIO.

OSA-Express QDIO connections are configured through a TRLE definition. All TRLEs are
defined as VTAM major nodes. For further information about MPC-related devices/interfaces
refer to Chapter 4, “Connectivity” on page 109.
A TRLE definition we used for our OSA-Express in QDIO mode is shown in Example 3-7.
Example 3-7 TRLE VTAM major node definition for device OSA2080
OSA2080 VBUILD TYPE=TRL
OSA2080P TRLE LNCTL=MPC, *
READ=2080, *
WRITE=2081, *
DATAPATH=(2082-2087), *
PORTNAME=OSA2080, 1 *
MPCLEVEL=QDIO
Because VTAM provides the DLC layer for TCP/IP, then VTAM must be started before TCP/IP.
The major node (in our case, OSA2080) should be activated when VTAM is initializing. This
will ensure the TRLE is active when the TCP/IP stack is started. This is accomplished by
placing an entry for OSA2080 in the VTAM startup list ATCCONxx. The portname 1
(Example 3-7) must also be the same as the device name defined in PROFILE.TCPIP data
set on the DEVICE and LINK statements.
This definition can be used for OSA-Express, OSA-Express 2 and OSA-Express 3 using only
port 0.
With OSA-Express 3, you can use both ports on the same TRL statement as shown in
Example 3-8.
Example 3-8 TRL VTAM majnode definition for two ports for device OSA2080
READ=2080, *
WRITE=2081, *
DATAPATH=(2082-2087), *
PORTNAME=OSA2080, *
PORTNUM=0, *
MPCLEVEL=QDIO
READ=2088, *
WRITE=2089, *
DATAPATH=(208A-208D), *
PORTNAME=OSA2081, *
PORTNUM=1, *
MPCLEVEL=QDIO
3.4.4 TCPIP.DATA
The Resolver configuration file is often called TCPIP.DATA. The TCPIP.DATA configuration
data set is the anchor configuration data set for the TCP/IP stack and all TCP/IP servers and
clients running on that stack.
The TCPIP.DATA configuration data set is read during initialization of all TCP/IP server and
client functions. TCPIP.DATA contains the configuration for the Resolver address space. We
define the way name-to-address or address-to-name resolution is performed by the Resolver.

TCPIP.DATA is also used by the TCP/IP applications to specify the TCP/IP stack it establishes
an affinity with. The associated TCP/IP stack name is specified with TCPIPJOBNAME
statement. Other stack-specific statements are HOSTNAME, which is the host name of the
TCP/IP stack, and DATASETPREFIX, which is the data set prefix (hlq) to be used for
searching a configuration data set.
The syntax for the parameters in the TCPIP.DATA file can be found in z/OS Communications
Server: IP Configuration Guide, SC31-8775. A sample TCPIP.DATA configuration file is
provided in hlq.SEZAINST(TCPDATA). You can define the TCPIP.DATA parameters in an
MVS data set or z/OS UNIX file system file.
For further information about TCPIP.DATA file and the Resolver address space, refer to
Chapter 2, “The Resolver” on page 21.
Testing TCPIP.DATA
HOMETEST is a TSO command that you can use to test active and current TCPIP.DATA
specifications. The HOMETEST command is meant to be issued only from TSO; therefore, it
uses the native MVS search order when locating configuration data sets and it uses Resolver
for doing name to IP address resolutions. Example 3-9 shows the output of this command.
Example 3-9 TCPIP.DATA with HOMETEST
EZA0619I Running IBM MVS TCP/IP CS V1R10 TCP/IP Configuration Tester
Resolver Trace Initialization Complete -> 2007/10/03 14:07:33.438588
res_init Resolver values:
Global Tcp/Ip Dataset = SYS1.TCPPARMS(GLBLDATA)
Default Tcp/Ip Dataset = TCPIPA.TCPPARMS(DEFAULT)
Local Tcp/Ip Dataset = //DD:SYSTCPD
==> TCPIPA.TCPPARMS(DATAA30)
Translation Table = TCPIPA.STANDARD.TCPXLBIN
UserId/JobName = CS03
Caller API = TCP/IP Pascal Sockets
Caller Mode = EBCDIC
(L) DataSetPrefix = TCPIPA
(L) HostName = WTSC30A
(L) TcpIpJobName = TCPIPA
(G) Search = ITSO.IBM.COM
IBM.COM
(G) NameServer = 10.12.6.7
(G) NsPortAddr = 53 (G) ResolverTimeout = 10
(G) ResolveVia = UDP (G) ResolverUdpRetries = 1
(L) Options NDots = 1
(L) Trace Resolver (*) SockNoTestStor
(*) AlwaysWto = NO (L) MessageCase = MIXED
(G) LookUp = LOCAL DNS
res_init Succeeded
res_init Started: 2007/10/03 14:07:33.469946
res_init Ended: 2007/10/03 14:07:33.469952
GetHostByName Started: 2007/10/03 14:08:14.952365
GetHostByName Resolving Name: WTSC30A
GetHostByName Trying Local Tables
Global IpNodes Dataset = TCPIPA.TCPPARMS(IPNODES)
Default IpNodes Dataset = None
Search order = CommonSearch
SITETABLE from globalipnodes TCPIPA.TCPPARMS(IPNODES)

- Lookup for WTSC30A.ITSO.IBM.COM
- Lookup for WTSC30A.IBM.COM
- Lookup for WTSC30A
ADDRTABLE from globalipnodes TCPIPA.TCPPARMS(IPNODES)
- Lookup for 10.1.1.10
GetHostByName Succeeded: IP Address(es) found:
IP Address(1) is 10.1.1.10
GetHostByName Ended: 2007/10/03 14:08:14.986069
***************************************************************************
EZA0611I The following IP addresses correspond to TCP Host Name: WTSC30A
EZA0612I 10.1.1.10
EZA0614I The following IP addresses are the HOME IP addresses defined in PROFIL
.TCPIP:
EZA0615I 10.1.30.10
EZA0615I 10.1.1.10
EZA0615I 10.1.2.10
EZA0615I 10.1.2.11
EZA0615I 10.1.3.11
EZA0615I 10.1.3.12
EZA0615I 10.1.2.12
EZA0615I 10.1.4.11
EZA0615I 10.1.5.11
EZA0615I 10.1.6.11
EZA0615I 10.1.7.11
EZA0615I 10.1.7.11
EZA0615I 10.1.8.10
EZA0615I 10.1.8.20
EZA0615I 127.0.0.1
EZA0618I All IP addresses for WTSC30A are in the HOME list!
EZA0622I Hometest was successful - all Tests Passed!
3.4.5 Configuring the local hosts file
You can set up the local hosts file to support local host name resolution. If you use only the
local hosts file for this purpose, your sockets applications will only be able to resolve names
and IP addresses that appear in your local hosts file.
If you need to resolve host names outside your local area, you can configure the Resolver to
use a domain name server (see the NSINTERADDR or NAMESERVER statement in the
TCPIP.DATA configuration file). A domain name server can be used in conjunction with the
local hosts file. If you have configured your Resolver to use a name server, it will always try to
do so, unless your applications were written with a RESOLVE_VIA_LOOKUP symbol in the
source code.
Refer to Chapter 2, “The Resolver” on page 21 for further explanation and details.

3.5 Implementing the TCP/IP stack
In this scenario we create a TCP/IP stack by the name of TCPIPA on the SC30 system (LPAR
A23). We define four OSAs and three HiperSockets interfaces and static routing. Figure 3-5
illustrates the OSA2080 and OSA20A0 pair connecting to the same VLAN using two different
OSA-Express features. The same applies to the OSA20C0 and OSA20E0 pair. We also
defined a dynamic XCF connection, which in our environment can use either a Coupling
Facility link or HiperSockets (CHPID F7).
Figure 3-5 Network diagram
To implement the TCP/IP stack to support base functions, perform the following steps:
1. Create a TCPIP.DATA file.
2. Create a PROFILE.TCPIP file.
3. Check BPXPRMxx.
4. Create a TCP/IP cataloged procedure.
5. Add RACF definitions.
6. Create a VTAM TRL major node for MP CIPA OSA.
Allocate the TCPPARMS library to be used for explicitly allocated configuration data sets for
the stack, or create a new member in your existing TCPPARMS library. For example, we
allocated TCPIPA.TCPPARMS(DATAA30).
HiperSockets CHPID F4 Devices E800-E81F IPADDR 10.1.4.x1
HiperSockets CHPID F6 Devices EA00-EA1F IPADDR 10.1.6.x1
HiperSockets CHPID F7 Devices EB00-EB1F (DYNAMICXCF) IPADDR 10.1.7.x1
TRUNK MODETRUNK MODE
A23 (SC30)
TCPIPA
PROFA30 (dynamic routes)
PROFAS30 (static routes)
VIPA3L 10.1.30.10/24
VIPA1L 10.1.1.10/24
VIPA2L 10.1.2.10/24
OSA2080I 10.1.2.11/24
OSA20A0I 10.1.2.12/24
OSA20C0I 10.1.3.11/24
OSA20E0I 10.1.3.12/24
IUTIQDF4L 10.1.4.11/24
IUTIQDF5L 10.1.5.11/24
IUTIQDF6L 10.1.6.11/24
XCF 10.1.7.11/24
VIPADEFINE 10.1.8.10/24
VIPARANGE 10.1.9.0/24
(10.1.9.10-19)
TCPIPB
PROFB31 (dynamic routes)
PROFBS31 (static routes)
VIPA3L 10.31.0.10/24
VIPA1L 10.1.1.20/24
VIPA2L 10.1.2.20/24
OSA2080I 10.1.2.21/24
OSA20A0I 10.1.2.22/24
OSA20C0I 10.1.3.21/24
OSA20E0I 10.1.3.22/24
IUTIQDF4L 10.1.4.21/24
IUTIQDF5L 10.1.5.21/24
IUTIQDF6L 10.1.6.21/24
XCF 10.1.7.21/24
(10.1.9.20-29)
A24 (SC31) A25 (SC32)
TCPIPC
PROFC32 (dynamic routes)
PROFCS32 (static routes)
VIPA1L 10.1.1.30/24
VIPA2L 10.1.2.30/24
OSA2080I 10.1.2.31/24
OSA20A0I 10.1.2.32/24
OSA20C0I 10.1.3.31/24
OSA20E0I 10.1.3.32/24
IUTIQDF4L 10.1.4.31/24
IUTIQDF5L 10.1.5.31/24
IUTIQDF6L 10.1.6.31/24
XCF 10.1.7.31/24
(10.1.9.20-29)
A29 (SC33)
TCPIPD
PROFD33 (dynamic routes)
PROFDS33 (static routes)
VIPA1L 10.1.1.40/24
VIPA2L 10.1.2.40/24
OSA2080I 10.1.2.41/24
OSA20A0I 10.1.2.42/24
OSA20C0I 10.1.3.41/24
OSA20E0I 10.1.3.42/24
IUTIQDF4L 10.1.4.41/24
IUTIQDF5L 10.1.5.41/24
IUTIQDF6L 10.1.6.41/24
XCF 10.1.7.41/24
(10.1.9.40-49)
VLAN 10
10.1.2.240
VLAN 11
10.1.3.240
OSA-Express 1000BASE-T
TRUNK MODE TRUNK MODE
SWITCH
CHPID 02
OSA2080
10.1.2.x1
2080-208F
CHPID 03
OSA20A0
10.1.2.x2
20A0-20AF
CHPID 04
OSA20C0
10.1.3.x1
20C0-20CF
CHPID 05
OSA20E0
10.1.3.x2
20E0-2E0F
XCF
10.1.7.x1

3.5.1 Create TCPIP.DATA file
We defined a global TCPIP.DATA and a local TCPIP.DATA for TCPIPA, as shown in
Example 3-10 and Example 3-11.
; *****************************************
; *****************************************
SEARCH ITSO.IBM.COM IBM.COM
DATASETPREFIX TCPIP
MESSAGECASE MIXED
NSPORTADDR 53
RESOLVEVIA UDP
RESOLVERTIMEOUT 10
LOOKUP LOCAL
We created a local TCPIP.DATA file for the TCPIPA stack.
Example 3-11 local TCPIP.DATA file
; *****************************************
; *****************************************
HOSTNAME WTSC30A 2
MESSAGECASE MIXED
1. Specifies the procedure name of TCPIPA stack.
2. Specifies the host name of the TCPIPA stack.
Update the Domain Name Server
If you are using a domain name server, ensure that it is updated with your new host name and
address.
Update the local hosts file
If you are not using a domain name server, edit your global ETC.IPNODES file or the local
ETC.IPNODES file and add your new host name and address.
3.5.2 Create the PROFILE.TCPIP file
We created a TCP/IP profile and included the statements described in this section.
INTERFACE statement
We configured two OSA-Express3 features, each having four ports. We configured only two
ports on each card with the INTERFACE statement. For redundancy we defined two VLANs,

with each pair using one port per feature and each pair attached to the same VLAN. This
facilitates ARP Takeover.
DEVICE and LINK statement
We defined HiperSockets and VIPA devices with the DEVICE and LINK statements, and the
others with the INTERFACE statement.
HOME statement
We assigned a IP address for each interface that was configured with a DEVICE/LINK
statement pair.
BEGINROUTES statement
We defined static routes with BEGINROUTES statement to route a traffic to other hosts on a
network using the OSA-Express or HiperSockets interfaces.
PORT statement
We reserved TCP ports for some applications with PORT statement
START statement
We defined a START statement to initialize the interfaces at the TCP/IP stack startup.
DYNAMICXCF statement
We defined a DYNAMICXCF statement to dynamically define the device to join the sysplex.
Example 3-12 shows a sample PROFILE.TCPIP file.
Example 3-12 PROFILE.TCPIP file
; *****************************************
; TCPIPA.TCPPARMS(PROFA30S)
; *****************************************
ARPAGE 20
;
GLOBALCONFIG NOTCPIPSTATISTICS
;
IPCONFIG DATAGRAMFWD SYSPLEXROUTING
;
DYNAMICXCF 10.1.7.11 255.255.255.0 1
;
SOMAXCONN 10
;
TCPCONFIG TCPSENDBFRSIZE 64K TCPRCVBUFRSIZE 64K SENDGARBAGE FALSE
TCPCONFIG TCPMAXRCVBUFRSIZE 256K
TCPCONFIG UNRESTRICTLOWPORTS
;
UDPCONFIG UNRESTRICTLOWPORTS
;
;INTERFACE OSA20x0I DEFINE IPAQENET (OSA-E) PORTNAME OSA20x0
;TRL MAJ NODE: OSA2080,OSA20A0,OSA20C0,AND OSA20E0
;
INTERFACE OSA2080I
DEFINE IPAQENET
PORTNAME OSA2080
IPADDR 10.1.2.11/24

VLANID 10
VMAC
;
INTERFACE OSA20A0I
DEFINE IPAQENET
PORTNAME OSA20A0
IPADDR 10.1.2.12/24
VLANID 10
VMAC
;
INTERFACE OSA20C0I
DEFINE IPAQENET
PORTNAME OSA20C0
IPADDR 10.1.3.11/24
VLANID 11
VMAC
;
INTERFACE OSA20E0I
DEFINE IPAQENET
PORTNAME OSA20E0
IPADDR 10.1.3.12/24
VLANID 11
VMAC
;
;HIPERSOCKETS DEFINITIONS
DEVICE IUTIQDF4 MPCIPA
LINK IUTIQDF4L IPAQIDIO IUTIQDF4
;
;STATIC VIPA DEFINITIONS
;
HOME
10.1.1.10 VIPA1L
10.1.2.10 VIPA2L
10.1.4.11 IUTIQDF4L
10.1.5.11 IUTIQDF5L
10.1.6.11 IUTIQDF6L
BEGINRoutes
; Direct Routes - Routes that are directly connected to my interfaces
; Destination Subnet Mask First Hop Link Name Packet Size
ROUTE 10.1.2.0/24 = OSA2080I MTU 1492
ROUTE 10.1.3.0/24 = OSA20C0I MTU 1492
ROUTE 10.1.3.0/24 = OSA20E0I MTU 1492
ROUTE 10.1.4.0/24 = IUTIQDF4L MTU 8192
;

PORT
20 TCP OMVS NOAUTOLOG ; FTP Server
21 TCP FTPDA1 ; control port
23 TCP TN3270A BIND 10.1.9.11 ; OE Telnet Server
500 UDP IKED ; @ADI
520 UDP OMPROUTE NOAUTOLOG ; OMPROUTE RIPV2 port
521 UDP OMPROUTE NOAUTOLOG ; OMPROUTE RIPV2 port
4500 UDP IKED ; @AD
514 UDP OMVS ; UNIX SyslogD Server 3
;
START OSA2080I
START OSA20C0I
START OSA20E0I
START OSA20A0I
START IUTIQDF4
START IUTIQDF5
START IUTIQDF6
3.5.3 Check BPXPRMxx
Refer to SYS1.PARMLIB(BPXPRMxx) and make sure you have your TCP/IP stack name
defined in it. If you do not have the stack name in BPXPRMxx, refer to 3.3.3, “Changes to
SYS1.PARMLIB members” on page 60.
3.5.4 Create TCP/IP cataloged procedure
We created a cataloged procedure for TCPIPA stack, as shown in Example 3-13.
Example 3-13 Address space JCL procedure (SC30)
//TCPIPA PROC PARMS='CTRACE(CTIEZB00),IDS=00',
// PROFILE=PROFA&SYSCLONE,TCPDATA=DATAA&SYSCLONE 1
// PARM=('&PARMS',
// 'ENVAR("RESOLVER_CONFIG=//''TCPIPA.TCPPARMS(&TCPDATA)''")')
//PROFILE DD DISP=SHR,DSN=TCPIPA.TCPPARMS(&PROFILE.)
//SYSTCPD DD DSN=TCPIPA.TCPPARMS(&TCPDATA.),DISP=SHR 2
1. Illustrates the use of SYSTEM SYMBOLS.
2. SYSTCPD DD statement pointing to TCPIPA.TCPPARMS(DATAA30).

3.5.5 Add RACF definitions
The RACF administrator needs to add RACF definitions to assign started task user IDs to
new address spaces, as shown in Example 3-14.
Example 3-14 Defining TCPIP*.* procedure to started task
ADDGROUP TCPGRP OMVS(UID(100))
ADDUSER TCPIP DFLTGRP(TCPGRP) OMVS(UID(0) HOME(/) PROGRAM(/bin/sh)) NOPASSWORD
SETROPTS GENERIC(STARTED)
SETROPTS CLASSACT(STARTED) RACLIST(STARTED)
DEFINE STARTED TCPIP*.* STDATA(USER(TCPIP) GROUP(TCPGRP))
SETROPTS RACLIST(STARTED) REFRESH
3.5.6 Create a VTAM TRL major node for MPCIPA OSA
We defined our TRLEs in VTAM. Remember to include it in the VTAM startup list in
ATCCONxx. Example 3-15 and Example 3-16 are sample TRL major nodes for one OSA
device. We then created TRLEs for all OSA devices.
Example 3-15 displays the TRLE VTAM major node definition for device OSA2080.
Example 3-15 TRLE VTAM major node definition for device OSA2080
READ=2080, *
WRITE=2081, *
DATAPATH=(2082-2087), *
PORTNAME=OSA2080, *
PORTNUM=0, *
MPCLEVEL=QDIO
READ=2088, *
WRITE=2089, *
DATAPATH=(208A-208D), *
PORTNAME=OSA2081, *
PORTNUM=1, *
MPCLEVEL=QDIO
Example 3-16 displays the TRLE’s VTAM major node definitions for devices OSA20A0 and
OSA20A1.
Example 3-16 TRLE VTAM major node definition for device OSA20A0
OSA20A0 VBUILD TYPE=TRL
OSA20A0P TRLE LNCTL=MPC, *
READ=20A0, *
WRITE=20A1, *
DATAPATH=(20A2-20A7), *
PORTNAME=OSA20A0, *
PORTNUM=0, *
MPCLEVEL=QDIO
*
READ=20A8, *

WRITE=20A9, *
DATAPATH=(20AA-20AE), *
PORTNAME=OSA20A1, *
PORTNUM=1, *
MPCLEVEL=QDIO
3.6 Activating the TCP/IP stack
If you IPL your z/OS system with PARMLIB definitions similar to our environment, you should
get messages similar to those shown in Example 3-17. These are some of the messages that
can be used to verify the accuracy of the current environment customization data sets used in
z/OS UNIX and TCP/IP initialization.
Note that messages issued by z/OS UNIX begin with the prefix BPX.
Example 3-17 IPL and start TCPIPA
/* IPL and start of TCPIPA
IEE252I MEMBER BPXPRM1A FOUND IN SYS1.PARMLIB 1
CEE3739I LANGUAGE ENVIRONMENT INITIALIZATION COMPLETE 2
IEE252I MEMBER CTIEZB00 FOUND IN SYS1.IBM.PARMLIB
IEE252I MEMBER CTIIDS00 FOUND IN SYS1.IBM.PARMLIB
IEE252I MEMBER CTINTA00 FOUND IN SYS1.PARMLIB
/*
EZZ4202I Z/OS UNIX - TCP/IP CONNECTION ESTABLISHED FOR TCPIPA
BPXF206I ROUTING INFORMATION FOR TRANSPORT DRIVER TCPIPA HAS BEEN 3
INITIALIZED OR UPDATED.
/*
EZZ4313I INITIALIZATION COMPLETE FOR DEVICE OSA2080
EZZ4313I INITIALIZATION COMPLETE FOR DEVICE OSA20C0
EZZ4313I INITIALIZATION COMPLETE FOR DEVICE OSA20E0
EZZ4340I INITIALIZATION COMPLETE FOR INTERFACE OSA20A0I
EZZ4340I INITIALIZATION COMPLETE FOR INTERFACE OSA20A0X
EZB6473I TCP/IP STACK FUNCTIONS INITIALIZATION COMPLETE.
EZZ4313I INITIALIZATION COMPLETE FOR DEVICE IUTIQDF5
EZB6473I TCP/IP STACK FUNCTIONS INITIALIZATION COMPLETE. 5
EZAIN11I ALL TCPIP SERVICES FOR PROC TCPIPA ARE AVAILABLE.
/*
EZBH006E GLOBALCONFIG SYSPLEXMONITOR RECOVERY was not specified when
IPCONFIG DYNAMICXCF or IPCONFIG6 DYNAMICXCF was configured.
/*
EZD1176I TCPIPA HAS SUCCESSFULLY JOINED THE TCP/IP SYSPLEX GROUP 4
EZBTCPCS
EZD1214I INITIAL DYNAMIC VIPA PROCESSING HAS COMPLETED FOR TCPIPA
EZZ4313I INITIALIZATION COMPLETE FOR DEVICE IUTIQDIO
/*
Note: If server-specific configuration data sets can be explicitly allocated using DD
statements, we recommend that you create the configuration data set as a member in the
stack-specific TCPPARMS library. If the data set has to be implicitly allocated, remember to
create it with the stack-specific data set prefix.

1. The first important message indicates whether the correct UNIX customization data set is
used. In our environment it is BPXPRM1A. This contains the root system upon which all
other file systems are mounted, and it is critical for the current establishment of the correct
UNIX Systems Services environment.
The next set of messages shows the initialization of SMS. SMS is a critical component,
because the zFSs are SMS-managed. Note that the file systems are mounted subsequently
starting with the root.
2. This message indicates that the LE environment is available to be exploited by TCP/IP
Lotus®, WebSphere®, and parts of the z/OS base, as well as by languages such as
C/C++, COBOL, and others.
The next set of messages indicates the successful establishment of the physical file system
and availability for socket services for both IPv4 and IPv6. The Resolver messages indicate
that the resolver process is available to support network resolution, which can be critical to
some applications. Note that the initialization of the Resolver is completed before TCP/IP.
3. The following two messages indicate the successful initialization of the UNIX Systems
Services environment and TCP/IP services according to the BPXPRMxx definitions.
4. Our environment is defined within a sysplex; therefore, message EZD1176I indicates the
connectivity to other active TCP/IP stacks within the sysplex.
Initialization of devices must be completed before they achieve READY status (displayed
using the NETSTAT DEVLNKS) and connected to the network.
5. The EZB6473I and EZAIN11I messages are the final initialization messages to complete
the successful initialization of the TCP/IP stack.
3.6.1 UNIX System Services verification
A few commands can be used to perform a simple verification of the z/OS UNIX environment
after an maintenance IPL; for example, D SMS verifies that the system is running a functional
SMS environment, as shown in Example 3-18.
Example 3-18 Output of D SMS command
RESPONSE=SC30
IGD002I 14:16:14 DISPLAY SMS 490
SCDS = SYS1.SMS.SCDS
ACDS = SYS1.SMS.ACDS
COMMDS = SYS1.SMS.COMMDS
DINTERVAL = 150
REVERIFY = NO
ACSDEFAULTS = NO
SYSTEM CONFIGURATION LEVEL INTERVAL SECONDS
SC30 2008/10/27 14:16:12 10
SC31 2008/10/27 14:16:06 10
SC32 2008/10/27 14:16:11 10
SC33 2008/10/27 14:16:07 10
WTSCPLX5 ---------- -------- N/A

Example 3-19 shows the output from the SMS display that supports four different LPARs. The
captured information pertains to SC30, SC31, SC32 and SC33.
Example 3-19 Displaying the OMVS system that is running
D OMVS,ASID=ALL
BPXO040I 14.18.45 DISPLAY OMVS 493
OMVS 000F ACTIVE OMVS=(1A) 1
USER JOBNAME ASID PID PPID STATE START CT_SECS
OMVSKERN BPXOINIT 0040 1 0 MRI--- 13.21.44 1.966 2
LATCHWAITPID= 0 CMD=BPXPINPR
SERVER=Init Process AF= 0 MF=00000 TYPE=FILE
IBMUSER CEA 0018 33619971 1 1F---P 13.21.51 .034
LATCHWAITPID= 0 CMD=CEAPSRVR
IBMUSER HZSPROC 002B 16842756 1 1R---B 13.21.51 7.777
LATCHWAITPID= 0 CMD=HZSTKSCH
NET NET 001D 50397189 1 1F---P 13.21.47 85.210
LATCHWAITPID= 0 CMD=ISTMGCEH
TCPIP NFSCLNT 0023 50397190 1 1R---- 13.21.51 2.667
LATCHWAITPID= 0 CMD=BPXVCLNY
OMVSKERN SYSLOGDA 0044 65543 1 1F---- 13.21.46 1.284
LATCHWAITPID= 0 CMD=/usr/sbin/syslogd -c -i -u -f
RMF RMFGAT 0048 65545 1 1R---P 13.21.49 1314.997
LATCHWAITPID= 0 CMD=ERB3GMFC
TCPIP TCPIP 0047 65546 1 MF---B 13.21.49 71.050
LATCHWAITPID= 0 CMD=EZBTCPIP
TCPIP TCPIP 0047 16842763 1 1F---B 13.21.51 71.050
LATCHWAITPID= 0 CMD=EZACFALG
TCPIP TCPIP 0047 65548 1 1F---B 13.21.51 71.050 3
LATCHWAITPID= 0 CMD=EZASASUB
TCPIP NFSCLNT 0023 33619981 1 1A---- 13.21.51 2.667
LATCHWAITPID= 0 CMD=BPXVCMT
IBMUSER JES2S001 002F 16842766 1 1R---- 13.21.51 1.506
LATCHWAITPID= 0 CMD=IAZNJTCP
OMVSKERN INETD1 0026 16842768 1 1FI--- 13.21.59 .008
LATCHWAITPID= 0 CMD=/usr/sbin/inetd /etc/inetd.conf
TCPIP NFSCLNT 0023 65553 1 HR---- 13.22.01 2.667
LATCHWAITPID= 0 CMD=GFSCINIT
SERVER=MVSNFSC AF= 0 MF=00000 TYPE=FILE
TCPIP PORTMAP 004B 33619986 1 1FI--- 13.22.01 .010
LATCHWAITPID= 0 CMD=PORTMAP
IBMUSER JES2S001 002F 33619987 1 1R---- 13.22.09 1.506
LATCHWAITPID= 0 CMD=IAZNJSTK
TCPIP TN3270 004A 16842772 1 MR---- 13.22.01 30.274
LATCHWAITPID= 0 CMD=EZBTZMST
TCPIP REXECD 004C 65557 1 1FI--- 13.22.01 .009
LATCHWAITPID= 0 CMD=RSHD
IBMUSER IOASRV 004D 16842774 1 1FI--- 13.22.01 .007
LATCHWAITPID= 0 CMD=IOAXTSRV
TCPIP FTPOE1 0041 65559 1 1FI--- 13.22.01 .011
LATCHWAITPID= 0 CMD=FTPD
TCPIP FTPMVS1 0043 65560 1 1FI--- 13.22.02 .010
LATCHWAITPID= 0 CMD=FTPD
TCPIP TCPIPA 0053 33620011 1 MF---B 13.24.59 1.483
LATCHWAITPID= 0 CMD=EZBTCPIP

TCPIP TCPIPA 0053 33620012 1 1F---B 13.25.02 1.483
LATCHWAITPID= 0 CMD=EZACFALG
TCPIP TCPIPA 0053 65581 1 1F---B 13.25.02 1.483
LATCHWAITPID= 0 CMD=EZASASUB
TCPIP OMPA 0055 16842799 1 HS---- 13.25.12 1.343
LATCHWAITPID= 0 CMD=OMPROUTE
In Example 3-19:
The OMVS member that is running is related to 1 BPXPRM97A.
The initialization process is running as superuser 2 OMVSKERN, and the PID is 1 (the first
process to start).
There is another TCP/IP started task running 3.
What is also significant here is that OMVS=DEFAULT is not displayed in the output. In our
previous review of the z/OS UNIX environment, we mentioned that the z/OS UNIX System
Services must be customized in full-function mode. The display tells you that, at the very
least, your system is not running in default mode (minimal mode).
Also notice the different TPC/IP stacks and tasks associated with them. There is TCPIPA and
TCPIP (the default stack), both executing EZBTCPIP. There are also multiple tasks
associated with the same RACF user ID, TCPIP. This offers the advantage of easier
maintenance and system definitions, However, this also presents the disadvantage of having
no distinguishing features among messages for individual tasks. Many users of TCP/IP and
UNIX System Services would assign individual RACF user IDs to each OMVS user for easier
problem determination.
For a thorough discussion on the use and implementation of RACF, refer to Communications
Server for z/OS V1R9 TCP/IP Implementation Volume 4: Security and Policy-Based
Networking, SG24-7535.
Example 3-20 shows the display of available file systems after the initialization of the z/OS
UNIX Systems Services environment. The display should list all of the files defined in the
mount statement in the BPXPRMxx member, which in our scenario is BPXPRM9A.
Example 3-20 Output of D OMVS,F
D OMVS,F
OMVS 000F ACTIVE OMVS=(1A)
TYPENAME DEVICE ----------STATUS----------- MODE MOUNTED LATCHES
ZFS 81 ACTIVE RDWR 10/25/2008 L=52
NAME=OMVS.SC33.WEB.HOD 13.29.34 Q=0
PATH=/SC33/web/hod
AGGREGATE NAME=OMVS.SC33.WEB.HOD
OWNER=SC33 AUTOMOVE=U CLIENT=Y
NAME=OMVS.SC33.VAR 13.29.28 Q=0
PATH=/SC33/var
AGGREGATE NAME=OMVS.SC33.VAR
NAME=OMVS.SC33.ETC 13.29.28 Q=0
PATH=/SC33/etc
AGGREGATE NAME=OMVS.SC33.ETC

NAME=WTSCPLX5.SC33.SYSTEM.ROOT 13.29.28 Q=0
PATH=/SC33
AGGREGATE NAME=WTSCPLX5.SC33.SYSTEM.ROOT
NAME=OMVS.SC31.WEB.BW311 13.29.23 Q=0
PATH=/SC31/web/bw311
AGGREGATE NAME=OMVS.SC31.WEB.BW311
NAME=OMVS.SC30.WEB.BW301 13.21.50 Q=0
PATH=/SC30/web/bw301
AGGREGATE NAME=OMVS.SC30.WEB.BW301
OWNER=SC30 AUTOMOVE=U CLIENT=N
NAME=OMVS.HOM.PRIVATE.HFS 13.21.45 Q=0
PATH=/pp/HOD/hostondemand/private
AGGREGATE NAME=OMVS.HOM.PRIVATE.HFS
OWNER=SC30 AUTOMOVE=Y CLIENT=N
NAME=OMVS.HOM.HFS 13.21.45 Q=0
PATH=/pp/HOD
AGGREGATE NAME=OMVS.HOM.HFS
NAME=OMVS.ZOSR1A.Z1ARE1.XML 13.21.44 Q=0
PATH=/Z1ARE1/usr/lpp/ixm
AGGREGATE NAME=OMVS.ZOSR1A.Z1ARE1.XML
NAME=OMVS.ZOSR1A.Z1ARE1.JAVA64V6 13.21.44 Q=0
PATH=/Z1ARE1/usr/lpp/java/J6.0_64
AGGREGATE NAME=OMVS.ZOSR1A.Z1ARE1.JAVA64V6
PATH=/Z1ARE1/usr/lpp/java/J6.0
PATH=/Z1ARE1/usr/lpp/java/J5.0_64
NAME=OMVS.ZOSR1A.Z1ARE1.JV390 13.21.43 Q=0
AGGREGATE NAME=OMVS.ZOSR1A.Z1ARE1.JV390

NAME=OMVS.ZOSR1A.Z1ARE1.ROOT 13.21.42 Q=0
PATH=/Z1ARE1
AGGREGATE NAME=OMVS.ZOSR1A.Z1ARE1.ROOT
AUTOMNT 17 ACTIVE RDWR 10/25/2008 L=33
NAME=*AMD/u 13.21.46 Q=0
PATH=/u
TFS 66 ACTIVE RDWR 10/25/2008 L=51
NAME=/SC33/TMP 13.29.28 Q=0
PATH=/SC33/tmp
MOUNT PARM=-s 500
NAME=/SC32/TMP 13.29.20 Q=0
PATH=/SC32/tmp
MOUNT PARM=-s 500
NAME=/SC31/TMP 13.29.16 Q=0
PATH=/SC31/tmp
MOUNT PARM=-s 500
NAME=/DEV 13.21.43 Q=0
PATH=/SC30/dev
MOUNT PARM=-s 10
NAME=/SC30/TMP 13.21.42 Q=0
PATH=/SC30/tmp
MOUNT PARM=-s 500
HFS 6673 ACTIVE RDWR 10/27/2008 L=55
NAME=CS04.HFS 11.15.10 Q=0
PATH=/u/cs04
HFS 6606 ACTIVE RDWR 10/27/2008 L=54
NAME=CS08.HFS 10.48.12 Q=0
PATH=/u/cs08
HFS 51 ACTIVE RDWR 10/25/2008 L=47
NAME=BBW6031.SBBOHFS 13.29.22 Q=0
PATH=/SC31/zWebSphereBW
PATH=/SC32/var
PATH=/SC32/etc

PATH=/SC32
PATH=/SC31/var
PATH=/SC31/etc
PATH=/SC31
NAME=BBW6030.SBBOHFS 13.21.49 Q=0
PATH=/SC30/zWebSphereBW
NAME=OMVS.PP.HFS 13.21.45 Q=0
PATH=/pp
PATH=/SC30/var
PATH=/SC30/etc
PATH=/SC30
NAME=WTSCPLX5.SYSPLEX.ROOT 13.21.41 Q=0
PATH=/
Example 3-21 shows some of the files defined in the active BPXPRM9A member for
comparative purposes only. We can compare the names defined in the active BPXPRM9A
member with the names that are actually active by using the D OMVS,F command.
Example 3-21 BPXPRM1A member
ROOT FILESYSTEM('WTSCPLX5.SYSPLEX.ROOT')
TYPE(HFS)
AUTOMOVE
MODE(RDWR)
MOUNT FILESYSTEM('WTSCPLX5.&SYSNAME..SYSTEM.ROOT'
MOUNTPOINT('/&SYSNAME.')
UNMOUNT
TYPE(HFS) MODE(RDWR)

MOUNT FILESYSTEM('OMVS.ZOSR1A.&SYSR1..ROOT')
MOUNTPOINT('/$VERSION')
AUTOMOVE
MOUNT FILESYSTEM('OMVS.&SYSNAME..ETC')
MOUNTPOINT('/&SYSNAME./etc')
UNMOUNT
MOUNT FILESYSTEM('OMVS.&SYSNAME..VAR')
MOUNTPOINT('/&SYSNAME./var')
UNMOUNT
MOUNT FILESYSTEM('/&SYSNAME./TMP')
TYPE(TFS) MODE(RDWR)
MOUNTPOINT('/&SYSNAME./tmp')
PARM('-s 500')
UNMOUNT
MOUNT FILESYSTEM('/DEV')
MOUNTPOINT('/dev')
TYPE(TFS)
PARM('-s 10')
UNMOUNT
MOUNT FILESYSTEM('OMVS.ZOSR1A.&SYSR1..JV390')
MOUNTPOINT('/usr/lpp/java/J1.4')
MOUNT FILESYSTEM('OMVS.ZOSR1A.&SYSR1..JAVA31V5')
MOUNTPOINT('/usr/lpp/java/J5.0_64')
MOUNTPOINT('/usr/lpp/java/J6.0_64')
MOUNT FILESYSTEM('OMVS.ZOSR1A.&SYSR1..XML')
MOUNTPOINT('/usr/lpp/ixm')
The OMVS processes can also be displayed within the z/OS UNIX environment, and similar
comparisons can be made. Use the shall environment to look at UNIX processes and to
execute the UNIX command ps -ef. This displays all processes and their environments in
forest or family tree format.
Refer to z/OS UNIX System Services Planning, GA22-7800 and z/OS UNIX System Services
User's Guide, SA22-7802 for detailed information about UNIX commands in the z/OS UNIX
environment.

Example 3-22 UNIX System Services processes display from the shell
1 @ SC30:/u/cs01>ps -ef
UID PID PPID C STIME TTY TIME CMD
BPXROOT 1 0 - Oct 25 ? 0:02 BPXPINPR
BPXROOT 33619971 1 - Oct 25 ? 0:00 CEAPSRVR
BPXROOT 16842756 1 - Oct 25 ? 0:08 HZSTKSCH
NET 50397189 1 - Oct 25 ? 1:29 ISTMGCEH
BPXROOT 50397190 1 - Oct 25 ? 0:02 BPXVCLNY
BPXROOT 65543 1 - Oct 25 ? 0:01 /usr/sbin/syslogd -c -i
BPXROOT 65543 1 - Oct 25 ? 0:01 /usr/sbin/syslogd -c -
-u -f /etc/sysloga.conf
BPXROOT 65545 1 - Oct 25 ? 22:55 ERB3GMFC
BPXROOT 65546 1 - Oct 25 ? 1:14 EZBTCPIP
BPXROOT 16842763 1 - Oct 25 ? 1:14 EZACFALG
BPXROOT 65548 1 - Oct 25 ? 1:14 EZASASUB
BPXROOT 33619981 1 - Oct 25 ? 0:02 BPXVCMT
BPXROOT 16842766 1 - Oct 25 ? 0:01 IAZNJTCP
BPXROOT 16842768 1 - Oct 25 ? 0:00 /usr/sbin/inetd
/etc/inet.conf
BPXROOT 65553 1 - Oct 25 ? 0:02 GFSCINIT
BPXROOT 33619986 1 - Oct 25 ? 0:00 PORTMAP
BPXROOT 33619987 1 - Oct 25 ? 0:01 IAZNJSTK
BPXROOT 16842772 1 - Oct 25 ? 0:31 EZBTZMST
BPXROOT 65557 1 - Oct 25 ? 0:00 RSHD
BPXROOT 16842774 1 - Oct 25 ? 0:00 IOAXTSRV
BPXROOT 65559 1 - Oct 25 ? 0:00 FTPD
BPXROOT 65560 1 - Oct 25 ? 0:00 FTPD
BPXROOT 33620011 1 - 13:25:00 ? 0:05 EZBTCPIP
BPXROOT 33620012 1 - 13:25:02 ? 0:05 EZACFALG
BPXROOT 65581 1 - 13:25:02 ? 0:05 EZASASUB
BPXROOT 16842799 1 - 13:25:13 ? 0:04 OMPROUTE
CS04 33620034 1 - 16:36:32 ? 0:02 OMVS
CS04 65603 33620034 - 16:36:32 ttyp0000 0:02 sh -L
BPXROOT 83951684 65603 - 16:37:12 ttyp0000 0:00 sh
BPXROOT 16842821 83951684 - 16:37:19 ttyp0000 0:00 ps -ef
Notice that in Example 3-22, the UNIX System Services after this initialization is running with
user ID BPXROOT. The reason for this is because RACF cannot map a UNIX System
Services UID to an MVS user ID correctly if there are multiple MVS user IDs defined with the
same UID. So RACF uses the last referenced MVS user ID.
Here are some typical UNIX commands:
The mkdir/u/cso1 command creates the directory for the user mount point. The
permission bits would be set as specified in the etc/profile or $home/.profile.
The ls -all command lists the files with their permission bits. From time to time you might
need to change the permission bits in the file.
The chmod command is used to change the permission bits associated with files.
The TSO/E interface can be used to work with zOS UNIX files. You can browse files using
the ISHELL PDSE interface or you can execute the obrowse command from the OMVS
shell environment. You can also edit files using the ISHELL tools, or you can use the oedit
command from the OMVS shell.

The ISHELL provides an ISPF look and feel. The OMVS shell provides a more UNIX or DOS
look and feel, and of course for real UNIX users there is the vi editor.
Starting z/OS Communications Server TCP/IP
Example 3-23 shows the startup of our TCP/IP stack.
Example 3-23 z/OS Communications Server TCP/IP startup
S TCPIPA
$HASP373 TCPIPA STARTED
IEE252I MEMBER CTIEZB00 FOUND IN SYS1.IBM.PARMLIB 1
IEE252I MEMBER CTINTA00 FOUND IN SYS1.PARMLIB
EZZ0300I OPENED PROFILE FILE DD:PROFILE
EZZ0309I PROFILE PROCESSING BEGINNING FOR DD:PROFILE
EZZ0316I PROFILE PROCESSING COMPLETE FOR FILE DD:PROFILE 2
EZZ0641I IP FORWARDING NOFWDMULTIPATH SUPPORT IS ENABLED
EZZ0350I SYSPLEX ROUTING SUPPORT IS ENABLED 3
EZZ0624I DYNAMIC XCF DEFINITIONS ARE ENABLED 4
EZZ0338I TCP PORTS 1 THRU 1023 ARE NOT RESERVED
EZZ0338I UDP PORTS 1 THRU 1023 ARE NOT RESERVED
EZZ0613I TCPIPSTATISTICS IS DISABLED 5
EZZ4202I Z/OS UNIX - TCP/IP CONNECTION ESTABLISHED FOR TCPIPA 6
EZZ4340I INITIALIZATION COMPLETE FOR INTERFACE OSA2080I
EZZ4340I INITIALIZATION COMPLETE FOR INTERFACE OSA20A0I
EZZ4340I INITIALIZATION COMPLETE FOR INTERFACE OSA20C0I
EZZ4340I INITIALIZATION COMPLETE FOR INTERFACE OSA20D0I
EZB6473I TCP/IP STACK FUNCTIONS INITIALIZATION COMPLETE. 7
EZAIN11I ALL TCPIP SERVICES FOR PROC TCPIPA ARE AVAILABLE.
EZD1176I TCPIPA HAS SUCCESSFULLY JOINED THE TCP/IP SYSPLEX GROUP
EZD1214I INITIAL DYNAMIC VIPA PROCESSING HAS COMPLETED FOR TCPIP
1. Shows how the member that defines CTRACE processing has been found (CTIEZB00).
This is discussed in 8.4.1, “Taking a component trace” on page 251.
2. Shows how the PROFILE.TCPIP for the stack has been found and processed.
3. Sysplexrouting is enabled, so communication between z/OS TCP/IP is possible.
4. Dynamic XCFs are enabled (DYNAMICXCF parameter).
5. TCPIPSTATICTICS will not be generated.
6. Shows how the stack has been bound to UNIX System Services. It indicates that the
Common INET pre-router has successfully obtained a copy of the IP layer routing table
from the stack.
7. The stack (TCP/IP) is successfully initialized and READY FOR WORK.
Note: Both obrowse and oedit are TSO commands. If you used telnet or rlogin to get to the
UNIX System Services shell, you have to use the cat command and the vi editor.
Important: Because TCP/IP shares its Data Link Controls (DLCs) with VTAM, you must
restart TCP/IP if you restart VTAM.

3.6.2 Verifying TCP/IP configuration
After the configuration files are updated we verified the configuration and we restarted the
TCP/IP address space, ensuring that we saw the following message:
EZB6473I TCP/IP STACK FUNCTIONS INITIALIZATION COMPLETE
If the message is not displayed, the messages issued by the TCP/IP address space should
describe why TCP/IP did not start.
Displaying the TCP/IP configuration
To display the enabled features and operating characteristics of a TCP/IP stack, enter any of
the following commands:
TSO/E command NETSTAT CONFIG
MVS command D TCPIP,procname,NETSTAT,CONFIG
UNIX shell command onetstat -f
Example 3-24 shows the output from the NETSTAT CONFIG display.
Example 3-24 NETSTAT CONFIG display
D TCPIP,TCPIPA,NETSTAT,CONFIG
TCP CONFIGURATION TABLE: 1
DEFAULTRCVBUFSIZE: 00065536 DEFAULTSNDBUFSIZE: 00065536
DEFLTMAXRCVBUFSIZE: 00262144 SOMAXCONN: 0000000010
MAXRETRANSMITTIME: 120.000 MINRETRANSMITTIME: 0.500
ROUNDTRIPGAIN: 0.125 VARIANCEGAIN: 0.250
VARIANCEMULTIPLIER: 2.000 MAXSEGLIFETIME: 30.000
DEFAULTKEEPALIVE: 00000120 DELAYACK: YES
RESTRICTLOWPORT: NO SENDGARBAGE: NO
TCPTIMESTAMP: YES FINWAIT2TIME: 600
TTLS: NO
UDP CONFIGURATION TABLE: 2
CHECKSUM: YES
RESTRICTLOWPORT: NO UDPQUEUELIMIT: YES
IP CONFIGURATION TABLE: 3
FORWARDING: YES TIMETOLIVE: 00064 RSMTIMEOUT: 00060
IPSECURITY: NO
ARPTIMEOUT: 01200 MAXRSMSIZE: 65535 FORMAT: LONG
IGREDIRECT: YES SYSPLXROUT: YES DOUBLENOP: NO
STOPCLAWER: NO SOURCEVIPA: NO
MULTIPATH: NO PATHMTUDSC: NO DEVRTRYDUR: 0000000090
DYNAMICXCF: YES
IPADDR: 10.1.7.11 SUBNET: 255.255.255.0 METRIC: 01
SECCLASS: 255
IQDIOROUTE: NO
TCPSTACKSRCVIPA: NO
IPV6 CONFIGURATION TABLE:
FORWARDING: YES HOPLIMIT: 00255 IGREDIRECT: NO
Note: See 1.3.3, “Reusable address space ID” on page 6 if you want to run TCPIP in a
reusable address space ID.

SOURCEVIPA: NO MULTIPATH: NO ICMPERRLIM: 00003
IGRTRHOPLIMIT: NO
IPSECURITY: NO
DYNAMICXCF: NO
TCPSTACKSRCVIPA: NO
SMF PARAMETERS: 4
TYPE 118:
TCPINIT: 00 TCPTERM: 00 FTPCLIENT: 00
TN3270CLIENT: 00 TCPIPSTATS: 00
TYPE 119:
TCPINIT: NO TCPTERM: NO FTPCLIENT: NO
TCPIPSTATS: NO IFSTATS: NO PORTSTATS: NO
STACK: NO UDPTERM: NO TN3270CLIENT: NO
IPSECURITY: NO
GLOBAL CONFIGURATION INFORMATION: 5
TCPIPSTATS: NO ECSALIMIT: 0000000K POOLLIMIT: 0000000K
MLSCHKTERM: NO XCFGRPID: IQDVLANID: 0
SEGOFFLOAD: NO SYSPLEXWLMPOLL: 060 MAXRECS: 100
EXPLICITBINDPORTRANGE: 00000-00000 IQDMULTIWRITE: NO
SYSPLEX MONITOR:
TIMERSECS: 0060 RECOVERY: NO DELAYJOIN: NO AUTOREJOIN: NO
MONINTF: NO DYNROUTE: NO
ZIIP:
IPSECURITY: NO IQDIOMULTIWRITE: NO
NETWORK MONITOR CONFIGURATION INFORMATION: 6
PKTTRCSRV: NO TCPCNNSRV: NO
SMFSRV: YES
IPSECURITY: YES
AUTOLOG CONFIGURATION INFORMATION: WAIT TIME: 0300
PROCNAME: OMPA JOBNAME: OMPA
PARMSTRING:
DELAYSTART: NO
END OF THE REPORT
Parameters such as SOURCEVIPA can be either ENABLED or DISABLED. A value of 01 in
the NETSTAT CONFIG display means it is ENABLED. In this example, the numbers
correspond to the following information:
1. The settings in effect in the TCPCONFIG parameters.
2. The settings for the UDPCONFIG parameters.
3. The settings in effect in the IPCONFIG parameters.
4. The settings in effect for SMFCONFIG.
5. The settings in effect for GLOBALCONFIG.
6. The setting in effect for Network Monitoring Information.

Displaying the status of devices
You can display the status of devices by using the MVS display command TSO NETSTAT, as
shown in Example 3-25, or UNIX onetstat -d.
Example 3-25 Results of device display
D TCPIP,TCPIPA,N,DE
........................................................................ Lines
deleted
INTFNAME: OSA2080I INTFTYPE: IPAQENET INTFSTATUS: READY 1
PORTNAME: OSA2080 DATAPATH: 2082 DATAPATHSTATUS: READY 1
SPEED: 0000001000
IPBROADCASTCAPABILITY: NO
VMACADDR: 020005749925 VMACORIGIN: OSA VMACROUTER: ALL
ARPOFFLOAD: YES 2 ARPOFFLOADINFO: NO
CFGMTU: 1492 ACTMTU: 1492
IPADDR: 10.1.2.11/24
VLANID: 10 3 VLANPRIORITY: DISABLED
DYNVLANREGCFG: NO DYNVLANREGCAP: YES
READSTORAGE: GLOBAL (4096K) INBPERF: BALANCED
CHECKSUMOFFLOAD: YES SEGMENTATIONOFFLOAD: YES 2
SECCLASS: 255 MONSYSPLEX: NO
MULTICAST SPECIFIC:
........................................................................ Lines
deleted
1. Indicates the overall status of the OSA interface OSA2080I: READY. If this status is not
READY, verify that the VTAM Major node is active. You can do this by using the VTAM
command D NET,TRL.
2. The OFFLOAD feature is enabled.
3. The VLAN ID defined on the LINK statement in the PROFILE data set.
Example 3-26 Results of the TRLE display
D NET,TRL,TRLE=OSA200P
IST075I NAME = OSA200P, TYPE = TRLE 788
IST1954I TRL MAJOR NODE = OSA2080
IST486I STATUS= ACTIV, DESIRED STATE= ACTIV 1
IST087I TYPE = LEASED , CONTROL = MPC , HPDT = YES
IST1715I MPCLEVEL = QDIO MPCUSAGE = SHARE
IST2263I PORTNAME = OSA2080 PORTNUM = 0 OSA CODE LEVEL = 0707
IST1577I HEADER SIZE = 4096 DATA SIZE = 0 STORAGE = ***NA***
IST1221I WRITE DEV = 2081 STATUS = ACTIVE STATE = ONLINE 2
IST1221I READ DEV = 2080 STATUS = ACTIVE STATE = ONLINE 2
IST1221I DATA DEV = 2082 STATUS = ACTIVE STATE = N/A 3
IST1724I I/O TRACE = OFF TRACE LENGTH = *NA*
IST1717I ULPID = TCPIPA
IST1815I IQDIO ROUTING DISABLED
IST1918I READ STORAGE = 4.0M(64 SBALS)
IST1757I PRIORITY1: UNCONGESTED PRIORITY2: UNCONGESTED
IST2190I DEVICEID PARAMETER FOR OSAENTA TRACE COMMAND = 02-03-00-82

IST1801I UNITS OF WORK FOR NCB AT ADDRESS X'0EDA9010'
IST1802I P1 CURRENT = 0 AVERAGE = 0 MAXIMUM = 0
IST1221I DATA DEV = 2083 STATUS = RESET STATE = N/A
IST314I END
1. The Major node is ACTIVE and ONLINE.
2. The READ and WRITE channels are ACTIVE and ONLINE.
3. The data channel is also ACTIVE.
Displaying storage usage
The z/OS Communications Server uses the Common Storage Manager (CSM) to manage
storage pools. The recommendation is to increase storage allocations by a minimum of
20 MB for TCP/IP in the CSA definition in IEASYSxx and the FIXED and ECSA definitions in
IVTPRMxx.
Check your storage utilization to ensure that you made the correct allocations. Storage usage
can also be controlled using the GLOBALCONFIG ECSALIMIT and GLOBALCONFIG
POOLLIMIT parameters. ECSALIMIT allows you to specify the maximum amount of extended
common service area (ECSA) that TCP/IP can use. POOLLIMIT allows you to specify the
maximum amount of authorized private storage that TCP/IP can use within the TCP/IP
address space. You can also use the MVS command D TCPIP,tcpproc,STOR to display
TCP/IP storage usage, as illustrated in Example 3-27.
Example 3-27 Results of storage display
D TCPIP,TCPIPE,STOR
EZZ8453I TCPIP STORAGE
EZZ8454I TCPIPA STORAGE CURRENT MAXIMUM LIMIT
EZZ8455I TCPIPA ECSA 9068K 9597K NOLIMIT
EZZ8455I TCPIPA POOL 8460K 8486K NOLIMIT
EZZ8459I DISPLAY TCPIP STOR COMPLETED SUCCESSFULLY

Verifying TCPIP.DATA statement values in z/OS
To display which TCPIP.DATA statement values are being used and where they are being
obtained from, use trace resolver output. You can obtain trace resolver output at your TSO
screen by issuing the following TSO commands:
alloc f(systcpt) dsn(*)
READY
netstat up
READY
free f(systcpt)
READY
Verifying TCPIP.DATA statement values in UNIX Systems Services
To display which TCPIP.DATA statement values are being used and where they are being
obtained from, use trace resolver output. You can obtain trace resolver output by issuing the
following z/OS UNIX shell commands:
#
export RESOLVER_TRACE=stdout
#
onetstat –u
#
set -A RESOLVER_TRACE
Verifying PROFILE.TCPIP
Many configuration values specified within the PROFILE.TCPIP file can be verified with the
TSO NETSTAT or z/OS UNIX onetstat commands. To verify the physical network and
hardware definitions, use the D TCPIP,,N,DEV, NETSTAT DEVLINKS or onetstat -d
commands. To see operating characteristics, use z/OS displays, namely NETSTAT CONFIG
or onetstat -f.
Verifying interfaces with PING and TRACERTE
PING and TRACERTE can be used in the TSO environment to verify adapters or interfaces
attached to the z/OS host. In the z/OS UNIX environment, oping and otracert can be used
with identical results. For information about the syntax and output of the commands, refer to
z/OS Communications Server: IP System Administrator’s Commands, SC31-8781. Given that
your PROFILE.TCPIP file contains the interfaces of your installation and that the TCPIP.DATA
file contains the correct TCPIPJOBNAME, the TCP/IP address space is configured and you
can go on to configuring routes, servers, and so on.
Verifying local name resolution with TESTSITE
Use the TESTSITE command to verify that the hlq.HOSTS.ADDRINFO and
hlq.HOSTS.SITEINFO data sets can correctly resolve the name of a host, gateway, or net.
For more information about the TESTSITE command, refer to z/OS Communications Server:
IP System Administrator’s Commands, SC31-8781.
Verifying PROFILE.TCPIP and TCPIP.DATA using HOMETEST
Use the HOMETEST command to verify the HOSTNAME, DOMAINORIGIN, SEARCH, and
NSINTERADDR TCPIP.DATA statements. HOMETEST will use the resolver to obtain the IP
addresses assigned to the HOSTNAME and compare them to the HOME list specified in
Tip: When directing trace resolver output to a TSO terminal, define the screen size to be
only 80 columns wide. Otherwise, trace output is difficult to read.

PROFILE.TCPIP. A warning message will be issued if any HOSTNAME IP addresses are
missing from the HOME list.
Activate TRACE RESOLVER if you would like detailed information about how the
HOSTNAME is resolved to IP addresses. The information will also include what TCPIP.DATA
data set names were used. This can be done by issuing the following TSO command before
running HOMETEST. The detailed information will be displayed on your TSO screen.
allocate dd(systcpt) da(*)
Issue the following TSO command after HOMETEST to turn off TRACE RESOLVER
output.
free dd(systcpt)
If you do not have TRACE RESOLVER turned on before you run HOMETEST, the output
shown in Example 3-28 is displayed.
Example 3-28 HOMETEST command output
EZA0619I Running IBM MVS TCP/IP CS V1R10 TCP/IP Configuration Tester
EZA9431I FTP.DATA file not found. Using hardcoded default values.
EZA0602I TCP Host Name is: WTSC30A
EZA0605I Using Name Server to Resolve WTSC30A
EZA0611I The following IP addresses correspond to TCP Host Name: WTSC30A
EZA0612I 10.1.1.10
EZA0614I The following IP addresses are the HOME IP addresses defined in
PROFILE.TCPIP:
EZA0615I 10.1.30.10
EZA0615I 10.1.1.10
EZA0615I 10.1.2.10
EZA0615I 10.1.2.11
EZA0615I 10.1.3.11
EZA0615I 10.1.3.12
EZA0615I 10.1.2.12
EZA0615I 10.1.4.11
EZA0615I 10.1.5.11
EZA0615I 10.1.6.11
EZA0615I 10.1.7.11
EZA0615I 10.1.7.11
EZA0615I 10.1.8.10
EZA0615I 10.1.8.20
EZA0615I 127.0.0.1
EZA0618I All IP addresses for WTSC30A are in the HOME list!
EZA0622I Hometest was successful - all Tests Passed!
3.7 Reconfiguring the system with z/OS commands
The z/OS Communications Server provides the VARY OBEYFILE command to change the
running TCP/IP configuration dynamically. This command replaces the OBEYFILE TSO
command.

The VARY command is an z/OS Console command. It allows you to add, delete, or
completely redefine all devices dynamically, as well as change TN3270 parameters, routing,
and almost any TCP/IP parameter in the profile. These changes are in effect until the TCP/IP
started task is started again, or another VARY OBEYFILE command overrides them.
Authorization is through the user’s RACF profile containing the MVS.VARY.TCPIP.OBEYFILE
definition. There is no OBEY statement in the PROFILE.TCPIP, which in earlier MVS TCP/IP
implementations provided authorization.
For further details about the VARY OBEYFILE command, see z/OS CS: IP System
Administrator’s Commands, SC31-8781. For more information about RACF definitions, see
Applications, SG24-7533.
3.7.1 Deleting a device and adding or changing a device
You can use the OBEYFILE command to reconfigure the devices being used by the stack.
Reconfiguration could be the deletion of existing devices, the addition of new devices, or the
redefinition of an existing device. The syntax of the statements for OBEYFILE processing is
the same as that being used in PROFILE.TCPIP.
Device reconfiguration is a three-step process:
1. Stop the device with an z/OS console command (VARY STOP) or with a VARY OBEYFILE
that names a data set in which the STOP command is defined.
2. Activate an OBEYFILE that deletes the links and the devices.
3. Activate an OBEYFILE that adds the new or changed links and devices and then starts
them.
Deleting and adding back a device
If you want to delete a device, then the order of the steps that you perform is important. The
DELETE statement in PROFILE.TCPIP allows you to remove LINK, DEVICE, and PORT or
PORTRANGE definitions. You must delete a resource that is defined using the INTERFACE
statement using the DELETE parameter.
The sequence for deleting and adding back a resources that was defined using the
INTERFACE statement is as follows:
1. Stop the device.
2. Delete the interface.
3. Add the new or changed interface.
4. Start the device.
Use the following steps to delete and add back a resource that was defined using the
DEVICE, LINK, or HOME statements:
1. Stop the device.
2. Remove the HOME address by excluding it from the full stack’s HOME list.
3. Delete the link.
4. Delete the device.
5. Add the new or changed device.
6. Add the new or changed link.
7. Add the HOME statements for the full stack.
8. Add the full gateway statements for the stack if you are using static routing.
9. Start the device.

3.7.2 Modifying a device
In this example, we want to change the IP address of our OSA-Express interface/device
OSA2080I from 10.1.2.11 to 10.1.2.14. This process involves stopping and deleting the
current interface or device, and then redefining and restarting it.
Example 3-29 and Example 3-30 show the interface OSA2080I, or link OSA2080L, active
with associated IP address 10.1.2.11.
Example 3-29 Displays netstat device before deletion (for INTERFACE defined)
D TCPIP,TCPIPA,N,DE
........................................................................ Lines
deleted
INTFNAME: OSA2080I INTFTYPE: IPAQENET INTFSTATUS: READY
PORTNAME: OSA2080 DATAPATH: 2082 DATAPATHSTATUS: READY
SPEED: 0000001000
SRCVIPAINTF: VIPA2L
CFGROUTER: NON ACTROUTER: NON
ARPOFFLOAD: YES ARPOFFLOADINFO: YES
IPADDR: 10.1.2.11/24
VLANID: NONE VLANPRIORITY: DISABLED
CHECKSUMOFFLOAD: YES
........................................................................ Lines
deleted
Example 3-30 Display netstat home before deletion (for DEVICE/LINK/HOME defined)
D TCPIP,TCPIPA,N,HO
........................................................................ Lines
deleted
LINKNAME: OSA2080I
ADDRESS: 10.1.2.11
FLAGS:
........................................................................ Lines
deleted
Notice the address of OSA2080I (10.1.2.11). We needed to change this in the running system
by stopping, deleting, redefining, and adding back the OSA-Express device and link and
home address.
Because the STOP command is executed as the last statement within an OBEYFILE
regardless of its position within the file, you cannot execute STOP and DELETE in one step.
Note: You can delete and redefine OSA-Express resources defined with either the
INTERFACE statement or the DEVICE, LINK, or HOME statements by following the same
procedure but by creating different OBEYFILE commands. Because the INTERFACE
statement is now the preferred way of defining OSA devices, we use that procedure first in
the following examples.

Trying to do so will result in the error messages. You should stop the interface or device with
console command, as shown in Example 3-31.
Example 3-31 Command to stop the interface or device
V TCPIP,TCPIPA,STOP,OSA2080I
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,STOP,OSA2080I
EZZ0053I COMMAND VARY STOP COMPLETED SUCCESSFULLY
EZZ4341I DEACTIVATION COMPLETE FOR INTERFACE OSA2080I
EZZ4315I DEACTIVATION COMPLETE FOR DEVICE OSA2080I
Then, delete it from the stack, as shown in Example 3-32.
Example 3-32 Command to delete the interface or device
V TCPIP,TCPIPA,O,TCPIPA.TCPPARMS(OBDELINT)
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,O,TCPIPA.TCPPARMS(OBDELINT)
EZZ0300I OPENED OBEYFILE FILE 'TCPIPA.TCPPARMS(OBDELINT)'
EZZ0309I PROFILE PROCESSING BEGINNING FOR 'TCPIPA.TCPPARMS(OBDELINT)'
ZZ0316I PROFILE PROCESSING COMPLETE FOR FILE 'TCPIPA.TCPPARMS(OBDELINT)'
EZZ0053I COMMAND VARY OBEY COMPLETED SUCCESSFULLY
Enter either the NETSTAT DEV or NETSTAT HOME commands to check that the device you
wanted to delete is missing from the list.
Example 3-33 and Example 3-34 show the statements necessary to delete the device.
Example 3-33 OBEYFILE member to delete the device OSA2080I (INTERFACE defined)
INTERFACE OSA2080I
DELETE
Example 3-34 OBEYFILE member to delete the device OSA2080 (DEVICE/LINK/HOME defined)
HOME
10.1.1.10 VIPA1L
10.1.2.10 VIPA2L
;;;10.1.2.11 OSA2080I
10.1.3.11 OSA20C0I
10.1.3.12 OSA20E0I
10.1.2.12 OSA20A0I
10.1.4.11 IUTIQDF4L
10.1.5.11 IUTIQDF5L
10.1.6.11 IUTIQDF6L
;
DELETE LINK OSA2080I
DELETE DEVICE OSA2080
Note: With DEVICE/LINK/HOME defined devices, you have to provide the complete
HOME definition that excludes the device that you want to delete, because the new HOME
statement replaces the existing one. This step is not necessary with devices defined using
the INTERFACE statement.

Then, add either the interface or the device and link back with the changed address
definition 3, as shown in Example 3-35 and Example 3-36.
Example 3-35 OBEYFILE member to add the interface
INTERFACE OSA2080I
DEFINE IPAQENET
PORTNAME OSA2080
IPADDR 10.1.2.14/24 3;
START OSA2080I
Example 3-36 OBEYFILE member to add the device (ADDA30)
DEVICE OSA2080 MPCIPA
LINK OSA2080I IPAQENET OSA2080 VLANID 10
;
HOME
10.1.1.10 VIPA1L
10.1.2.10 VIPA2L
10.1.2.14 OSA2080I 3
10.1.3.11 OSA20C0I
10.1.3.12 OSA20E0I
10.1.2.12 OSA20A0I
10.1.4.11 IUTIQDF4L
10.1.5.11 IUTIQDF5L
10.1.6.11 IUTIQDF6L
Issue the command shown in Example 3-37 to add the device and link associated with its own
IP address.
Example 3-37 Adding the device and link
V TCPIP,TCPIPA,O,TCPIPA.TCPPARMS(OBADDINT)
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,O,TCPIPA.TCPPARMS(OBADDINT)
EZZ0300I OPENED OBEYFILE FILE 'TCPIPA.TCPPARMS(OBADDINT)'
EZZ0309I PROFILE PROCESSING BEGINNING FOR 'TCPIPA.TCPPARMS(OBADDINT)'
ZZ0316I PROFILE PROCESSING COMPLETE FOR FILE 'TCPIPA.TCPPARMS(OBADDINT)'
Then, follow with a display to verify the addition to the stack, as shown in Example 3-38.
Example 3-38 Display with OSA2080 using a new address
D TCPIP,TCPIPE,N,HOME
EZD0101I NETSTAT CS V1R10 TCPIPA
........................................................................ Lines
deleted
LINKNAME: OSA2080I
ADDRESS: 10.1.2.14
FLAGS:
........................................................................ Lines
deleted

3.8 Job log versus syslog as diagnosis tool
In the past, the TCP/IP job log was used to detect problems. Most procedures now send
messages to the syslogd daemon or the MVS console log. Refer to Communications Server
for z/OS V1R9 TCP/IP Implementation Volume 2: Standard Applications, SG24-7533 for more
information about the syslog daemon. Individual server documentation also provides
information about diagnosis.
3.9 Message types: Where to find them
For an explanation of z/OS UNIX and TCP/IP messages or SNA sense codes, refer to the
publications listed in Table 3-1.
Table 3-1 Messages and return code publications
When you install and customize the Communications Server for z/OS IP, it can be very
helpful to have the following documentation and product publications available:
Implementation and migration plans, fallback plans, and test plans that you have created
and customized for your environment
Printouts of procedures and data sets that you will be using for the implementation
z/OS Program Directory, Program Number 5694-A01, GI10-0670
z/OS XL C/C++ Run-Time Library Reference, SA22-7821
Message type Publication
Messages with prefix BPX z/OS MVS System Messages, Vol 3 (ASB-BPX), SA22-7633
Messages with prefix EZA For Communications Server for z/OS IP, refer to z/OS Communications Server:
IP Messages Volume 1 (EZA), SC31-8783
Messages with prefix EZB For Communications Server for z/OS IP, refer to z/OS Communications Server:
IP Messages Volume 2 (EZB, EZD), SC31-8784
Messages with prefix EZY For Communications Server for z/OS IP, refer to z/OS Communications Server:
IP Messages Volume 3 (EZY), SC31-8785
Messages with prefix EZZ and
SNM™
For Communications Server for z/OS IP, refer to z/OS Communications Server:
IP Messages Volume 4 (EZZ, SNM), SC31-8786
Messages with prefix FOMC,
FOMM, FOMO, FSUC, and FSUM
z/OS UNIX System Services Messages and Codes, SA22-7807
Eight-digit SNA sense codes and
DLC codes
z/OS Communications Server: IP and SNA Codes, SC31-8791
UNIX System Services return
codes and reason codes

z/OS Communications Server: IP Messages Volume 1 (EZA), SC31-8783
z/OS Communications Server: IP Messages Volume 2 (EZB, EZD), SC31-8784
z/OS Communications Server: IP Messages Volume 3 (EZY), SC31-8785
z/OS Communications Server: IP Messages Volume 4 (EZZ, SNM), SC31-8786
OSA-Express Customer’s Guide and Reference, SA22-7935
z/OS UNIX System Services Planning, GA22-7800
z/OS UNIX System Services User’s Guide, SA22-7801
z/OS MVS System Messages, Vol 1 (ABA-AOM), SA22-7631
z/OS MVS System Messages, Vol 2 (ARC-ASA), SA22-7632
z/OS MVS System Messages, Vol 3 (ASB-BPX), SA22-7633
z/OS MVS System Messages, Vol 4 (CBD-DMO), SA22-7634
z/OS MVS System Messages, Vol 5 (EDG-GFS), SA22-7635
z/OS MVS System Messages, Vol 6 (GOS-IEA), SA22-7636
z/OS MVS System Messages, Vol 7 (IEB-IEE), SA22-7637
z/OS MVS System Messages, Vol 8 (IEF-IGD), SA22-7638
z/OS MVS System Messages, Vol 9 (IGF-IWM), SA22-7639
z/OS MVS System Messages, Vol 10 (IXC-IZP), SA22-7640

Chapter 4. Connectivity
In today’s networked world, the usability of a computer system is defined by its connectivity.
While there are many ways for TCP/IP traffic to reach IBM mainframes, this chapter discusses
the most commonly used and the most dynamic types of mainframe connectivity.
Detailed topics regarding these interfaces are provided, including useful implementation
information, design scenarios, and setup examples.
4
Section Topic
4.1, “What is connectivity” on page 110 Network connectivity options supported by z/OS
Communications Server TCP/IP and IBM System z
servers as well as key characteristics of VLAN
implementation
4.2, “Recommended interfaces” on
page 112
Recommended interfaces supported by System z
hardware and z/OS Communications Server
4.3, “Connectivity for the z/OS
environment” on page 120
Basic implementation information for z/OS and
Communications Server when connecting to the
immediate LAN environment
4.4, “OSA-Express connectivity” on
page 123
Configuration examples, with dependencies,
considerations, and our recommendations for an
OSA-Express interface
4.5, “HiperSockets connectivity” on
page 133
considerations, and our recommendations for a
HiperSockets interface
4.6, “Dynamic XCF connectivity” on
page 138
considerations, and our recommendations for a dynamic
XCF interface
4.7, “Controlling and activating devices”
on page 144
Commands to start and stop devices, as well as activate
modified device definitions
4.8, “Problem determination” on
page 146
How to determine why certain connectivity options are
not working

4.1 What is connectivity
Connectivity is the pipeline through which data is exchanged between clients and servers
through physical and logical communication interfaces and the network. IBM System z
servers provide a wide range of interface options for connecting your z/OS system to an IP
network or to another IP host. Some interfaces offer point-to-point or point-to-multipoint
connectivity. Others support Local Area Network (LAN) connectivity.
Figure 4-1 depicts the physical interfaces (and device types) provided by System z servers.
The physical network interface is enabled through z/OS Communications Server (TCP/IP)
definitions.
Figure 4-1 System z - physical interfaces
4.1.1 System z network connectivity
System z network connectivity is handled by the physical and logical interfaces to enable the
transport of IP datagrams. Using the OSI model as an example, it spans Layer 1 (physical
layer) and Layer 2 (data link control layer). The z/OS Communications Server supports
several types of interfaces connecting to different networking environments. These
environments vary from point-to-point connections (such as MPCPTP, CTC, and CLAW), to
LAN connections (such as LCS and MPCIPA). The supported IPv4 interfaces are listed in
Table 4-1 on page 111.
CTC (FICON
or ESCON)
System p
or OEM
Servers
HYPERchannel
CLAW
MPCPTP
MPCPTP (XCF) CF
Sysplex
Environment
CDLC (NCP)
3745/3746
System z
Servers
Token Ring
Ethernet
LCS/MPCIPA
(GbE)
LCS/MPCIPA (FENET)
(1000BASE-T)
MPCIPA
(10 GbE LR)
ATM
Network
ATM (Native)
ATM (LANE)
LCS/MPCIPA

Chapter 4. Connectivity 111
Table 4-1 System z network interfaces
For further information about these protocols, refer to z/OS Communications Server: IP
Configuration Reference, SC31-8776.
Interface type Attachment type Protocol type Description
Asynchronous
transfer mode
(ATM)
ATM Native mode through
OSA-Express
ATM network Enables TCP/IP to send data to an
ATM network using an OSA-Express
ATM adapter.
Channel data link
control (CDLC)
Network Control Program
through 3745/3746
Point-to-point ESCON® attachments can be used
to provide native IP transport
between the 3746 IP and host
systems running the z/OS
Communications Server.
Common link
access to
workstation
(CLAW)
IBM System p®
Channel attached routers
Point-to-point
Point-to-Multipoint
Provides access from IBM System p
server directly to a TCP/IP stack
over a channel.
Can also be used to provide
connectivity to other vendor
platforms.
Channel-to-
channel (CTC)
FICON/ESCON channel Point-to-point Provides access to TCP/IP hosts by
way of a CTC connection
established over a FICON or
ESCON channel.
HYPERchannel Series A devices Point-to-Multipoint Provides access to TCP/IP hosts by
way of a series A devices and series
DX devices that function as series A
devices.
LAN Channel
Station (LCS)
OSA-Express:
1000BASE-T
Fast Ethernet
Token Ring
ATM Native and LAN
Emulation
LAN:
IEEE802.3
IEEE802.3
IEEE802.5
ATM network
A variety of channel adapters
support a protocol called the LCS.
The most common are
OSA-Express features.
MultiPath Channel
IP Assist
(MPCIPA)
HiperSocketsa
OSA-Express:
10 Gigabit Ethernet
Gigabit Ethernet
1000BASE-T
Fast Ethernet
Token Ring
ATM LAN Emulation
a. Can also be used in conjunction with DYNAMICXCF
Internal LAN
LAN:
IEEE802.3
IEEE802.3
IEEE802.3
IEEE802.3
IEEE802.5
ATM network
Provides access to TCP/IP hosts,
using OSA-Express in Queued
Direct I/O (QDIO) mode and
HiperSockets using the internal
Queued Direct I/O (iQDIO).
MultiPath Channel
Point-to-Point
(MPCPTP)
IUTSAMEH (XCF link) Point-to-point Provides access to directly connect
z/OS hosts or z/OS LPARs, or by
configuring it to utilize Coupling
Facility links (if it is part of a sysplex).
SAMEHOST (Data
Link Control)
SNALINK LU0
SNALINK LU6.2
X25NPSI
Point-to-point
Point-to-point
X.25 network
Enables communication between
z/OS Communications Server IP
and other servers running on the
same MVS image.

4.2 Recommended interfaces
This section discusses the recommended interfaces supported by System z hardware and
z/OS Communications Server. We highly recommend their use because they deliver the best
throughput and performance, as well as offer the most flexibility and highest levels of
availability. These interfaces include:
OSA-Express
HiperSockets
Dynamic Cross-system Coupling Facility (dynamic XCF)
4.2.1 High-bandwidth and high-speed networking technologies
z/OS Communications Server supports high-bandwidth and high-speed networking
technologies provided by OSA-Express and HiperSockets.
The OSA-Express features comply with the most commonly used IEEE standards, used in
LAN environments.
HiperSockets is used for transporting IP traffic between TCP/IP stacks running in logical
partitions (LPARs) within a System z server at memory speed.
Both interfaces use the System z I/O architecture called queued direct input/output (QDIO).
QDIO is a highly efficient data transfer mechanism that satisfies the increasing volume of
applications and bandwidth demands. It dramatically reduces system overhead, and
improves throughput by using system memory queues and a signaling protocol to directly
exchange data between the OSA-Express microprocessor and network software, using data
queues in main memory and utilizing Direct Memory Access (DMA).
The components that make up QDIO are Direct Memory Access (DMA), Priority Queuing,
dynamic OSA Address Table building, LPAR-to-LPAR communication, and Internet Protocol
(IP) Assist functions.
HiperSockets implementation is based on the OSA-Express QDIO protocol, hence the name
internal QDIO (iQDIO). The System z microcode for HiperSockets emulates the link control
layer of an OSA-Express QDIO interface. The communication is through system memory of
the server using I/O queues. IP traffic is transferred at memory speeds between LPARs,
eliminating the I/O subsystem overhead and external network delays.
z/OS Communications Server can only transport IP traffic over OSA-Express in QDIO mode
and HiperSockets. However, SNA can be transported over IP connections using
encapsulation technologies such as Enterprise Extender (EE) and TN3270.
For more information about EE, refer to Enterprise Extender Implementation Guide,
SG24-7359. For TN3270 details, refer to Communications Server for z/OS V1R9 TCP/IP
Implementation Volume 2: Standard Applications, SG24-7533.
Recommendation: Some OSA-Express features also support LCS (known as non-QDIO
mode). However, we recommend the use of QDIO mode in conjunction with the
OSA-Express Ethernet features wherever possible.
With QDIO, I/O interrupts and I/O path-lengths are minimized, resulting in significantly
improved performance versus non-QDIO mode, reduction of System Assist Processor
(SAP®) utilization, improved response time, and server cycle reduction.

4.2.2 OSA-Express (MPCIPA)
As mentioned, the OSA-Express can use the I/O architecture called QDIO when defined as
channel type (CHPID) OSD. QDIO provides a highly optimized data transfer interface that
eliminates the need for channel command words (CCWs) and interrupts during data
transmission, resulting in accelerated TCP/IP packet transmission. This is done by providing
a data queue between TCP/IP and the OSA-Express. OSA-Express uses a direct memory
access (DMA) protocol to transfer the data to and from the TCP/IP stack.
The OSA-Express also provides the offloading of IP processing from the host, which is called
IP assist (IPA). With IP assist, the OSA-Express offloads the following processing from the
host:
All MAC handling is done in the card. The TCP/IP stack no longer has to fully format the
datagrams for LAN-specific media.
ARP processing for identifying the physical address.
Packet filtering, screening, and discarding of LAN packets.
The Dynamic OSA Address Table (OAT) allows for IP addresses defined in the HOME
statement of the TCP/IP stack to be downloaded into the OSA-Express when the interface is
started.
Table 4-2 lists the OSA-Express3, OSA-Express2 and OSA-Express Ethernet features that
are available on the System z servers. Included is the mode of operation in which they can
run and the necessary TCP/IP and VTAM definition types.
Table 4-2 OSA-Express features
OSA-Express VLAN support
The OSA-Express Ethernet features also support IEEE standards 802.1p/q (priority tagging
and VLAN identifier tagging). Deploying VLAN IDs enables a physical LAN to be partitioned
or subdivided into discrete virtual LANs. This support is provided by the z/OS TCP/IP stack
and OSA-Express in QDIO mode. It allows a TCP/IP stack to register specific single or
multiple VLAN IDs for both IPv4 and IPv6 for the same OSA-Express port. Note that the
VLAN IDs for IPv4 can be different than the VLAN ID for IPv6.
When a VLAN ID is configured for an OSA-Express interface in the TCP/IP stack, the
following occurs:
The TCP/IP stack becomes VLAN-aware or enabled, and the OSA-Express port is
considered to be part of a VLAN.
During activation, the TCP/IP stack registers the VLAN ID value to the OSA-Express port.
OSA-Express feature Operation
mode
TCP/IP
device type
TCP/IP link type VTAM
definitions
10 GbE LR QDIO MPCIPA IPAQENET TRLE
GbE QDIO MPCIPA IPAQENET TRLE
1000BASE-T
QDIO MPCIPA IPAQENET TRLE
Non-QDIO LCS ETHERNet, 802.3, or
ETHEROR802.3
N/A
Note: The INTERFACE statement is required if one stack is going to attach to multiple
VLANs though one OSA port.

A VLAN tag is added to all outbound packets.
The OSA-Express port filters all inbound packets based on the configured VLAN ID.
If the TCP/IP stack is also configured with PRIRouter or SECRouter for an OSA-Express port
that has a VLAN ID defined, then the stack serves as an IP router for the configured VLAN ID.
VLAN support of Generic Attribute Registration Protocol GVRP
GVRP is defined in the IEEE 802.1p standard for the control of IEEE 802.1q VLANs. It can be
used to help simplify networking administration and management of VLANs. With GVRP
support, an OSA-Express2 port can register or de-register its VLAN IDs with a
GVRP-capable switch and dynamically update its table as the VLANs change. Support of
GVRP is exclusive to System z9® or above and is applicable to all of the OSA-Express2
features when in QDIO mode. Defining DYNVLANREG in the LINK statement of the
OSA-Express2 port will enable GVRP.
OSA-Express router support
OSA-Express also provides primary (PRIRouter) and secondary (SECRouter) router support.
This function allows a single TCP/IP stack, on a per-protocol (IPv4 and IPv6) basis, to register
and act as a router stack based on a given OSA-Express port. Secondary routers can also be
configured to provide for conditions in which the primary router becomes unavailable and the
secondary router takes over for the primary router. Figure 4-2 shows how the PRIRouter
function works in a shared OSA environment.
Figure 4-2 How PRIRouter works with a shared OSA
In Figure 4-2, the terminal user connects to 10.1.4.41. Note that each stack sharing OSA1
has registered the IP addresses for VIPAs, OSAs, and the HiperSockets in the OSA Address
Table (OAT). However, the address 10.1.4.41 is not represented in OSA1’s OAT. Therefore,
the packet from the terminal that arrives at OSA1 is sent to the primary routing TCP/IP stack
LPAR A LPAR B LPAR C
PRIRouter SECRouter
HS4 10.1.4.11
VIPA 10.1.1.10
OSA 10.1.2.11
HiperSockets Network 10.1.4.0/24
Connect to 10.1.4.41
LPAR D
OSA 1
HS4 10.1.4.21
VIPA 10.1.1.20
OSA 10.1.2.21
HS4 10.1.4.31
VIPA 10.1.1.30
OSA 10.1.2.31
HS4 10.1.4.41
VIPA 10.1.1.40
OSA 10.1.3.41
OSA 2
VIPA 10.1.1.10
OSA 10.1.2.11
HS4 10.1.4.11
VIPA 10.1.1.20
OSA 10.1.2.21
HS4 10.1.4.21
VIPA 10.1.1.30
OSA 10.1.2.31
HS4 10.1.4.31
VIPA 10.1.1.40
OSA 10.1.3.41
HS4 10.1.4.41

in LPAR A. The TCP/IP stack in LPAR A uses its routing table to forward the packet to LPAR
D, where IP address 10.1.4.41 resides.
The connection to IP address 10.1.4.31 is simpler. Because the address is represented in the
OAT of OSA1, the OSA can immediately forward the request to the correct TCP/IP stack in
LPAR C.
If LPAR A should become unavailable, then the TCP/IP stack in LPAR B or C will take over the
routing responsibility for OSA1.
VLAN and primary/secondary router support
The OSA-Express primary router support takes into consideration VLAN ID support (VLAN ID
registration and tagging) and interacts with it. OSA-Express supports a primary and
secondary router on a per-VLAN basis (per registered VLAN ID).
Therefore, if an OSA interface is configured with a specific VLAN ID and also configured as a
primary or secondary router, that stack serves as a router for just that specific VLAN. This
allows each OSA-Express (CHPID) to have a primary router per VLAN. Configuring primary
routers (one per VLAN) has many advantages and preserves traffic isolation for each VLAN.
If OSA-Express ports are shared across multiple TCP/IP routing stacks, consider using virtual
MAC support for your environment instead of the PRIRouter and SECRouter options. See
Chapter 6, “VLAN and Virtual MAC support” on page 209 for details.
For more information regarding OSA-Express features and capabilities, refer to OSA-Express
Implementation Guide, SG24-5948.
4.2.3 HiperSockets (MPCIPA)
HiperSockets, also known as internal Queued Direct I/O (iQDIO), is a hardware feature that
provides high-speed LPAR-to-LPAR communications within the same sever (through
memory). It also provides secure data flows between LPARs and high availability, if there is no
network attachment dependency or exposure to adapter failures.
HiperSockets can be used to communicate among consolidated servers within a single
System z server. All the hardware boxes running these separate servers can be eliminated,
along with the cost, complexity, and maintenance of the networking components that
interconnect them.
Consolidated servers that have to access corporate data residing on the System z server can
do so at memory speeds, bypassing all the network overhead and delays.
HiperSockets can be customized to accommodate varying traffic sizes. With HiperSockets, a
maximum frame size can be defined according to the traffic characteristics transported for
each HiperSockets.
Because there is no server-to-server traffic outside the System z server, a much higher level
of network availability, security, simplicity, performance, and cost effectiveness is achieved as
compared with servers communicating across a LAN, such as:
HiperSockets has no external components. It provides a very secure connection. For
security purposes, servers can be connected to different HiperSockets or VLANs within
the same HiperSockets. All security features, like IPSec or IP filtering, are available for
HiperSockets interfaces as they are with other TCP/IP network interfaces.
HiperSockets looks like any other TCP/IP interface; therefore, it is transparent to
applications and supported operating systems.

HiperSockets can also improve TCP/IP communications within a sysplex environment
when the DYNAMICXCF is used (for example, in cases where Sysplex Distributor uses
HiperSockets within the same System z server to transfer IP packets to the target
systems).
The HiperSockets device is represented by the IQD channel ID (CHPID) and its associated
subchannel devices. All LPARs that are configured in HCD/IOCP to use the same IQD CHPID
have internal connectivity and, therefore, have the capability to communicate using
HiperSockets.
VTAM will build a single HiperSockets MPC group using the subchannel devices associated
with a single IQD CHPID. VTAM will use two subchannel devices for the read and write control
devices, and 1 to 8 devices for data devices. Each TCP/IP stack will be assigned a single data
device.
Therefore, in order to build the MPC group, there must be a minimum of three subchannel
devices defined (within HCD) and associated with the same IQD CHPID. The maximum
number of subchannel devices that VTAM will use is 10 (supporting 8 data devices or 8
TCP/IP stacks) per LPAR or MVS image.
When the server that supports HiperSockets and the CHPIDs has been configured in HCD
(IOCP), TCP/IP connectivity is provided if:
DYNAMICXCF is configured on the IPCONFIG (IPv4) or the IPCONFIG6 (IPv6)
statements.
A user-defined HiperSockets (MPCIPA) DEVICE and LINK for IPv4 or (IPAQIDIO)
INTERFACE for IPv6 is configured and started.
IQD CHPID can be viewed as a logical LAN within the server. System z servers allow up to
16 separate IQD CHPIDs, creating the capability of having up to 16 separate logical LANs
within the same server.
Each IQD CHPID can be assigned to a set of LPARs (configured in HCD), making it possible
to isolate these LPARs in separate logical LANs, as shown in of Figure 4-3.
Figure 4-3 HiperSockets: Multiple logical LANs
LPAR 1 LPAR 2
Production
LPAR 3 LPAR 4
Test
HiperSockets
(CHPID FD)
HiperSockets
(CHPID FE)
HiperSockets
(CHPID FF)
TCP/IP
Stack A
TCP/IP
Stack B
TCP/IP
Stack C
TCP/IP
Stack D
System z Server

HiperSockets multiple write
The HiperSockets multiple write facility moves multiple buffers of data with a single write
operation. This facility was added to reduce CPU utilization and to improve performance for
large outbound messages over HiperSockets.
To enable the HiperSockets multiple write facility on all HiperSockets interfaces, including
interfaces created for dynamic XCF, add the IQDMULTIWRITE parameter to the
GLOBALCONFIG statement.
For more information, see Appendix B, “Additional parameters and functions” on page 315.
HiperSockets multiple write assist with IBM zIIP
On an IBM System z10, an additional assist for HiperSockets data that is using the multiple
write facility is available through the IBM System z10 Integrated Information Processor (zIIP).
To enable HiperSockets traffic that is using the multiple write facility to be processed on
available zIIPs, specify the ZIIP IQDIOMULTIWRITE parameter on the GLOBALCONFIG
statement.
HiperSockets VLAN support
HiperSockets connections defined through DYNAMICXCF coding or through individual
DEVICE and LINK statement coding also support VLAN tagging. This allows you to split the
internal LAN represented by a single HiperSockets CHPID into multiple virtual LANs,
providing isolation for security or administrative purposes. Only stacks attached to the same
HiperSockets VLAN can communicate with each other. Stacks attached to a different
HiperSockets VLAN on the same CHPID cannot use the HiperSockets path to communicate
with the stacks on a different VLAN.
HiperSockets accelerator
The Communications Server takes advantage of the technological advances and
high-performing nature of the I/O processing offered by HiperSockets with the IBM System z
servers and OSA-Express, using the QDIO architecture. This is achieved by optimizing IP
packet forwarding processing that occurs across these two types of technologies. This
function is referred to as HiperSockets Accelerator. It is a configurable option, and is activated
by defining the IQDIORouting option on the IPCONFIG statement.
When the TCP/IP stack is configured with HiperSockets Accelerator, it allows IP packets
received from HiperSockets to be forwarded to an OSA-Express port (or vice versa) without
the need for those IP packets to be processed by the TCP/IP stack.
Restriction: HiperSockets multiple write is effective only on an IBM System z10™ and
when z/OS is not running as a guest in a z/VM® environment.
Note: The VLAN ID assigned to a HiperSockets device applies to both IPv4 and IPv6
connections over that CHPID.

When using this function, one or more LPARs contain the routing stack, which manages
connectivity through OSA-Express ports to the LAN, while the other LPARs connect to the
routing stack using the HiperSockets, as shown in Figure 4-4.
Figure 4-4 HiperSockets Accelerator
Detailed information about the subject of HiperSockets is available in HiperSockets
Implementation Guide, SG24-6816.
4.2.4 Dynamic XCF
You have a choice of defining the XCF connectivity to other TCP/IP stacks individually or
using the dynamic XCF definition facility. Dynamic XCF significantly reduces the number of
definitions that you need to create whenever a new system joins the sysplex or when you
need to start up a new TCP/IP stack. These changes become more numerous as the number
of stacks and systems in the sysplex grows. This could lead to configuration errors. With
dynamic XCF, you do not need to change the definitions of the existing stacks in order to
accommodate the new stack.
From an IP topology perspective, DYNAMICXCF establishes fully meshed IP connectivity to
all other z/OS TCP/IP stacks in the sysplex. You only need one end-point specification in each
stack for fully meshed connectivity to all other stacks in the sysplex. When a new stack gets
started, Dynamic XCF connectivity is automatically established.
Note: This example is intended purely to demonstrate IP traffic flow. We do not
recommend implementing HiperSockets Accelerator using a single LPAR.
LPAR A LPAR B LPAR C LPAR D
System z Server
TCP/IP
Stack A
TCP/IP
Stack B
TCP/IP
Stack C
TCP/IP
Stack D
HiperSockets
(CHPID FE)
HiperSockets
(CHPID FD)
LPAR E
OSA
Gigabit Ethernet Network
OSA
Note: Only one dynamic XCF network is supported per sysplex.

Dynamic XCF is required to support Sysplex Distributor and nondisruptive dynamic VIPA
movement (discussed in detail in Communications Server for z/OS V1R9 TCP/IP
Implementation Volume 3: High Availability, Scalability, and Performance, SG24-7534).
Dynamic XCF uses Sysplex Sockets support, allowing the stacks to communicate with each
other and exchange information such as VTAM CPNAMEs, MVS SYSCLONE value, and IP
addresses. The dynamic XCF definition is activated by coding the IPCONFIG DYNAMICXCF
parameter in the TCP/IP profile.
Dynamic XCF creates definitions for DEVICE, LINK, HOME, and BSDROUTINGPARMS
statements and the START statement dynamically. When activated, the dynamic XCF devices
and links appear to the stack as though they had been defined in the TCP/IP profile. They can
be displayed using standard commands, and they can be stopped and started.
During TCP/IP initialization the stack joins the XCF group, ISTXCF, through VTAM. When
other stacks in the group discover the new stack, the definitions are created automatically, the
links are activated, and the remote IP address for each link is added to the routing table. After
the remote IP address has been added, IP traffic can flow across one of the following
interfaces:
IUTSAMEH (within the same LPAR)
HiperSockets (within the same server)
XCF signaling (different server, either using the Coupling Facility link or a CTC connection)
Dynamic XCF support is illustrated in Figure 4-5.
Figure 4-5 Dynamic XCF support
LPAR 1
System z Server 1
TCP/IP
Stack A
TCP/IP
Stack B
HiperSocketsIUTSAMEH
LPAR 2
TCP/IP
Stack C
Coupling Facility Link
LPAR 3
TCP/IP
Stack D
System z Server 2
CF
Channel-to-Channel
(CTC)
(XCF
Signaling)

HiperSockets DYNAMICXCF connectivity
z/OS images within the same server with DYNAMICXCF coded will use HiperSockets
DYNAMICXCF connectivity instead of standard XCF connectivity, under these conditions:
The TCP/IP stacks must be on the same server.
For the DYNAMICXCF HiperSockets device (IUTIQDIO), the stacks must be using the
same IQD CHPID, even with different channel subsystems (spanning).
The stacks must be configured (HCD) to use HiperSockets.
For IPv6 HiperSockets connectivity, both stacks must be at z/OS V1R7 or higher.
The initial HiperSockets activation must complete successfully.
When an IPv4 DYNAMICXCF HiperSockets device and link are created and successfully
activated, a subnetwork route is created across the HiperSockets link. The subnetwork is
created by using the DYNAMICXCF IP address and mask. This allows any LPAR within the
same server to be reached, even ones that are not within the sysplex. To do that, the LPAR
that is outside of the sysplex environment must define at least one IP address for the
HiperSockets endpoint that is within the subnetwork defined by the DYNAMICXCF IP address
and mask.
When multiple stacks reside within the same LPAR that supports HiperSockets, both
IUTSAMEH and HiperSockets links or interfaces will coexist. In this case, it is possible to
transfer data across either link. Because IUTSAMEH links have better performance, it is
always better to use them for intra-stack communication. A host route will be created by
DYNAMICXCF processing across the IUTSAMEH link, but not across the HiperSockets link.
For additional information about dynamic XCF, Sysplex Distributor, and nondisruptive
dynamic VIPA movement refer to Communications Server for z/OS V1R9 TCP/IP
Implementation Volume 3: High Availability, Scalability, and Performance, SG24-7534.
4.3 Connectivity for the z/OS environment
The subsequent sections focus on the interface implementation only, which means
establishing Layer 2 and a subset of Layer 3 (IP addressing) connectivity. For details beyond
the basic implementation of the immediate LAN environment, also refer to:
Chapter 5, “Routing” on page 153 for IP routing details
Chapter 6, “VLAN and Virtual MAC support” on page 209 for use of virtual MAC
addresses
Chapter 7, “Sysplex subplexing” on page 225 for isolating TCP/IP stack in a sysplex

To design connectivity in a z/OS environment, you must take the following considerations into
account:
As a server environment, network connectivity to the external corporate network should be
carefully designed to provide a high-availability environment, avoiding single points of
failures.
If a z/OS LPAR is seen as a stand-alone server environment on the corporate network, it
should be designed as an endpoint.
If a z/OS LPAR will be used as a front-end concentrator (for example, making use of
HiperSockets Accelerator), it should be designed as an intermediate network or node.
Based on these considerations, in the following sections we present best practice scenarios
for building a z/OS Communications Server TCP/IP configuration, using OSA-Express
(QDIO), HiperSockets (iQDIO), and dynamic XCF.
We built our connectivity scenarios with two OSA-Express3 1000BASE-T features (four ports
each) that are connected to the LAN environment (one layer3 switch). We also implemented a
HiperSockets internal LAN to interconnect all LPARs within the same System z10. Finally, we
used dynamic XCF connectivity for the Sysplex environment.
The scenarios we discuss are as follows:
4.4.3, “Configuring OSA-Express with VLAN ID” on page 125
4.5.3, “Configuring HiperSockets” on page 134
4.6.3, “Configuring DYNAMICXCF” on page 139
can provide value, in general we recommend implementing only one TCP/IP stack per
LPAR. The reasons for this recommendation are as follows:
throughput.
BIND-specific support where the two HTTP server instances are each associated to
statement.
One example where multiple stacks can have value is when an LPAR needs to be
connected to multiple isolated security zones in such a way that there is no network level
connectivity between the security zones. In this case, a TCP/IP stack per security zone can
be used to provide that level of isolation, without any network connectivity between the
stacks.
Note: In our environment we connected all the OSA ports to one switch, but in a
production implementation it is best to connect your OSAs to at least two switches

For a complete picture of our implementation environment, refer to Appendix D, “Our
implementation environment” on page 357.
4.3.1 IOCP definitions
Example 4-1 is an excerpt of the IOCP statements we used in our System z environment
(only showing OSA-Express CHPID 02 and HiperSockets CHPID F4). These statements are
required by the input/output subsystem and the operating system. Because all of our
OSA-Express and HiperSockets connectivity will be used across all four LPARs, we defined
the CHPIDs as shared.
Example 4-1 IOCP statements
ID MSG2='SYS6.IODF33 - 2008-10-21 16:27',SYSTEM=(2097,1), *
LSYSTEM=SCZP201, *
TOK=('SCZP201',00800006991E2094162723470108295F00000000,*
00000000,'08-10-21','16:27:23','SYS6','IODF33')
RESOURCE PARTITION=((CSS(0),(A0A,A),(A0B,B),(A0C,C),(A0D,D),(A*
0E,E),(A0F,F),(A01,1),(A02,2),(A03,3),(A04,4),(A05,5),(A*
06,6),(A07,7),(A08,8),(A09,9)),(CSS(1),(A1A,A),(A1B,B),(*
A1C,C),(A1D,D),(A1E,E),(A1F,F),(A11,1),(A12,2),(A13,3),(*
A14,4),(A15,5),(A16,6),(A17,7),(A18,8),(A19,9)),(CSS(2),*
(A2A,A),(A2B,B),(A2C,C),(A2D,D),(A2E,E),(A2F,F),(A21,1),*
(A22,2),(A23,3),(A24,4),(A25,5),(A26,6),(A27,7),(A28,8),*
(A29,9)),(CSS(3),(A31,1),(A32,2),(A33,3),(*,4),(*,5),(*,*
6),(*,7),(*,8),(*,9),(*,A),(*,B),(*,C),(*,D),(*,E),(*,F)*
))
CHPID PATH=(CSS(2),02),SHARED, *
PARTITION=((A23,A24,A25,A29),(=)),PCHID=580,TYPE=OSD
PARTITION=((A23,A24,A25,A29),(=)),PCHID=581,TYPE=OSD
PARTITION=((A23,A24,A25,A29),(=)),PCHID=5B0,TYPE=OSD
PARTITION=((A23,A24,A25,A29),(=)),PCHID=5B1,TYPE=OSD
CHPID PATH=(CSS(0,1,2,3),F4),SHARED, *
NOTPART=((CSS(0),(A0D,A0E,A0F),(=)),(CSS(1),(A1E,A1F),(=*
)),(CSS(2),(A2E,A2F),(=))),TYPE=IQD
CNTLUNIT CUNUMBR=E800,PATH=((CSS(2),F4)),UNIT=IQD
IODEVICE ADDRESS=(E800,032),CUNUMBR=(E800),UNIT=IQD
CNTLUNIT CUNUMBR=E900,PATH=((CSS(2),F5)),UNIT=IQD
IODEVICE ADDRESS=(E900,032),CUNUMBR=(E900),UNIT=IQD
CNTLUNIT CUNUMBR=EA00,PATH=((CSS(2),F6)),UNIT=IQD
IODEVICE ADDRESS=(EA00,032),CUNUMBR=(EA00),UNIT=IQD
CNTLUNIT CUNUMBR=2080,PATH=((CSS(2),02)),UNIT=OSA
IODEVICE ADDRESS=(2080,015),CUNUMBR=(2080),UNIT=OSA
Note: In this chapter, we define only our LPARs as end points.

IODEVICE ADDRESS=208F,UNITADD=FE,CUNUMBR=(2080),UNIT=OSAD
CNTLUNIT CUNUMBR=20A0,PATH=((CSS(2),03)),UNIT=OSA
IODEVICE ADDRESS=(20A0,015),CUNUMBR=(20A0),UNIT=OSA
IODEVICE ADDRESS=20AF,UNITADD=FE,CUNUMBR=(20A0),UNIT=OSAD
CNTLUNIT CUNUMBR=20C0,PATH=((CSS(2),04)),UNIT=OSA
IODEVICE ADDRESS=(20C0,015),CUNUMBR=(20C0),UNIT=OSA
IODEVICE ADDRESS=20CF,UNITADD=FE,CUNUMBR=(20C0),UNIT=OSAD
CNTLUNIT CUNUMBR=20E0,PATH=((CSS(2),05)),UNIT=OSA
IODEVICE ADDRESS=(20E0,015),CUNUMBR=(20E0),UNIT=OSA
IODEVICE ADDRESS=20EF,UNITADD=FE,CUNUMBR=(20E0),UNIT=OSAD
4.3.2 VTAM definitions
Before getting started with configuring the scenarios in the following sections, it is important
to understand the role of VTAM in the TCP/IP configuration.
z/OS Communications Server provides a set of High Performance Data Transfer (HPDT)
services that includes MultiPath Channel (MPC), a high-speed channel interface designed for
network protocol use (for example, APPN or TCP/IP).
Multiple protocols can either share or have exclusive use of a set of channel paths to an
attached platform. MPC provides the ability to have multiple device paths, defined as a single
logical connection.
The term MPC group is used to define a single MPC connection that can contain multiple
read and write paths. The number of read and write paths does not have to be equal, but
there must be at least one read and write path defined within each MPC group.
MPC groups are defined using the Transport Resource List (TRL), where each defined MPC
group becomes an entry (that is, a TRLE) in the TRL table. The configuration and control of
the MultiPath Channel (MPC) interfaces are provided by VTAM. They are enabled in VTAM as
TRLE minor nodes.
You must define the channel paths that are a part of the group in the TRLE. Each TRLE is
identified by a resource_name. For OSA-Express, the TRLE also has a port_name to identify
the association between VTAM and TCP/IP, allowing connectivity to the OSA-Express port.
OSA-Express3 Gigabit Ethernet and 1000Base-T also defines port_num to identify which
port the TRLE definition applies to.
For HiperSockets, the TRLE is generated dynamically by VTAM.
For details about defining a TRLE, refer to z/OS Communications Server: SNA Resource
Definition, SC31-8778.
4.4 OSA-Express connectivity
Configuring an OSA-Express (QDIO mode) in a single stack scenario is the simplest way to
implement your z/OS TCP/IP stack into a LAN environment. This scenario, however, still
needs to be planned to avoid any single points of failure. Therefore, we must have at least two
OSA-Express features connecting to two different switches in the network.
Because we are dealing with multiple LPARs in our server, for redundancy purposes we have
shared the OSA-Express ports (CHPID type OSD) across all LPARs.

In this scenario, we have two OSA-Express3 1000BASE-T features, each with four ports, two
ports per channel. One port of each channel was used unless the second port was needed
for testing of new functions. This allowed us to have four CHPIDs (02, 03, 04, and 05), shared
by our four LPARs (SC30, SC31, SC32 and SC33), as shown in Figure 4-6.
To make better use of our OSA-Express ports and to control data traffic patterns, we defined
one port on each OSA-Express feature with a separate VLAN ID, creating two subnetworks to
be used by all LPARs. In a high availability configuration, these OSA-Express ports will be the
path to all of our IP addresses for the LAN environment.
Figure 4-6 OSA-Express (QDIO) implementation
SC30
TCPIPA
VIPA1L 10.1.1.10/24
OSA2080I 10.1.2.11/24
OSA20A0I 10.1.2.12/24
OSA20C0I 10.1.3.11/24
OSA20E0I 10.1.3.12/24
TCPIPB
VIPA1L 10.1.1.20/24
OSA2080I 10.1.2.21/24
OSA20A0I 10.1.2.22/24
OSA20C0I 10.1.3.21/24
OSA20E0I 10.1.3.22/24
SC31 SC32
TCPIPC
VIPA1L 10.1.1.30/24
OSA2080I 10.1.2.31/24
OSA20A0I 10.1.2.32/24
OSA20C0I 10.1.3.31/24
OSA20E0I 10.1.3.32/24
SC33
TCPIPD
VIPA1L 10.1.1.40/24
OSA2080I 10.1.2.41/24
OSA20A0I 10.1.2.42/24
OSA20C0I 10.1.3.41/24
OSA20E0I 10.1.3.42/24
VLAN 10
10.1.2.240
VLAN 11
10.1.3.240
SWITCH
CHPID 02
OSA2080
10.1.2.x1
2080-208F
CHPID 03
OSA20A0
10.1.2.x2
20A0-20AF
CHPID 04
OSA20C0
10.1.3.x1
20C0-20CF
CHPID 05
OSA20E0
10.1.3.x2
20E0-2E0F

4.4.1 Dependencies
To implement this scenario, we have the following dependencies:
The OSA-Express port must be defined as CHPID type OSD to the server using HCD or
IOCP to enable QDIO. This CHPID must be defined as shared to all LPARs that will use
the OSA-Express port (see Example 4-1 on page 122).
To define an OSA-Express port in QDIO mode, we use the MPCIPA DEVICE statement,
specifying the PORTNAME value from the TRLE definition as the device_name. The
TRLE must be defined as MPCLEVEL=QDIO.
The Virtual LAN identifiers (VLAN IDs) defined to each OSA-Express port must be
recognized by the switch.
The switch ports where the OSA-Express ports are connected must be configured in trunk
mode.
When planning connectivity for a LAN environment, there might not be a requirement to
isolate data traffic or services for certain servers or clients as we have shown in this scenario.
Therefore, VLAN IDs can be omitted.
If there is a requirement for VLANs, however, we recommend adding the VLAN IDs to your IP
addressing scheme to aid in the mapping of IP addresses to VLANs based on data traffic
patterns or access to resources.
Also, to simplify administration and management of VLANs, consider using Generic Attribute
VLAN Registration Protocol wherever possible. For details, refer to “VLAN support of Generic
Attribute Registration Protocol GVRP” on page 114.
4.4.3 Configuring OSA-Express with VLAN ID
To implement OSA-Express (QDIO) in our environment, we performed these tasks:
1. Verify the switch port configuration.
2. Define a TRLE in VTAM to represent each OSA-Express port.
In the TCP/IP profile:
1. Create DEVICE and LINK or INTERFACE statements for each OSA-Express port.
2. Create a HOME address to each defined LINK.
3. Define the characteristics of each LINK statement using BSDROUTINGPARMS.
We explain these tasks in more detail in the following sections.
Verify the switch port configuration
It is important to be aware of the switch configuration and definitions to which the
OSA-Express ports will be connected. You will need confirm the following information:
The switch ports to which the OSA-Express ports are connected.
Table 4-3 shows the OSA-Express and switch port assignment with VLAN IDs and mode
type in our configuration.

Table 4-3 OSA-Express and switch port assignment with VLAN IDs
The IP subnetwork and mask.
We used the following:
– Subnetwork 10.1.2.0, mask 255.255.255.0 for VLAN 10
– Subnetwork 10.1.3.0, mask 255.255.255.0 for VLAN 11
The appropriate switch ports should be defined in trunk mode, as shown in Example 4-2.
Example 4-2 Switch port definition from Switch 1 port 1/41
interface GigabitEthernet1/41
switchport
switchport trunk encapsulation dot1q
switchport mode trunk
no ip address
Define a TRLE in VTAM to represent each OSA-Express port
Each OSA-Express port must have a TRLE definition defined; see Example 4-3. The
PORTNAME 1 must match the device name of the DEVICE definition or the portname in
INTERFACE definition in the TCP/IP profile. The PORTNUM 2 operand is optional (default 0),
but required when defining the second port of an OSA-Express3. The statement MPCLEVEL
3 must be specified as QDIO.
Example 4-3 TRLE definition
READ=2080, *
WRITE=2081, *
DATAPATH=(2082-2088), *
1 PORTNAME=OSA2080, *
2 PORTNUM=0, *
3 MPCLEVEL=QDIO
For all OSA-Express ports in our scenarios, we used the following PORTNAMES:
OSA2080
OSA20A0
OSA20C0
OSA20E0
OSA-Express port Connects to switch Switch port VLAN ID (mode)
CHPID 02 (2080) Switch 1 Interface GIGA 1/8 10 (Trunk mode)
CHPID 03 (20A0) Switch 1 interface GIGA 1/41 10 (Trunk mode)
CHPID 04 (20C0) Switch 1 Interface GIGA 1/43 11 (Trunk mode)
CHPID 05 (20E0) Switch 1 Interface GIGA 1/19 11 (Trunk mode)

Create DEVICE and LINK or INTERFACE statements for each
OSA-Express port
The next step is to create the device and link or interface statements for each OSA-Express
port, as shown in Example 4-4.
The device definition of an OSA-Express port must be set as an MPCIPA device type 1. The
link definition describes the type of transport used (in our case, QDIO Ethernet, defined as
IPAQENET 2). VLAN ID 3 defines the VLAN number the packets will be tagged with as they
are being sent out to the switch.
Example 4-4 OSA-Express device and link definitions
;OSA DEFINITIONS
;TRL MAJ NODE: OSA2080,OSA20A0,OSA20C0,AND OSA20E0
DEVICE OSA2080 MPCIPA 1
LINK OSA2080L IPAQENET 2 OSA2080 VLANID 10 3
DEVICE OSA20C0 MPCIPA
LINK OSA20C0L IPAQENET OSA20C0 VLANID 11
DEVICE OSA20E0 MPCIPA
LINK OSA20E0L IPAQENET OSA20E0
DEVICE OSA20A0 MPCIPA
LINK OSA20A0L IPAQENET OSA20A0
The alternative interface statement of OSA-Express ports combines the definitions otherwise
coded in the device, link, home, beginroutes and bsdroutingparms statements, and as such
requires a label 1, the type of transport used (QDIO Ethernet, defined as IPAQENET 2 is the
only type allowed for IPv4 devices), a portname 3 matching the TRLE portname, an IP
address and optional subnetmask 4, optional MTU size 5, VLANID 6, VMAC 7 (required when
setting multiple VLANs on the same physical OSA port) and SOURCEVIPAINT 8 which
associates a specific VIPA with this interface.
Example 4-5 OSA-Express interface definition
INTERFACE OSA20A0I 1
DEFINE IPAQENET 2
PORTNAME OSA20A0 3
IPADDR 10.1.2.12/24 4
MTU 1492 5
VLANID 20 6
VMAC 7
SOURCEVIPAINT VIPA2L 8
Note: We encourage and recommend the use of the INTERFACE statement as it groups
all the definition required in the one spot.
Note: You can only define a single VLAN per each OSA port with device and link
statement. If you want to define multiple VLANs on a single OSA port, you need to define it
with the interface statement.
Note: If SOURCEVIPAINT is coded, the whole INTERFACE definition block must be
defined in PROFILE after the VIPA DEVICE and LINK statements are defined.

Create a HOME address to each defined LINK
Each link configured must have its own IP address. Our OSA-Express ports are defined with
the IP addresses shown in Example 4-6.
Example 4-6 OSA-Express HOME addresses
HOME
10.1.2.11 OSA2080L
10.1.3.11 OSA20C0L
10.1.3.12 OSA20E0L
10.1.2.12 OSA20A0L
Define the characteristics of each LINK statement using
BSDROUTINGPARMS
To define the link characteristics, such as MTU size 1 and subnet mask 2, we used the
BSDROUTINGPARMS statements (see Example 4-7).
If not supplied, defaults are used from static routing definitions in BEGINROUTES or the
OMPROUTE configuration (dynamic routing definitions), if implemented.
If the link characteristics, BEGINROUTES statements, or the OMPROUTE configuration are
not defined, then the stack’s interface layer (based on hardware capabilities) and the
characteristics of devices and links are used. This, however, might not provide the
performance or function desired.
Example 4-7 BSDRoutingparms statements
BSDROUTINGPARMS TRUE
; Link name MTU Cost metric Subnet Mask Dest address
VIPA1L 1492 1 0 255.255.255.252 0
OSA2080L 1492 0 255.255.255.0 2 0
OSA20A0L 1492 0 255.255.255.0 0
OSA20C0L 1492 0 255.255.255.0 0
OSA20E0L 1492 0 255.255.255.0 0
ENDBSDROUTINGPARMS
Note: This step is not required when defining OSA ports through the INTERFACE
statement.
Note: This step is not required when defining OSA ports through the INTERFACE
statement.
Note: Static and dynamic routing definitions will override or replace the link characteristics
defined through the BSDROUTINGPARMS statements. Refer to Chapter 5, “Routing” on
page 153 for more information about static and dynamic routing.

4.4.4 Verifying the connectivity status
In this section, we verify the status of the OSA devices defined to the TCP/IP stack and
VTAM.
Verifying the device status in TCP/IP stack
To verify the status of all devices being activated in the TCP/IP stack we use the NETSTAT
command with the DEVLIST option, as shown in Example 4-8.
Example 4-8 Using command D TCPIP,TCPIPA,N,DEV to verify the Device status
D TCPIP,TCPIPA,N,DEV
........................................................................ Lines
deleted
DEVNAME: OSA2080 DEVTYPE: MPCIPA
DEVSTATUS: READY
LNKNAME: OSA2080L LNKTYPE: IPAQENET LNKSTATUS: READY
SPEED: 0000001000
ACTMTU: 8992
VLANID: 10 VLANPRIORITY: DISABLED
BSD ROUTING PARAMETERS:
MTU SIZE: 1492 METRIC: 90
DESTADDR: 0.0.0.0 SUBNETMASK: 255.255.255.0
MULTICAST SPECIFIC:
MULTICAST CAPABILITY: YES
GROUP REFCNT SRCFLTMD
----- ------ --------
224.0.0.5 0000000001 EXCLUDE
SRCADDR: NONE
224.0.0.1 0000000001 EXCLUDE
SRCADDR: NONE
LINK STATISTICS:
BYTESIN = 19920
INBOUND PACKETS = 177
INBOUND PACKETS IN ERROR = 0
INBOUND PACKETS DISCARDED = 0
INBOUND PACKETS WITH NO PROTOCOL = 0
BYTESOUT = 18648
OUTBOUND PACKETS = 186
OUTBOUND PACKETS IN ERROR = 0
OUTBOUND PACKETS DISCARDED = 0
........................................................................ Lines
deleted
INTFNAME: OSA20A0I INTFTYPE: IPAQENET INTFSTATUS: READY
PORTNAME: OSA20A0 DATAPATH: 20A2 DATAPATHSTATUS: READY
SPEED: 0000001000

IPADDR: 10.1.2.12/24
MULTICAST SPECIFIC:
----- ------ --------
224.0.0.1 0000000001 EXCLUDE
SRCADDR: NONE
INTERFACE STATISTICS:
BYTESIN = 84
INBOUND PACKETS = 1
BYTESOUT = 0
Displaying TCP/IP device resources in VTAM
The device drivers for TCP/IP are provided by VTAM. When CS for z/OS IP devices are
activated, there must be an equivalent Transport Resource List Element (TRLE) defined to
VTAM. The devices that are exclusively used by z/OS Communications Server IP have
TRLEs that are automatically generated for them.
Because the device driver resources are provided by VTAM, you have the ability to display the
resources using VTAM display commands.
To display a list of all TRLEs active in VTAM, use the command D NET,TRL, as shown in
Example 4-9.
Example 4-9 D NET,TRL command output
D NET,TRL
IST097I DISPLAY ACCEPTED
IST350I DISPLAY TYPE = TRL 605
IST924I -------------------------------------------------------------
IST1954I TRL MAJOR NODE = ISTTRL
IST1314I TRLE = ISTT3032 STATUS = ACTIV CONTROL = XCF
IST1314I TRLE = IUTIQDF6 STATUS = ACTIV CONTROL = MPC
IST1314I TRLE = IUTIQDIO STATUS = ACTIV CONTROL = MPC
IST1314I TRLE = IUTSAMEH STATUS = ACTIV CONTROL = MPC
IST1454I 8 TRLE(S) DISPLAYED
IST924I -------------------------------------------------------------

IST1954I TRL MAJOR NODE = TRLTONET
IST1314I TRLE = MPCNET STATUS = ACTIV CONTROL = MPC
IST924I -------------------------------------------------------------
IST1314I TRLE = OSA2040P STATUS = ACTIV CONTROL = MPC
IST924I -------------------------------------------------------------
IST924I -------------------------------------------------------------
IST1954I TRL MAJOR NODE = OSA20A0
IST1314I TRLE = OSA20A0P STATUS = ACTIV CONTROL = MPC
IST924I -------------------------------------------------------------
IST1954I TRL MAJOR NODE = OSA20C0
IST1314I TRLE = OSA20C0P STATUS = ACTIV CONTROL = MPC
IST924I -------------------------------------------------------------
IST1954I TRL MAJOR NODE = OSA20E0
IST1314I TRLE = OSA20E0P STATUS = ACTIV CONTROL = MPC
IST314I END
You can also display information of TRLEs grouped by control type, such as MPC or XCF
devices, as shown in Example 4-21.
Example 4-10 D NET,TRL,CONTROL=MPC
D NET,TRL,CONTROL=MPC
IST350I DISPLAY TYPE = TRL
IST924I -------------------------------------------------------------
IST924I -------------------------------------------------------------
IST1954I TRL MAJOR NODE = TRLTONET
IST1314I TRLE = MPCNET STATUS = ACTIV CONTROL = MPC
IST924I -------------------------------------------------------------
IST924I -------------------------------------------------------------
IST1314I TRLE = OSA20A0P STATUS = ACTIV CONTROL = MPC

IST924I -------------------------------------------------------------
IST1954I TRL MAJOR NODE = OSA20C0
IST1314I TRLE = OSA20C0P STATUS = ACTIV CONTROL = MPC
IST924I -------------------------------------------------------------
IST1954I TRL MAJOR NODE = OSA20E0
IST1314I TRLE = OSA20E0P STATUS = ACTIV CONTROL = MPC
IST314I END
We can also get specific information about a single TRLE, using the TRLE name as shown in
Example 4-11, for an OSA-Express device.
Example 4-11 D NET,TRL,TRLE=OSA2080P
IST486I STATUS= ACTIV, DESIRED STATE= ACTIV
IST1716I PORTNAME = OSA2080 LINKNUM = 0 OSA CODE LEVEL = 087A
IST1221I WRITE DEV = 2081 STATUS = ACTIVE STATE = ONLINE
IST1221I READ DEV = 2080 STATUS = ACTIVE STATE = ONLINE
IST1221I DATA DEV = 2082 STATUS = ACTIVE STATE = N/A
IST2190I DEVICEID PARAMETER FOR OSAENTA TRACE COMMAND = 02-03-00-02
IST1801I UNITS OF WORK FOR NCB AT ADDRESS X'131B3010'
IST314I END

4.5 HiperSockets connectivity
HiperSockets provides very fast TCP/IP communications between different logical partitions
(LPARs) through the system memory of the System z server. The LPARs that are connected
this way form an internal LAN, passing data between the LPARs at memory speeds, and
thereby totally eliminating the I/O subsystem overhead and external network delays.
To create this scenario, we define the HiperSockets, which is represented by the IQD CHPID
and its associated devices. All LPARs that are configured to use the shared IQD CHPID have
internal connectivity, and therefore have the capability to communicate using HiperSockets.
In our environment we use three IQD CHPIDs (F4, F5, and F6). Each will create a separate
logical LAN with its own subnetwork. Figure 4-7 depicts these interfaces to our scenario.
Figure 4-7 HiperSockets implementation scenario
4.5.1 Dependencies
The dependencies are:
The HiperSockets must be defined as CHPID type IQD to the server using HCD or IOCP.
This CHPID must be defined as shared to all LPARs that will be part of the HiperSockets
internal LAN (see Example 4-1 on page 122).
When explicitly defined, a correspondent TRLE must be created in VTAM using a port
name IUTIQDxx, where xx is the CHPID number.
When more than one IQD CHPID is configured to a specific LPAR, the VTAM start option
IQDCHPID must be used to specify which specific IQD CHPID this LPAR should use.
A23 (SC30)
TCPIPA
IUTIQDF4L 10.1.4.11/24
IUTIQDF5L 10.1.5.11/24
IUTIQDF6L 10.1.6.11/24
TCPIPB
IUTIQDF4L 10.1.4.21/24
IUTIQDF5L 10.1.5.21/24
IUTIQDF6L 10.1.6.21/24
A24 (SC31) A25 (SC32)
TCPIPC
IUTIQDF4L 10.1.4.31/24
IUTIQDF5L 10.1.5.31/24
IUTIQDF6L 10.1.6.31/24
A26 (SC33)
TCPIPD
IUTIQDF4L 10.1.4.41/24
IUTIQDF5L 10.1.5.41/24
IUTIQDF6L 10.1.6.41/24
Note: In both cases, the TRLE is dynamically built by VTAM. The IQDCHPID VTAM
start option controls the VTAM selection of which IQD CHPID (and related devices) to
include in the HiperSockets MPC group (IUTIQDIO) when it is dynamically built for
DYNAMICXCF connectivity.
For additional details regarding how to configure a user-defined HiperSockets device or
interface, refer to z/OS Communications Server: IP Configuration Reference,
SC31-8776.

For isolation of IP traffic between LPARs through HiperSockets, consider using VLANs, which
means that you can logically subdivide the internal LAN for a HiperSockets CHPID into
multiple virtual LANs. Therefore, stacks that configure the same VLAN ID for the same CHPID
can communicate over that given HiperSockets, while stacks that have no VLAN ID or a
different VLAN ID configured cannot.
For HiperSockets, the VLAN ID applies to IPv4 and IPv6 connections. HiperSockets
VLAN IDs can be defined using the VLANID parameter on a LINK or INTERFACE statement.
Valid VLAN IDs are in the range of 1 to 4094.
4.5.3 Configuring HiperSockets
The steps to implement HiperSockets are basically the same as with an OSA-Express
interface. What changes is that there is no external configuration to be done, and the TRLE is
created dynamically by VTAM.
The steps in the TCP/IP profile are as follows:
1. Create a DEVICE and LINK statements for each HiperSockets CHPID.
2. Create a HOME address to each defined LINK.
3. Define the characteristics of each LINK statement using BSDROUTINGPARMS.
Create a DEVICE and LINK statements for each HiperSockets CHPID
When defining an MPCIPA HiperSockets, use the DEVICE statement to specify the IQD
CHPID hexadecimal value. The reserved device name prefix IUTIQDxx must be specified.
The suffix xx indicates the hexadecimal value of the corresponding IQD CHPID that was
configured with HCD or IOCP.
Define the device and link statements for each HiperSockets CHPID being implemented, as
shown in Example 4-12. A HiperSockets CHPID must be defined as an MPCIPA type of
device 1.
The link definition describes the type of transport being used. A HiperSockets link is defined
as IPAQIDIO 2.
Example 4-12 HiperSockets device and link definitions
;HiperSockets definition. The TRLE is dynamically created on VTAMs
DEVICE IUTIQDF4 MPCIPA 1
LINK IUTIQDF4L IPAQIDIO 2 IUTIQDF4
Important: The hexadecimal value specified here represents the CHPID, and it cannot be
the same value as that used for the dynamic XCF HiperSockets interface.

Create a HOME address to each defined LINK
Each link configured must have its own IP address. Our HiperSockets links are defined with
the IP addresses, as shown in Example 4-13.
Example 4-13 HiperSockets HOME addresses
HOME
10.1.4.11 IUTIQDF4L
10.1.5.11 IUTIQDF5L
10.1.6.11 IUTIQDF6L
Define the characteristics of each LINK statement using
BSDROUTINGPARMS
To define the link characteristics, such as MTU size (1) and subnet mask (2), we used the
BSDROUTINGPARMS statements (see Example 4-14 on page 135). If not supplied, defaults
will be used from static routing definitions in BEGINROUTES or the OMPROUTE
configuration (dynamic routing definitions), if implemented.
If the link characteristics, BEGINROUTES statements, or the OMPROUTE configuration are
not defined, then the stack's interface layer (based on hardware capabilities) and the
characteristics of devices and links are used. This, however, might not provide the
performance or function desired.
Example 4-14 BSDRoutingparms statements
VIPA1L 1492 0 255.255.255.252 0
OSA2080L 1492 0 255.255.255.0 0
OSA20A0L 1492 0 255.255.255.0 0
OSA20C0L 1492 0 255.255.255.0 0
OSA20E0L 1492 0 255.255.255.0 0
IUTIQDF4L 8192 1 0 255.255.255.0 2 0
IUTIQDF5L 8192 0 255.255.255.0 0
IUTIQDF6L 8192 0 255.255.255.0 0
ENDBSDROUTINGPARMS
4.5.4 Verifying the connectivity status
In this section, we verify the status of all devices defined to the TCP/IP stack or VTAM.
Verifying the device status in TCP/IP stack
To verify the status of all devices being activated in the TCP/IP stack we use the NETSTAT
Example 4-15 Using command D TCPIP,TCPIPA,N,DEV to verify the HiperSockets connection
DEVNAME: IUTIQDF4 DEVTYPE: MPCIPA
DEVSTATUS: READY
LNKNAME: IUTIQDF6L LNKTYPE: IPAQIDIO LNKSTATUS: READY
Note: Static and dynamic routing definitions will override or replace the link characteristics
defined through the BSDROUTINGPARMS statements. Refer to Chapter 5, “Routing” on
page 153 for more information about static and dynamic routing.

NETNUM: N/A QUESIZE: N/A
ACTMTU: 8192
READSTORAGE: GLOBAL (2048K)
MULTICAST SPECIFIC:
----- ------ --------
224.0.0.6 0000000001 EXCLUDE
SRCADDR: NONE
224.0.0.5 0000000001 EXCLUDE
SRCADDR: NONE
224.0.0.1 0000000001 EXCLUDE
SRCADDR: NONE
SRCADDR: NONE
LINK STATISTICS:
BYTESIN = 34931365
BYTESOUT = 16987569
For TRLEs that are generated dynamically, the device type and address can be decoded from
the generated TRLE name. The format of the TRLE name is IUTtaaaa:
IUT Fixed for all TRLEs that are generated dynamically.
t Shows the device type, which indicates the following:
C Indicates this is a CDLC device.
H Indicates this is a HYPERCHANNEL device.
I Indicates this a QDIO device.
L Indicates this is a LCS device.
S Indicates this is a SAMEHOST device.
W Indicates this is a CLAW device.
X Indicates this is a CTC device.
aaaa The read device number. For SAMEHOST connections, this is a sequence
number.

To display a list of all TRLEs active in VTAM, use the D NET,TRL command, as shown in
Example 4-16.
D NET,TRL
IST924I -------------------------------------------------------------
IST924I -------------------------------------------------------------
The D NET,TRL,TRLE command that is used to obtain information about a HiperSockets
device is shown in Example 4-17.
Example 4-17 D NET,TRL,TRLE=IUTIQDF6
D NET,TRL,TRLE=IUTIQDF6
IST075I NAME = IUTIQDF6, TYPE = TRLE 620
IST1716I PORTNAME = LINKNUM = 0 OSA CODE LEVEL = *NA*
IST1221I WRITE DEV = EA01 STATUS = ACTIVE STATE = ONLINE
IST1221I READ DEV = EA00 STATUS = ACTIVE STATE = ONLINE
IST1221I DATA DEV = EA02 STATUS = ACTIVE STATE = N/A
IST1801I UNITS OF WORK FOR NCB AT ADDRESS X'0EB5B010'
IST1221I DATA DEV = EA03 STATUS = RESET STATE = N/A

IST314I END
4.6 Dynamic XCF connectivity
The last connectivity scenario that we add to our environment connects all images within the
same sysplex environment through a dynamic XCF connection that is created by the
DYNAMICXCF definition in the TCP/IP profile.
After being defined, DYNAMICXCF provides connectivity between stacks under the same
LPAR by using the IUTSAMEH device (SAMEHOST) and between LPARs through
HiperSockets using a IUTiQDIO device. To connect other z/OS images or other servers, an
XCF Coupling Facility link is created.
In our scenario, we use DYNAMICXCF through HiperSockets with IQD CHPID F7. So, by
defining the DYNAMICXCF statement, we create the XCF subnetwork through HiperSockets,
as shown in Figure 4-8.
Figure 4-8 Dynamic XCF environment
4.6.1 Dependencies
The dependencies are as follows:
All z/OS hosts must belong to the same sysplex.
VTAM must have XCF communications enabled by specifying XCFINIT=YES or
XCFINIT=DEFINE as a startup parameter or by activating the VTAM XCF local SNA major
node, ISTLSXCF. For details about configuration, refer to z/OS Communications Server:
SNA Network Implementation, SC31-8777.
A23 (SC30)
TCPIPA
XCF 10.1.7.11/24
TCPIPB
XCF 10.1.7.21/24
A24 (SC31) A25 (SC32)
TCPIPC
XCF 10.1.7.31/24
A26 (SC33)
TCPIPD
XCF 10.1.7.41/24
XCF
10.1.7.x1

DYNAMICXCF must be specified in the TCP/IP profile of each stack.
The IQD CHPID being used for the DYNAMICXCF device cannot be the user-defined
HiperSockets device (IQD CHPID). To avoid this, a VTAM start option, IQDCHPID, can be
used to identify which IQD CHPID will be used by DYNAMICXCF.
z/OS Communications Server has improved and optimized Sysplex IP routing. In a sysplex
environment, you might prefer to use a connection other than a Coupling Facility link for
cross-server connectivity because XCF is heavily used by other workloads (in particular, for
distributed application data sharing).
This option can be configured with the VIPAROUTE statement in the VIPADYNAMIC
statement. It allows for the use of OSA-Express features such as 1000BASE-T Ethernet,
Gigabit Ethernet and 10 Gigabit Ethernet. For details refer to Communications Server for
z/OS V1R9 TCP/IP Implementation Volume 3: High Availability, Scalability, and Performance,
SG24-7534.
z/OS Communications Server supports sysplex subplexing in conjunction with HiperSockets
and DYNAMICXCF. Refer to Chapter 7, “Sysplex subplexing” on page 225, for details about
restricting data traffic flow among certain TCP/IP stacks in a sysplex environment.
4.6.3 Configuring DYNAMICXCF
To implement XCF connections in our environment, you can use three different types of
devices:
DynamicXCF HiperSockets device (IUTIQDIO) for connections between z/OS LPARs
within the same server
DynamicXCF SAMEHOST device (IUTSAMEH) for stacks within the same LPAR
VTAM dynamically created ISTLSXCF to connect z/OS LPARs in other servers within the
same sysplex
Figure 4-8 on page 138 shows the DynamicXCF implementation in our environment using
HiperSockets CHPID F7.
When you use dynamic XCF for sysplex configuration, make sure that XCFINIT=YES or
XCFINIT=DEFINE is coded in the VTAM start options.
If XCFINIT=NO was specified, issue the VARY ACTIVATE command for the ISTLSXCF major
node. This ensures that XCF connections between TCP stacks on different VTAM nodes in
the sysplex can be established.

The VTAM ISTLSXCF major node must be active for DYNAMICXCF work, except for the
following scenarios:
Multiple TCP/IP stacks on the same LPAR; a dynamic SAMEHOST definition is generated
whether or not ISTLSXCF is active.
HiperSockets is configured and enabled across multiple z/OS LPARs that are in the same
sysplex and the same server. If this is the case, a dynamic IUTIQDIO link is created
whether ISTLSXCF is active or not.
To implement DYNAMICXCF in our environment, we coded the IPCONFIG definitions in the
TCP/IP profile, as shown in Example 4-18. To control the IP subnetwork used to connect all
z/OS images, we define the XCF IP address, the IP mask, and the link cost in the
DYNAMICXCF statement 1.
Example 4-18 IPCONFIG DYNAMICXCF configuration
IPCONFIG DATAGRAMFWD SYSPLEXROUTING IPSECURITY
DYNAMICXCF 10.1.7.11 255.255.255.0 1 1
4.6.4 Verifying connectivity status
In this section, we verify the status of all devices that are defined to the TCP/IP stack or
VTAM.
Verifying the device status in the TCP/IP stack
To verify the status of all devices being activated in the TCP/IP stack, use the NETSTAT
Example 4-19 Using command D TCPIP,TCPIPA,N,DEV to verify the device status
........................................................................ Lines
deleted
DEVNAME: IUTSAMEH DEVTYPE: MPCPTP
DEVSTATUS: SENT SETUP
LNKNAME: EZASAMEMVS LNKTYPE: MPCPTP LNKSTATUS: NOT ACTIVE
ACTMTU: UNKNOWN
SECCLASS: 255
MULTICAST SPECIFIC:
----- ------ --------
224.0.0.6 0000000001 EXCLUDE
SRCADDR: NONE
224.0.0.5 0000000001 EXCLUDE
SRCADDR: NONE
224.0.0.1 0000000001 EXCLUDE
SRCADDR: NONE
LINK STATISTICS:
BYTESIN = 0
INBOUND PACKETS = 0

BYTESOUT = 0
DEVNAME: IUTIQDIO DEVTYPE: MPCIPA
DEVSTATUS: READY
LNKNAME: IQDIOLNK0A01070B LNKTYPE: IPAQIDIO LNKSTATUS: READY
ACTMTU: 8192
VLANID: NONE
SECCLASS: 255
IQDMULTIWRITE: DISABLED
MULTICAST SPECIFIC:
----- ------ --------
224.0.0.6 0000000001 EXCLUDE
SRCADDR: NONE
224.0.0.5 0000000001 EXCLUDE
SRCADDR: NONE
224.0.0.1 0000000001 EXCLUDE
SRCADDR: NONE
LINK STATISTICS:
BYTESIN = 0
INBOUND PACKETS = 0
BYTESOUT = 16128
Note: The link name for device IUTIQDIO is defined dynamically as IQDIOLNK0A01070B.
In the link name, 0A01070B is the hexadecimal value of the assigned IP address
(10.1.7.11).

For TRLEs that are generated dynamically, the device type and address can be decoded from
the generated TRLE name. The format of the TRLE name is IUTtaaaa:
IUT Fixed for all TRLEs that are generated dynamically.
t Shows the device type, which indicates the following:
C Indicates this is a CDLC device.
H Indicates this is a HYPERCHANNEL device.
I Indicates this a QDIO device.
L Indicates this is a LCS device.
S Indicates this is a SAMEHOST device.
W Indicates this is a CLAW device.
X Indicates this is a CTC device.
aaaa The read device number. For SAMEHOST connections, this is a sequence
number.
For XCF links, the format of the TRLE name is ISTTxxyy. ISTT is fixed, xx is the SYSCLONE
value of the originating VTAM, and yy is the SYSCLONE value of the destination VTAM.
To display a list of all TRLEs active in VTAM use the D NET,TRL command, as shown in
Example 4-20.
D NET,TRL
IST924I -------------------------------------------------------------
IST924I -------------------------------------------------------------
IST314I END
You can display information of TRLEs grouped by control type, such as MPC or XCF devices,
as shown in Example 4-21.
Example 4-21 D NET,TRL,CONTROL=XCF
D NET,TRL,CONTROL=XCF
IST924I -------------------------------------------------------------
IST924I -------------------------------------------------------------

You can also display XCF TRLE-specific information, as shown in Example 4-22.
Example 4-22 D NET,TRL,TRLE=ISTT3031
D NET,TRL,TRLE=ISTT3031
IST075I NAME = ISTT3031, TYPE = TRLE 624
IST087I TYPE = LEASED , CONTROL = XCF , HPDT = *NA*
IST1715I MPCLEVEL = HPDT MPCUSAGE = SHARE
IST1717I ULPID = ISTP3031
IST1503I XCF TOKEN = 0200002F00200002 STATUS = ACTIVE
IST1502I ADJACENT CP = USIBMSC.SC31M
IST314I END
The DYNAMICXCF configuration created a HiperSockets TRLE named IUTIQDIO. The
related TRLE status can also be displayed, as shown in Example 4-23.
Example 4-23 D NET,TRL,TRLE=IUTIQDIO
D NET,TRL,TRLE=IUTIQDIO
IST075I NAME = IUTIQDIO, TYPE = TRLE 628
IST1716I PORTNAME = IUTIQDF7 LINKNUM = 0 OSA CODE LEVEL = *NA*
IST1221I WRITE DEV = EB01 STATUS = ACTIVE STATE = ONLINE
IST1221I READ DEV = EB00 STATUS = ACTIVE STATE = ONLINE
IST1221I DATA DEV = EB02 STATUS = ACTIVE STATE = N/A
IST1801I UNITS OF WORK FOR NCB AT ADDRESS X'13143010'
IST1221I DATA DEV = EB03 STATUS = RESET STATE = N/A

The DYNAMICXCF configuration created a SAMEHOST TRLE named IUTSAMEH. The
related TRLE status can be displayed, as shown in Example 4-24.
Example 4-24 D NET,TRL,TRLE=IUTSAMEH
D NET,TRL,TRLE=IUTSAMEH
IST075I NAME = IUTSAMEH, TYPE = TRLE 634
IST1715I MPCLEVEL = HPDT MPCUSAGE = SHARE
IST314I END
The DYNAMICXCF statement dynamically generates the DEVICE, LINK, and HOME
statements. It also starts the device when the TCP/IP stack is activated, as we can see in the
messages shown in Example 4-25.
Example 4-25 DYNAMICXCF messages
EZZ0350I SYSPLEX ROUTING SUPPORT IS ENABLED
EZZ0624I DYNAMIC XCF DEFINITIONS ARE ENABLED
EZD1176I TCPIPA HAS SUCCESSFULLY JOINED THE TCP/IP SYSPLEX GROUP EZBTCPCS
EZZ4324I CONNECTION TO 10.1.7.51 ACTIVE FOR DEVICE IUTSAMEH 1
EZZ4313I INITIALIZATION COMPLETE FOR DEVICE IUTSAMEH
EZZ4324I CONNECTION TO 10.1.7.31 ACTIVE FOR DEVICE IUTSAMEH 1
EZZ4313I INITIALIZATION COMPLETE FOR DEVICE IUTIQDIO 2
1. Indicates that the TCPIPA stack has been connected to the other stacks through XCF
using a SAMEHOST device.
2. Indicates that XCF will also use HiperSockets to connect other TCP/IP stacks within the
same server, using a IUTIQDIO device.
4.7 Controlling and activating devices
After all required connectivity definitions are defined in the TCP/IP profile and the stack is
started, you have the option to start and stop devices, as well as activate modified device
definitions. In this section we show the commands used to perform these tasks.
4.7.1 Starting a device
A device can be started by any of the following methods:
Defining the START statement in the TCP/IP profile, as shown in Example 4-26.
Example 4-26 Start statements in TCP/IP profile
START OSA2080
START OSA20C0
START OSA20E0
START OSA20A0

START IUTIQDF4
START IUTIQDF5
START IUTIQDF6
Using the z/OS console command VARY TCPIP,tcpipproc,start,devicename.
Creating a file with a start statement and using the z/OS console command
Vary TCPIP,tcpipproc,OBEYFILE,datasetname. The file defined by the file name has the
START statement to activate the desired device or devices.
Using any of the starting methods will result in a series of messages, as shown in
Example 4-27.
Example 4-27 Starting a TCP/IP device
V TCPIP,TCPIPA,START,OSA2080
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,START,OSA2080
EZZ0053I COMMAND VARY START COMPLETED SUCCESSFULLY
4.7.2 Stopping a device
You can stop a device using any of the following methods:
Using the z/OS console command Vary TCPIP,tcpipproc,STOP,devicename.
Creating a file with the stop statement to the desired device or devices and using the z/OS
console command Vary TCPIP,tcpipproc,OBEYFILE,datasetname.
When you stop a device, you see messages as shown in Example 4-28.
Example 4-28 Stop command resulting messages
V TCPIP,TCPIPA,STOP,OSA2080
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,STOP,OSA2080
EZZ4329I LINK OSA20A0L HAS TAKEN OVER ARP RESPONSIBILITY FOR INACTIVE LINK
OSA2080L
EZZ4315I DEACTIVATION COMPLETE FOR DEVICE OSA2080
4.7.3 Activating modified device definitions
You can activate modified device definitions by issuing the OBEY command:
Vary TCPIP,tcpipproc,OBEYFILE,datasetname
Note: When an OSA-Express device is stopped or loses its connection to the switch,
another OSA-Express device defined to the TCP/IP stack will take over the IP address. A
gratuitous ARP is broadcasted on the LAN to advertise the new MAC address related to
the IP address being taken over. Message EZZ4329I in Example 4-28 indicates this action.

Authorization to use this command is through the user’s RACF profile. The datasetname
variable cannot be a z/OS UNIX file system file. The data set contains the modified TCP/IP
configuration statements. See Example 4-29.
Example 4-29 OBEYFILE example
;Original BSDROUTINGPARMS statement for link OSA2080
;BSDROUTINGPARMS TRUE
;OSA2080L 1492 0 255.255.255.0 0
;ENDBSDROUTINGPARMS
;Modified BSDROUTINGPARMS statement for link OSA20C0
OSA2080L 1024 0 255.255.255.0 0
ENDBSDROUTINGPARMS
Isolating network problems is an essential step to verify a connectivity problem in your
environment. This section introduces commands and techniques that can use to diagnose
network connectivity problems related to a specific interface. The diagnostic commands that
we discuss in this section are available for either the z/OS UNIX environment or the TSO
environment.
The ping command
The ping command can be very useful for determining if a destination address can be
reached in the network. Based on the results, it is possible to define whether the problem is
related to the interface being tested, or whether it is a network-related problem.
Using ping, you can verify the following information:
The directly-attached network is defined correctly.
The device is properly connected to the network.
The device is able to send and receive packets on the network.
The remote host is able to receive and send packets.
Important: Dynamic XCF cannot be changed by using the OBEYFILE command. If you
want to change the IPCONFIG DYNAMICXCF parameters, stop TCP/IP, code a new
IPCONFIG DYNAMICXCF statement in the initial profile, and restart TCP/IP.

When you issue a ping command, you can receive any of the responses listed in Table 4-4.
Table 4-4 Using the ping command as a debugging tool
The Netstat command
You can use the Netstat command to verify the TCP/IP configuration. You need to check the
information that is provided in the output from the Netstat command against the values in the
configuration data sets for the TCP/IP stack. To verify connectivity status from an interface
perspective, use the following Netstat options:
Netstat HOME/-h
Displays all defined interfaces and their IP addresses, even those interfaces that are
created dynamically, as shown in Example 4-30.
Example 4-30 NETSTAT HOME command results
D TCPIP,TCPIPA,N,HOME
HOME ADDRESS LIST:
LINKNAME: VIPA3L
ADDRESS: 10.1.30.10
FLAGS:
LINKNAME: VIPA1L
ADDRESS: 10.1.1.10
FLAGS: PRIMARY
LINKNAME: VIPA2L
ADDRESS: 10.1.2.10
FLAGS:
LINKNAME: OSA2080L
ADDRESS: 10.1.2.11
FLAGS:
LINKNAME: OSA20C0L
ADDRESS: 10.1.3.11
FLAGS:
LINKNAME: OSA20E0L
ADDRESS: 10.1.3.12
FLAGS:
LINKNAME: OSA20A0L
ADDRESS: 10.1.2.12
FLAGS:
LINKNAME: IUTIQDF4L
ADDRESS: 10.1.4.11
FLAGS:
ping command
(direct network)
ping response Possible cause and actions
ping 10.1.2.11
(intf osa2080l)
CS V1R10: Pinging host 10.1.2.11
sendMessage(): EDC8130I Host
cannot be reached.
The interface being tested has a problem.
Use the Netstat command to verify the interface
status.
ping 10.1.2.11
(intf osa2080l)
Ping #1 timed out.
The ICMP packet has been sent to the network,
but the destination address is either invalid or it is
not able to answer. Correct the destination
address or verify the destination host status.
This problem should be verified in the network.
ping 10.1.2.11
(intf osa2080l)
This is the expected response. The interface is
working.

LINKNAME: IUTIQDF5L
ADDRESS: 10.1.5.11
FLAGS:
LINKNAME: IUTIQDF6L
ADDRESS: 10.1.6.11
FLAGS:
ADDRESS: 10.1.7.11
FLAGS:
LINKNAME: IQDIOLNK0A01070B
ADDRESS: 10.1.7.11
FLAGS:
LINKNAME: VIPL0A01080A
ADDRESS: 10.1.8.10
FLAGS:
LINKNAME: VIPL0A010814
ADDRESS: 10.1.8.20
FLAGS: INTERNAL
LINKNAME: LOOPBACK
ADDRESS: 127.0.0.1
FLAGS:
INTFNAME: LOOPBACK6
ADDRESS: ::1
TYPE: LOOPBACK
FLAGS:
END OF THE REPORT
Netstat DEVLINKS/-d
Displays the status of each interface, physical and logical, that is defined in the TCP/IP
stack, as illustrated in Example 4-31 (only one interface shown as a sample).
Example 4-31 NETSTAT DEVLINKS command results
D TCPIP,TCPIPA,N,DEV,INTFN=OSA2080I
SPEED: 0000001000
IPADDR: 10.1.2.11/24
CHECKSUMOFFLOAD: YES SEGMENTATIONOFFLOAD: YES
MULTICAST SPECIFIC:
----- ------ --------
224.0.0.1 0000000001 EXCLUDE
SRCADDR: NONE

BYTESIN = 84
INBOUND PACKETS = 1
BYTESOUT = 824
IPV4 LAN GROUP SUMMARY
LANGROUP: 00002
NAME STATUS ARPOWNER VIPAOWNER
---- ------ -------- ---------
OSA2080I ACTIVE OSA2080I YES
OSA20A0I ACTIVE OSA20A0I NO
END OF THE REPORT
Netstat ARP/-R (for OSA-Express devices)
Used to query the ARP cache for a given address. Use this command when the remote
host does not answer as expected, to check whether an ARP entry has been created for
the remote host. It also allows you to check if the relationship between the IP and MAC
address is the expected one. The resulting display is shown in Example 4-32.
Example 4-32 D TCPIP,TCPIPA,N,ARP command results
DISPLAY TCPIP,TCPIPA,N,ARP
QUERYING ARP CACHE FOR ADDRESS 10.1.2.13
INTERFACE: OSA2080I ETHERNET: 020003749925
INTERFACE: OSA20A0I ETHERNET: 02009E749661
INTERFACE: OSA20C0I ETHERNET: 02004E749A7F
INTERFACE: OSA20C0I ETHERNET: 02004F749A7F
INTERFACE: OSA20C0I ETHERNET: 020056749A7F
INTERFACE: OSA20C0I ETHERNET: 00145E749A7E
INTERFACE: OSA20C0I ETHERNET: 0014F1464600
INTERFACE: OSA20E0I ETHERNET: 02000674979B
INTERFACE: OSA20E0I ETHERNET: 0014F1464600
INTERFACE: IUTIQDF4L

END OF THE REPORT
These commands can help you to locate connectivity problems. If they do not, the next step in
debugging a direct attached network problem is to gather documentation that shows more
detailed information about traffic problems related to the interface and network.
To get this detailed information, the z/OS Communications Server typically uses the
component trace to capture event data and save it to an internal buffer—or write the internal
buffer to an external writer, if requested. You can later format these trace records using the
Interactive Problem Control System (IPCS) subcommand CTRACE.
To debug a network connectivity problem you can use the Component trace with either of the
two specific components, as follows:
SYSTCPIP component trace with options
– VTAM, which shows all of the nondata-path signaling occurring between the devices
and VTAM
– VTAMDATA, which shows data-path signaling between the devices and VTAM,
including a snapshot of media headers and some data
SYSTCPDA component trace, used with the VARY TCPIP,PKTTRACE command. You can
use the PKTTRACE statement to copy IP packets as they enter or leave TCP/IP, and then
examine the contents of the copied packets.
For more information about how to set up and activate a CTRACE, refer to Chapter 8,
“Diagnosis” on page 239.
OSA-Express network traffic analyzer (OSAENTA) trace
This trace provides a way to trace inbound and outbound frames for an OSA-Express2
feature in QDIO mode.
– The function allows the z/OS Communications Server to control and format the tracing
of frames collected in the OSA-Express2 feature at the network port.
– It also provides the capability to trace frames discarded by the OSA-Express2 feature.
SYSTCPOT is a new CTRACE component for collecting NTA trace data. The trace records
can be formatted using the IPCS CTRACE command, specifying a component name of
SYSTCPOT.
Important: Using this option slows performance considerably; therefore, use it with
caution.

For more information about how to set up and enable the network traffic analyzer, refer to
Chapter 8, “Diagnosis” on page 239.
For additional information, refer to:
HiperSockets Implementation Guide, SG24-6816
OSA-Express Implementation Guide, SG24-5948
z/OS Communications Server: SNA Resource Definition, SC31-8778

Chapter 5. Routing
One of the major functions of a network protocol such as TCP/IP is to efficiently interconnect
a number of disparate networks. These networks can include LANs and WANs, fast and slow,
reliable and unreliable, inexpensive and expensive connections.
To interconnect these networks, some level of intelligence is needed at the boundaries to look
at the data packets as they pass, and make rational decisions as to where and how they
should be forwarded. This is known as IP routing. In this chapter we look at the various types
of IP routing supported in a z/OS environment.
This chapter includes the following topics.
5
Section Topic
5.1, “Basic concepts” on page 154 The basic concepts of IP routing
5.2, “Routing in the z/OS environment” on
page 160
Key characteristics of IP routing in z/OS
Communications Server
5.3, “Dynamic routing protocols” on
page 163
Detailed characteristics of dynamic routing protocols
5.4, “Implementing static routing in z/OS”
on page 173
The implementation tasks and configuration examples
for static routing
5.5, “Implementing OSPF routing in z/OS
with OMPROUTE” on page 179
The implementation tasks and configuration examples
for OSPF dynamic routing
5.6, “Problem determination” on
page 198
Techniques for problem determination

5.1 Basic concepts
When we talk about networks, one of the key issues is how to transport data across the
network. Based on the OSI reference model, the act of moving data traffic across a network
from a source to a destination can be accomplished either by bridging or routing this data
between the endpoints.
Bridging is often compared with routing, which might seem to accomplish precisely the same
thing. However, note the primary difference between these functions:
Bridging occurs at Layer 2 (the data link control layer) of the OSI reference model.
Routing occurs at Layer 3 (the network layer).
This distinction provides bridging and routing with different information to use in the process
of moving information from source to destination, so the two functions accomplish their tasks
in different ways.
5.1.1 Terminology
To help understand the concepts described in this section, Table 5-1 lists some of the
common IP routing-related terms. Most of the functions or protocols listed are supported by
the z/OS Communications Server.
Table 5-1 IP routing terms
In order to route packets on the network, each network interface must have a unique IP
address assigned. Whenever a packet is sent, the destination and source IP addresses are
included in the packet’s header information. The network layer (Layer 3) of the TCP/IP stack
examines the destination IP address to determine how the packet should be forwarded. The
packet is either sent to its destination on the same network (direct routing) or, based on a
routing table entry, to another network using a router (indirect routing).
Term Definition
Routing The process used in an IP network to deliver a datagram to the correct destination.
Static routing Routing that is manually configured and does not change automatically in response
to network topology changes.
Replaceable static routes Static routes that can be replaced by OMPROUTE.
Dynamic routing Routing that is dynamically managed by a routing daemon and automatically
changes in response to network topology changes.
Routing daemon A server process that manages the IP routing table.
Autonomous system (AS) A group of routers exchanging routing information through a common routing
protocol. A single AS can represent a large number of IP networks.
Router A device or host that interprets protocols at the Internet Protocol (IP) layer and
forwards datagrams on a path toward their correct destination.
Gateway A router that is placed between networks or subnetworks. The term is used to
represent routers between autonomous systems.
Interior gateway protocols (IGP) Dynamic route update protocol used between dynamic routers running on TCP/IP
hosts within a single autonomous system.
Exterior gateway protocols (EGP) Dynamic route update protocols used between routers that are placed between two
or more autonomous systems.

Chapter 5. Routing 155
5.1.2 Direct routes, indirect routes, and default route
Every IP host is capable of routing IP datagrams and maintaining an IP routing table. There
are three types of entries in an IP routing table:
Direct routes
The networks to which the host is directly attached are called direct routes. If the
destination host is attached to the same physical network as the source host, IP
datagrams can be directly exchanged. This is done by encapsulating the IP datagram in
the physical network frame.
Indirect routes
The networks to which the host is not directly attached and reachable through one or more
IP routers are called indirect routes. When the destination host is not connected to a
network directly attached to the source host, the only way to reach the destination is
through one or more IP routers. The routing entry with destination IP address and the IP
address of the first router (the next hop) is called an indirect route in the IP routing
algorithm.
The IP address of the first router is the only information needed by the source host to send
a packet to the destination host. If the source and destination hosts are on the same
physical network, but defined in different subnetworks, indirect routing is used to
communicate between the endpoints. A router is needed to forward packets between
subnetworks.
The default route
The default route entry contains the IP address of the first router (the next hop) to be used
when the destination IP address or network is not found in any of the direct or indirect
routes.
Figure 5-1 illustrates these routing entries.
Figure 5-1 Sample network with multiple subnetworks
This example has hosts and routers located in multiple networks, and to achieve connectivity
between these hosts, the routers are connected to multiple networks, creating a path between
them.
Host BHost A
10.1.1.0 / 24
192.168.1.0 / 24 172.16.1.0 / 24
Host DHost C Router A Router B
192.168.1.1192.168.1.103
10.1.1.101 10.1.1.102
172.16.1.104
10.1.1.210.1.1.1
172.16.1.2
192.168.2.0 / 24
Host E
192.168.2.105
192.168.2.1

In this scenario, if host A wants to connect to host D, both resources must create and maintain
a routing table to define which path has to be used to reach its destination. Host A in this
example might contain the (symbolic) entries as listed in Table 5-2.
Table 5-2 IP routing table for Host A
The routing table contains routes to different routers in this network. When host A has an IP
datagram to forward, it determines which IP address to forward it to using the IP routing
algorithm and the routing table.
Because Host A is directly attached to network 10.1.1.0/24, it maintains a direct route for this
network. To reach other networks such as 192.168.1.0/24 and 172.16.1.0/24, it must have an
indirect route through router A and router B, respectively, because these networks are not
directly attached to it. Another option is to define a default route. If the indirect route to the
network is not defined explicitly, the default route is used.
In this example, Host A reaches to Host B using the direct route. To reach Host C
(192.168.1.103), it uses the indirect route to 192.168.1.0/24 and forwards the packet to
Router A (10.1.1.1).
Likewise, to reach Host D, it uses the indirect route to 172.16.1.0/24 and forwards the packet
to Router B (10.1.1.2). The indirect route to Host E (192.168.2.105) is not explicitly defined in
the Host A. So, the default route is used and the Host A forwards the packet to Router A
(10.1.1.1).
To reach any given IP network address, each host or router in the network needs to know only
the next hop’s IP address and not the full network topology.
5.1.3 Route selection
IP uses a unique algorithm to route an IP datagram. In a network without subnetworks, each
host in the path from source host to destination host will:
1. Inspect the destination address of the packet.
2. Divide the destination address into network and host addresses.
3. Determine whether the network is directly attached:
– If so, send the IP datagram directly to the destination.
– If not, send the IP datagram to the next router, as defined by the routing tables.
Destination IP address of Next Hop Router
10.1.1.0/24 Directly connected
192.168.1.0/24 10.1.1.1 (Router A)
172.16.1.0/24 10.1.1.2 (Router B)
Default 10.1.1.1 (Router A)
127.0.0.1 Loopback
Note: The /24 (a prefix), represents the length of subnet mask (a 24-bit mask, in this
case).

In a subnetted network, each host in the path from source host to destination host will:
1. Inspect the destination address of the packet.
2. Divide the destination address into subnetwork and host addresses.
3. Determine whether the subnetwork is directly attached:
– If so, forward the packet directly to the destination.
– If not, forward the packet to the next router as defined in the routing tables.
If two or more indirect routes are defined for the same destination, the route selection
depends on the implementation of the routers or hosts. Some implementation always uses
the top entry in the list, and some implementation uses all routes to distribute the packets. In
some cases it is configurable with the provided parameters.
If two or more indirect routes are defined for the same destination but with different subnet
mask length, the route with longest mask length is selected. This method is called the longest
match.
5.1.4 Static routing and dynamic routing
In this section we explain the two ways to set up the necessary routing table in a system:
using static routing, or dynamic routing.
Static routing
Static routing requires you to manually configure the routing tables yourself. This task is part
of the configuration steps you follow when customizing TCP/IP. It implies that you know the
address of every network you want to communicate with and how to get there. That is, you
must know the address of the first router on the way.
The task of statically defining all necessary routes can be simple for a small network. It offers
the advantage of avoiding the network traffic overhead of a dynamic route update protocol. It
also allows you to enforce rigid control on the allocation of addresses and resource access.
However, it will require manual reconfiguration if you move or add a resource.
The another drawback of static routing is that, even if the network failure occurs in the
intermediate path to the destination, the routing table remains unchanged and keeps sending
the packet according to the statically defined next hop routers. Sometimes it might cause the
network to be unreachable. Also, if you fail to define the right next hop router in the route
entry, the routers keep forwarding the packet using that entry. Even if there is a better route,
the router does not change its next hop router until the changes are made to the static route
entry.
If your network environment is small and manageable, with few to no network changes
anticipated, then using static routes is an option (keeping in mind that your z/OS system is
basically an application server environment). A good practice is to define only the default
gateways to the exterior networks, and let the routers do the exterior routing. You can
implement the static routing between the z/OS system and external router, and still let the
external routers use the dynamic routing protocol to exchange route information.
Dynamic routing
Dynamic routing removes the need for static definition of the routing table. The network
routing table is built dynamically, automatically exchanging route information among the
routers in the network. This sharing of the routing information enables the routers to always
calculate the best path through the network to any destination. When a network outage

occurs in the intermediate route to the destination, the routers exchange the information
about the outage and the best path is recalculated.
If your routing tables are complex due to network growth, or if the system must act as a
gateway, it is far easier to let the system do the work for you by using dynamic routing.
The drawback of dynamic routing is the burden of route information exchange. There are
some configuration techniques you can use to reduce this burden, as explained in 5.2,
“Routing in the z/OS environment” on page 160.
Dynamic routing protocols can be divided into two types: interior gateway protocols, and
exterior gateway protocols.
Interior gateway protocols (IGPs) are dynamic route update protocols used between dynamic
routers running on TCP/IP hosts within a single autonomous system. These protocols are
used by the routers to exchange information about which IP routes the IP hosts that they have
knowledge of. By exchanging IP routing information with each other, the routers are able to
maintain a complete picture of all available routes inside an autonomous system.
Exterior gateway protocols (EGPs) are dynamic route update protocols that are used
between routers that are placed between two or more Autonomous Systems.
OSPF and RIP
In this section we discuss the interior gateway protocols OSPF, RIP version1, and RIP
version2, which are supported by z/OS Communications Server.
Open Shortest Path First (OSPF)
OSPF uses a link state or shortest path first algorithm. OSPF’s most significant advantage
compared to RIP is the reduced time needed to converge after a network change. In
general, OSPF is more complicated to configure than RIP and might not be suitable for
small networks.
Routing Information Protocol (RIP)
RIP uses a distance vector algorithm to calculate the best path to a destination based on
the number of hops in the path. RIP has several limitations. Some of the limitations that
exist in RIP version 1 are resolved by RIP version 2.
RIP version 2 expands RIP version 1. Among the improvements are support for
multicasting and variable subnetting. Variable subnetting allows the division of networks
into variable size subnets.
IPv6 OSPF
IPv6 OSPF (OSPFv3) uses a link state or shortest path first algorithm to calculate the best
path to a destination. IPv6 OSPF has the same advantages and more complicated
configuration compared to IPv6 RIP (as with OSPF compared to RIP).
IPv6 RIP
IPv6 RIP uses the same distance vector algorithm used by RIP to calculate the best path
to a destination. It is intended to allow routers to exchange information for computing
routes through an IPv6-based network.

Table 5-3 lists the main characteristics of the routing protocols supported by the z/OS
Communications Server.
Table 5-3 Interior Gateway Protocol characteristics
5.1.5 Choosing the routing method
The choice of a routing protocol is a major decision for the network administrator, and has a
major impact on overall network performance. The selection depends on the network
complexity, size, and administrative policies. The protocol chosen for one type of network
might be inappropriate for other types of networks. Each unique environment must be
evaluated against a number of fundamental design requirements, as explained here.
Scalability to large environments
The potential growth of the network dictates the importance of this requirement. If support
is needed for large, highly redundant networks, then link state or hybrid algorithms should
be considered. Distance vector algorithms do not scale into these environments. Static
routing also does not usually scale into large environments.
Stability during outages
Distance vector algorithms can introduce network instability during outage periods. The
counting to infinity problems might cause routing loops or other non-optimal routing paths.
Link state or hybrid algorithms reduce the potential for these problems. Static routing can
provide stability if the platform implements protocols like Virtual Router Redundancy
Protocol (VRRP), Hot Standby Router Protocol (HSRP), or if redirected routes are
accepted.
On a z platform, OSAs can provide stability in a static routing environment through a
feature called ARP Takeover. Refer to Communications Server for z/OS V1R9 TCP/IP
Implementation Volume 3: High Availability, Scalability, and Performance, SG24-7534., for
more detailed information about ARP Takeover.
RIP v1 RIP v2 IPv6 RIP OSPF IPv6 OSPF
Algorithm Distance
vector
Distance
vector
Distance
vector
Shortest
path first
Shortest
path first
Network load a
a. Depends on network size and stability.
High High High Low Low
CPU processing
requirements a
Low Low Low High High
IP network design
restrictions
Many Some Some Virtually
none
Virtually
none
Convergence® time Up to 180
seconds
Up to 180
seconds
Up to 180
seconds
Low Low
Multicast support b
b. Multicast saves CPU cycles on hosts that do not require certain periodic updates, such as
OSPF link state advertisements or RIP-2 routing table updates. Multicast frames are filtered
out, either in the device driver or directly on the interface card, if this host has not joined the
specific multicast group.
No Yes Yes Yes Yes
Multiple equal-cost
routes
No c
c. RIP in OMPROUTE allows multiple equal-cost routes only for directly connected destination
over redundant interfaces.
No c
No c
Yes Yes

Speed of convergence
Triggered updates provide the ability to immediately initiate convergence when a failure is
detected. All three types of protocols support this feature.
One contributing factor to convergence is the time required to detect a failure. In OSPF
networks, a series of “hello” packets must be missed before convergence begins.
In RIP environments, subsequent route advertisements must be missed before
convergence in initiated.
These detection times increase the time required to restore communication. In static
routing environments, convergence is a factor limited by the time it takes to update static
routing tables manually.
Metrics
Metrics provide the ability to groom appropriate routing paths through the network. Link
state algorithms consider bandwidth when calculating routes.
Vendor interoperability
The types of devices deployed in a network indicate the importance of this requirement. If
the network contains equipment from a number of vendors, then standard routing
protocols should be used. The IETF has dictated the operating policies for the distance
vector and link state algorithms described in this book. Implementing these algorithms
avoids any interoperability problems encountered with nonstandard protocols.
The administrator must assess the importance of each of these requirements when
determining the appropriate routing protocol for an environment.
5.2 Routing in the z/OS environment
This section discusses the two IP routing methods provided by z/OS Communications Server.
It also describes OMPROUTE and what to consider when implementing dynamic and static
routes.
5.2.1 Static routing
In z/OS Communications Server, the static routes are defined with the BEGINROUTES
statement block in the TCP/IP profile. The defined static routes are installed into the routing
table of the TCP/IP stack. The GATEWAY statement also can be used in the TCP/IP profile to
define static routes, but it is an obsolete statement. Instead, we recommend the use of the
BEGINROUTES statement block.
Static routing can be combined with dynamic routing through the use of the OMPROUTE
routing daemon. If the ROUTE statement in the BEGINROUTES statement block is coded
with NOREPLACEABLE, then the static route is always preferred over the dynamically
learned route for the same destination with the same subnet mask length.
If two or more routes to the same destination with same subnet mask length are defined in the
z/OS Communications Server routing table, then the TCP/IP stack always uses the first active
entry, by default. If you specify a IPCONFIG MULTIPATH statement in the TCP/IP profile, all
routes for the same destination are used by per connection or per packet, depending on
which option you specify for MULTIPATH.

5.2.2 Dynamic routing using OMPROUTE
In z/OS Communications Server IP, there is a multiprotocol routing daemon for dynamic
routing called OMPROUTE. (The term daemon is used in UNIX to refer to a background
server process.) It provides an alternative to the static TCP/IP routing definitions. The z/OS
host running with OMPROUTE becomes an active OSPF or RIP router in a TCP/IP network.
Either or both of these routing protocols can be used to dynamically maintain the routing
table.
Supported dynamic routing protocols
OMPROUTE supports the OSPF, RIP version 1, and RIP version 2 routing protocols.
For IPv4, OMPROUTE implements the OSPF protocol described in RFC 1583 (OSPF version
2), the OSPF subagent protocol described in RFC 1850 (OSPF version 2 Management
Information Base), and the RIP protocols described in RFC 1058 (Routing Information
Protocol) and in RFC 1723 (RIP version 2 - Carrying Additional Information).
For IPv6, OMPROUTE implements the IPv6 RIP protocol described in RFC 2080 (RIPng for
IPv6) and the IPv6 OSPF protocol described in RFC 2740 (OSPF for IPv6).
How OMPROUTE works
OMPROUTE manages an OMPROUTE routing table. OMPROUTE installs the routes that are
learned dynamically through other routers with routing protocol (OSPF or RIP) to the TCP/IP
stack’s routing table. When routing a packet to its destination, the TCP/IP stack makes
decisions for route selection based on TCP/IP stack’s routing table, not the OMPROUTE
routing table.
A one-to-one relationship exists between an OMPROUTE and a TCP/IP stack. OSPF/RIP
support for multiple TCP/IP stacks requires multiple instances of OMPROUTE. The affinity to
the TCP/IP stack is made by specifying the TCPIPJobname statement with the TCP/IP stack
name in TCPIP.DATA file that OMPROUTE uses.
OMPROUTE supports Virtual IP Addressing (VIPA) to handle network interface failures by
switching to alternate paths. VIPA routes are included in the OSPF and RIP advertisements to
adjacent routers. Adjacent routers learn about VIPA routes from advertisements and can use
them to reach destinations at the z/OS.
OMPROUTE does not make use of the BSDROUTINGPARMS statement. Instead, its
parameters are defined in the OMPROUTE configuration file. The OMPROUTE configuration
file is used to define both OSPF and RIP environments.
For IPv4, the OSPF and RIP protocols are communicated over interfaces defined with the
OSPF_INTERFACE and RIP_INTERFACE configuration statements. Interfaces that are not
involved in the communication of the RIP or OSPF protocol are configured with the
INTERFACE configuration statement (unless it is a non-point-to-point interface and all default
values specified on the INTERFACE statement are acceptable).
If both OSPF and RIP protocols are used in an OMPROUTE environment, then OSPF takes
precedence over RIP. OSPF routes will be preferred over RIP routes to the same destination.
Note: If the INTERFACE statement is used in the TCP/IP stack to define an interface, the
subnet mask and MTU coded in OMPROUTE need to agree, or OMPROUTE will issue an
error message and use the values you configure to OMPROUTE.

OMPROUTE allows the generation of multiple, equal-cost routes to a destination (with OSPF,
not RIP). If there are multiple routes for same destination with the same subnet mask length,
the stack uses the first active route for all traffic. If you specify an IPCONFIG MULTIPATH
statement in the TCP/IP profile, the stack uses all routes for the same destination per
connection or per packet, depending on which option you specify for MULTIPATH.
Considerations
Note that when coding static routes in BEGINROUTES statements, in conjunction with the
OMPROUTE configuration, you have the following options for static routes:
NOREPLACEABLE (the default)
REPLACEABLE
OMPROUTE does not replace a NOREPLACEABLE static route, even it if has detected a
dynamic route to the same destination, and the TCP/IP stack uses a NOREPLACEABLE
static route to forward the packet. OMPROUTE replaces a REPLACEABLE static route if it
detects a dynamic route to the same destination. The REPLACEABLE option enables the last
resort to the destination in cases where OMPROUTE has not detected a dynamic route to the
destination.
Also, take care to ensure that the z/OS Communications Server host is not overly burdened
with routing work. Unlike routers or other network boxes whose sole purpose is routing, an
application host z/OS Communications Server will be doing many things other than routing,
and it is not desirable for a large percentage of machine resources (memory and CPU) to be
used for routing tasks, as can happen in very complex or unstable networks.
The most common and recommended way to use dynamic routing in the z/OS environment is
to define the stack as a OSPF Stub Area or even better as a Totally Stubby Area.
Stub Areas minimize storage and CPU processing at the nodes that are part of the Stub Area
because they maintain less knowledge about the topology of the Autonomous System (AS)
than do other types of non-backbone routers. They maintain knowledge only of intra-area
destinations and summaries of inter-area destinations and default routes within the AS in
order to reach external destinations.
A Totally Stubby Area receives less routing information than a Stub Area. It only knows of
intra-area destinations and default routes within the Stub Area to reach external destinations.
5.2.3 Policy-based routing
In a TCP/IP environment, the route is selected based on the destination IP address of the
packet. The TCP/IP routing table is looked up for the matching entry for the destination IP
address. This means that all types of packets destined to the same destination IP address,
including interactive traffic (TSO, for example) and bulk traffic (FTP, for example), are
forwarded to the same next hop router. In some cases, the bulk traffic might cause traffic
congestion and can lead to a performance problem for interactive traffic.
The policy-based routing determines the destination based on the defined policy. Traffic
descriptors such as TCP/UDP port numbers, application name, and source IP addresses can
be used to define the policy to enable the optimized route selection.
Policy-based routing can use both static routes and dynamic routes, which are obtained with
the OMPROUTE routing daemon.
For detailed information about policy-based routing, refer to Communications Server for z/OS
V1R9 TCP/IP Implementation Volume 4: Security and Policy-Based Networking, SG24-7535.

5.3 Dynamic routing protocols
z/OS Communications Server supports two different type of dynamic routing:
Open Shortest Path First
Routing Information Protocol
5.3.1 Open Shortest Path First
This section provides a brief overview of the Open Shortest Path First (OSPF) routing
protocol.
The OSPF protocol is based on link-state or shortest path first technology. In other words,
OSPF routing tables contain details of the connections between routers, their status (active or
inactive), their cost (desirability for routing), and so on.
Updates are broadcast whenever a link changes status, and consist merely of a description of
the changed status. OSPF can divide its network into topology subsections, known as areas,
within which broadcasts are confined. OSPF has been designed for the TCP/IP Internet
environment. In CS for z/OS IP, OSPF is configured using the UNIX daemon OMPROUTE.
OSPF features include the following:
OSPF supports variable length subnetting.
OSPF can be configured so that all its protocol exchanges are authenticated.
Only trusted routers can participate in an AS that has been configured with authentication.
Least-cost routing allows you to configure path costs based on any combination of
network parameters. Bandwidth, delay, and metric cost are some examples.
There are no limitations to the routing metric. Although RIP restricts the routing metric to
16 hops, OSPF has virtually no restrictions.
Multipath routing is allowed. OSPF supports multiple paths of equal cost that connect the
same points. These paths are then used for network load distribution, resulting in more
use of the network bandwidth.
OSPF’s area routing capability provides an additional level of routing protection and a
reduction in routing protocol traffic.
OSPF terminology
This section describes some of the more common IP routing-related terms and concepts
used in OSPF.
Router ID
This is a 32-bit number allocated to each router in the OSPF network protocol. This
number is unique in the autonomous system. It represents the IP address of an interface
defined on the OSPF node.
For the z/OS implementation of the Router ID in OSPF, we recommend the use of a static
VIPA address. Do not use a Dynamic VIPA as the Router ID, because the movement of the
Router ID causes confusion in the OSPF routing protocol exchanges.
Areas
OSPF networks can be divided into areas. An area consists of networks and routers that
are logically grouped together. All routers within an area maintain the same topology
database.

All OSPF networks consist of at least one area, typically the backbone area. If you define
more than one area, one of the areas must be the backbone area and the other area or
areas are defined as non-backbone areas.
Backbone area
All OSPF networks should have a backbone area. The area identifier of the backbone area
is always 0.0.0.0. The backbone area is special in that it distributes routing information to
all areas connected to it.
Area border routers
These are routers that connect two or more areas. The area border router maintains a
topology database of each area to which it is attached. All area border routers must have
at least one interface in the backbone area. A virtual link can be used to satisfy this
requirement.
AS boundary routers
These are the routers that connect the OSPF internetwork and exchange reachability
information with other routers in other Autonomous Systems. They can use the exterior
gateway protocols. The AS boundary routers are used to import static routes, RIP routes
into the OSPF network (and vice versa).
Virtual link
This is a logical link that connects an area that does not have a physical link to a backbone
area. The link is treated as a point-to-point link.
Neighboring routers
Routers that have interfaces to the same connection are called neighboring routers. To
become neighbors, routers must belong to the same OSPF area, use the same security
scheme, and have the same Hello and Dead intervals.
Adjacency
Neighboring routers are considered adjacent after they have exchanged link state
information and synchronized their topology database.
Link State Advertisement
Link State Advertisement (LSA) is the unit of data describing the topology of the network
and its adjacent routers. LSAs are flooded to other routers after the Hello protocol has
established connection.
Link state database
Also called the topology database, the link state database contains the link state
advertisements that describe the OSPF area. Each router within the OSPF area maintains
an identical copy of the link state database.
Flooding
Flooding is the OSPF function that distributes link state advertisements and synchronizes
the link state database between routers after the network topology has changed.
OSPF Hello protocol
The OSPF Hello protocol is used to detect and establish contact with neighboring routers.
It dynamically maintains the relationship by periodically sending a Hello packet to all
adjacent routers.
Non-backbone area
There are several types of non-backbone areas. A non-backbone area is identified by a
four-octet area number that is not 0.0.0.0. There is a standard non-backbone area. There

are also two special types of non-backbone areas: the Stub area and the Totally Stubby
Area.
Stub Area
A Stub Area is a non-backbone area that is connected to the backbone area through an
Area Border Router. The Stub Area does not receive advertisements about destinations
that are in other Autonomous Systems. Such advertisements are called “external link state
advertisements” because they refer to Autonomous Systems external to this Autonomous
System.
The Stub Area knows only about intra-area destinations within the Stub Area. It knows
about the Totally Stubby Area destinations that exist outside the Stub Area. It reaches
external destinations through default routes sent to it by the ABR. With smaller link-state
databases and smaller routing tables, Stub Areas consume less CPU storage and fewer
CPU cycles.
Totally Stubby Area
Nodes in a Totally Stubby Area consume even less CPU storage and fewer CPU cycles for
OSPF processing, because they maintain knowledge only of the intra-area destinations
and the default routes to reach inter-area and external destinations.
Designated router
A designated router (DR) is a router on a shared multi-access medium such as a LAN or
ATM network. A DR performs most of the OSPF protocol activities for that network, like
synchronizing database information and informing members of the broadcast network of
changes to the network. The DR must be adjacent to all other routers on the broadcast
medium. Every network or subnetwork on a broadcast network must have a DR and
preferably a backup designated router (BDR).
Note: We recommend that, if possible, you define z/OS OSPF nodes as members of a
Totally Stubby Area in order to reduce the size of the link state database and reduce the
CPU cycles required to produce a routing table. If Totally Stubby is not an option, then
we recommend that you find other ways to minimize storage and CPU.
For example, you might integrate a mainframe network running OSPF with a router
network running Enhanced Interior Gateway Routing Protocol (EIGRP) to take
advantage of the filtering capabilities of EIGRP, thus reducing the amount of protocol
traffic between the OSPF network and the EIGRP network.

Backup designated router (BDR)
The BDR is also adjacent to all other routers on the medium. It listens to DR
conversations, and takes over if the DR fails. After the DR fails, the BDR becomes the DR
and a new BDR is elected according to the router priority value. The router priority value is
between 0 and 127. If you do not want a router to be elected a DR, configure it with a
router priority of zero.
Transit Area
A Transit Area is an area through which the virtual link ends. Remember that virtual links
behave like point-to-point links.
Link-state routing
Link-state routing is a concept used in the routing of packet-switched networks. The routers
tell every router in the network about its closest neighbors. The entire routing table is not
distributed from any router, only the part of the table containing its neighbors. Basically,
implementing link-state routing by OSPF uses the following process:
Routers identify other routing devices on directly connected networks, and exchange
identification information with them.
Routers advertise the details of directly connected network links and the cost of those
links by exchanging link state advertisements (LSAs) with other routers in the network.
Each router creates a link state database based on the link state advertisements, and the
database describes the network topology for the OSPF area.
All routers in an area maintain an identical link state database.
A routing table is constructed from the link state database.
Link state advertisements are normally sent under the following circumstances:
When a router discovers a new neighbor has been added to the area network
When a connection to a neighbor is unavailable
When the cost of a link changes
When basic LSA refreshes are transmitted every 30 minutes
Note: We recommend that you define non-z/OS routers attached to z/OS OSPF LAN
broadcast networks as the DRs. z/OS CPU utilization is reduced if a non-z/OS router
performs the work of the DR.
There is one exception to this rule when dealing with a HiperSockets network. A
HiperSockets network is also a broadcast network; however, only z/OS, z/VM, or
Linux® on System z nodes participate in a HiperSockets network. Therefore, at least
some node inside the mainframe must be a DR on a HiperSockets LAN.
Complications can occur if the z/OS node is the DR on a LAN network when parallel
interfaces into the LAN over a shared OSA exist. Shared OSAs can route over the
shared OSA port without entering the network.
If the packet arrives over the backup interface instead of the primary parallel interface,
the recipient discards the packet. The databases at the nodes become corrupted due to
missing information, and lost adjacencies can result.
Therefore, we recommend that you not allow z/OS nodes with parallel interfaces and
shared LANs to be the DR. If a z/OS node must be the DR, it should be connected to
the broadcast medium through a non-shared OSA port.

Each area has its own topology and has a gateway that connects it to the rest of the network.
It dynamically detects and establishes contacts with its neighboring routers by periodically
sending Hello packets.
Link-state advertisements (LSAs)
As mentioned previously, OSPF routers exchange one or more link state advertisements with
adjacent routers. LSAs describe the state and cost of an individual router’s interfaces that are
within a specific area, and the status of an individual network component.
There are five types of LSAs:
Router LSAs (Type-1) describe the state and cost of the routers’ interfaces within the area.
They are generated by every OSPF router and are flooded throughout the area.
Network LSAs (Type-2) describe all routers attached to the network. They are generated
by the designated router and are flooded through the area.
Summary LSAs (Type-3) describe routes to destinations in other areas in the OSPF
network. They are generated by an area border router.
Summary LSAs (Type-4) are also generated by an area border router and describe routes
to an AS boundary router.
AS External LSAs (Type-5) describe routes to destinations outside the OSPF network.
They are generated by an AS boundary router.
Link-state database
The link-state database is a collection of OSPF Link State Advertisements. OSPF, being a
dynamic IP routing protocol, does not need to have routes defined to it. It dynamically
discovers all the routes and the attached routers through its Hello part of the protocol. The
OSPF Hello part of the protocol transmits Hello packets to all its router neighbors to establish
connection. After the neighbors have been discovered, the connection is made.
Before the link state databases are exchanged, however, the OSPF routers transmit only their
LSA headers. After receiving the LSA headers, they are examined for any corruptions. If
everything is fine, the request for the most recent LSAs is made. This process is bidirectional
between routers.
After the Hello protocol has concluded that all the connections have been established, the link
state databases are synchronized. This exchange is performed starting with the most recently
updated LSAs. The link state databases are synchronized until all router LSAs in the network
(within an area) have the same information. The link state protocol maintains a loop-free
routing because of the synchronization of the link state databases.
Physical network types
OSPF supports a combination of different physical networks. In this section, we give a brief
description of each physical network and how OSPF supports them.
Point-to-point
This refers to a network that connects two routers together. A PPP serial line that connects
two routers is an example of a point-to-point network.
Point-to-multipoint
This refers to networks that support more than two attached routers with no broadcast
capabilities. These networks are treated as a collection of point-to-point links. OSPF does
not use designated routers on point-to-multipoint networks. The Hello protocol is used to
detect the status of the neighbors.

Broadcast multiaccess
This refers to networks that support more than two attached routers and are capable of
addressing a single message to all the attached routers. OSPF's Hello Protocol discovers
the adjacent routers by periodically sending and receiving Hello packets. This is a typical
example of how OSPF exploits a broadcast network. OSPF utilizes multicast in a
broadcast network if implemented.
Nonbroadcast multiaccess (NBMA)
This refers to networks that support more than two attached routers, but have no
broadcast capabilities. Because NBMA does not support multicasting, the OSPF Hello
packets must be specifically addressed to each router. And because OSPF cannot
discover its neighbors through broadcasting, more configuration is required: all routers
attached to the NBMA network must be configured. These routers must be configured
whether or not they are eligible to become designated routers.
5.3.2 Routing Information Protocol
This section provides an overview of the Routing Information Protocol (RIP) protocol. RIP is
designed to manage relatively small networks.
RIP uses a hop count (distance vector) to determine the best possible route to a network or
host. The hop count is also known as the routing metric, or the cost of the route. A router is
defined as being zero hops away from its directly connected networks, one hop away from
networks that can be reached through one gateway, and so on. The fewer hops, the better.
The route that has the fewest hops will be the preferred path to a destination. A hop count of
16 means infinity, or that the destination cannot be reached. Thus, very large networks with
more than 15 hops between potential partners cannot make use of RIP.
The information is kept in a distance vector table, which is periodically advertised to each
neighboring router. The router also receives updates from neighboring gateways and uses
these to update its routing tables. If an update is not received for three minutes, a gateway is
assumed to be down, and all routes through that gateway are set to a metric of 16 (infinity).
Basic distance vector algorithm
The following procedure is carried out by every entity that participates in the RIP routing
protocol. This must include all of the gateways in the system. Hosts that are not gateways can
participate as well.
Keep a table with an entry for every possible destination in the system. The entry contains
the distance D to the destination, and the first gateway G on the route to the network.
Periodically, send a routing update to every neighbor. The update is a set of messages
that contains all the information from the routing table. It contains an entry for each
destination, with the distance shown to that destination.
When a routing update arrives from the neighbor G', add the metric associated with the
network that is shared with G'. Call the resulting distance D'. Compare the resulting
distance with the current routing table entries.
If the new distance D' for N is smaller than the existing value D, then adopt the new route.
That is, change the table entry for N to have metric D' and gateway G'. If G' is the gateway
from which the existing route came, G' = G, then use the new metric, even if it is larger
than the old one.

RIP version 1
RIP is a protocol that manages IP routing table entries dynamically. The gateways using RIP
exchange their routing information in order to allow the neighbors to learn of topology
changes. The RIP server updates the local routing tables dynamically, resulting in current and
accurate routing tables. The protocol is based on the exchange of protocol data units (PDUs)
between RIP servers (such as OMPROUTE).
There are various types of PDUs, but the two most important PDUs are:
REQUEST PDU This PDU is sent from an RIP server as a request to other RIP servers
to transmit their routing tables immediately.
RESPONSE PDU This PDU is sent from an RIP server to other RIP servers either as a
response to a REQUEST PDU or as a result of expiration of the
broadcast timer (every 30 seconds).
RIP V1 limitations
Because RIP is designed for a specific network environment, it has some limitations as
described here. Consider these limitations before implementing RIP in your network.
RIP V1 declares a route invalid if it passes through 16 or more gateways. Therefore,
RIP V1 places a limitation of 15 hops on the size of a large network.
RIP V1 uses fixed metrics to compare alternative routes versus actual parameters, such
as measured delay, reliability, and load. This means that the number of hops is the only
parameter that differentiates a preferred route from non-preferred routes.
The routing tables can take a relatively long time to converge or stabilize.
RIP V1 does not support variable subnet masks or variable subnetting because it does not
pass the subnet mask in its routing advertisements. Variable subnet masking refers to the
capability of assigning different subnet masks to interfaces that belong to the same Class
A, B, or C network.
RIP V1 does not support discontiguous subnets. Discontiguous subnets are built when
interfaces belong to the same Class A, B, or C network, but to different subnets that are
not adjacent to each other. Rather, they are separated from each other by interfaces that
belong to a different network.
With RIP version 1, discontiguous subnets represent unreachable networks. If you find it
necessary to build discontiguous subnets, you must use one of the following techniques:
– An OSPF implementation
– RIP version 2 protocol
– Static routing
RIP version 2
Rather than being another protocol, RIP V2 is an extension to the functions provided by RIP
V1. To use these new functions, RIP V2 routers exchange the same RIP V1 messages. The
version field in the message will specify version number 2 for RIP messages that use
authentication or carry information in any of the newly defined fields.
RIP V2 protocol extensions provide features such as:
Route tags to provide EGP-RIP and BGP-RIP implementation
Route tags are used to separate internal RIP routes (routes for networks within the RIP
routing domain) from external RIP routes, which might have been imported from an EGP
(external gateway protocol) or another IGP. OMPROUTE does not generate route tags, but
preserves them in received routes and readvertises them when necessary.

Variable subnetting support
Variable length subnet masks are included in routing information so that dynamically
added routes to destinations outside subnetworks or networks can be reached.
Immediate next hop for shorter paths
Next hop IP addresses, whenever applicable, are included in the routing information. Their
purpose is to eliminate packets being routed through extra hops in the network.
OMPROUTE will not generate immediate next hops, but will preserve them if they are
included in RIP packets.
Multicasting to reduce load on hosts
An IP multicast address 224.0.0.9, reserved for RIP version 2 packets, is used to reduce
unnecessary load on hosts that are not listening to RIP version 2 messages. RIP version 2
multicasting is dependent on interfaces that are multicast-capable.
Authentication for routing update security
Authentication keys can be included in outgoing RIP version 2 packets for authentication
by adjacent routers as a routing update security protection. Likewise, incoming RIP
version 2 packets are checked against local authentication keys. The authentication keys
are configurable on a router-wide or per-interface basis.
Configuration switches for RIP V1 and RIP V2 packets
Configuration switches are provided to selectively control which versions of RIP packets
are to be sent and received over network interfaces. You can configure them router-wide
or per-interface.
Supernetting support
The supernetting feature is part of the Classless InterDomain Routing (CIDR) function.
Supernetting provides a way to combine multiple network routes into fewer supernet
routes. Therefore, the number of network routes in the routing tables becomes smaller for
advertisements. Supernet routes are received and sent in RIP V2 messages.
RIP V2 packets are backward compatible with existing RIP V1 implementations. A RIP V1
system will process RIP V2 packets but without the RIP V2 extensions, and broadcast them
as RIP V1 packets to other routers. Note that routing problems might occur when variable
subnet masks are used in mixed RIP V1 and RIP V2 systems. RIP V2 is based on a distance
vector algorithm, just as RIP V1 is.
5.3.3 IPv6 dynamic routing
Dynamic routing in a IPv6 network can be implemented in a z/OS Communications Server in
two different ways:
IPv6 dynamic routing using router discovery
IPv6 dynamic routing using OMPROUTE
IPv6 dynamic routing using router discovery
Enabling IPv6 router discovery in the z/OS Communications Server requires no additional
z/OS Communications Server configuration. All that is needed is at least one IPv6 interface
that is defined and started, and at least one adjacent router through that interface that is
configured for IPv6 router discovery. If these things exist, then the z/OS Communications
Server begins receiving router advertisements from the adjacent routers.

Depending on the configuration in the adjacent routers, the following types of routes can be
learned from the received router advertisements:
Default route, for which the originator of the router advertisement is the next hop
Direct routes (no next hop) to prefixes that reside on the link shared by the z/OS
Communications Server and the originator of the router advertisement
IPv6 dynamic routing using OMPROUTE
For IPv6, OMPROUTE implements the IPv6 RIP protocol described in RFC 2080 (RIPng for
IPv6) and the IPv6 OSPF protocol described in RFC 2740 (OSPF for IPv6). It provides an
alternative to the static TCP/IP gateway definitions.
The z/OS host running with OMPROUTE becomes an active OSPF or RIP router in a TCP/IP
network. Either or both of these routing protocols can be used to dynamically maintain the
host IPv6 routing table. For example, OMPROUTE can detect when a route is created, is
temporarily unavailable, or if a more efficient route exists. If both IPv6 OSPF and IPv6 RIP
protocols are used simultaneously, then IPv6 OSPF routes will be preferred over IPv6 RIP
routes to the same destination.
RIPng or RIP next generation
RIP Next Generation (RIPng) is a distance vector routing protocol for IPv6 that is defined in
RFC 2080. RIPng for IPv6 is an adaptation of the RIP V2 protocol to advertise IPv6 network
prefixes. RIPng for IPv6 uses UDP port 521 to periodically advertise its routes, respond to
requests for routes, and advertise route changes.
RIPng for IPv6, like other distance vector protocols, has a maximum distance of 15, in which
15 is the accumulated cost (hop count). Locations that are a distance of 16 or further are
considered unreachable. RIPng for IPv6 is a simple routing protocol with a periodic
route-advertising mechanism designed for use in small to medium-sized IPv6 networks.
RIPng for IPv6 does not scale well to a large or very large IPv6 network.
Differences between RIPng and RIP-2
There are two important distinctions between RIP-2 and RIPng:
Support for authentication
The RIP-2 standard includes support for authenticating a node transmitting routing
information. RIPng does not include any native authentication support. Rather, RIPng
uses the security features inherent in IPv6.
In addition to authentication, these security features provide the ability to encrypt each
RIPng packet. This can control the set of devices that receive the routing information.
One consequence of using IPv6 security features is that the AFI field within the RIPng
packet is eliminated. There is no longer a need to distinguish between authentication
entries and routing entries within an advertisement.
Support for IPv6 addressing formats
The fields contained in RIPng packets were updated to support the longer IPv6 address
format.
OSPF for IPv6
OSPF for IPv6 is a link state routing protocol defined in RFC 2740 and designed for routing
table maintenance within a single autonomous system. OSPF for IPv6 is an adaptation of the
OSPF routing protocol version 2 for IPv4 defined in RFC 2328.

IPv6 OSPF is classified as an Interior Gateway Protocol (IGP). This means that it distributes
routing information between routers belonging to a single autonomous system (AS), a group
of routers all using a common routing protocol. The IPv6 OSPF protocol is based on link-state
or shortest path first (SPF) technology.
At a glance, the OSPF implementation is basically the same as it is for IPv4, except for some
primary differences.
Primary differences between IPv6 OSPF and IPv4 OSPFv2
IP addressing and topology semantics have been separated where possible (many LSAs do
not carry IP addresses at all, only abstract topology information). Removing IP addressing
from the topology description makes OSPFv3 more protocol-independent.
New LSA types are added (to carry addressing and link-local information). Because IP
addressing has been removed from some of the basic LSA types, new LSA types are
provided to communicate IP addresses, which routers then correlate to topology information
in other LSA types.
The Concept of Flooding Scope is added (scopes are link, area, autonomous system). It
indicates how far an advertisement can be flooded. For example, link scope means an LSA
can only be flooded on the originating link.
Support for Unknown LSA types is added (this makes the protocol more extensible).
Unknown LSA types can be ignored, or they can be stored and forwarded by the router,
depending on the settings of bits in the LSA type field. This vastly improves interoperability
between routers running different versions of the protocol. For example, a designated router
could conceivably have a lower level of support than another router on the same link; because
the designated router floods on behalf of the other routers on the link, it could store and
forward unknown LSA types received from its peers.
Multiple OSPF instances are supported on a link. An “instance id” field is added to OSPF
headers, and OSPF processes only process packets whose instance ID matches their own.
This opens up the possibility of one link belonging to completely different autonomous
systems.
Subnet loses its importance, replaced by link (because multiple IPv6 prefixes per link are
allowed and expected, routing by subnet/prefix makes less sense). In OSPFv2, most routing
is done by subnet. In OSPFv3 it is done by link. This is because in IPv6 a subnet (prefix) does
not always uniquely identify a link, and a link can have more than one prefix assigned.

5.4 Implementing static routing in z/OS
In this section we implement a static routing scenario, as illustrated in Figure 5-2. We only
provide definition examples for the TCPIPA stack on SC30 because the examples for the
TCPIPB stack on SC31 are similar. On TCPIPA, we define direct routes for interfaces such as
OSA and HiperSockets and indirect routes for TCPIPB VIPAs. We also define default routes
through our switches (layer 3 switch).
Figure 5-2 Static routing scenario
5.4.1 Dependencies
All subnetworks defined in the TCP/IP stack that are used by the application servers,
including static and dynamic VIPAs, must also have static routing definitions in the routers In
our case, the layer 3 switches (routers) do not need static route definitions for direct routes.
We defined indirect routes for TCPIPA and TCPIPB VIPAs in the routers.
When planning to design a static routing environment on a z/OS Communications Server, you
need to address some issues. Keep in mind that static routes are configured manually for
each router by the system administrator. Available network interfaces and routes through the
network must be determined before the routes are configured. Except for potential ICMP
router redirections, routers do not communicate with each other about the topology of the
network.
The routing table’s management is manual, thus increasing the possibility of outages caused
by definition errors. If a destination (sub)network becomes unreachable, then the static routes
TRUNK
VLAN10
TRUNK
VLAN11
SC30
TCPIPA
PROFAS30 (Static routes)
VIPA1L 10.1.1.10/24
VIPA2L 10.1.2.10/24
VIPA3L 10.1.30.10/24
OSA2080L 10.1.2.11/24
OSA20A0L 10.1.2.12/24
OSA20C0L 10.1.3.11/24
OSA20E0L 10.1.3.12/24
IUTIQDF4L 10.1.4.11/24
IUTIQDF5L 10.1.5.11/24
IUTIQDF6L 10.1.6.11/24
TCPIPB
PROFBS31 (Static routes)
VIPA1L 10.1.1.20/24
VIPA2L 10.1.2.20/24
VIPA3L 10.1.31.10/24
OSA2080L 10.1.2.21/24
OSA20A0L 10.1.2.22/24
OSA20C0L 10.1.3.21/24
OSA20E0L 10.1.3.22/24
IUTIQDF4L 10.1.4.21/24
IUTIQDF5L 10.1.5.21/24
IUTIQDF6L 10.1.6.21/24
SC31
CHPID 02
OSA2080
10.1.2.x1
2080-208F
CHPID 03
OSA20A0
10.1.2.x2
20A0-20AF
CHPID 04
OSA20C0
10.1.3.x1
20C0-20CF
CHPID 05
OSA20E0
10.1.3.x2
20E0-2E0F
10.1.2.240 10.1.3.240
SWITCH 1
TRUNK
VLAN10
TRUNK
VLAN11

for that (sub)network will remain in the routing table, and packets will still be forwarded to the
destination. The only way to remove static routes from the routing table is for the network
administrator to update the routing table.
We recommend that you define as few static routing definitions as possible when
implementing a static routing environment, keeping in mind that our z/OS system is basically
an application server environment. It is good practice to define only the default gateways to
the exterior networks, and let the routers do the exterior routing. You can implement the static
routing between the z/OS system and external router, and still let the external router use the
dynamic routing protocol.
In the router, we recommend that you define only the route definitions to the VIPA
subnetworks. The interior subnetworks, such as XCF and HiperSockets, do not usually need
to be reached by the corporate network, so they do not need to be defined.
To implement the static routing scenario, follow these steps:
1. Update the TCP/IP profile.
2. Configure the router.
Update the TCP/IP profile
In the TCP/IP profile, use the BEGINROUTES block and ROUTE statement to define the
following routes:
A direct route to all local interfaces (except static VIPAs, dynamic VIPAs, or XCF)
To define a direct route, specify = for its First Hop.
An indirect route to the subnetwork
To define a direct route, specify the IP address of the next hop router for its first hop.
Default gateway statements to route all packets being sent to unknown destinations
Example 5-1 shows our definition example.
When multiple default routes are defined, the traffic will be sent to the first default route
defined. If the MULTIPATH parameter is specified on the IPCONFIG statement, then all
default routes will be used.
Example 5-1 Direct routes configuration
; *****************************************
; TCPIPA.TCPPARMS(PROFA30S)
; *****************************************
.....
BEGINRoutes
ROUTE 10.1.2.0 255.255.255.0 = 1 OSA2080L MTU 1492
ROUTE 10.1.2.0/24 = 1 OSA20A0L MTU 1492
ROUTE 10.1.3.0/24 = 1 OSA20C0L MTU 1492
ROUTE 10.1.3.0/24 = 1 OSA20E0L MTU 1492
ROUTE 10.1.4.0/24 = 2 IUTIQDF4L MTU 8192
;

; Indirect Routes - Routes that are not directly connected to my interfaces
; Destination Subnet Mask First Hop Link Name Packet Size ;
ROUTE 10.1.1.20/32 10.1.4.21 IUTIQDF4L MTU 8192
ROUTE 10.1.100.0/24 10.1.2.240 3 OSA2080L MTU 1492
ROUTE 10.1.100.0/24 10.1.2.240 3 OSA20A0L MTU 1492
ROUTE 10.1.100.0/24 10.1.3.240 3 OSA20C0L MTU 1492
ROUTE 10.1.100.0/24 10.1.3.240 3 OSA20E0L MTU 1492
;
; Default Routes - Routes directly connected to my interfaces
ROUTE DEFAULT 10.1.2.240 4 OSA2080L MTU 1492
ROUTE DEFAULT 10.1.2.240 4 OSA20A0L MTU 1492
ROUTE DEFAULT 10.1.3.240 4 OSA20C0L MTU 1492
ROUTE DEFAULT 10.1.3.240 4 OSA20E0L MTU 1492
;
ENDROUTES
1. Define the direct routes for OSA interfaces. Specify the subnet mask with decimal format
(such as 255.255.255.0) or the prefix length.
2. Define the direct routes for HiperSockets interfaces.
Note that the first hop parameter is defined as an equal sign (=) 1 to identify this as a direct
route.
3. Define the indirect routes to reach the external network. The next hop is router 1
(10.1.2.240 and 10.1.3.240).
4. Define the default routes, to reach the external network, which are not explicitly defined as
indirect routes. The next hop is router 1 (10.1.2.240 and 10.1.3.240).
Configure the router
Define the static routes to the VIPA or the physical interfaces which are not on the subnet that
the routers are directly connected to (HiperSockets, for example). In our example, 10.1.2.0/24
and 10.1.3.0/24 are direct routes of the router, and we do not need to define the static routes
for those subnets.
Example 5-2 shows the example of router (layer 3 switch) configuration.
Example 5-2 Static route definition in router
.....
ip route 10.1.1.10 255.255.255.255 10.1.2.11 1
ip route 10.1.2.10 255.255.255.255 10.1.2.11 1
ip route 10.1.30.10 255.255.255.255 10.1.2.11 1
.....
In this example, the number corresponds to the following information:
1. Define the static route to the static VIPA in TCPIPA. The next hop address is the IP
address of the OSA physical interface. In our example we define this static route with
32-bit mask (255.255.255.255), but you can use a mask length shorter than 32-bit.

To activate and verify the static routing scenario, follow these steps:
1. Apply changes to TCP/IP profile.
2. Verify the connectivity.
Apply changes to TCP/IP profile
To apply the changes to static routes, do one of the following:
Restart the TCP/IP stack.
Modify the TCP/IP definition with VARY TCPIP,procname,OBEYFILE command.
After you perform one of these tasks, then all static routes are listed in the TCP/IP routing
table.
Example 5-3 illustrates applying changes by using the OBEYFILE command.
Example 5-3 Applying changes with the OBEYFILE command
V TCPIP,TCPIPA,O,DSN=TCPIPA.TCPPARMS(PROFA30S)
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,O,DSN=TCPIPA.TCPPARMS(P
ROFA30S)
EZZ0300I OPENED OBEYFILE FILE 'TCPIPA.TCPPARMS(PROFA30S)'
EZZ0309I PROFILE PROCESSING BEGINNING FOR 'TCPIPA.TCPPARMS(PROFA30S)'
....
EZZ0316I PROFILE PROCESSING COMPLETE FOR FILE 'TCPIPA.TCPPARMS(PROFA30S)'
.....
Verify the connectivity
To verify if the static routing table is built as expected, the following commands are useful.
Display the device status
Use the D TCPIP,TCPIPA,Netstat,DEVlink command to review the status of all devices
defined in the TCP/IP environment. If a device is not ready, there will be no routing through
this device. Example 5-4 shows the resulting display of this command.
Example 5-4 Netstat DEVlink command display
DEVSTATUS: READY 1
LNKNAME: OSA2080L LNKTYPE: IPAQENET LNKSTATUS: READY 1
NETNUM: N/A QUESIZE: N/A SPEED: 0000001000
Important: When using the OBEYFILE command, include all static routes that you want to
define. The OBEYFILE command replaces the entire BEGINROUTES block.
Note: Netstat commands can be executed as TSO commands, z/OS UNIX shell
commands, or Display commands on the system console. Our examples are the result of
Display commands on the system console, but their output is identical to the TSO and
z/OS UNIX shell output.

ACTMTU: 8992
MULTICAST SPECIFIC:
----- ------ --------
224.0.0.1 0000000001 EXCLUDE
SRCADDR: NONE
LINK STATISTICS:
BYTESIN = 2492
BYTESOUT = 536
.....
1. Make sure the DEVSTATUS and LNKSTATUS are both READY.
Display routing table
Use the Netstat ROUTe command to display the routing table in a TCP/IP stack. A sample of
the command is shown in Example 5-5.
Example 5-5 Netstat ROUTe resulting display
D TCPIP,TCPIPA,N,ROUTE
IPV4 DESTINATIONS
DESTINATION GATEWAY FLAGS REFCNT INTERFACE
DEFAULT 10.1.2.240 UGS 4 000000 OSA2080L 1
DEFAULT 10.1.2.240 UGS 000001 OSA20A0L
DEFAULT 10.1.3.240 UGS 000000 OSA20C0L
DEFAULT 10.1.3.240 UGS 000000 OSA20E0L
10.1.1.10/32 0.0.0.0 UH 000000 VIPA1L
10.1.1.20/32 10.1.4.21 UGHS 000000 IUTIQDF4L 2
10.1.2.0/24 0.0.0.0 US 000000 OSA2080L 3
10.1.2.0/24 0.0.0.0 US 000000 OSA20A0L
10.1.2.10/32 0.0.0.0 UH 000000 VIPA2L
10.1.2.11/32 0.0.0.0 UH 000000 OSA2080L
10.1.2.12/32 0.0.0.0 UH 000000 OSA20A0L
10.1.3.0/24 0.0.0.0 US 000000 OSA20C0L
10.1.3.0/24 0.0.0.0 US 000000 OSA20E0L
10.1.3.11/32 0.0.0.0 UH 000000 OSA20C0L

10.1.3.12/32 0.0.0.0 UH 000000 OSA20E0L
10.1.100.0/24 10.1.2.240 UGS 000000 OSA2080L
10.1.100.0/24 10.1.2.240 UGS 000000 OSA20A0L
10.1.100.0/24 10.1.3.240 UGS 000000 OSA20C0L
10.1.100.0/24 10.1.3.240 UGS 000000 OSA20E0L
127.0.0.1/32 0.0.0.0 UH 000001 LOOPBACK
IPV6 DESTINATIONS
DESTIP: ::1/128
GW: ::
INTF: LOOPBACK6 REFCNT: 000000
FLGS: UH MTU: 65535
END OF THE REPORT
1. The default route is defined. If there are multiple default route entries as shown in the
example, only the first active entry (interface OSA2080L) is used.
2. The indirect route to VIPA in TCPIPB is defined.
3. The direct route for OSA physical interface is defined.
4. S in the FLAG field stands for non-replaceable static route entry. For replaceable static
route entries, FLAG Z would be displayed.
Check the connectivity using PING command
The PING command can be executed using the TSO PING command or the z/OS UNIX ping
command. Example 5-6 shows the display of the TSO PING command; the ping is
successful.
In a CINET environment where multiple TCP/IP stacks are configured, use the TCP option for
the TSO PING command and the -p option for the z/OS UNIX ping command to specify the
TCP/IP stack name you want to issue the ping command from.
You do not need to specify these options if the user issuing this command is already
associated to the TCP/IP stack (with SYSTCPD DD, for example).
You do not need to specify these options if your environment is an INET environment where
only one TCP/IP stack is configured.
TSO PING 10.1.1.20 (TCP TCPIPA
***
Example 5-7 shows the display of z/OS UNIX ping command.
Example 5-7 z/OS UNIX ping command display
CS08 @ SC30:/u/cs08>ping -p TCPIPA 10.1.1.20
CS08 @ SC30:/u/cs08>

Verify the selected route with TRACEROUTE command
Traceroute can be invoked by either the TSO TRACERTE command or the z/OS UNIX shell
traceroute/otracert command. Example 5-8 shows the example of the display. We see the
router 1 (10.1.2.240) is the next hop router to reach the destination IP address 10.1.100.221.
TSO TRACERTE command and the -a option for the z/OS UNIX traceroute command to
specify the TCP/IP stack name you want to issue the TRACEROUTE command from.
You do not need to specify these options if the user issuing this command is already
associated to the TCP/IP stack (with SYSTCPD DD, for example).
You do not need to specify these options if your environment is an INET environment where
only one TCP/IP stack is configured.
Example 5-8 Tracerte command results
CS V1R10: Traceroute to 10.1.100.221 (10.1.100.221
1 router1 (10.1.2.240) 0 ms 0 ms 0 ms
2 10.1.100.221 (10.1.100.221) 0 ms 0 ms 0 ms
***
5.5 Implementing OSPF routing in z/OS with OMPROUTE
In this scenario we show a dynamic routing implementation. In our example we configure
OSPF for lesser network load, more IP network design flexibility, and lower convergence time
compared to RIP v1 and RIP v2 (see Table 5-3 on page 159). Although OSPF requires higher
CPU processing, we can reduce that requirement by making the z/OS Communications
Server a part of the OSPF Stub Area or Totally Stubby Area.

Figure 5-3 depicts the environment we use for the OSPF scenario. The TCPIPA stack is
running on SC30. We create the OMPROUTE procedure OMPA to establish affinity to
TCPIPA. Likewise, we create OMPB for TCPIPB on SC31.
Figure 5-3 Dynamic routing scenario, using OSPF
We define a z/OS TCP/IP to be a member of OSPF Totally Stubby Area. The external routers
(layer 3 switches) represent the ABRs between the Totally Stubby Area and the backbone
area. We made the external routers to be DR or BDR to reduce the routing workloads
required in the z/OS.
Because the configuration examples for TCPIPB and OMPB on SC31 are similar to those
examples for TCPIPA and OMPA on SC30, we only show the configuration examples on
SC30.
5.5.1 Dependencies
The IP routers that will be involved in establishing access to the external network must
support OSPF, and the configuration parameters set in OMPROUTE must be consistent with
those defined to the IP routers.
SC30
TCPIPA
PROFA30 (Dynamic routes)
VIPA1L 10.1.1.10/24
VIPA2L 10.1.2.10/24
VIPA3L 10.1.30.10/24
OSA2080I 10.1.2.11/24
OSA20A0I 10.1.2.12/24
OSA20C0I 10.1.3.11/24
OSA20E0I 10.1.3.12/24
IUTIQDF4L 10.1.4.11/24
IUTIQDF5L 10.1.5.11/24
IUTIQDF6L 10.1.6.11/24
TCPIPB
PROFB31 (Dynamic routes)
VIPA1L 10.1.1.20/24
VIPA2L 10.1.1.20/24
VIPA3L 10.1.31.10/24
OSA2080I 10.1.2.21/24
OSA20A0I 10.1.2.22/24
OSA20C0I 10.1.3.21/24
OSA20E0I 10.1.3.22/24
IUTIQDF4L 10.1.4.21/24
IUTIQDF5L 10.1.5.21/24
IUTIQDF6L 10.1.6.21/24
SC31
CHPID 02
OSA2080
10.1.2.x1
2080-208F
CHPID 03
OSA20A0
10.1.2.x2
20A0-20AF
CHPID 04
OSA20C0
10.1.3.x1
20C0-20CF
CHPID 05
OSA20E0
10.1.3.x2
20E0-2E0F
TRUNK
VLAN10
SWITCH 1
TRUNK
VLAN10
10.1.2.240
VLAN10
10.1.3.240
VLAN11
Area 0.0.0.2
Totally Stub Area
Area 0.0.0.0
TRUNK
VLAN11
TRUNK
VLAN11

A z/OS Communications Server host is usually used as an application server and the routing
daemon is running primarily to provide access to network resources and vice versa. With this
in mind, take care to ensure that the z/OS Communications Server host is not overly
burdened with routing work.
The z/OS Communications Server should not be configured as a backbone router, either
intentionally or inadvertently. Careful network design can minimize the routing burdens on the
z/OS Communications Server (application host), without compromising accessibility.
5.5.3 Recommendations
We recommend that you define the z/OS Communications Server environment as an OSPF
Stub Area to reduce the CPU process needed for managing the routing table. A Stub Area
can be configured so that route summaries from other areas are not flooded into the Stub
Area by the area border routers. When this is done, only routes to destinations within the Stub
Area are shared among the hosts. Default routes are used to represent all destinations
outside the Stub Area. The Stub Area’s resources are still advertised to the network at large
by the area-border routers. You can use this optimization, sometimes referred to as a Totally
Stubby Area.
We also recommend that you make the external routers be DR or BDR, and do not allow
z/OS systems to be DR or BDR, in order to reduce the routing burden for z/OS systems. DR
or BDR is selected in each LAN segment or VLAN. However, on HiperSockets links, z/OS
systems are the only participants. One of the z/OS on the HiperSockets network has to take
the role of DR (and optionally, another one can take the role of BDR).
To implement and configure OMPROUTE in the z/OS Communications Server, follow these
steps:
1. Create the OMPROUTE cataloged procedure.
2. Define the OMPROUTE environment variables.
3. Update the TCPIP.DATA file.
4. RACF-authorize user IDs for starting OMPROUTE.
5. Start syslogd.
6. Change port 520 and 521 definitions to NOAUTOLOG.
7. Create the OMPROUTE configuration file.
8. Configure routers.
In the sections that follow, we show only the configuration examples for the TCPIPA stack and
omit the examples for the TCPIPB stack. We do not define any static routes in TCP/IP profile
in conjunction with the dynamic routing.
Create the OMPROUTE cataloged procedure
We create the OMPROUTE cataloged procedure by copying the sample in
hlq.SEZAINST(OMPROUTE) to our PROCLIB. We specify the STDENV file name and
OMPCFG file name, as shown in Example 5-9.
Example 5-9 OMPROUTE cataloged procedure
//OMPA30 PROC STDENV=OMPENA&SYSCLONE 1
//OMPA30 EXEC PGM=OMPROUTE,REGION=0M,TIME=NOLIMIT,

// PARM=('POSIX(ON) ALL31(ON)',
// 'ENVAR("_BPXK_SETIBMOPT_TRANSPORT=TCPIPA"',
// '"_CEE_ENVFILE=DD:STDENV")/') 2
//STDENV DD DISP=SHR,DSN=TCPIP.SC&SYSCLONE..STDENV(&STDENV)
//SYSOUT DD SYSOUT=*
//OMPCFG DD DSN=TCPIPA.TCPPARMS(OMPA&SYSCLONE.),DISP=SHR 3
//CEEDUMP DD SYSOUT=*,DCB=(RECFM=FB,LRECL=132,BLKSIZE=132)
1. Specifies the STDENV variable. We can use a common procedure for all images within
the same server environment by specifying the &SYSCLONE variable. The &SYSCLONE
value for this LPAR is 30.
2. Each OMPROUTE procedure in the same server will have its own environment variables
based on this DD.
3. The OMPCFG DD card permits you to specify the OMPROUTE configuration file within
the JCL. The DD card enables the use of an MVS system symbol that can make the
procedure shareable across TCP/IP stacks. If you specify the configuration file here, you
can omit the statement OMPROUTE_FILE from the STDENV file.
Define the OMPROUTE environment variables
To define our OMPROUTE environment variables we use a STDENV file, pointed to by the
STDENV DD statement in our OMPROUTE procedure. Example 5-10 shows the STDENV
file we use in our example.
Example 5-10 OMPROUTE environment variables
; *****************************************
; TCPIP.SC30.STDENV(OMPENA30)
; *****************************************
RESOLVER_CONFIG=//'TCPIPA.TCPPARMS(DATAA&SYSCLONE.)' 1
;OMPROUTE_FILE=//'TCPIPA.TCPPARMS(OMPA30)' 2
OMPROUTE_DEBUG_FILE=/etc/omproute/debug30a
OMPROUTE_DEBUG_FILE_CONTROL=100000,5
1. Specify the TCPIP.DATA file. The &SYSCLONE value for this LPAR is 30. If you do not
want to use MVS system symbols, you can define the hard-coded member name as
shown:
RESOLVER_CONFIG=//'TCPIPA.TCPPARMS(DATAA30)'
2. We can omit the OMPROUTE_FILE statement if we have coded the OMPCFG DD
statement in the OMPROUTE started procedure.
With the appropriate naming conventions, we can make both the OMPROUTE
environment variable file and the OMPROUTE started procedure shareable across
Tip: OMPROUTE can be started as a z/OS procedure, or from the z/OS shell, or from
AUTOLOG.

Update the TCPIP.DATA file
Our test environment is running under CINET. With CINET there is often a global TCPIP.DATA
file and a stack-specific local TCPIP.DATA file. The keywords specified in the global
TCPIP.DATA cannot be overridden with parameters in any local TCPIP.DATA files.
In the CINET environment, the Global Resolver configuration file contains keywords that are
shared with all TCP/IP stacks on the z/OS image, and should omit the stack-specific
keywords such as TCPIPJobname and Hostname. Those parameters should be specified in
the local TCPIP.DATA file. If a specific parameter is not found in the global TCPIP.DATA, the
local TCPIP.DATA file is searched according to the search order. You can read more about the
Resolver in Chapter 2, “The Resolver” on page 21.
Example 5-11 shows the global TCPIP.DATA file used in our example.
; *****************************************
; *****************************************
NSPORTADDR 53
RESOLVEVIA UDP
RESOLVERTIMEOUT 10
LOOKUP LOCAL DNS
Then each stack has a stack-specific local TCPIP.DATA file identifying stack-specific
parameters such as TCPIPJobname and Hostname. Example 5-12 shows the local
TCPIP.DATA file used in our example.
Example 5-12 Local TCPIP.DATA file
; *****************************************
; *****************************************
HOSTNAME WTSC30A
DATASETPREFIX TCPIPA 2
MESSAGECASE MIXED
1. Specify the TCP/IP stack name that OMPROUTE should establish affinity to, using the
TCPIPJobname statement.
2. Specify the data set prefix (hlq) that OMPROUTE should use.
In an INET environment, usually only a global TCPIP.DATA file is used. It should contain the
keywords (TCPIPJobname and DATASETPREFIX) used by OMPROUTE. The
TCPIPJobname parameter specifies the name of TCP/IP stack with which OMPROUTE
establishes an affinity.
Important: When defining the STDENV (_CEE_ENVFILE) file with a z/OS data set, the
data set must be allocated with RECFM=V. Using RECFM=F or FB is not recommended,
because the fixed setting enables padding with blanks for the environment variables.

RACF-authorize user IDs for starting OMPROUTE
To reduce the risk of an unauthorized user starting OMPROUTE and affecting the contents of
the routing table, users who start OMPROUTE must be RACF-authorized to the entity
MVS.ROUTEMGR.OMPROUTE and require a UID of zero (0). In our test environment, we
executed the command shown in Example 5-13.
Example 5-13 RACF commands to authorize the stating of OMPROUTE
RDEFINE OPERCMDS (MVS.ROUTEMGR.OMPROUTE) UACC(NONE)
PERMIT MVS.ROUTEMGR.OMPROUTE ACCESS(CONTROL) CLASS(OPERCMDS) ID(OMPA) 1
SETROPTS RACLIST(OPERCMDS) REFRESH
1. Specify the OMPROUTE cataloged procedure name for ID parameter.
Start syslogd
Syslogd can and should be used to receive the specified messages from OMPROUTE. It can
be configured to receive all OMPROUTE non-critical messages. Update the syslogd.conf file
to isolate all OMPROUTE messages to a specific output destination file. Example 5-14 shows
how we configured the syslogd to receive all error, warning, info, and notice messages in a
syslog file.
Example 5-14 Syslogd configuration file
##**********************************************************************
#* *
#* syslog.conf - Defines the actions to be taken for the specified *
#* facilities/priorities by the syslogd daemon. *
#* *
*.OMPA*.*.err /tmp/syslog/ompa.err.log 1
1. Specify the syslog output destination file name for the OMPA-related messages.
Change port 520 and 521 definitions to NOAUTOLOG
If OMPROUTE is started with AUTOLOG and only the OSPF protocol is used, it is important
to do one of the following tasks:
Ensure that the RIP UDP port (520) and the IPv6 RIP UDP port (521) are not reserved by
the PORT statement in the PROFILE.TCPIP.
Add the NOAUTOLOG parameter to the PORT statement, as shown in Example 5-15.
Example 5-15 Ports 520 and 521 defined as NOAUTOLOG
; *****************************************
; TCPIPA.TCPPARMS(PROFA30)
; *****************************************
.....
520 UDP OMPA NOAUTOLOG ; OMPROUTE IPv4 RIPV2
521 UDP OMPA NOAUTOLOG ; OMPROUTE IPv6 RIPV2
.....
Important: OMPROUTE must be started by a RACF-authorized user ID.

Create the OMPROUTE configuration file
We defined the parameters for OSPF implementation in the OMPROUTER configuration file.
Example 5-16 shows the configuration we used in our example. We defined a z/OS TCP/IP to
be a Totally Stubby Area, the interfaces as part of the Stub Area, and other parameters.
The search order for OMPROUTE configuration file is as follows:
1. OMPCFG DD statement in the OMPROUTE started procedure
2. OMPROUTE_FILE environment variable
3. /etc/omproute.conf
4. hlq.ETC.OMPROUTE.CONF
Example 5-16 OMPROUTE configuration file
Area Area_Number=0.0.0.2 1
Stub_Area=YES 2
Authentication_type=None
Import_Summaries=Yes; 3
OSPF
RouterID=10.1.30.10 4
Comparison=Type2
DR_Max_Adj_Attempt = 10 5
Demand_Circuit=YES;
Global_Options
Ignore_Undefined_Interfaces=YES 6
;
Routesa_Config Enabled=No;
; Static vipa
OSPF_Interface IP_address=10.1.30.10 7
Name=VIPA3L 8
Subnet_mask=255.255.255.0
Attaches_To_Area=0.0.0.2 9
Advertise_VIPA_Routes=HOST_ONLY 10
Cost0=10 11
MTU=65535;
; Static vipa
OSPF_interface ip_address=10.1.1.10
name=VIPA1L
subnet_mask=255.255.255.0
Advertise_VIPA_Routes=HOST_ONLY
attaches_to_area=0.0.0.2
cost0=10
mtu=65535
name=VIPA2L
cost0=10
mtu=65535
; OSA Qdio VLAN10
OSPF_Interface IP_address=10.1.2.* 12
Important: If you fail to take one of these actions, OMPROUTE will be periodically
canceled and restarted by TCP/IP.

Router_Priority=0 13
Attaches_To_Area=0.0.0.2
Cost0=100
MTU=1492;
; OSA Qdio VLAN11
OSPF_Interface IP_address=10.1.3.*
Router_Priority=0
Cost0=100
MTU=1492;
; Hipersockets 10.1.4.x
Router_Priority=1
Cost0=90
MTU=8192;
Router_Priority=1
Cost0=90
MTU=8192;
Router_Priority=1
Cost0=90
MTU=8192;
;
; Dynamic vipa VIPADEFINE
ospf_interface ip_address=10.1.8.*
cost0=10
mtu=65535
;
cost0=10
mtu=65535
;
;AS_Boundary_routing 14
; Import_Direct_Routes=yes;

1. Define the OSPF Area (Area 2).
2. Indicates Area 2 is a Stub Area.
3. Import_Summaries has meaning only if coded in an ABR. It makes the area connected to
the ABR a Totally Stubby Area. If you coded the parameter in OMPROUTE on a Stub
Area, it is ignored but it functions as a reminder that the ABR -- the layer 3 switch -- is
defining our Stub Area as a Totally Stubby Area.
4. Defines the router internal IP address to be represented as the router ID.
5. Defines the DR_MAX_ADJ_ATTEMPT parameter on the OSPF to enable this function.
OMPROUTE will then report and control futile neighbor state loops during the adjacency
formation process. Futile neighbor state loops are automatically detected and reported
using message EZZ8157I. If a parallel OSPF interface is not available, adjacency
formation attempts continue to be retried over the same interface. If parallel OSPF are
available, an interface change is reported using message EZZ8158I.
6. Tells OSPF not to build an INTERFACE statement automatically for interfaces not defined
in the OMPROUTE configuration file.
7. Defines a specific interface to be an OSPF interface. When the specific IP address is
coded (not the wildcard as in 12) the NAME statement must also be configured (see 7).
8. The NAME statement identifies the link as an OSPF interface. The NAME statement must
match the name specified in the LINK statement in the TCP/IP profile.
9. Defines the interface should belong to Area 2.
10.If the OSPF_Interface is a VIPA link, you can use this parameter to tell OMPROUTE how
you want the VIPA address to be advertised. By default both the host and the subnet
routes are advertised. Only the VIPA host route is advertised when this option is set to
HOST_ONLY. We recommend the use of HOST_ONLY for VIPAs unless you have a
compelling reason to advertise the subnet route.
11.We define the interface cost of VIPA to be 10, HiperSockets to be 90, and OSA to be 100.
We made the cost of HiperSockets smaller than OSA so that the HiperSockets route is
preferred for the mainframe-to-mainframe communication.
12.When defining OSPF_Interface IP_address with a wild card (*), all interfaces within the
defined range will be seen as OSPF interfaces. Individual definitions with wild cards can
be used for seeding other OMPROUTE configuration files. Remember that the unique
RouterID of each file makes the entire file unshareable unless MVS system symbolics are
employed.
Note: The RouterID must be unique on each OMPROUTE configuration. We highly
recommend that you code the RouterID statement (4), either with the static VIPA
address or with an interface IP address, because the dynamic VIPAs (DVIPAs) that can
move between z/OS hosts within a sysplex.
OMPROUTE cycles through all the OSPF interfaces until it finds a non-DVIPA interface
if no RouterID is coded. A message (EZZ8134I) will be issued if a Dynamic VIPA is
explicitly coded or chosen as a RouterID, because this is not recommended.
The interface with an IP address which represents RouterID (6) has to be coded
explicitly as shown in Example 5-16, not using the wild card (*). Therefore, if the
RouterID is hard-coded as it is in this example, only portions of the configuration file can
be shared across systems.

13.The z/OS Communications Server should be prevented from becoming the designated
router in the LAN environment, when routers that are present can perform this function. To
do this, define statement Router_Priority with value 0.
14.Stub Areas do not permit importation of OSPF external, direct, or static routes; although
the z/OS Communications Server on this node can learn about them, they will not be
advertised. Therefore, the AS_Boundary_Routing statement is useless in this
configuration and it is commented out. If it is not commented out, it is ignored when the
node belongs to a Stub Area or Totally Stubby Area.
Our next example of an OMPROUTE configuration file can be shared across multiple stacks
using MVS system symbols and too we can to use the statement INCLUDE. It can group
OMPROUTE configuration statements that are common to several OMPROUTE instances
into a single file. You do not need to repeat the configuration information in multiple places, we
need only put the INCLUDE.
The use of MVS system symbols and statement INCLUDE in the OMPROUTE configuration
file are introduced in Communications Server. We show it in Example 5-17.
Example 5-17 Shareable OMPROUTE configuration file using MVS system symbols and INCLUDE
OSPF
RouterID=10.1.&SYSCLONE..10 1
Comparison=Type2
Demand_Circuit=YES;
Global_Options
Ignore_Undefined_Interfaces=YES
Routesa_Config Enabled=No;
; Static vipa
OSPF_Interface IP_address=10.1.&SYSCLONE..10 2
Name=VIPA3L
Cost0=10
MTU=65535;
INCLUDE //'TCPIPA.TCPPARMS(OMPA30IN)' 3
This OMROUTE configuration file is now completely shareable. We have fully exploited
wildcards, the MVS system symbolics and the statement INCLUDE.
1. We used a MVS system symbol &SYSCLONE value to express the OSPF_Interface that
is also used to represent our RouterID of 10.1.0.10 (the &SYSCLONE value resolves to 30
on this LPAR; we used only one digit starting with the second digit of the &SYSCLONE
value).
2. We used the same SYSCLONE value to define the OSPF_Interface.
3. We used the INCLUDE TCPIPA.TCPPARMS(OMPA30IN), and put in this file the
statements of common interfaces Dynamic XCF. Example 5-18 shows this data set.

Example 5-18 Data set OMPA30IN with include configuration
;Dynamic XCF
interface ip_address=10.1.7.*
mtu=65535;
5.5.5 Configure routers
In our router, we created a router service 100, which is analogous to an OMPROUTE
procedure (or OSPF process). We defined the OSPF configuration for a Totally Stubby Area
under this process.
To configure router 1, we used the configuration statements shown in Example 5-19.
Example 5-19 Router A configuration statements
interface Loopback1
ip address 10.1.200.1 255.255.255.0
!
interface Vlan10
ip address 10.1.2.240 255.255.255.0
ip ospf cost 100
ip ospf priority 100
!
interface Vlan11
ip address 10.1.3.240 255.255.255.0
ip ospf cost 100
!
router ospf 100 1
router-id 10.1.3.240 2
log-adjacency-changes
area 2 stub no-summary 3
network 10.1.2.0 0.0.0.255 area 2 4
network 10.1.3.0 0.0.0.255 area 2 4
network 10.1.100.0 0.0.0.255 area 2 4
network 10.200.1.0 0.0.0.255 area 0 5
default-information originate always metric-type 1
1. Designates the process 100 to be an OSPF routing service.
2. Defines the router ID of this process (100).
3. Creates an OSPF area to this process (Area 2) and defines it to be a Stub Area.
4. Defines the network range designated to Area 2. All interfaces within this IP address range
(10.10.0.0) will belong to Area 2.
5. Defines the network range designated to the backbone Area 0. All interfaces within this IP
address range (10.200.0.0) will belong to Area 0.

To activate and verify the OMPROUTE configuration, perform the following steps:
1. Start OMPROUTE.
2. Verify the configuration.
Start OMPROUTE
OMPROUTE can be started from an z/OS procedure, from the z/OS shell, or from
AUTOLOG.
In our test environment we started the OMPROUTE from the z/OS procedure, as shown in
Example 5-20.
Example 5-20 OMPROUTE initialization
S OMPA
$HASP100 OMPA ON STCINRDR
IEF695I START OMPA WITH JOBNAME OMPA IS ASSIGNED TO USER
TCPIP , GROUP TCPGRP
$HASP373 OMPA STARTED
IEE252I MEMBER CTIORA00 FOUND IN SYS1.PARMLIB
EZZ7800I OMPA STARTING 1
EZZ7975I OMPA IGNORING UNDEFINED INTERFACE EZASAMEMVS 2
EZZ7475I ICMP WILL IGNORE REDIRECTS DUE TO ROUTING APPLICATION BEING
ACTIVE
EZZ8100I OMPA SUBAGENT STARTING
IEA989I SLIP TRAP ID=X13E MATCHED. JOBNAME=RMFGAT , ASID=0043.
EZZ7898I OMPA INITIALIZATION COMPLETE
1. The procedure name OMPA appears in several of the informational messages: EZZ7871I,
EZZ975I, and EZZ8100I. This facilitates problem determination in a SYSPLEX or CINET
environment with messages flowing to a single console.
2. Message EZZ975I shows the effect of “Ignore_Undefined_Interfaces=YES” coding in the
OMPROUTE configuration file shown in Example 5-16 on page 185.
You can use the AUTOLOG statement to start OMPROUTE automatically during TCP/IP
initialization. Insert the name of the OMPROUTE start procedure in the AUTOLOG statement
of the PROFILE.TCPIP data set (see Example 5-21).
Example 5-21 AUTOLOG statements
; *****************************************
; TCPIPA.TCPPARMS(PROFA30)
; *****************************************
.....
AUTOLOG 5
OMPA ; OMPROUTE procedure
ENDAUTOLOG
.....

Verify the configuration
To verify that OMPROUTE is configured correctly as we defined, we can use either the
DISPLAY or the MODIFY command.
In this section, we show some of the most useful DISPLAY commands and outputs. To see
other display command options and to get more detailed information about specific
commands, refer to z/OS Communications Server: IP System Administrator’s Commands,
SC31-8781.
To display OSPF configuration information, use the Display OMPROUTE,OSPF,LIST,ALL
command. The sample display is shown in Example 5-22.
Example 5-22 D TCPIP,TCPIPA,OMP,OSPF,LIST,ALL command display
D TCPIP,TCPIPA,OMP,OSPF,LIST,ALL
EZZ7831I GLOBAL CONFIGURATION 413
TRACE: 0, DEBUG: 1, SADEBUG LEVEL: 0
STACK AFFINITY: TCPIPA
OSPF PROTOCOL: ENABLED
EXTERNAL COMPARISON: TYPE 2
AS BOUNDARY CAPABILITY: DISABLED
DEMAND CIRCUITS: ENABLED
DR MAX ADJ. ATTEMPT: 10
EZZ7832I AREA CONFIGURATION
AREA ID AUTYPE STUB? DEFAULT-COST IMPORT-SUMMARIES?
0.0.0.2 0=NONE YES 1 YES 1
0.0.0.0 0=NONE NO N/A N/A
EZZ7833I INTERFACE CONFIGURATION
IP ADDRESS AREA COST RTRNS TRDLY PRI HELLO DEAD DB_E*
10.1.8.10 0.0.0.2 10 N/A N/A N/A N/A N/A N/A
10.1.6.11 0.0.0.2 90 5 1 1 10 40 40
10.1.5.11 0.0.0.2 90 5 1 1 10 40 40
10.1.4.11 0.0.0.2 90 5 1 1 10 40 40
10.1.2.12 0.0.0.2 100 5 1 0 10 40 40
10.1.3.12 0.0.0.2 100 5 1 0 10 40 40
10.1.3.11 0.0.0.2 100 5 1 0 10 40 40
10.1.2.11 0.0.0.2 100 5 1 0 10 40 40 2
10.1.2.10 0.0.0.2 10 N/A N/A N/A N/A N/A N/A
10.1.1.10 0.0.0.2 10 N/A N/A N/A N/A N/A N/A 3
10.1.30.10 0.0.0.2 10 N/A N/A N/A N/A N/A N/A
ADVERTISED VIPA ROUTES
10.1.8.10 /255.255.255.255 10.1.2.10 /255.255.255.255
10.1.1.10 /255.255.255.255 10.1.30.10 /255.255.255.255
1. The Area 2 is defined as a Totally Stubby Area.
2. The OSA interface has Router_Priority=1, Hello_Interal=10, Dead_Interval=40 specified
to establish neighbors with other routers.
3. The VIPA interface does not have Router_Priority, Hello_Interval, or Dead_Interval
specified because they do not establish neighbors.

Display OSPF interfaces
Use the Display OMPROUTE,OSPF,INTERFACE command to display the defined OSPF
interfaces and their current status. Our display example is shown in Example 5-23.
Example 5-23 D TCPIP,TCPIPA,OMP,OSPF,INTERFACE command display
D TCPIP,TCPIPA,OMPR,OSPF,INTERFACE
EZZ7849I INTERFACES 400
IFC ADDRESS PHYS ASSOC. AREA TYPE STATE #NBRS #ADJS
10.1.8.10 VIPL0A01080A 0.0.0.2 VIPA N/A N/A N/A
10.1.6.11 IUTIQDF6L 0.0.0.2 BRDCST 32 4 2
10.1.5.11 IUTIQDF5L 0.0.0.2 BRDCST 32 4 2
10.1.4.11 IUTIQDF4L 0.0.0.2 BRDCST 32 4 2
10.1.3.12 OSA20E0I 0.0.0.2 BRDCST 32 4 1 1
10.1.3.11 OSA20C0I 0.0.0.2 BRDCST 2 0 0
10.1.2.12 OSA20A0I 0.0.0.2 BRDCST 32 3 1
10.1.2.14 OSA2081I 0.0.0.2 BRDCST 2 0 0
10.1.2.11 OSA2080I 0.0.0.2 BRDCST 2 0 0
10.1.2.10 VIPA2L 0.0.0.2 VIPA N/A N/A N/A
10.1.1.10 VIPA1L 0.0.0.2 VIPA N/A N/A N/A 2
10.1.30.10 VIPA3L 0.0.0.2 VIPA N/A N/A N/A
* -- LINK NAME TRUNCATED
1. The OSA interface is attached to Area 2 and has four neighbors established.
2. The VIPA interface is attached to Area 2 but does not establish neighbors.
Display OSPF neighbors
Use the Display OMPROUTE,OSPF,NBRS command to display the OSPF neighbors and
their current status. Our display example is shown in Example 5-24.
Example 5-24 D TCPIP,TCPIPA,OMP,OSPF,NBRS command display
D TCPIP,TCPIPA,OMPR,OSPF,NBRS
EZZ7851I NEIGHBOR SUMMARY 392
NEIGHBOR ADDR NEIGHBOR ID STATE LSRXL DBSUM LSREQ HSUP IFC
10.1.3.240 10.1.3.240 128 0 0 0 OFF OSA20E0I 1
10.1.3.41 10.1.3.10 8 0 0 0 OFF OSA20E0I 2
10.1.2.22 10.1.1.20 8 0 0 0 OFF OSA20A0I 2
10.1.2.240 10.1.3.240 128 0 0 0 OFF OSA20A0I 1
10.1.2.22 10.1.31.10 8 0 0 0 OFF OSA20A0I 2
10.1.4.21 10.1.31.10 128 0 0 0 OFF IUTIQDF4L 3
10.1.5.21 10.1.31.10 128 0 0 0 OFF IUTIQDF5L 3
10.1.6.21 10.1.31.10 128 0 0 0 OFF IUTIQDF6L 3
* -- LINK NAME TRUNCATED

1. The neighbor with router 1 is established in each VLAN that OSA belongs to. The state is
128 (Full).
2. The neighbor with TCPIPB stack is established on the OSA interface. The state is
8 (2-way), because router 1 and router 2 are DR/BDR, so TCPIPA and TCPIPB are both
DR other.
3. The neighbor with TCPIPB stack is established on the HiperSockets interface. The state is
128 (Full), because TCPIPB is the DR on the HiperSockets subnet.
Display OSPF routers
Use the Display OMPROUTE,OSPF,ROUTERS command to display the OSPF routes to
ABRs and ASBRs. Our display example is shown in Example 5-24 on page 192.
Example 5-25 D TCPIP,TCPIPA,OMP,OSPF,ROUTERS command display
D TCPIP,TCPIPA,OMPR,OSPF,ROUTERS
EZZ7855I OSPF ROUTERS 402
DTYPE RTYPE DESTINATION AREA COST NEXT HOP(S)
BR SPF 10.1.3.240 0.0.0.2 100 10.1.2.240 * 1
1. Router 1 is the ABRs.
Display OMPROUTE routing table
Use the Display OMPROUTE,RTTABLE command to display the OMPROUTE routing table.
Our display example is shown in Example 5-26.
Example 5-26 D TCPIP,TCPIPA,OMP,RTTABLE command display
D TCPIP,TCPIPA,OMPR,RTTABLE
EZZ7847I ROUTING TABLE 404
TYPE DEST NET MASK COST AGE NEXT HOP(S)
SPIA 0.0.0.0 0 101 35859 10.1.2.240 (5) 1
DIR* 10.1.1.0 FFFFFF00 1 37110 10.1.1.10 2
DIR* 10.1.1.10 FFFFFFFF 1 37110 VIPA1L 2
SPF 10.1.1.12 FFFFFFFF 90 37098 10.1.4.12 (2) 3
SPF 10.1.1.20 FFFFFFFF 90 37098 10.1.4.21 (2)
SPF 10.1.1.40 FFFFFFFF 110 35859 10.1.2.42 (5)
SPF* 10.1.2.0 FFFFFF00 100 35859 OSA2080I (3)
DIR* 10.1.2.10 FFFFFFFF 1 37110 VIPA2L 2
SPF 10.1.2.17 FFFFFFFF 90 37098 10.1.4.12 (2)
SPF* 10.1.3.0 FFFFFF00 100 37103 OSA20C0I (2)
SPF* 10.1.4.0 FFFFFF00 80 37100 IUTIQDF4L
SPF 10.1.8.10 FFFFFFFF 90 35859 10.1.4.12 (4)
SPF 10.1.8.20 FFFFFFFF 90 37098 10.1.4.21 (2)
DEFAULT GATEWAY IN USE.
TYPE COST AGE NEXT HOP
SPIA 101 13248 10.1.2.240 (3)
0 NETS DELETED, 1 NETS INACTIVE
EZZ8052I OMPC SEND TO 224.0.0.5 BLOCKED BY TCPIP 0 NETS DELETED, 3 NETS INACTIVE

1. Only the default route is advertised from ABR.
2. Direct routes to the subnet to which local interfaces belong are listed.
3. Indirect routes to the VIPA in TCPIPB are listed.
Display TCP/IP routing table
Use the Netstat command to display the OSPF routes to ABRs and ASBRs. Our display
example is shown in Example 5-27.
Example 5-27 D TCPIP,TCPIPA,Netstat,ROUTE command display
D TCPIP,TCPIPA,N,ROUTE,MAX=*
IPV4 DESTINATIONS
DEFAULT 10.1.2.240 UGO 000000 OSA2080I 1
DEFAULT 10.1.2.240 UGO 000000 OSA20A0I
DEFAULT 10.1.3.240 UGO 000000 OSA20C0I
DEFAULT 10.1.3.240 UGO 000000 OSA20E0I
10.1.1.10/32 0.0.0.0 UH 000000 VIPA1L
10.1.1.12/32 10.1.4.12 UGHO 000000 IUTIQDF4 2
10.1.1.12/32 10.1.5.12 UGHO 000000 IUTIQDF5
10.1.1.20/32 10.1.4.21 UGHO 000000 IUTIQDF4
10.1.1.20/32 10.1.5.21 UGHO 000000 IUTIQDF5
10.1.1.40/32 10.1.2.42 UGHO 000000 OSA2080I
10.1.1.40/32 10.1.2.42 UGHO 000000 OSA20A0I
10.1.1.40/32 10.1.3.41 UGHO 000000 OSA20C0I
10.1.1.40/32 10.1.3.41 UGHO 000000 OSA20E0I
10.1.2.0/24 0.0.0.0 UO 000000 OSA2080I
127.0.0.1/32 0.0.0.0 UH 000004 LOOPBACK
IPV6 DESTINATIONS
DESTIP: ::1/128
GW: ::
INTF: LOOPBACK6 REFCNT: 000000
FLGS: UH MTU: 65535
END OF THE REPORT
1. The default routes to the router 1 is listed. We do not have IPCONFIG MULTIPATH
specified, so the first active default route entry (interface OSA2080I and gateway address
10.1.2.240) is always used for a destination that does not have an explicit route entry.
2. Indirect routes to the VIPA in TCPIPB stack are listed. We do not have IPCONFIG
MULTIPATH specified, so the first active route entry (interface IUTIQDF4L) is always used
for the VIPA destination.
Check the connectivity using PING command
The PING command can be executed with the TSO PING command or the z/OS UNIX ping
command. Example 5-28 shows the display of the TSO PING command. We see the ping is
successful.
the TSO PING command and the -p option for the z/OS UNIX ping command to specify the
TCP/IP stack name from which you want to issue the ping command.

You do not need to specify those options if the user issuing this command is already
associated to the TCP/IP stack (with SYSTCPD DD, for example). There is no need to specify
these options if your environment is an INET environment where only one TCP/IP stack is
configured.
**
Example 5-29 shows the display of z/OS UNIX ping command.
CS08 @ SC30:/u/cs08>ping -p TCPIPA 10.1.1.20
Verify the selected route with the TRACEROUTE command
traceroute/otracert command. Example 5-30 shows an example of the display. We see that
the router 1 (10.1.2.240) is the next hop router to reach destination IP address 10.1.100.221.
the TSO TRACERTE command and the -a option for the z/OS UNIX traceroute command to
specify the TCP/IP stack name from which you want to issue the TRACEROUTE command.
You do not need to specify those options if the user issuing this command is already
those options if your environment is an INET environment where only one TCP/IP stack is
configured.
TSO TRACERTE 10.1.100.221 (TCP TCPIPA
CS V1R10 Traceroute to 10.1.100.221 (10.1.100.221)
1 router1 (10.1.2.240) 0 ms 0 ms 0 ms
2 10.1.100.221 (10.1.100.221) 0 ms 0 ms 0 ms
***
5.5.7 Managing OMPROUTE
You can manage OMPROUTE from a z/OS operator console. Commands are available to
perform the following:
Stop OMPROUTE.
Modify OMPROUTE.
Display OMPROUTE.
Stop OMPROUTE from z/OS console
OMPROUTE can be stopped from the z/OS console by issuing STOP <procname> or MODIFY
<procname>,KILL.

Example 5-31 shows the display.
Example 5-31 Stopping OMPROUTE from z/OS console
P OMPA
EZZ7804I OMPA EXITING
ITT120I SOME CTRACE DATA LOST, LAST 5 BUFFER(S) NOT WRITTEN
$HASP395 OMPA ENDED
Stop OMPROUTE from z/OS UNIX shell
You can also stop OMPROUTE from a z/OS UNIX shell superuser ID by issuing the kill
command to the process ID (PID) associated with OMPROUTE. To determine the PID, use
one of the following methods:
From the z/OS console, issue D OMVS,U=userid (where userid is the user ID that started
omproute from the shell). From the resulting display, look at the PID number related to
OMPROUTE, as shown in Example 5-32 (1).
Example 5-32 Stopping OMPROUTE from z/OS UNIX
D OMVS,U=TCPIP
BPXO040I 14.56.39 DISPLAY OMVS 617
OMVS 000E ACTIVE OMVS=(7A)
USER JOBNAME ASID PID PPID STATE START CT_SECS
TCPIP OMPA 00EF 50397483 1 1 HS---- 14.43.13 243.843
LATCHWAITPID= 0 CMD=OMPROUTE
From the z/OS UNIX shell, issue the ps -ef command, as shown in Example 5-33 (1).
Example 5-33 ps -ef command in z/OS UNIX shell
CS03 @ SC30:/u/cs03>ps -ef
UID PID PPID C STIME TTY TIME CMD
BPXROOT 1 0 - Oct 11 ? 0:14 BPXPINPR
BPXROOT 16842754 1 - Oct 11 ? 1:07 BPXVCMT
BPXROOT 50397483 1 1 - 14:43:14 ? 4:10 OMPROUTE 1
CS03 @ SC30:/u/cs03>kill 50397483 1
Modify OMPROUTE configuration
We can use the MODIFY (F) command to change some configuration statements and to
start, stop, or change the level of OMPROUTE tracing and debugging, as follows:
F procname,RECONFIG command: Used to reread the OMPROUTE configuration file,
adding new OSPF_interfaces
F procname,ROUTESA=ENABLE/DISABLE command: Used to enable or disable the
OMPROUTE subagent
F procname,OSPF,WEIGHT,NAME=<if_name>,COST=<cost> command: Changes dynamically
the cost of an OSPF interface
In OSPF environments in which there might be a problem with some remote hardware (for
example, router, switch, or network cable) that is beyond detection by z/OS hardware or
software, OMPROUTE can get into an infinite neighbor state loop over one of its interfaces
with a neighbor. This loop might contribute to increased workload. In LAN configurations in
which there are parallel OSPF interfaces that can reach the same neighbor for adjacency
formation, unless you are using OMPROUTE futile neighbor state loop detection or unless
you manually fix the problem, the backup interfaces are not used until after an outage occurs

for the OSPF interface that was initially involved in an adjacency formation attempt with a
designated router
We can use the MODIFY (F) command to suspend and, after fixing the problem, activate an
OSPF interface using the F procname,OSPF,INTERFACES,NAME=interfname,SUSPEND or
ACTIVATE command, which suspends or activates the OMPROUTE interface. In
Example 5-34, we shows these commands and the status of the interface. First, we suspend
the interface OSA20A01 (1), then we issue the display and see the state 1* (suspend) 2
Finally, we reactivate the interface to normal status 3.
Example 5-34 MODIFY SUSPEND and ACTIVATE commands
F OMPA,OSPF,INTERFACES,NAME=OSA20A0I,SUSPEND 1
EZZ7866I OMPA MODIFY COMMAND ACCEPTED
EZZ8159I OMPA MODIFY SUSPEND COMMAND FOR OSPF IPV4 INTERFACE OSA20A0I
IS SUCCESSFUL
D TCPIP,TCPIPA,OMP,OSPF,INTERFACES
EZZ7849I INTERFACES 803
IFC ADDRESS PHYS ASSOC. AREA TYPE STATE #NBRS
#ADJS
10.1.6.11 IUTIQDF6L 0.0.0.2 BRDCST 64 1 1
10.1.5.11 IUTIQDF5L 0.0.0.2 BRDCST 32 2 2
10.1.4.11 IUTIQDF4L 0.0.0.2 BRDCST 32 2 2
10.1.3.12 OSA20E0I 0.0.0.2 BRDCST 32 4 1
10.1.3.11 OSA20C0I 0.0.0.2 BRDCST 2 0 0
10.1.2.12 OSA20A0I 0.0.0.2 BRDCST 1* 0 0 2
10.1.2.14 OSA2081I 0.0.0.2 BRDCST 1 0 0
F OMPA,OSPF,INTERFACES,NAME=OSA20A0I,ACTIVATE 3
EZZ7866I OMPA MODIFY COMMAND ACCEPTED
EZZ8160I OMPA MODIFY ACTIVATE COMMAND FOR OSPF IPV4 INTERFACE
OSA20A0I IS SUCCESSFUL
Display OMPROUTE information
We can use the MODIFY (F) command instead of the DISPLAY TCPIP command to display
information for OMPROUTE. Both commands provide the same information and use the
same statements, as shown in the following samples:
F procname,RTTABLE command: The resulting display provides the same contents as
though we were using D TCPIP,procnamename,OMP,RTTABLE.
F procname,OSPF,LIST ALL command: The resulting display provides us the same
contents as though we were using D TCPIP,procnamename,OMP,OSPF,LIST ALL.
Note: Use the MODIFY SUSPEND command to stop OSPF traffic on an OSPF interface,
rather than using the VARY TCPIP command to deactivate the corresponding physical
interface in TCPIP. This will allow existing sessions using static routes on the affected
interface not to be disrupted.

Start, stop, or change the level of OMPROUTE tracing and debugging
We can use the MODIFY (F) command to start, stop, or change the level of tracing and
debugging.
F procname,TRACE=n: For OMPROUTE tracing for initialization and IPv4 routing protocols;
n can be 0–2.
F procname,DEBUG=n: For OMPROUTE debugging for initialization and IPv4 routing
protocols; n can be 0–4.
F procname,SADEBUG=n: For OMPROUTE subagent debugging; n can be 0 or 1.
For further information about these commands and options, refer to z/OS Communications
Server: IP System Administrator’s Commands, SC31-8781.
When implementing a network environment with indirect access to external hosts or networks
using routing definitions, it is important to understand how to isolate networking problems.
This means that using the correct diagnostic tools and techniques is essential. In this section
we describe the tools and techniques needed to debug routing problems in a static routing
environment and in a dynamic OSPF routing environment. To debug a network problem in a
z/OS environment, we suggest following the flow shown in Figure 5-4.

Figure 5-4 Routing problem determination flow
The descriptions for the tags shown in Figure 5-4 are as follows:
1. Use the ping command to determine whether there is connectivity to the destination IP
address. More information about the ping command can be found in “PING command
(TSO or z/OS UNIX)” on page 200.
2. If the ping command fails immediately, there might not be a route to the destination host or
subnet. Use the Netstat ROUTE/ -r command to display routes to the network, as shown
in Example 5-5 on page 177. Verify that TCP/IP has a route to the destination address.
If there is no route, proceed to step 3. If a route does exist, then proceed to step 4.
3. If there is no route to the destination, problem resolution depends on whether static or
dynamic routing is being used. In either case, do the following:
a. If TCP/IP is configured using Static Routing, review and correct the configuration.
b. If OMPROUTE is being used to generate dynamic routes, verify and correct the
configuration. If it seems correct, then diagnose the problem using the debugging tools
described in “Diagnosing an OMPROUTE problem” on page 202.
Verify IP Routing to a
destination Host
Route
verified OK
Yes
No
External
Network
problem
Verify and
correct the
Dynamic
route
definition
Verify and
correct the
interface
config
problem
Ping to the
destination
address
OK?
Using
Dynamic
Routing?
Ping first
Hop OK?
Verify and
correct the
device
problem
Verify and
correct the
static route
definition
Route to
the
destination
OK?
The
Device is
ready?
1
YesYes
Yes
No No
No No
3a2 3
5b4 5
4a 5a
Yes

4. If a route exists, verify that the route is correct for the destination. Determine whether the
gateway identified for the route to the destination is reachable. To verify this, use the PING
command to confirm connectivity to the gateway.
Do one of the following:
a. If the gateway responds to a ping, it means there is a network problem at the gateway
or beyond. To get further debug information, use the traceroute command with the
final destination address to determine which hop in the route is failing.
b. If the gateway does not respond to a ping, proceed to step 5.
5. Determine which network interface is associated with the route to the destination. Verify
that it is operational by issuing the Netstat Devlink command, as shown in Example 5-4
on page 176.
Based on the resulting display, do one of the following:
a. If the device is ready, the problem might be in the interface configuration. Check the
network configuration (VLAN ID, IP address, subnet mask, and so on). Correct this and
resume testing.
Otherwise, a packet trace should be taken to verify that the packets are being sent to
the network. A LAN Analyzer could also be used to verify the network traffic in the
switch port where the OSA-Express port is connected.
b. If the device is not ready, the problem might be that the device is not varied online to
z/OS, or that there is an error in the device configuration. Also verify the VTAM TRLE
definitions, HCD/IOCP configuration, as well as the physical connection, cable, and
switch port.
5.6.1 Commands to diagnose networking connectivity problems
In this section we describe briefly the commands that can be used to diagnose connectivity
problems. For additional help and information about diagnosing problems, refer to z/OS
Communications Server: IP System Administrator’s Commands, SC31-8781.
PING command (TSO or z/OS UNIX)
We used the ping command to verify:
The route to the remote network is defined correctly.
The router is able to forward packets to the remote network.
The remote host is able to send and receive packets on the network.
The remote host has a route back to the local host.
The ping command can be executed with the TSO PING command or the z/OS UNIX ping
command. Example 5-35 shows the display of TSO PING command. We see the ping is
successful.
the TSO PING command and the -p option for the /OS UNIX ping command to specify the
TCP/IP stack name from which you want to issue the ping command. You do not need to
specify those options if you are issuing this command in the associated TCP/IP stack (with
SYSTCPD DD, for example). There is no need to specify this option if your environment is an
INET environment where only one TCP/IP stack is configured.

***
Example 5-36 shows the display of the z/OS UNIX ping command.
CS08 @ SC30:/u/CS08>ping -p TCPIPA 10.1.1.20
TRACEROUTE command
traceroute/otracert command.
Traceroute displays the route that a packet takes to reach the requested target. Traceroute
starts at the first router and uses a series of UDP probe packets with increasing IP time-to-live
(TTL) or hop count values to determine the sequence of routers that must be traversed to
reach the target host. The output generated by this command can be seen in Example 5-37.
the TSO TRACERTE command and the -a option for the z/OS UNIX traceroute command to
specify the TCP/IP stack name from which you want to issue the TRACEROUTE command.
Note that you do not need to specify those options if the user issuing this command is already
those options if your environment is an INET environment where only one TCP/IP stack is
configured.
Example 5-37 TSO Tracerte command results
TSO TRACERTE 10.1.100.221 (TCP TCPIPA
CS V1R10: Traceroute to 10.1.100.221 (10.1.100.221)
1 router1 (10.1.2.240) 0 ms 0 ms 0 ms
2 10.1.100.221 (10.1.100.221) 0 ms 0 ms 0 ms
***
Example 5-38 shows the display of the z/OS UNIX traceroute command.
Example 5-38 z/OS UNIX traceroute command result
CS08 @ SC30:/u/cs08>traceroute -a TCPIPA 10.1.100.221
Enter ESC character plus C or c to interrupt
1 router1 (10.1.2.240) 0 ms 0 ms 0 ms
2 10.1.100.221 (10.1.100.221) 0 ms 0 ms 0 ms
Tip: Using a name instead of IP address would need the Resolver or DNS to do the
translation. This adds more variables to the problem determination, and should be avoided
when you are diagnosing network problems. Use the host IP address instead.

Netstat Devlink command (console or z/OS UNIX)
Use the D TCPIP,procname,NETSTAT, DEVLINK command to display the status and
associated configuration values for a device and its defined interfaces. From the z/OS UNIX
shell, use the netstat -d -p procname command. The results are identical in the console or
the z/OS UNIX shell. Example 5-4 on page 176 shows a sample display.
Netstat Route command (console or z/OS UNIX)
Use the D TCPIP,procname,NETSTAT,ROUTE command to display the current routing tables
for TCP/IP. From z/OS UNIX shell, use the netstat -r -p procname command. Example 5-27
on page 194 shows a sample display.
5.6.2 Diagnosing an OMPROUTE problem
This section describe methods that you can use to diagnose an OMPROUTE problem.
Useful commands
In addition to the commands that we show in 5.6.1, “Commands to diagnose networking
connectivity problems” on page 200, you can use additional commands to diagnose
OMPROUTE problems, as described here.
D TCPIP,TCPIPA,OMP,OSPF,NBRS command
This command displays all the OSPF neighbors. Make sure you have established the
neighbor with other routers as you expected. Example 5-24 on page 192 shows a sample
display.
D TCPIP,TCPIPA,OMP,RTTABLE command
This command displays the OMPROUTE routing table. Make sure you have the expected
route listed in the table. If you have multiple routes for the destination, with different costs,
only the best route (least cost route) is added to the OMPROUTE and TCP/IP routing tables.
Example 5-26 on page 193 shows a sample display.
D TCPIP,TCPIPA,OMP,RTTABLE,DELETED command
This command displays all of the route destinations that have been deleted from the
OMPROUTE routing table since the initialization of OMPROUTE at this node. The routes that
have changed the next hop are not considered deleted, and are therefore not displayed with
this command. Example 5-39 shows the results of this display after OMPROUTE is
terminated at SC31 (OMPB), another member of the SYSPLEX.
Example 5-39 Deleted OMPROUTE destinations
D TCPIP,TCPIPA,OMPR,RTTABLE,DELETED
EZZ8137I IPV4 DELETED ROUTES 182
TYPE DEST NET MASK COST AGE NEXT HOP(S)
DEL 10.1.1.20 FFFFFFFF 16 66 NONE
3 NETS DELETED, 2 NETS INACTIVE
Observing initialization messages and taking traces
If these commands do not help, use traces for further diagnosis and verify whether you have
any error messages related to OMPROUTE during the startup process. To do so, examine
SYSLOGD, JES MSG output and the console log for errors.

If there is no apparent error message that could help you to solve the problem, then prepare
OMPROUTE to generate more detailed information by using the debug tools available in
OMPROUTE. This can be activated by coding the Debug and Trace options in the startup
procedure, or by using the MODIFY command to implement these options.
Using OMPROUTE trace and debug for initialization
A trace from startup is ideal because some information is only shown in the trace at startup,
and because the time for problem determination and resolution is faster when the trace
captures the entire flow of events rather than just a small subset of events.
An OMPROUTE trace from startup can be enabled by coding the trace options after the
forward slash (/) in the PARM field of the OMPROUTE catalogued procedure, as shown in
Example 5-40.
Example 5-40 Trace options defined in the OMPROUTE startup procedure
//OMP30A PROC STDENV=STDENV&SYSCLONE
//OMP30A EXEC PGM=OMPROUTE,REGION=4096K,TIME=NOLIMIT,
// '"_CEE_ENVFILE=DD:STDENV")/-t2 -d1')
//*
//STDENV DD DISP=SHR,DSN=TCPIPA.OMPROUTE.&STDENV
If a trace cannot be enabled from startup, then the following commands can dynamically
enable and disable tracing:
To enable:
– MODIFY omproute,TRACE=2 (TRACE6=2 for IPv6)
– MODIFY omproute,DEBUG=1 (DEBUG6=1 for IPv6)
To disable:
– MODIFY omproute,TRACE=0 (TRACE6=0 for IPv6)
– MODIFY omproute,DEBUG=0 (DEBUG6=0 for IPv6)
Trace output is sent to one of the following locations:
A destination referenced by the OMPROUTE_DEBUG_FILE environment variable (which
is coded in the STDENV DD data set).
STDOUT DD, but trace output is only output to this location if OMPROUTE_DEBUG_FILE
is not defined, and the trace is started at initialization.
/{TMPDIR}/omproute_debug (TMPDIR is usually /tmp.)
By default, OMPROUTE will create five debug files, each 200 KB in size, for a total of 1 MB of
trace data. The size and number of trace files can be controlled with the
OMPROUTE_DEBUG_CONTROL environment variable. For further information about the
TRACE and DEBUG options, refer to z/OS Communications Server: IP Diagnosis Guide,
GC31-8782.
Important: Using the OMPROUTE Trace and Debug options and directing the output to
z/OS UNIX file system files generates additional overhead that might cause OSPF
adjacency failures or other routing problems. To prevent that, change the output destination
to the CTRACE Facility.

Using OMPROUTE CTRACE to get debugging information
As mentioned, the overhead problems that can occur when using z/OS UNIX file system files
to save the trace and debug output data can be resolved by using the CTRACE facility. To use
this facility, we strongly recommend using the OMPROUTE option (DEBUGTRC) in the
startup procedure, which changes the output destination of the OMPROUTE trace. In this
section we briefly describe how to define and use CTRACE to debug OMPROUTE problems.
You can start the OMPROUTE CTRACE anytime by using the command TRACE CT. Or it can
be activated during OMPROUTE initialization. If not defined, OMPROUTE component trace is
started with a buffer size of 1 MB and the MINIMUM tracing option.
A parmlib member can be used to customize the parameters and to initialize the trace. The
default OMPROUTE Component Trace parmlib member is the SYS1.PARMLIB member
CTIORA00. The parmlib member name can be changed by using the
OMPROUTE_CTRACE_MEMBER environment variable.
In addition to specifying the trace options, you can also change the OMPROUTE trace buffer
size. (Note that the buffer size can be changed only at OMPROUTE initialization.)The
maximum OMPROUTE trace buffer size is 100 MB. The OMPROUTE REGION size in the
OMPROUTE catalog procedure must be large enough to accommodate a large buffer size.
When OMPROUTE is initialized using the DEBUGTRC option, we recommend that you use a
larger internal CTRACE buffer or an external writer. When using the internal CTRACE buffer,
we must get a DUMP of OMPROUTE in order to see the trace output.
In this section we illustrate the steps needed to start the CTRACE for OMPROUTE and direct
the trace output to an external writer:
1. Create a CTWTR procedure in your SYS1.PROCLIB, as shown in Example 5-41.
Example 5-41 CTWTR procedure
//CTWTR PROC
//*
2. Prepare the SYS1.PARMLIB member CTIORA00 to get the desired output data.
Example 5-42 shows a sample of CTIORA00 contents.
Example 5-42 CTIORA00 sample
/*********************************************************************/
/* */
/* DESCRIPTION = This parmlib member causes component trace for */
/* the TCP/IP OMPROUTE application to be initialized */
/* with a trace buffer size of 1M */
/* */
/* This parmlib member only lists those TRACEOPTS */
/* values specific to OMPROUTE. For a complete list */
/* of TRACEOPTS keywords and their values see */
/* z/OS MVS INITIALIZATION AND TUNING REFERENCE. */
/* */
/* */
/* $MAC(CTIORA00),COMP(OSPF ),PROD(TCPIP ): Component Trace */

/* SYS1.PARMLIB member */
/* */
/*********************************************************************/
TRACEOPTS
/* ---------------------------------------------------------------- */
/* ---------------------------------------------------------------- */
/* WTRSTART(CTWTR) a */
/* ---------------------------------------------------------------- */
/* ---------------------------------------------------------------- */
ON
/* OFF */
/* ---------------------------------------------------------------- */
/* CTRACE buffers reside in OMPROUTE Private storage */
/* which is in the regions address space. */
/* ---------------------------------------------------------------- */
BUFSIZE(50M) b
WTR(CTWTR) a
/* ---------------------------------------------------------------- */
/* ---------------------------------------------------------------- */
/* OPTIONS( c */
/* 'ALL ' */
/* ,'MINIMUM ' */
/* ,'ROUTE ' */
/* ,'PACKET ' */
/* ,'OPACKET ' */
/* ,'RPACKET ' */
/* ,'IPACKET ' */
/* ,'SPACKET ' */
,'DEBUGTRC' d
/* ) */
In this example, the letters correspond to the following information:
– a Define whether we are going to use an external writer to save the output trace data.
– b Define the CTRACE buffer size allocated in the OMPROUTE private storage.
– c Define the trace options to be used to get specific debug information. MINIMUM is
the default option.
– d This option indicates the output data generated from Debug and Trace options
activated in the OMPROUTE startup procedure will be sent to CTRACE.
3. Start the OMPROUTE procedure using the desired Debug and Trace options, as shown in
Example 5-43.
Example 5-43 OMPROUTE procedure
//OMP30A PROC STDENV=STDENV&SYSCLONE
//OMP30A EXEC PGM=OMPROUTE,REGION=4096K,TIME=NOLIMIT,
// '"_CEE_ENVFILE=DD:STDENV")/-t2 -d1') a
//*

//STDENV DD DISP=SHR,DSN=TCPIPA.OMPROUTE.&STDENV
In this example, the letters correspond to the following information:
– a The parameters -t (trace) and -d (debug) define how detailed we want the output
data to be. We recommend using -t2 and -d1.
To verify whether CTRACE has been started as expected, display the CTRACE status,
issuing the console command shown in Example 5-44.
Example 5-44 Displaying OMPROUTE CTRACE status
D TRACE,COMP=SYSTCPRT,SUB=(OMPA)
IEE843I 17.01.01 TRACE DISPLAY 820
SYSTEM STATUS INFORMATION
ST=(ON,0256K,00512K) AS=ON BR=OFF EX=ON MT=(ON,024K)
TRACENAME
=========
SYSTCPRT
MODE BUFFER HEAD SUBS
=====================
OFF HEAD 3
NO HEAD OPTIONS
SUBTRACE MODE BUFFER HEAD SUBS
--------------------------------------------------------------
OMPA ON 0010M
ASIDS *NONE*
JOBNAMES *NONE*
OPTIONS MINIMUM ,DEBUGTRC
WRITER CTWTR
4. We can also use TRACE CT command to define the options we want after OMPROUTE
has been initialized, as seen in Example 5-45.
Example 5-45 TRACE CT command flow
6. Stop the CTRACE by issuing the command in Example 5-46.
Example 5-46 Stopping CTRACE
TRACE CT,OFF,COMP=SYSTCPRE,SUB=(RESOLV32)

7. Save the trace contents into the trace file created by the CTWRT procedure, by executing
the command in Example 5-47.
Example 5-47 Saving the trace contents
TRACE CT,ON,COMP=SYSTCPRT,SUB=(OMPA)
8. Stop the external writer procedure CTWTR by issuing the command shown in
Example 5-48.
Example 5-48 Stopping CTWTR
TRACE CT,WTRSTOP=CTWTR
IEF196I AHL904I THE FOLLOWING TRACE DATASETS CONTAIN TRACE DATA :
IEF196I CS03.CTRACE1
IEF196I CS03.CTRACE2
AHL904I THE FOLLOWING TRACE DATASETS CONTAIN TRACE DATA : 864
CS03.CTRACE1
CS03.CTRACE2
ITT111I CTRACE WRITER CTWTR TERMINATED BECAUSE OF A WTRSTOP REQUEST.
IEF196I IEF142I CTWTR CTWTR - STEP WAS EXECUTED - COND CODE 0000
IEF196I IEF285I CS03.CTRACE1 KEPT
IEF196I IEF285I VOL SER NOS= COMST2.
IEF196I IEF285I CS03.CTRACE2 KEPT
IEF196I IEF285I VOL SER NOS= COMST2.
9. Change the OMPROUTE Debug and Trace level, as shown in Example 5-49, to avoid
performance problems using the MODIFY command.
Example 5-49 Modifying Debug and Trace level
F OMPA,TRACE=0
EZZ7866I OMPROUTE MODIFY COMMAND ACCEPTED
F OMPA,DEBUG=0
After these steps, the trace file must be formatted, using the following IPCS command, into
the IPCS Subcommand screen (option 6), as shown in Example 5-50.
Example 5-50 Formatting the OMPROUTE CTRACE
CTRACE COMP(SYSTCPRT) FULL

The resulting display will show the Resolver process entries, as shown in Example 5-51.
Example 5-51 Sample of formatted OMPROUTE CTRACE
SC30 DEBUGTRC 00060001 21:39:23.679072 Start Trace Message
EZZ7838I Using configuration file: //'TCPIPA.TCPPARMS(OMPA30S)'
========================================================================0000000F
11/23 21:39:23 post-checking on OSPF interface 10.10.1.230(STAVIPA1LNK)
========================================================================00000010
11/23 21:39:23 post-checking on OSPF interface 10.10.2.0(NO NAME)
========================================================================00000011
========================================================================00000012
========================================================================00000013
========================================================================00000014
For more information about OMPROUTE diagnosis, refer to z/OS Communications Server: IP
For more details on these topics, refer to:
z/OS Communications Server: IP Diagnosis Guide, GC31-8782

Chapter 6. VLAN and Virtual MAC support
Virtual LAN (VLAN) technology is becoming more important in network planning for many
customers. A VLAN is a configured logical grouping of nodes using switches. Nodes on a
VLAN can communicate as though they were on the same LAN. You need a router to
communicate across VLANs.
Virtual Medium Access Control (VMAC) support for z/OS Communications Server is a
function that affects the operation of an OSA interface at the OSI layer 2 level. This is the Data
Link Control (DLC) layer with its sub-layer Medium Access Control (MAC) layer.
6
Section Topic
6.1, “Virtual MAC overview” on page 210 The VMAC concept, and the environment in
which it can be used
6.2, “Virtual MAC implementation” on page 213 An implementation example of VMACs
6.3, “Virtual LAN overview” on page 217 VLAN basics
6.4, “VLAN Implementation on z/OS” on page 218 Single VLAN and multiple VLAN
implementation scenarios on z/OS

6.1 Virtual MAC overview
Prior to the introduction of the virtual MAC function, an OSA interface only had one MAC
address. This restriction caused problems when using load balancing technologies in
conjunction with TCP/IP stacks that share OSA interfaces. The single MAC address of the
OSA also causes a problem when using TCP/IP stacks as a forwarding router for packets
destined to unregistered IP addresses.
VMAC support enables an OSA interface to have not only a physical MAC address, but also
many distinct virtual MAC addresses for each device or interface in a stack. That is, each
stack can define up to eight VMACs per protocol (IPv4 or IPv6) for each OSA interface.
With the use of VMACs, forwarding decision in the OSA can be made without having to
involve OSI layer 3 level (network layer / IP layer). From a LAN perspective, the OSA interface
with a VMAC appears as a dedicated device or interface to a TCP/IP stack. Packets destined
for a TCP/IP stack are identified by an assigned VMAC address and packets sent to the LAN
from the stack use the VMAC address as the source MAC address. This means that all IP
addresses associated with a TCP/IP stack are accessible using their own VMAC address,
instead of sharing a single physical MAC address of an OSA interface.
6.1.1 Why use virtual MACs
A shared OSA environment can be a challenge in certain network designs, and it requires
careful planning when selecting the correct TCP/IP stacks to act as routers.
As mentioned in “OSA-Express router support” on page 114, the PRIRouter and SECRouter
functions enable routing through a TCP/IP stack to IP addresses that are not registered in the
OSA. The stack that has the OSA interface defined with PRIRouter will receive packets
destined for IP addresses that do not reside in the given stack. The stack will then forwards
the packets to the next hop.
Only one PRIRouter can be defined per OSA interface, although multiple SECRouters can be
defined to an OSA interface for other TCP/IP routing stacks. However, only one SECRouter
function can take over services if the PRIRouter is not available. If the first SECRouter
function is not available, then the next defined SECRouter will forward IP packets to the
associated stack. This means the OSA interface cannot serve multiple TCP/IP routing stacks
concurrently even with the use of the PRIRouter and SECRouter functions.
Another challenge with shared OSA interfaces is one that requires load balancing of traffic
across multiple TCP/IP stacks and IP addresses. For example, certain load balancing
technologies use a concept of distributing packets to the appropriate adjacent systems based
on knowledge of the MAC address.
We use load balancing (LB) with Sysplex Distributor to illustrate this challenge. If there is a
shared OSA environment, the MAC address is attached to the Sysplex Distributor and to the
selected target system. However, the target IP address can reside on a system other than the
Sysplex Distributor.
As a result, the LB forwarding agent sends the packets to be distributed to the OSA’s physical
MAC address, but the OSA only knows to send the information to the system that has
registered the target address; it does not know to forward the information to the actual target
stack. Mechanisms that are in place to overcome this challenge are Generic Resource
Encapsulation (GRE) and Network Address Translation (NAT).

Chapter 6. VLAN and Virtual MAC support 211
VMAC is a solution for both these problems and we recommend defining VMAC whenever
multiple TCP/IP stacks share an OSA interface. VMAC support can provide the following:
Allow for multiple concurrent TCP/IP routing stacks sharing an OSA interface
Simplify the LAN infrastructure
Eliminate the need for PRIRouter/SECRouter
Improve outbound routing
Improve IP workload balancing
Remove the dependency on GRE and NAT
Note that there are two modes that can be used with load balancing technologies:
Directed mode is where the load balancer converts the destination IP address (cluster IP
address) to an IP address owned by the target system, using NAT. When IP packets from
the target system are sent back to the clients, the load balancer converts the source IP
address back to the cluster IP address. Therefore, the packets must return through the
same load balancer that will recognize the changes and do the reverse mapping to ensure
packets can flow from the original destination to the original source.
Dispatch mode does not convert IP addresses, therefore eliminating the need for
performing NAT. This mode requires VMAC support if the target stacks share the OSAs. In
addition, all target applications must bind to the IP address specified by INADDR_ANY (or
in6addr_any for IPv6), and the cluster IP address must be defined to the stack. The cluster
IP address must not be advertised through a dynamic routing protocol. Otherwise, some
systems might not have work routed to them. This can be done by defining the cluster IP
address in the HOME list as a loopback address.
For more information regarding load balancing modes (directed and dispatch), refer to z/OS
Communications Server: IP Configuration Guide, SC31-8775.
6.1.2 Virtual MAC concept
Figure 6-1 on page 212 depicts how the definition of VMACs in the TCP/IP stacks gives the
appearance of having a dedicated OSA interface on each stack. When packets arrive at the
shared OSA interface, the individual VMAC assignments allow the packets to be forwarded
directly to the correct stack. In the example shown, no individual stack needs to be defined as
a primary or secondary router, thus offloading this function from a TCP/IP stack.

Figure 6-1 Forwarding packets to VMAC targets
This simplifies a shared OSA configuration significantly. Defining VMACs has very little
administrative overhead. It is also an alternative to GRE or NAT when load balancing
technologies are used. In Figure 6-1, the Dynamic VIPA targets are found without the use of
GRE and without routing through the Sysplex Distributor. One of the options for defining
VMACs permits the OSA to bypass IP address lookup. As a result, when the packet arrives at
the correct VMAC, it is routed to the stack even though the DDVIPA is not registered in the
OAT.
For IPV6, TCP/IP uses the VMAC address for all neighbor discovery address resolution flows
for that stack’s IP addresses, and likewise uses the VMAC as the source MAC address for all
IPv6 packets sent from that stack. Again, from a LAN perspective, the OSA interface with a
VMAC appears as a dedicated device to that stack.
Note: VMAC definitions on a device in a TCP/IP stack override any NONRouter,
PRIRouter, or SECRouter parameters on devices in a TCP/IP stack. If necessary, selected
stacks on a shared OSA can define the device with VMAC and others can define the
device with PRIRouter and SECRouter capability.
LPAR A
Sysplex Distributor
Service Manager
LPAR B
Target Stack
LPAR C
Target Stack
Device OSA
VMAC [ <mac1> ]
XCF 10.1.7.11
VIPA 10.1.1.10
OSA 10.1.2.11
DDVIPA 10.1.8.10
LPAR D
Target Stack
OSA 1
MAC aaaa.bbbb.cccc
XCF 10.1.7.21
VIPA 10.1.1.20
OSA 10.1.2.21
[ DDVIPA 10.1.8.10 ]
XCF 10.1.7.31
VIPA 10.1.1.30
OSA 10.1.2.31
[ DDVIPA 10.1.8.10 ]
XCF 10.1.7.41
VIPA 10.1.1.40
OSA 10.1.2.41
[ DDVIPA 10.1.8.10 ]
XCF 10.1.7.11
VIPA 10.1.1.10
OSA 10.1.2.11
DDVIPA 10.1.8.10
XCF 10.1.7.21
VIPA 10.1.1.20
OSA 10.1.2.21
XCF 10.1.7.31
VIPA 10.1.1.30
OSA 10.1.2.31
XCF 10.1.7.41
VIPA 10.1.1.40
OSA 10.1.2.41
Device OSA
VMAC [ <mac2> ]
Device OSA
VMAC [ <mac3> ]
Device OSA
VMAC [ <mac4> ]
VMAC [ <mac1> ] VMAC [ <mac2> ] VMAC [ <mac3> ] VMAC [ <mac4> ]
ARP
Cache
10.1.2.11 vmac1
10.1.2.21 vmac2
10.1.2.31 vmac3
10.1.2.41 vmac4
Router
Forwarding Agent
ARP
Cache
XCF
10.1.7.0/24
10.1.2.0/24

6.1.3 Virtual MAC address assignment
The VMAC address can be defined in the stack, or generated by the OSA. If generated by the
OSA, it is guaranteed to be unique from all other physical MAC addresses and from all other
VMAC addresses generated by any OSA-Express feature.
The same VMAC can be defined for both IPv4 and IPv6 usage, or a stack can use one VMAC
for IPv4 and one for IPv6. Also, a VLAN ID can be associated with an OSA-Express device or
interface defined with a VMAC.
6.2 Virtual MAC implementation
In this section, we show a scenario using VMAC as a replacement for PRIRouter and
SECRouter. However the same implementation would apply to an environment using load
balancing technologies. For details regarding load balancing technologies, refer to
Communications Server for z/OS V1R9 TCP/IP Implementation Volume 3: High Availability,
Scalability, and Performance, SG24-7534.
When implementing VMAC support, keep in mind the following points:
The VMAC function is only available for OSA interfaces configured in QDIO mode.
Each stack can define one VMAC per protocol (IPv4 or IPv6) for each OSA interface.
If a VMAC is defined, the stack will not receive any packets destined to the physical MAC.
VLAN IDs also apply to VMACs such as physical MACs.
Allow the OSA to generate VMAC addresses.
When configuring VMACs to solve load balancing issues, remember to:
– Remove GRE tunnels as appropriate.
– Change external load balancer configurations (such as directed mode to dispatch
mode).
Note: We recommend letting the OSA generate the VMACs instead of assigning an
address in the TCP/IP profile. If VMACs are defined in the LINK statement, they must be
defined as locally administered MAC addresses, and should be unique to the LAN on
which they reside.
Note: VMAC support is only available with the IBM System z9 and z10 Enterprise Class
servers.

6.2.1 IP routing when using VMAC
In our scenario, as illustrated in Figure 6-2, we define VMACs to make two TCP/IP stacks act
as forwarding stacks to route unregistered IP addresses, using OMPRoute. TCPIPA and
TCPIPC share an OSA interface. We configured TCPIPA to forward packets to TCPIPB, and
we configured TCPIPC to forward packets to TCPIPD.
Figure 6-2 IP Routing using VMAC
We omitted the DEVICE, LINK, and HOME statements for OSA20C0 on TCPIPB and
TCPIPD, and modified the IP routing definitions on all stacks.
Note that Figure 6-2 is used only for demonstration purposes. We do not recommend
implementing any configuration with single-points-of-failure.
Configuring the VMAC
The VMAC is defined on the LINK statement in the TCP/IP profile. Example 6-1 and
Example 6-2 show the VMAC definitions for TCPIPA and TCPIPC. In our example, we defined
VMAC for OSA with VLAN ID. However, VLAN ID is not a prerequisite.
Example 6-1 Device and link statements - VMAC definition for TCPIPA
LINK OSA20C0L IPAQENET OSA20C0 VLANID 11 VMAC 020012345678 1
If VMAC is defined without a MAC address 2, then OSA generates a VMAC using a part of the
“burned-in” MAC address of the OSA. You can also specify the MAC address for VMAC 1. If
you decide to specify a MAC address, it must be a locally administered address, which means
bit 6 of the first byte is 1 and bit 7 of the first byte is 0.
SC31
TCPIPB
SC30
TCPIPA
SC32
TCPIPC
SC33
TCPIPD
OSA20C0
VMAC
0200.1234.5678
VMAC
VIPA 10.1.1.20 VIPA 10.1.1.40VIPA 10.1.1.10
OSA20C0 10.1.3.11
VIPA 10.1.1.30
OSA20C0 10.1.3.31
SC30 10.1.3.11 VMAC 0200.1234.5678
SC32 10.1.3.31 VMAC 0200.021A.7454
HiperSockets 10.1.4.0/24 HiperSockets 10.1.5.0/24
Router 1

Example 6-2 Device and link statements - VMAC definition for TCPIPC
LINK OSA20C0L IPAQENET OSA20C0 VLANID 11 VMAC 2
There is no need to define PRIRouter or SECRouter on the DEVICE statement. When VMAC
is specified on LINK statement, PRIRouter or SECRouter is ignored.
6.2.2 Verification
We verified that VMAC was correctly defined in TCPIPA (see Example 6-3). We specified a
MAC address 1 for the OSA in TCPIPA, so VMACORIGIN is CFG 2.
Example 6-3 Display VMAC on TCPIPA
DEVNAME: OSA20C0 DEVTYPE: MPCIPA
DEVSTATUS: READY
LNKNAME: OSA20C0L LNKTYPE: IPAQENET LNKSTATUS: READY
VMACADDR: 020012345678 1 VMACORIGIN: CFG 2 VMACROUTER: ALL
We verified that VMAC was correctly defined in TCPIPC (see Example 6-4). Because we did
not specify a MAC address for the OSA in TCPIPC, the OSA generated the MAC address 3.
Because this is a OSA-generated MAC address, VMACORIGIN is OSA 4.
Example 6-4 Display VMAC on TCPIPC
D TCPIP,TCPIPC,N,DEV
DEVNAME: OSA20C0 DEVTYPE: MPCIPA
DEVSTATUS: READY
LNKNAME: OSA20C0L LNKTYPE: IPAQENET LNKSTATUS: READY
VMACADDR: 0200021A7454 3 VMACORIGIN: OSA 4 VMACROUTER: ALL
We can also see the VMAC in the OSA Address Table (OAT) queried by OSA/SF (see
Example 6-5). OSA registers all IP addresses (including VIPA) in the TCP/IP stack, and maps
them to the VMAC address.
Note that the last three bytes of the OSA-generated VMAC 7 are identical to that of the
universal MAC address (“burned-in” address) of the OSA 5. The first byte of the
OSA-generated VMAC is always 02, in order to make the VMAC a locally administered
address. To make the VMAC unique among all TCP/IP stacks, the second and third bytes are
used as a counter that is incremented each time OSA generates a MAC address.
Note: z/OS Communications Server V1R10 has been enhanced and IPV4 interfaces
VLANs can be defined using the INTERFACE statement. More details are available in
“INTERFACE” on page 72.

Example 6-5 Display OAT queried with OSA/SF
c-Local MAC address --------------> 00096B1A7454
Universal MAC address ----------> 00096B1A7454 5
************************************************************************
Image 2.3 (A23 ) CULA 0
00(20C0)* MPC N/A OSA20C0P (QDIO control) SIU ALL
02(20C2) MPC 00 No4 No6 OSA20C0P (QDIO data) SIU ALL
VLAN 11 (IPv4)
VMAC IP address
REG 020012345678 6 010.001.001.010
REG 020012345678 010.001.003.011
REG 020012345678 010.001.004.011
************************************************************************
00(20C0)* MPC N/A OSA20C0P (QDIO control) SIU ALL
02(20C2) MPC 00 No4 No6 OSA20C0P (QDIO data) SIU ALL
VLAN 11 (IPv4)
VMAC IP address
REG 0200021A7454 7 010.001.001.030
HOME 0200021A7454 010.001.003.031
REG 0200021A7454 010.001.005.031
Example 6-6 shows the ARP cache of the router. IP address 10.1.3.11 in TCPIPA is mapped
to the VMAC defined in TCPIPA 8, and IP address 10.1.3.31 in TCPIPC is mapped to the
VMAC defined in TCPIPC 9.
Note that each IP address is mapped to a different MAC address, even if these stacks share
the same OSA interface. OSA responds to ARP requests for all registered IP addresses by
using a VMAC instead of a “burned-in” MAC address.
According to the routing table, the router chooses 10.1.3.11 as the next hop for destination
address 10.1.1.20, and chooses 10.1.3.31 as the next hop for destination address 10.1.1.40.
The router forwards the packet with the destination IP address 10.1.1.20 to the destination
MAC address 0200.1234.5678. When the packet reaches the OSA interface, OSA forwards
the packet to TCPIPA, because OSA knows the VMAC 200.1234.5678 is mapped to TCPIPA.
The same can be said for the TCPIPC VMAC.
Example 6-6 Display ARP cache in Router 1
Router1#sh arp
Internet 10.1.3.11 10 0200.1234.5678 8 ARPA Vlan11
Internet 10.1.3.31 20 0200.021a.7454 9 ARPA Vlan11

Example 6-7 shows that the two stacks (TCPIPA and TCPIPC) sharing one OSA interface are
able to route packets correctly.
Example 6-7 Display traceroute from Router 1
Router1#traceroute 10.1.1.20
1 10.1.3.11 0 msec 0 msec 0 msec
2 10.1.1.20 0 msec 0 msec 0 msec
Router1#traceroute 10.1.1.40
1 10.1.3.31 4 msec 0 msec 0 msec
2 10.1.1.40 0 msec 0 msec 0 msec
6.3 Virtual LAN overview
A virtual LAN (VLAN) is the grouping of workstations, independent of physical location, that
have a common set of requirements. VLANs have the same attributes as physical LANs,
although they might not be located physically on the same LAN segment.
A VLAN configuration provides several benefits:
VLANs can improve network performance by reducing traffic on a physical LAN. VLANs
can enhance security by isolating traffic.
VLANs provide more flexibility in configuring networks.
VLANs can be used to increase link optimization by allowing networks to be organized for
optimum traffic flow through implementation of network segregation and a quality of
service policy.
VLANs can be used to increase bandwidth and reduce overhead.
6.3.1 Types of connections
VLANs operate by defining switch ports as members of virtual LANs. Devices on a VLAN can
use three types of connections, based on whether the connected devices are VLAN-aware or
VLAN-unaware. VLAN-aware devices understand VLAN memberships (which users belong to
a particular VLAN) and VLAN formats.
Ports used to attach VLAN-unaware equipment are called access ports, while ports used to
connect to other switches or VLAN-aware servers are known as trunk ports. Network frames
generated by VLAN-aware equipment are marked with a tag, which identifies the frame to the
VLAN.
The types of connections include:
Trunk mode
Trunk mode indicates that the switch should allow all VLAN ID tagged packets to pass
through the switch port without altering the VLAN ID. This mode is intended for servers
that are VLAN capable. It filters and processes all VLAN ID tagged packets. In trunk mode,
the switch expects to see VLAN ID tagged packets inbound to the switch port.
Access mode
Access mode indicates that the switch should filter on specific VLAN IDs and only allow
packets that match the configured VLAN IDs to pass through the switch port. The VLAN ID

is then removed from the packet before it is sent to the server. That is, VLAN ID filtering is
controlled by the switch. In access mode, the switch expects to see packets without VLAN
ID tags inbound to the switch port.
Hybrid mode
Hybrid mode is a combination of the previous two modes. This mode defines a port where
both VLAN-aware and VLAN-unaware devices are attached. A hybrid port can have both
tagged and untagged frames.
6.4 VLAN Implementation on z/OS
In this section, we discuss single and multiple VLANs and their configuration.
6.4.1 Single VLAN per OSA
Figure 6-3 shows one physical LAN subdivided into two VLANs, VLAN A and VLAN B. To
configure VLAN for an OSA-Express in QDIO mode, you specify a VLAN ID in the TCP/IP
profile. Prior to V1R10, the only way to access multiple VLANs from a given z/OS stack was to
use multiple OSAs.
The z/OS stack registers the VLAN ID to OSA which means that the OSA:
Appends a VLAN tag with this VLAN ID on all outbound packets (Note: For IPv6 unicast
packets, the stack appends the VLAN tags)
Filters out any inbound packets that have a VLAN tag containing a different VLAN ID
Figure 6-3 Single VLAN per OSA
z/OS
TCP/IP
App A
VLAN ID 'B' (MAC B)
OSA a
Physical LAN
VLAN BVLAN A
App B
VLAN ID 'A' (MAC A)
Single VLAN ID per OSA
Single VLAN ID per OSA
OSA b
Note:
The current support is
a single VLAN per OSA
per stack per IP version

6.4.2 Multiple VLAN
Figure 6-4 on page 220 shows the new function provided with V1R10. With V1R10, multiple
VLANs can be configured for the same OSA-Express feature (up to eight for IPv4 and eight
for IPv6) from the same z/OS stack. This is done by defining multiple interfaces to the same
OSA-Express, one for each VLAN ID.
Multiple VLAN provides:
OSA port consolidation: The multiple VLAN function allows a customer to consolidate
multiple OSAs (for example, three 1 Gb OSA ports) into a single OSA (for example, one
10 Gb OSA port) serving multiple VLANs.
Server consolidation: The multiple VLAN function allows a customer to consolidate
multiple application servers across multiple stacks into a single z/OS image where the
traffic related to these servers is on unique VLANs.
Improved QoS with Policy-based routing: The V1R9 policy-based routing function
allows a z/OS stack to make routing decisions for IPv4 traffic that take into account
additional criteria such as job name, source port, destination port, protocol type (TCP or
UDP), source IP address, NetAccess security zone, and multilevel secure environment
security label. It enables to route traffic meeting a certain criteria to one VLAN and traffic
meeting a different criteria to another VLAN.
Defining Multiple VLANs
The INTERFACE statement in the TCPIP profile that was used to define IPV6 OSA interfaces,
is extended to use the IPV4 QDIO OSA devices, as shown in Example 6-8.
Example 6-8 INTERFACE statement
INTERFACE OSAQDIO024
DEFINE IPAQENET
PORTNAME OSAQDIO02
SOURCEVIPAINT VIPAV4 1
IPADDR 10.1.1.1/24
MTU 8992
VLANID 200 2
VMAC ROUTEALL 3
For a detailed description of the INTERFACE statement refer to “INTERFACE” on page 72. In
this example, the numbers correspond to the following information:
1. For IPV4 source VIPA specify the VIPA LINKNAME. For IPV6 source VIPA specify the
interface name specified on the VIRTUAL6 interface statement.
2. This is the VLAN ID of the VLAN.
3. Specifies that all IP traffic destined to the virtual MAC is forwarded by the OSA-Express
device to the TCP/IP stack.
Note: Non QDIO IPV4 network interfaces are defined using the old syntax of DEVICE and
LINK.

Figure 6-4 Multiple VLANs in z/OS
6.4.3 Multiple VLANs configuration guidelines
To define multiple interfaces to the same OSA express or define multiple VLANs on the same
OSA express port or more then one OSA express port, follow these rules:
Configure each IPv4 interface for the OSA-Express feature in the TCP/IP profile using the
INTERFACE statement for IPAQENET rather than DEVICE/LINK/HOME. Configure each
IPv6 interface using the INTERFACE statement for IPAQENET6.
Configure a VLANID value on each IPv4 and each IPv6 INTERFACE statement for this
OSA. Within each IP version, VLANID values must be unique.
Configure the VMAC parameter on each of these INTERFACE statements with the default
ROUTEALL attribute. The VMAC address can either be specified or OSA-generated. If
you specify a VMAC address, it must be unique for each INTERFACE statement.
Configure a unique subnet for each IPv4 interface for this OSA-Express feature using the
subnet mask specification on the IPADDR parameter on the INTERFACE statement.
To use multiple VLANs for an OSA port, you need to configure a separate interface to the
OSA port for each VLAN. Each of these interfaces requires a separate DATAPATH device
in the TRLE definition. Furthermore, each DATAPATH device requires a certain amount of
fixed storage. See, “VTAM considerations” on page 222.
VLAN IDs must be unique on a single OSA port within a single stack. If you code multiple
INTERFACEs from one stack to the same OSA and does not configure a VLAN ID for one
INTERFACE, the INTERFACE definition will rejected.
If one INTERFACE within a stack that is connecting to OSA port is implemented with
VLAN/VMAC, then ALL INTERFACES connecting to the same OSA Port within that stack
must specify VLAN/VMAC.
If more than one INTERFACE is defined for a particular IP version for a single OSA port
within a stack, then the VLANID, VMAC and IP subnet values must be unique on each of
z/OS
TCP/IP
App A
VLAN ID 'B' (subnet / VMAC B)
OSA a
Physical LAN
VLAN B
VLAN A
App B
VLAN ID 'A' (subnet / VMAC A)
Multiple VLAN IDs per OSA Multiple VLAN IDs per OSA
Policy Based Routing
could be used for outbound
traffic to select VLANs
Note: By using ROUTEALL attribute you allow interface to forward IP packet. You can
use ROUTELOCAL attribute if you do not want the interface to forward IP packet.

the INTERFACE statements. If parallel interfaces are desired. with the same IP subnet
and same VLANID, then the parallel INTERFACE statements must be coded on different
OSA ports.
When a z/OS TCP/IP stack has access to multiple OSAs that are on the same physical
LAN and when a VLAN ID is configured on any of the OSAs, it is recommended that this
stack configure a VLAN ID for all OSAs on the same physical LAN. That is, do not mix
VLAN and no-VLAN on the same physical network when a stack has access to the same
LAN through multiple OSAs. Doing otherwise can cause problems with various ARP
takeover scenarios.
The multi-VLAN configuration Rules apply only within a stack. That is, each stack on a
shared OSA port is completely independent of any other stacks sharing the OSA port.
Therefore, if you have one TCP/IP stack (at V1R10 or earlier) sharing an OSA port with a
second TCP/IP stack (at V1R10 or higher), the first stack can be configured to use the
DEVICE/LINK statement for a single connection to a shared OSA port and the second
stack can be configured to use the INTERFACE statement for any connections to the
shared OSA port.
A network switch can establish VLANIDs on some connections of a trunk port to a single
OSA port. The switch can also configure other connections with what is called a Native
VLANID or a Default VLANID on the same trunk port to the shared OSA port. If a single
TCP/IP stack has configured multiple VLAN connections to the switch and one of those
connections is to the Native VLAN, then the z/OS TCP/IP stack must set a VLANID for the
Native VLAN on that connection. Do not mix Native VLAN and other VLANIDs on the
same OSA port to the same TCP/IP stack.
Source VIPA
Use the following guidelines when selecting a source VIPA in V1R10:
Prior to V1R10, for IPv4, when source VIPA is in effect, the stack selects a source VIPA
based on the order of the home list (from the ordering of IP addresses in the HOME
statement in the profile). So, for IPv4, the user controls source VIPA selection using the
HOME statement.
For IPv6, there is no HOME statement. The user controls source VIPA selection using the
SOURCEVIPAINTERFACE parameter on the INTERFACE statement.
In V1R10, source VIPA selection for interfaces defined with the IPv4 INTERFACE
statement works the same way as IPv6 (using the SOURCEVIPAINTERFACE parameter
which must point to the link name of an IPv4 static VIPA).
For IPv4 interfaces defined using DEVICE/LINK, source VIPA selection continues to work
based on the ordering of the home list.
You can specify SOURCEVIPAINTERFACE for every VLAN you define. The VIPA IP
address can be in the same or different subnet from the IP address of the OSA interface.
ARP processing
In QDIO mode, the OSA performs all address resolution protocol (ARP) processing for IPv4.
The z/OS stack informs the OSA of the IP addresses for which it should perform ARP
processing. Because the z/OS stack also supports configurations where ARPs flow for VIPAs
(which one might see on some flat network configurations using static routing), the stack also
informs the OSA of the VIPAs for which it should perform ARP processing. OSA sends
Note: Some switch vendors use VLAN ID 1 as the default value when a VLAN ID value is
not explicitly configured. It is recommended that you avoid the value of 1 when configuring
a VLAN ID value. By convention the “Native VLANID” is often coded as “1”.

gratuitous ARPs for these IP addresses during interface takeover scenarios to provide fault
tolerance.
If the OSA is defined using DEVICE/LINK statements, then the stack will inform OSA to
perform ARP processing for all VIPAs in the home list, which can result in numerous
unnecessary gratuitous ARPs for VIPAs in an interface takeover scenario. However, if using
the IPv4 INTERFACE statement for IPAQENET, and subnet mask is configured (non-0
num_mask_bits) on the IPADDR parameter of the INTERFACE statement, then the stack will
inform OSA to only perform ARP processing for a VIPA if the VIPA is configured in the same
subnet as the OSA.
VTAM considerations
The QDIOSTG VTAM start parameter specifies how much storage VTAM keeps available for
all OSA QDIO devices. Each OSA express QDIO DATAPATH device consumes large amount
of fixed storage. The QDIOSTG value can be overridden by using the READSTORAGE
parameter on the IPAQENET LINK or the INTERFACE statement un the TCPIP profile. As
every VLAN adds another OSA device (DATAPATH) and environment it is recommended in a
multi-VLAN to use VTAM tuning statistics and evaluate the needs and storage.
6.4.4 Verification
We performed TCPIP device displays and retrieved the OSA address Table (OAT) to present
how multiple VLANs are recognized by the system. Example 6-9 shows the output of TCPIP
device display. We defined two VLANs and a source VIPA on the interface statement.
Example 6-9 Multiple VLAN device display
D TCPIP,TCPIPC,N,DEV,INTFN=OSA20A0A VLAN 10
EZD0101I NETSTAT CS V1R10 TCPIPC 258
INTFNAME: OSA20A0A INTFTYPE: IPAQENET INTFSTATUS: READY
SPEED: 0000001000
VMACADDR: 0200D3749660 VMACORIGIN: OSA VMACROUTER: ALL
SRCVIPAINTF: VIPA2L 1
IPADDR: 10.1.2.32/24 2
VLANID: 10 VLANPRIORITY: DISABLED 3
D TCPIP,TCPIPC,N,DEV,INTFN=OSA20A0B VLAN 11
INTFNAME: OSA20A0B INTFTYPE: IPAQENET INTFSTATUS: READY
SPEED: 0000001000
VMACADDR: 0200D4749660 VMACORIGIN: OSA VMACROUTER: ALL
SRCVIPAINTF: VIPA2L 1
IPADDR: 10.1.3.33/24 2

VLANID: 11 VLANPRIORITY: DISABLED 3
The source VIPA address specified on the Interface statement 1
The IP address and the subnet mask assigned to this VLAN 2
The VLAN ID 3
Example 6-10 OAT of a CHPID defined as multiple VLANs and source VIPA
A0(20A0)* MPC N/A OSA20A0 (QDIO control) SIU ALL
A2(20A2) MPC 00 No4 No6 OSA20A0 (QDIO data) SIU ALL
VLAN 10 (IPv4)
VMAC IP address
HOME 0200D3749660 010.001.002.030 1
HOME 0200D3749660 010.001.002.032 2
A3(20A3) MPC 00 No4 No6 OSA20A0 (QDIO data) SIU ALL
VLAN 11 (IPv4)
VMAC IP address
HOME 0200D4749660 010.001.003.033 3
1. Source VIPA address as defined on the Interface statement
2. VLAN 10 IP address and the assigned VMAC
3. VLAN 11 IP address and the assigned VMAC
6.5 References
For more information about the VMAC function, refer to the following documentation:
Note: The same VMAC is assigned for the VLAN IP address and the source VIPA IP
address.
Because VLAN 11 is on different IP subnet mask than the source VIPA, the source VIPA is
not displayed on this VLAN.

Chapter 7. Sysplex subplexing
In large sysplex environments, there can be strict security requirements to isolate access to
certain VTAM nodes or TCP/IP stacks within the sysplex. A z/OS Communications Server
function, called subplexing, provides this type of support. It enables the user to implement
automatically controlled access to subplex groups.
As mentioned, the subplexing support is also for VTAM nodes. However, this chapter only
describes subplexing for TCP/IP stacks. For information about VTAM subplexing, refer to SNA
Network Implementation Guide, SC31-8777.
7
Section Topic
7.1, “Introduction” on page 226 The subplexing concept, and the environment in which it
can be used
7.2, “Subplex environment” on page 228 Our TCP/IP subplexing environment
7.3, “Load Balancing Advisor and
subplexing” on page 229
The Load Balancing Advisor allows any external load
balancing solution to become sysplex aware
7.4, “Subplex implementation” on
page 231
Implementation examples of TCP/IP subplexing

7.1 Introduction
Prior to subplexing, VTAM and TCP/IP sysplex functions were deployed sysplex-wide and
users had to implement complex resource controls and disable many of the dynamic XCF and
routing functions to support multiple security zones. For example, as shown in Figure 7-1,
TCP/IP stacks access different networks with diverse security requirements within the same
sysplex:
In the upper configuration, two TCP/IP stacks in the left LPARs access an internal
network. The TCP/IP stacks in the right two LPARs access the external network.
Presumably, the security requirements would include isolating external traffic from the
internal network. However, all TCP/IP stacks in the sysplex can dynamically establish
connectivity with all the other TCP/IP stacks in the sysplex.
In the lower configuration, TCP/IP stacks in the same LPAR have different security
requirements. The first stack in each LPAR connects to the internal network, and the
second stack connects to the external network. Through the IUTSAMEH connection, the
two stacks in each LPAR can establish connectivity with each other dynamically and
possibly violating security policies.
Figure 7-1 Sysplex connectivity - examples
With subplexing, you can build security zones. Only members within the same security zone
can communicate with each other. Subplex members are VTAM nodes and TCP/IP stacks
that are grouped in security zones to isolate communication.
Internal Network External Network
(e.g. Internet)
Appl1 Appl2
TCPIPA
Appl3 Appl4
TCPIPB
VTAM
z/OS LPAR
Appl1 Appl2
TCPIPA
Appl3 Appl4
TCPIPB
VTAM
z/OS LPAR
IUTSAMEH IUTSAMEH
XCFHiperSockets
Communications with all TCP/IP
stacks, including via IUTSAMEH
Multi-purpose LPARs
with dual TCP/IP stacks
XCFHiperSockets
External Network
(e.g. Internet)
z/OS LPAR
Appl1 Appl2
TCPIP
VTAM
z/OS LPAR
Appl1 Appl2
TCPIP
VTAM
z/OS LPAR
Appl1 Appl2
TCPIP
VTAM
z/OS LPAR
Appl1 Appl2
TCPIP
VTAM
Internal Network
Communications with all TCP/IP stacks
Dedicated LPARs with
single TCP/IP stacks

Chapter 7. Sysplex subplexing 227
Concept of subplexing
A subplex is a subset of a sysplex that consists of selected members. Those members are
connected and they communicate through dynamic cross-system coupling facility (XCF)
groups to each other, using the following methods:
XCF links (for cross-system IP and VTAM connections)
IUTSAMEH (for IP connections within an LPAR)
HiperSockets (IP connections cross-LPAR in the same server)
Subplexes do not communicate with members outside the subset of the sysplex. For
example, in Figure 7-2, TCP/IP stacks with connectivity to the internal network can be
isolated from TCP/IP stacks connected to the external network using subplexing.
Figure 7-2 Subplexing multiple security zones
TCP/IP stacks are defined as members of a subplex group with a defined group ID. For
example, in Figure 7-2 TCP/IP stacks within subplex 1 are able to communicate only with
stacks within the same subplex group. They are not able to communicate with stacks in
subplex 2.
In an environment where a single LPAR has access to internal and external networks through
two TCP/IP stacks, those stacks are assigned to two different subplex group IDs. Even though
IUTSAMEH is the communication method, it is controlled automatically through the
association of subplex group IDs, thus creating two separate security zones within the LPAR.
Dedicated LPARs with
single TCP/IP stacks
External Network
(e.g. Internet)
z/OS LPAR
Appl1 Appl2
TCPIP
VTAM
z/OS LPAR
Appl1 Appl2
TCPIP
VTAM
z/OS LPAR
Appl1 Appl2
TCPIP
VTAM
z/OS LPAR
Appl1 Appl2
TCPIP
VTAM
Internal Network
External Network
(e.g.Internet)
VTAM VTAM
z/OS LPAR
Appl3 Appl4
TCPIPB
Subplex 2
Appl3 Appl4
TCPIPB
Subplex 2
Appl1 Appl2
TCPIPA
Appl1 Appl2
TCPIPA
Subplex 1Subplex 1
IUTSAMEH
Communications
within same Subplex
VLAN IDs may be
associated with Subplex
VLAN IDs may be
associated with Subplex
No communications to
dissimilar Subplexes
Internal Network
IUTSAMEH
No communications to
dissimilar Subplexes
HiperSockets XCF
Subplex 2Subplex 1
HiperSockets
Multi-purpose LPARs
with dual TCP/IP stacks
z/OS LPAR
XCF

7.2 Subplex environment
In this section we describe the environment used to demonstrate subplexing in a multiple
security zone, based on Figure 7-2 on page 227. All LPARs in our scenarios were configured
in a single server with multiple stacks for demonstration purposes only.
Figure 7-3 illustrates our TCP/IP subplexing environment with the following attributes:
The first subplex is a VTAM subplex, which is not within the scope of this book. However,
when defining only a TCP/IP subplex, a default VTAM subplex is defined automatically.
The second subplex was configured with TCP/IP C stacks running in LPARs A23 and A24,
representing the internal subplex.
The third subplex was configured with TCP/IP D stacks running in LPARs A24 and A25,
representing the external subplex.
Figure 7-3 Our TCP/IP subplexing environment
We do not describe or discuss OSA connectivity in this chapter. For details regarding OSA
functions and configuration information refer to Chapter 4, “Connectivity” on page 109.
Recommendation: Network connectivity provided through an OSA port in a multiple
security zone environment should not be shared across different subplex groups. The OSA
ports and HiperSockets connections should be physically isolated or logically separated
using firewall and VLAN technologies.
Note: Although there are specialized cases where multiple stacks per LPAR can provide
value, we generally recommend implementing only one TCP/IP stack per LPAR whenever
possible.
Note: A TCP/IP subplex uses VTAM XCF support for DYNAMICXCF connectivity.
Therefore, a TCP/IP stack cannot span different VTAM subplexes.
z/OS LPAR: A25
VTAM
SC32 (NN)
z/OS LPAR: A23
VTAM
SC30 (NN)
z/OS LPAR: A24
VTAM
SC31 (NN)
TCP/IP C TCP/IP C
VTAM Subplex
IP Subplex 11
TCP/IP D TCP/IP D
IP Subplex 22

7.3 Load Balancing Advisor and subplexing
The Load Balancing Advisor is a z/OS Communications Server component that allows any
external load balancing solution to become sysplex aware. Subplex support for Load
Balancing Advisor enhances the Load Balancing Advisor and the Load Balancing Agent
function, so that they can participate in a sysplex subplexing. Prior to this support, only one
Load Balancing Advisor was implemented in an LPAR. In a multiple TCP/IP stack
environment, one Load Balancing Agent reported on all servers on all stacks, not just those
stacks in a subplex.
With subplex support for Load Balancing Advisor, more than one Advisor can be active in the
sysplex at any given time. In fact, there should be one Advisor active for each subplex in the
sysplex that participates in load balancing through the Load Balancing Advisor. Each Advisor
reads configuration data from a file, which can exist as a z/OS UNIX file, a PDS or PDSE
member, or a sequential data set.
In the configuration file for each Advisor, the sysplex_group_name statement specifies the
TCP/IP sysplex group name in the form of EZBTvvtt, where vv is the VTAM subplex group ID
that is specified on the VTAM XCFGRPID start option and tt is the TCP/IP subplex group ID
specified by the XCFGRPID parameter on the GLOBALCONFIG statement in the TCP/IP
profile. If no VTAM subplex ID is specified when VTAM is started, then vv is CP. If no TCP/IP
subplex ID is specified in the TCP/IP profile, then tt is CS. If you have a default subplex in your
sysplex (that is, a subplex in which both the VTAM and TCP/IP subplex IDs are not specified),
configure the Load Balancing Advisor for that subplex with a sysplex group name of EZBTCPCS.
In Figure 7-4, a Load Balancing Advisor application is configured to allow an external LBA to
connect to the Internet subplex and the intranet production subplex.
Figure 7-4 Load Balancing Advisor in subplexed sysplex
LB1 is balancing connections to applications running on TCP/IP stacks in the Internet IP
subplex on LPAR1 and LPAR2. The TCP/IP sysplex group name is EZBTCPCS (VTAM
XCFGRPID 01 and TCP/IP XCFGRPID 01). This is the default TCP/IP sysplex group name
Note: XCFGRPID is explained in 7.4.1, “XCF group names” on page 232.
LPAR2
Internet SNA subplex
VTAM XCFGRPID:Default (01)
Internet SNA subplex
VTAM XCFGRPID:Default (01)
LPAR1 LPAR3 LPAR4 LPAR5
VTAM2VTAM2VTAM1VTAM1
Internet IP subplex
TCP/IP XCFGRPID:Default (01)
Internet IP subplex
TCP/IP XCFGRPID:Default (01)
TCPIP2TCPIP2TCPIP1TCPIP1
Intranet SNA subplex
VTAM XCFGRPID: 21
Intranet SNA subplex
VTAM XCFGRPID: 21
VTAM3VTAM3 VTAM4VTAM4 VTAM5VTAM5
Intranet Production IP subplex
TCP/IP XCFGRPID: 02
Intranet Production IP subplex
TCP/IP XCFGRPID: 02
TCPIP3TCPIP3 TCPIP4TCPIP4 TCPIP5TCPIP5
TCPIP8TCPIP8
Intranet Dev. IP subplex
TCP/IP XCFGRPID: 04
TCPIP7TCPIP7TCPIP6TCPIP6
LBAG0101LBAG0101
LBAD0101LBAD0101
LBAG0101LBAG0101
LBAD2102LBAD2102
LBAG2102LBAG2102 LBAG2102LBAG2102 LBAG2102LBAG2102
LB2 IntranetLB2 IntranetLB2LB2 IntranetLB1 InternetLB1 InternetLB1 InternetLB1LB1 Internet

when the TCP/IP subplex ID is 0101 (the default VTAM and TCP/IP XCFGRPID). LB1
connects to the Load Balancing Advisor in this subplex. The Advisor job, LBAD0101, is
configured to use stacks that are members of TCP/IP subplex ID of 0101. A single instance of
this Advisor can run in LPAR1 or LPAR2. It is currently running in LPAR1. Two Agents are
configured to use the stacks that are members of TCP/IP subplex ID of 0101. The Agent job
names are LBAG0101 on LPAR1 and LBAG0101 on LPAR2.
LB2 is balancing connections to applications running TCP/IP stacks in the intranet production
IP subplex on LPAR3, LPAR4, and LPAR5. The TCP/IP sysplex group name is EZBT2102
(VTAM XCFGRPID 21 & TCP/IP XCFGRPID 02). The TCP/IP subplex ID is 2102. LB2
connects to a Load Balancing Advisor in this subplex. The Advisor, LBAD2102, is configured
to use stacks that are members of the TCP/IP subplex ID of 2102. A single instance of this
Advisor can run in LPAR3, LPAR4, or LPAR5. It is currently running in LPAR3. Three agents
are configured to use stacks that are members of TCP/IP subplex ID of 2102. The three agent
job names are as follows:
LBAG02102 on LPAR3
LBAG2102 on LPAR4
LBAG2102 on LPAR5
There is no Load Balancing for applications that are running in the intranet development IP
subplex. Therefore, no Advisor and no Agents need to run in this subplex. If you want to load
balance in the intranet development IP subplex, configure an Advisor instance to run on either
LPAR4 or LPAR5. Also, configure an Agent instance to run on both LPAR4 and LPAR5, and
configure the Advisor and Agent applications to use stacks that are members of TCP/IP
subplex ID 2104 (TCPIP6 and TCPIP7).
There are two subplexes in the three LPARs on the right side of the figure. The production IP
subplex has TCP/IP subplex ID 2102 because the VTAM XCF group ID is 21 and the TCP/IP
XCF group ID is 02. Subplex 2102 spans LPAR3, LPAR4, and LPAR5. The TCP/IP sysplex
group name is EZBT2102. This subplex includes the following stacks:
Stack TCPIP3 on LPAR3
Stacks TCPIP5 and TCPIP8 on LPAR5
The Development IP subplex spans only LPAR4 and LPAR5. This subplex has a TCP/IP
subplex ID of 2104 which is VTAM XCF group ID 21 and TCP/IP XCF group ID 04. The
TCP/IP sysplex group name EZBT2104. This subplex includes the following stacks:
Note: Although there are two TCP/IP stacks in LPAR5 in subplex 2102, there is only one
Load Balancing Agent for that subplex on that LPAR. The one agent reports on all servers
in that LPAR in that subplex.
Note: A TCP/IP subplex cannot span multiple VTAM subplexes, because all TCP/IP stacks
on an LPAR use the same VTAM for their dynamic XCF communication.

7.4 Subplex implementation
TCP/IP stacks in the sysplex must be at z/OS V1R8 or later under the following conditions:
Complete isolation between TCP/IP stacks in different subplexes is required.
HiperSockets are used in support of dynamic XCF connectivity for TCP/IP stacks in a
subplex.
TCP/IP stacks in different subplexes accessing HiperSockets with the same CHPID.
An IP subplex is built through association of selected TCP/IP stack members to an XCF
group. This is done by defining the XCFGRPID parameter in the GLOBALCONFIG statement
of the TCP/IP profile. The subplex is created automatically at the start of the first stack
member using this XCFGRPID definition plus the dynamic XCF IP address taken from the
IPCONFIG statement DYNAMICXCF.
If the IP traffic for a defined subplex uses HiperSockets, which is the recommended method
for cross-LPAR connectivity within the same server, then an additional parameter
(IQDVLANID) in the GLOBALCONFIG is needed for the HiperSockets VLAN ID of the
HiperSockets connection built with the DYNAMICXCF definition. Values from 2 to 31 are valid
for XCFGRPID, while IQDVLANID allows values from 1 to 4094. If defining HiperSockets with
DEVICE and LINK statements, the parameter VLANID on the LINK statement is required for
assigning the VLAN for the subplex.
Figure 7-5 depicts our subplexing environment. It shows three LPARs with a VTAM subplex,
and two IP subplexes 11 and 22. Because we did not define the VTAM subplex, the
XCFGRPID value for the VTAM subplex automatically defaults to CP.
Figure 7-5 Subplex configuration
Requirement: A z890 or z990 at GA2 hardware level, or a z9 EC or z9 BC, is required to
support VLAN IDs on HiperSockets.
z/OS LPAR: A25
VTAM
SC32 (NN)
z/OS LPAR: A23
VTAM
SC30 (NN)
z/OS LPAR: A24
VTAM
SC31 (NN)
VTAM IQDCHPID: F7
TCP/IP C
VIPA:10.30.1. 230
TCP/IP C
VIPA:10.30.1. 241
IP Subplex 11
(internal subplex)
IP Subplex 22
(external subplex)
OSPF_Area=0.0.0.2
Stub_Area=YES
VTAM Subplex
XCFGRPID:11 IQDVLANID:11
XCF
10.30.20.0/24
.100 .101HiperSockets
XCFGRPID:(default to CP)
TCP/IP D
VIPA:10.40.1. 241
TCP/IP D
VIPA:10.40.1. 221
XCF 10.20.40.0/24

7.4.1 XCF group names
Basically, XCF group names for subplexes are created through the XCFGRPID parameter for
the VTAM and TCP/IP environment; for example:
For defining a VTAM subplex, use the XCFGRPID parameter in the VTAM start option. For
detailed information about group and structure names, refer to SNA Network
Implementation Guide, SC31-8777.
For defining a TCP/IP subplex, use the XCFGRPID parameter on the GLOBALCONFIG
statement in the TCP/IP profile.
For TCP/IP, both the VTAM group ID suffix and the TCP group ID suffix will be used to build
the TCP/IP group name. This group name is also used to join the sysplex. Remember, when
starting TCP/IP under Sysplex Autonomics control in previous z/OS releases, the stack joined
the sysplex group with the name EZBTCPCS. You can verify this using the D XCF,GROUP
command.
EZBTCPCS is the default TCP/IP group name. The format of this group name is EZBTvvtt,
where vv is a 2-digit VTAM group ID suffix, specified on the VTAM XCFGRPID start option
(the default is CP if not specified) and tt is a 2-digit TCP group ID suffix, specified on the
XCFGRPID parameter of the GLOBALCONFIG statement (the default is CS if not specified).
In our scenario (see Example 7-3 on page 234 3), we defined XCFGRPID 11 for TCP/IP, and
we did not define an XCFGRPID for VTAM. The result was an XCF group name of EZBTCP11
(Example 7-4 on page 235 6).
You might recognize that both XCFGRPIDs are important in creating the subplex group name.
Be aware that changing the VTAM XCFGRPID will change the XCF group name for the
TCP/IP stack. Thus, the stack is no longer a member of the previous TCP/IP subplex group.
For example, in our environment no VTAM XCFGRPID was defined and XCFGRPID 11 was
specified for TCP/IP. Therefore, the XCF group name was dynamically built as EZBTCP11. If
we add XCFGRPID=02 to the VTAM start option, then the new XCF group name will be
EZBT0211.
Although nothing was changed in the TCP/IP profile definitions in this example, the TCP/IP
stack with the new subplex group name is no longer a member of the previous subplex
(EZBTCP11). Thus, the TCP/IP stack will lose the connectivity to the subplex.
Important: If VTAM is brought down and restarted with a different XCFGRPID, the TCP/IP
stacks must be stopped and restarted to pick up the new VTAM subplex group ID.
Otherwise, the TCP/IP stacks will continue to act as though there were in the original
sysplex group, resulting in unpredictable connectivity.

7.4.2 TCP/IP structures
This section is intended for TCP/IP implementations using functions for Sysplex-wide Security
Associations (SWSA) or for SYSPLEXPORTS, which is needed for sysplex-wide source VIPA
to use one source VIPA for all outbound TCP connections within the sysplex.
SWSA list structure (EZBDVIPA)
This stores information about IPSec tunnels addressed to distributed DVIPAs within the
sysplex or subplex. This information is used to renegotiate IPSec tunnels in case of
distributed DVIPA takeover. SWSA is enabled through definitions in the IPSEC statement.
SYSPLEXPORTS list structure (EZBEPORT)
This contains all the ephemeral ports allocated in support of the sysplex-wide source VIPA
function. Ephemeral ports that establish connections with external servers and use the
sysplex-wide source VIPA function are allocated as participating clients from TCP/IP
stacks within the sysplex or subplex.
This function is defined using TCPSTACKSOURCEVIPA on the IPCONFIG statement and
SYSPLEXPORTS on the VIPADISTRIBUTE statement.
If TCP and VTAM Coupling Facility structures are used, names must also be unique for each
subplex in order to preserve separation between the subplexes. This means that the TCP
structures EZBDVIPA and EZBEPORT must be appended with the VTAM and TCP XCF
group ID suffixes to the end of the structure names (for example, EZBDVIPAvvtt and
EZBEPORTvvtt, where vv is the 2-digit VTAM group ID suffix specified on the XCFGRPID
start option and tt is the 2-digit TCP group ID specified in the TCP/IP profile).
The default suffixes are as follows:
If no VTAM XCFGRPID is specified, then the structure names will be EZBDVIPA01tt and
EZBEPORT01tt.
If no TCP/IP XCFGRPID is specified, then a null value is used for tt when the structure
names are built.
If no VTAM XCFGRPID and no TCP/IP XCFGRPID are specified, then vv and tt are both
null.
The TCP structure names, including the suffixes, must be defined in the sysplex CFRM policy
(see Example 7-1).
Example 7-1 TCP/IP structure example for SYSPLEXPORTS - subplex 11
STRUCTURE NAME(EZBEPORT0111)
INITSIZE(4096)
SIZE(8192)
PREFLIST(FACIL02,FACIL01)
For more information regarding TCP and VTAM structures, refer to z/OS MVS Setting Up a
Sysplex, SA22-7625.
The following sections describe the implementation for each subplex in detail.
Note: Example 7-1 is only a sample. The size depends on the number of source DVIPAs
and concurrently established TCP outbound connections from all
TCPSTACKSOURCEVIPA of the participating stacks within the sysplex. The ephemeral
port number for each connection is stored to avoid duplicate source port numbers.

7.4.3 Subplex 11: Internal subplex
Figure 7-6 depicts the configuration for IP Subplex 11 (the internal subplex).
Figure 7-6 Subplex 11- internal subplex
TCP/IP profile definitions for subplex 11 in LPAR A24 stack C
Because we used automatically defined HiperSockets for the IP traffic within the subplex, we
only had to add the VTAM start option IQDCHPID = F7 1. This CHPID is used when
HiperSockets are implemented under z/OS.
The VTAM start option is needed by VTAM to automatically create the Transmission Resource
List Element (TRLE) for the HiperSockets interface of the stack. The TRLE points to its
IUTQDIO name, which is defined to the TCP/IP profile DEVICE name. The PORTNAME
created by VTAM is IUTQDxx, where xx is the used Channel Path ID (CHPID).
The DYNAMICXCF function also requires the VTAM start option XCFINIT=YES 2, which
creates the XCF major node dynamically.
Example 7-2 ATCSTRxx definitions needed for DYNAMICXCF and HiperSockets interface
SYS1.VTAMLST(ATCSTR31)
IQDCHPID=F7, 1
XCFINIT=YES 2
Example 7-3 shows the TCP/IP profile definitions needed for assigning stack C in LPAR 24 to
subplex 11. Based on the parameters XCFGRPID 3 and IQDVLANID 4, stack C belongs to
subplex 11. The group interface is defined using the IPCONFIG parameter DYNAMICXCF
with its IP address 10.30.20.101 5.
Example 7-3 TCP/IP profile - subplex definitions for stack C in LPAR 24
GLOBALCONFIG
XCFGRPID 11 3
IQDVLANID 11 4
Tip: You can check your VTAM start options by using the D NET,VTAMOPTS command.
z/OS LPAR: A23 z/OS LPAR: A24
VTAM IQDCHPID: F7
TCP/IP C
VIPA:10.30.1. 230
TCP/IP C
VIPA:10.30.1. 241
XCF
10.30.20.0/24
IP Subplex 11
OSPF_Area = 0.0.0.2
Stub_Area = YES

;
IPCONFIG
DYNAMICXCF 10.30.20.101 255.255.255.0 8 5
The definitions for LPAR A23 are not shown because the XCFGRPID is the same. Only the
DNAMICXCF IP address 5 is different (10.30.20.100).
Verification of the subplex 11
The group name used is in the form EZBTvvtt, where vv is the 2-digit VTAM group ID suffix
specified on the XCFGRPID start option or default (CP) and tt is the TCP group.
In our scenarios we did not define the VTAM start option XCFGRPID. A display from LPAR
A24 TCP/IP stack C (see Example 7-4) shows that the stack is a member of the VTAM
subplex group ID CP and TCP/IP subplex group 11, with the name EZBTCP11 6.
In the same LPAR there is another stack member of subplex group 22 with the name
EZBTCP22 7 (see definitions in 7.4.4, “Subplex 22: External subplex” on page 237).
Example 7-4 Displays of XCF groups
D XCF,GROUP
IXC331I 12.13.08 DISPLAY XCF 229
GROUPS(SIZE): ATRRRS(3) COFVLFNO(3) DBCDU(3)
EZBTCPCS(5) EZBTCP11(2) 6
EZBTCP22(2) 7 IDAVQUI0(3) IGWXSGIS(6)
IOEZFS(3) IRRXCF00(3) ISTCFS01(3)
ISTXCF(3) IXCLO00A(3) IXCLO00B(3)
IXCLO006(3) SYSBPX(3) SYSCNZMG(3)
The number between the parenthesis is related to the number of stacks active in the XCF
group.
Example 7-5 displays that the stack in LPAR A24 is located in subplex 11 with its name
EZBTCP11 9. The definitions for the subplex 22 (EZBTCP22) are described in 7.4.4,
“Subplex 22: External subplex” on page 237.
Example 7-5 Display of specific stacks that belong to an XCF group
D TCPIP,TCPIPC,SYSPLEX,GROUP
EZZ8270I SYSPLEX GROUP FOR TCPIPC AT SC31 IS EZBTCP11 9
D TCPIP,TCPIPD,SYSPLEX,GROUP
EZZ8270I SYSPLEX GROUP FOR TCPIPD AT SC31 IS EZBTCP22
The Netstat Config display shows the XCFGRPID 10 and the IQDVLANID 11.
Example 7-6 Netstat Config with XCFGRPID and IQDVLANID for stack C
D TCPIP,TCPIPC,NETSTAT,CONFIG
GLOBAL CONFIGURATION INFORMATION:
Note: We used the same value for XCFGRPID and IQDVILANID. These values do not
have to match. XCFGRPID allows values from 2 to 31, while IQDVLANID allows values
from 1 to 4094.

MLSCHKTERM: NO XCFGRPID: 11 10 IQDVLANID: 11 11
SYSPLEXWLMPOLL: 060
SYSPLEX MONITOR:
The command Netstat Device also shows the HiperSockets connection with VLANID 12,
which is the same value as IQDVLANID, as shown in Example 7-6 on page 235.
Example 7-7 Netstat Device showing the HiperSockets VLAN ID
D TCPIP,TCPIPC,NETSTAT,DEV
DEVNAME: IUTIQDIO DEVTYPE: MPCIPA
DEVSTATUS: READY
LNKNAME: IQDIOLNK0A1E1465 LNKTYPE: IPAQIDIO LNKSTATUS: READY
ACTMTU: 8192
DYNVLANREGCFG: NO DYNVLANREGCAP: NO
SECCLASS: 255
MULTICAST SPECIFIC:
GROUP REFCNT
----- ------
224.0.0.5 0000000001
224.0.0.1 0000000001
LINK STATISTICS:
BYTESIN = 57156
BYTESOUT = 18296

7.4.4 Subplex 22: External subplex
Figure 7-7 depicts the configuration for IP Subplex 22 (the external subplex). Note that both
subplexes are using the same HiperSockets (CHPID F7).
Figure 7-7 Subplex 22 - external subplex
TCP/IP profile definitions for subplex 22 in LPAR A24 stack D
If you compare the definitions for stack D (shown in Example 7-8) with stack C (shown in
Example 7-3 on page 234), you discover that only XCFGRPID 1, IQDVLANID 2, and
DYNAMICXCF IP address 3 values are different.
Example 7-8 TCP/IP profile: Subplex definitions for stack D in LPAR A24
GLOBALCONFIG
XCFGRPID 22 1
IQDVLANID 22 2
;
IPCONFIG
DYNAMICXCF 10.20.40.101 255.255.255.0 8 3
TCP/IP profile definitions for subplex 22 in LPAR A25 stack D
If you compare the definitions for stack D in LPAR 25 with stack D in LAPR 24 (see
Example 7-8), you will discover that XCFGRPID 4 and IQDVLANID 5 have the same values.
Only the DYNAMICXCF IP address value 6 is different.
Example 7-9 TCP/IP profile: Subplex definitions for stack D in LPAR A25
GLOBALCONFIG
XCFGRPID 22 4
IQDVLANID 22 5
;
IPCONFIG
DYNAMICXCF 10.20.40.102 255.255.255.0 8 6
z/OS LPAR: A25z/OS LPAR: A24
TCP/IP D
VIPA:10.40.1. 241
TCP/IP D
VIPA:10.40.1. 221
XCF
10.20.40.0/24
VTAM IQDCHPID: F7
IP Subplex 22
OSPF_Area = 0.0.0.2
Stub_Area = YES

Verification of the subplex 22
The command netstat config shows the definitions used by the stack.
Example 7-10 Netstat config from LPAR 24 stack D
D TCPIP,TCPIPD,NETSTAT,CONFIG
EZD0101I NETSTAT CS V1R8 TCPIPD 286
MLSCHKTERM: NO XCFGRPID: 22 IQDVLANID: 22
SYSPLEXWLMPOLL: 060
SYSPLEX MONITOR:
7.4.5 Access verifications
We executed ping commands from all TCP/IP stacks in all LPARs. Example 7-11 shows a
ping to IP address 10.30.20.101 (XCF and HiperSockets interface) from outside Subplex 11,
which failed. All ping requests within each subplex were successful. Requests from other
subplex groups or non-subplex groups were rejected.
Example 7-11 Ping test
===> ping 10.30.20.101
Ping #1 timed out
7.4.6 LBA connected to a subplex
Ensure that the Advisor and Agent are configured for a subplexed environment.
There should be one Agent on each LPAR in the subplex.
The Agents report to the Advisor only about applications within their subplex.
If the Agent is configured with sysplex_group_name EZBTvvtt, the Agent will report only
applications that are on the VTAM subplex vv and TCP/IP stacks with subplex tt.
When configured for subplexing, the Agents will not report on other applications in the
same LPAR.
As of z/OS V1R10, there can be more than one Agent in an LPAR if they are in different
subplexes.
IP addresses used as the source IP address for outbound Agent connection to the Advisor
should be configured/owned by the proper stacks.
The DVIPA for the Advisor needs to be defined in all the stacks associated with the
subplex (and where a restart of the Advisor can occur).
7.5 References
For more information about subplexing, refer to the following publications:

Chapter 8. Diagnosis
A key topic in any TCP/IP network infrastructure is documenting and analyzing problems. In
this chapter we describe tools available in z/OS Communications Server as well as
techniques to gather and diagnose problems related to the TCP/IP environment.
8
Section Topic
8.1, “Debugging a problem in a z/OS
TCP/IP environment” on page 240
Problem determination techniques and the tools available
to debug a problem in z/OS Communications Server -
TCP/IP component
8.2, “Logs to diagnose CS for z/OS IP
problems” on page 242
Why logs are important in problem analysis
8.3, “Useful commands to diagnose CS
for z/OS IP problems” on page 243
Commands used to debug network problems
8.4, “Gathering traces in CS for z/OS IP”
on page 250
Using z/OS Component Trace Service to capture trace
data for the main z/OS Communications Server - TCP/IP
component
8.5, “OSA-Express2 Network Traffic
Analyzer” on page 267
Using OSAENTA to diagnose OSA problems
8.6, “Additional tools for diagnosing CS
for z/OS IP problems” on page 285
Other tools that can be used to diagnose network
problems

8.1 Debugging a problem in a z/OS TCP/IP environment
In a TCP/IP network, several different types of problems can arise. Therefore, the support
staff needs to develop debugging techniques that can help them better understand, define,
and debug such problems. In this section we discuss a problem determination approach that
uses logs, standard commands, tools, and utilities.
When problems arise in a TCP/IP environment, they can sometimes be very challenging to
isolate. Without the proper tools, techniques, and knowledge of the environment, it can be
very difficult to debug any problem. The culprit could be any one of the many components
between the affected endpoints.
Therefore, we suggest categorizing the problem. Problems in TCP/IP networks can usually be
classified into three major categories:
Network connectivity problems
These occur when a z/OS server cannot establish a connection with another server or
client because the node is unreachable (for example, it does not respond to the ping
command).
Application-related problems
These occur when a host is reachable, but communication with the desired application
fails.
Stack-related problems
These occur when the z/OS TCP/IP stack does not work as implemented, or ends with a
dump.
Most problems can easily be associated to one of these categories and the information
needed to debug them can be retrieved from logs, commands, or utilities.
Logs are the first and most important tool to help you understand the nature of the problem. In
logs you will find messages that might explain what happened or even lead you to the actions
needed to solve the problem.
Sometimes, however, problems like connectivity or routing do not provide messages that
clearly show what went wrong. Therefore, you need further information, which can be
obtained by using commands such as Netstat, Ping, or Traceroute. If the commands do not
provide enough information to solve or isolate the problem, then you can invoke the z/OS
Communications Server trace utilities that gather data as it passes through the devices and
the stack.
Many problems related to the TCP/IP stack are due to configuration errors. Here you can use
logs to find useful messages that indicate were the error is located.
If the TCP/IP stack happens to abend, a dump is generated. In such a situation, the dump
and related information can be sent to IBM Support for further analysis.
8.1.1 An approach to problem analysis
When performing problem analysis, it is essential that you have readily available current,
accurate documentation describing the physical and logical network environment. This
documentation should include network diagrams, naming conventions, addressing schemes,
and system configuration information.

Chapter 8. Diagnosis 241
When a problem occurs, the first step is to verify that the operating environment is behaving
as expected. After this is confirmed, you can then focus on other areas. To help isolate the
problem, a useful approach is to answer such basic questions including:
Is the TCP/IP stack running correctly?
This generic question can help determine whether the problem is stack-related. It can be
answered by verifying the behavior of the entire Communications Server for z/OS IP
environment.
Usually the tools used to answer this question are the logs where messages related to the
problem can be found (see 8.2, “Logs to diagnose CS for z/OS IP problems” on page 242)
and tools that receive information using the Network Management Interface (see 8.6,
“Additional tools for diagnosing CS for z/OS IP problems” on page 285).
If the problem is an abend, save the generated dump for analysis. The configuration
should also be checked for inconsistencies. If you conclude it is not a stack-related
problem, then the next step will be based on your findings to determine whether it is a
network- or application-related problem.
Has this ever worked before? If so, what has changed?
These two basic questions might seem obvious, but they are in fact the most common
reasons for problems encountered in a Communications Server for z/OS IP environment.
If the problem is with a production and stable environment, you must first check whether
any changes have been made. In some cases, changes do not take affect until a system
or stack recycle is done. The only useful approach in this case is to keep track of any
changes and always use change management processes.
If you are dealing with a new implementation, was a step-by-step approach being used? If
so, you will probably know in which step the problem occurred and can adapt your problem
determination procedure based on the step being implemented.
Are the physical connections and interfaces active and working properly?
This question is related to a connectivity problem, and it leads to checking interface
definitions and status. You also need to look at the log files, and use commands to
determine whether the interfaces are operational. The Netstat command can be used to
verify this, as discussed in 8.3, “Useful commands to diagnose CS for z/OS IP problems”
on page 243.
If it is an intermittent problem, or if you cannot find the cause of the problem,
Communications Server for z/OS IP provides a set of trace tools that you can use to
gather more information. See 8.4, “Gathering traces in CS for z/OS IP” on page 250.
Can the destination host be reached?
In cases where the physical connections are up and running, but a specific host cannot be
reached, the problem is probably related to routing. In this case, you need to look at the
logs files for related error messages. You can also use commands such as ping,
traceroute, and netstat to discover why you are not able to reach this host.
If these steps do not provide you with enough information to isolate the problem, you will
need to use the packet trace utility as described in 8.4, “Gathering traces in CS for z/OS
IP” on page 250. A packet trace allows you to check if there is any data going to or coming
from the host you are trying to reach.
Is the problem affecting multiple connections?
There might be a problem with the proper configuration of a firewall policy, an incorrect
interface configuration, or an application problem.
The approach in this case is to review the configuration files, looking for inconsistencies.
Also examine the log files, which might contain error messages about this problem. If

necessary, you can also debug this problem using the component trace for event and
packet tracing; see 8.4, “Gathering traces in CS for z/OS IP” on page 250.
Is this problem related to a single application?
To analyze application problems, you need general knowledge of the application protocol.
You should know what transport protocol is used, which port numbers are used, how a
connection is established, and the application protocol semantics.
Mainly, the following tools are used to diagnose application problems:
– Debugging commands
– Specific application traces
– Packet trace
– Component trace
You can check whether an application is running by using display commands. With
TELNET, for example, the D TCPIP,,TELNET and V TCPIP,,TELNET commands can be
used to verify and control Telnet connections.
Specific application traces are useful for following the execution of an application (either
client or server), and checking whether there are error messages. The application trace
might not be sufficient to diagnose some problems because it shows the commands
(rather than the data) exchanged during a connection.
For an in-depth investigation you need to use a packet trace, which can be interpreted
relatively easily for standard applications (see 8.4, “Gathering traces in CS for z/OS IP” on
page 250), or a CTRACE (when requested by IBM).
8.2 Logs to diagnose CS for z/OS IP problems
To start the problem determination process, the most important step is to pull together reliable
information to verify, classify, and define possible lines of action to resolve a problem.
Examining logs is an excellent starting point in the problem determination process. Logs
contain different types of messages (informational, error-based, and warning-based) that
provide very useful information. Logs are very important in the problem determination
process because they can be the only source of information about a problem.
For example, in a production environment, problems are often business- or service-related,
and end users are the first to notice there is a problem (usually, because they are unable to
access applications or execute services). The operational response taken when a problem is
discovered is often based on business or service recovery; it is usually only after these
actions are taken that support personal are called upon to evaluate and determine why the
outage occurred in the first place. In some cases, there is no information given other than a
problem description based on the business or service point of view, with no technical
perspective.
In many situations, the information obtained during the problem determination process comes
from separate logs (system, application, and stack logs). To be able to build a clear picture of
the problem or outage, all significant information must be correlated.
Because of this, we recommend that you implement syslogd to control where all messages
are sent. This way, you will have a single place to refer to when debugging a problem. The
syslogd process is a UNIX process that logs UNIX application messages to one or more files.
TCP/IP services that run as UNIX processes log application messages using syslogd can
consolidate logging information from several systems to one system through UDP
communications.

For further information about setting up syslogd, refer to Communications Server for z/OS
V1R9 TCP/IP Implementation Volume 2: Standard Applications, SG24-7533.
8.3 Useful commands to diagnose CS for z/OS IP problems
To solve problems it is important to know what tools are available and how to make best use
of them. Some commands or utilities can be used to review configuration options or settings;
others can be used to test connectivity.
In this section we describe briefly the main commands that you can use to diagnose problems
in a Communications Server for z/OS IP environment. For additional help and detailed
information about the commands described and other commands that can be used for
problem determination, refer to z/OS Communications Server: IP System Administrator’s
Commands, SC31-8781, and z/OS Communications Server: IP Diagnosis Guide,
GC31-8782.
In this section, we describe these commands:
PING command (TSO or z/OS UNIX)
TRACEROUTE command
Netstat command (console, TSO, or z/OS UNIX)
8.3.1 PING command (TSO or z/OS UNIX)
The PING command is relatively simple, but it is one of the best tools you can use to check
basic connectivity. It sends an ICMP echo request message to the target system and waits for
an ICMP echo reply message. Because this command uses only two ICMP messages (echo
request and echo response), it cannot be used to test transport or application protocols. In
order for PING to work, the sending system and all intermediate systems must be correctly
set up for both the outbound and inbound journeys.
Typically, PING is used to verify:
The route to a network is defined correctly.
The router is able to forward packets to the network.
The remote host is able to send and receive packets on the network
The remote host has a route back to the local host.
In most cases, the default options of PING are used. However, in a z/OS Communications
Server environment, using the default options might lead to a false conclusion, given the
number of interfaces that can be used to transport the ICMP request.
This command provides several options that can be used to analyze a problem in more detail.
For example, the intf option of the TSO ping command (or the -i option, if you use the z/OS
UNIX ping command) specifies the local interface over which the packets are sent. This can
be useful to determine if a remote host is reachable through the desired path.
Table 8-1 on page 244 shows the available options that can be used with the ping command
in TSO and z/OS UNIX environments.
Tip: Using names instead of IP address needs the Resolver or DNS to do the translation,
thus adding more variables to the problem determination task. This should be avoided
when diagnosing network problems. Use the host IP address instead.

Table 8-1 Options available with PING
Figure 8-1 illustrates the use of the PING command for problem determination.
Figure 8-1 Using the PING command with the interface option
This is a situation where a PING might work even when the expected route to the endpoint is
down. In this case the endpoint was accessed using an alternate route. However, using the
PING command without the correct option would hide the problem, as shown in Example 8-1.
Example 8-1 ping command without the intf option
ping 10.1.3.220 (tcp tcpipc
***
Options TSO z/OS UNIX
Address type (ipv4 /ipv6) Addrtype -A
Number of ping iteractions Count -c
Interface to be used as path Intf -i
Amount of data being sent Length -l
Do not resolve IP addresses to host names (used with Pmtu) NOName -n
Determine the path MTU size of a host in the network. PMTU -P
Source IP address Srcip -s
TCP/IP stack to be used. TCP -p
How long it waits for a response Timeout t
Help information HELP or ? -h or -?
SC32
TCPIPC
Router 1 Router 2
OSA20A0 OSA20C0
10.1.2.31
10.1.2.240 10.1.3.220
10.1.3.31
10.1.1.31

To avoid such confusion, indicate which path to verify by using the interface (intf) option, as
shown in Example 8-2.
Example 8-2 ping command with the intf option
ping 10.1.3.220 (tcp tcpipc intf osa20c0l
sendMessage(): EDC8130I Host cannot be reached. (errno2=0x74420291)
***
After using the correct command, you can see there is a problem using interface OSA20C0L,
which is the direct connection to the 10.1.3.0 subnetwork.
Using the PMTU option
Use the PMTU option on the PING command to determine where fragmentation is necessary
in the network. The PMTU YES option differs from the PMTU IGNORE option in the way the
PING completes its echo function. Refer to z/OS Communications Server: IP System
Administrator’s Commands, SC31-8781, for a detailed discussion about the PMTU option.
Example 8-3 shows a PING with a very large packet size, with no PMTU option specified. We
used the noname option to avoid a reverse DNS lookup on the IP address.
Example 8-3 Using PING without the PMTU option
ping 10.1.1.10 (noname tcp tcpipb l 25000 c 1 t 1
***
Example 8-4 shows that by adding the PMTU YES option 1 to the ping command, you can
determine at which hop 2 the fragmentation is necessary, and the MTU size 3.
Example 8-4 Using PING with the PMTU option
ping 10.1.1.10 (noname tcp tcpipb l 25000 c 1 t 1 pmtu yes 1
Ping #1 needs fragmentation at: 10.1.7.21 2
Next-hop MTU size is 8192 3
***
By varying the size of the ping packet, you can work your way through the path to the hop
requiring fragmentation, as shown in Example 8-5.
Example 8-5 Varying the PING packet size
ping 10.1.1.10 (noname tcp tcpipb l 6000 c 1 t 1 pmtu yes
***
***
Ping #1 needs fragmentation at: 10.1.5.21 (10.1.5.21)

Next-hop MTU size is 8192
***
Example 8-6 illustrates the use of the PMTU IGNORE option.
Example 8-6 PING with the PMTU IGNORE option
ping 10.1.1.10 (noname tcp tcpipb l 25000 c 1 t 1 pmtu ignore
Ping #1 needs fragmentation at: 10.1.7.21
Next-hop MTU size is 8192
***
8.3.2 TRACEROUTE command
The traceroute (z/OS UNIX) or tracerte (TSO) command is used to determine the route that
IP datagrams follow through the network. Traceroute is based on ICMP and UDP. It sends an
IP datagram with a time-to-live (TTL) of 1 to the destination host. The first router decrements
the TTL to 0, discards the datagram, and returns an ICMP Time Exceeded message to the
source. In this way, the first router in the path is identified. This process is repeated with
successively larger TTL values to identify the exact series of routers in the path to the
destination host.
On most platforms, the traceroute command sends UDP datagrams to the destination host.
These datagrams reference a port number outside the standard range. The source knows
when it has reached the destination host when it receives an ICMP ‘Port Unreachable’
message.
Traceroute displays the route that a packet takes to reach the requested target. The output
generated by this command can be seen in Example 8-7.
1 10.1.2.240 (10.1.2.240) 0 ms 0 ms 0 ms
2 10.1.100.222 (10.1.100.222) 0 ms 0 ms 0 ms
***
8.3.3 The netstat command (console, TSO, or z/OS UNIX)
The netstat command provides information about the status of the local host, including
information about TCP/IP configuration, connections, network clients, gateways, and devices.
It also has options to drop connections for users who have the MVS.VARY.TCPIP.DROP
statement defined in their RACF profile.
As shown in Figure 8-2, there is a variety of Netstat options, and these can be further
qualified by filter criteria, depending on the option you choose. The output can be displayed to
the terminal (default), to a data set (report), or to the REXX data stack. The Output Format
(short or long) supports IPv6 addresses.

Figure 8-2 Netstat command options—target output (filter select)
The remainder of this section shows examples of netstat commands used for diagnostic
purposes, and their outputs.
Example 8-8 displays the results of the d tcpip,tcpipa,netstat,conn command.
Example 8-8 d tcpip,tcpipa,nestat,conn command
D TCPIP,TCPIPA,NETSTAT,CONN
USER ID CONN STATE
FTPDC1 0000001A LISTEN
LOCAL SOCKET: ::..21
FOREIGN SOCKET: ::..0
JES2S001 00000013 LISTEN
TN3270C 00000018 LISTEN
END OF THE REPORT
Use the D TCPIP,tcpipproc,NETSTAT, DEVLINK command to display the status and
associated configuration values for a device and its defined interfaces. This command can be
filtered to display only the interface you want, as shown in Example 8-9.
Example 8-9 D TCPIP,TCPIPC,N,DEV,INTFN=OSA2080L
D TCPIP,TCPIPC,N,DEV,INTFN=OSA2080L
DEVSTATUS: READY
LNKNAME: OSA2080L LNKTYPE: IPAQENET LNKSTATUS: READY
APPLD/-G
APPLname/-N
CLIent/-E
CONNType/-X
HOSTName/-H
INTFName/-K
IPAddr/-I
IPPort/-B
LUName/-L
NOTN3270/-T
POLicyn/-Y
POrt/-P .
(applicable to
selected options)
BYTEinfo*
CLients
CONFIG
COnn
DEvlinks
DRop
Gate
HElp
HOme
PORTList
ROUTe*
SOCKets
STATs*
TELnet*
Up
ALL
ALLConn
ARp*
CACHinfo
IDS*
ND
SLAP
SRCIP
TTLS
VCRT*
VDPT*
VIPADCFG
VIPADyn
Options FilterOutput options
FORMat (IPV6)
REPort (TSO only)
Stack (TSO only)
Target
TCP/IP stack
Select

ACTMTU: 8992
MTU SIZE: N/A METRIC: 00
MULTICAST SPECIFIC:
----- ------ --------
224.0.0.1 0000000001 EXCLUDE
SRCADDR: NONE
LINK STATISTICS:
BYTESIN = 240
INBOUND PACKETS = 3
BYTESOUT = 84
LANGROUP: 00001
LNKNAME LNKSTATUS ARPOWNER VIPAOWNER
------- --------- -------- ---------
OSA20A0L ACTIVE OSA20A0L YES
OSA2080L ACTIVE OSA2080L NO
1 OF 1 RECORDS DISPLAYED Outbound Packets Discarded = 0
The D TCPIP,tcpipproc,NETSTAT,ROUTE command displays the current routing tables for
TCP/IP, and it can be filtered to show specific routes as shown in Example 8-10.
Example 8-10 D TCPIP,TCPIPC,N,ROUTE,IPADDR=10.1.100.0/24
D TCPIP,TCPIPC,N,ROUTE,IPADDR=10.1.100.0/24
IPV4 DESTINATIONS
10.1.100.0/24 10.1.2.240 UGO 000000 OSA2080L
10.1.100.0/24 10.1.2.240 UGO 000000 OSA20A0L
10.1.100.0/24 10.1.3.240 UGO 000000 OSA20C0L
10.1.100.0/24 10.1.3.240 UGO 000000 OSA20E0L
END OF THE REPORT
You can optionally display additional application connection data by using the APPLDATA
parameter on the NETSTAT CONN and NETSTAT ALLCONN commands. Example 8-11
contrasts the output of two NETSTAT CONN commands: one without the APPLDATA
parameter 1, the other with the APPLDATA parameter 2. The TN3270 server populates the

APPLDATA field with connection data, as documented in z/OS Communications Server: IP
Configuration Reference, SC31-8776. The TN3270 appldata fields shown for the connection
are the component ID, LU name, the SNA application name, connection mode, client type,
security method, security level, and security cipher 3.
Example 8-11 NETSTAT CONN without and with the APPLDATA option
D TCPIP,TCPIPB,N,conn 1
EZD0101I NETSTAT CS V1R10 TCPIPB 385
USER ID CONN STATE
TN3270B 00000111 ESTBLSH
LOCAL SOCKET: ::FFFF:10.1.1.20..23
FOREIGN SOCKET: ::FFFF:10.1.1.20..1028
D TCPIP,TCPIPB,N,conn,appldata 2
USER ID CONN STATE
APPLICATION DATA: EZBTNSRV SC31BB05 SC31TS03 3T B 3
You can optionally display the report provided by the netstat ALL/-A, that is now available
when using the DISPLAY TCPIP,,NETSTAT command, in addition to being available using the
TSO or z/OS UNIX shell environment. You can filter this command to display only the client
IPADRR that you want, and receive a complete details of this session, such as the maximum
segment size in use, as shown in Example 8-12.
Example 8-12 D TCPIP,TCPIPB,N,ALL,IPADDR=10.1.100.222
D TCPIP,TCPIPB,N,ALL,IPADDR=10.1.100.222
CLIENT NAME: FTPDB1 CLIENT ID: 00000149
BYTESIN: 00000000000000000107
BYTESOUT: 00000000000000000520
SEGMENTSIN: 00000000000000000021
SEGMENTSOUT: 00000000000000000022
LAST TOUCHED: 15:52:31 STATE: FINWAIT2
RCVNXT: 4035242407 SNDNXT: 1484416018
CLIENTRCVNXT: 4035242407 CLIENTSNDNXT: 1484416018
INITRCVSEQNUM: 4035242299 INITSNDSEQNUM:
SNDUNA: 1484416018 RTT_SEQ:
1484416017
SNDUNA: 1484416018 RTT_SEQ:
1484416017
MAXIMUMSEGMENTSIZE: 0000001452 DSFIELD: 00
ROUND-TRIP INFORMATION:
SMOOTH TRIP TIME: 142.000 SMOOTHTRIPVARIANCE: 103.000 DSFIELD:
00
ROUND-TRIP INFORMATION:
SMOOTH TRIP TIME: 142.000 SMOOTHTRIPVARIANCE: 103.000
You can filter the output of the NETSTAT CONN,APPLDATA command by adding the APPLD
filter option and specifying the filter criteria. The APPLDATA field is a total of 40 bytes. By

using an asterisk (*) in the filter criteria, you can filter on any part of the 40 bytes.
Example 8-13 shows several filter criteria strings being used.
Example 8-13 NETSTAT CONN APPLDATA with APPLD filter
D TCPIP,TCPIPA,N,conn,appldata,appld=*tnsrv*
USER ID CONN STATE
APPLICATION DATA: EZBTNSRV SC31BB05 SC31TS03 3T B
END OF THE REPORT
D TCPIP,TCPIPA,N,conn,appldata,appld=*sc31*
USER ID CONN STATE
APPLICATION DATA: EZBTNSRV SC31BB05 SC31TS03 3T B
END OF THE REPORT
8.4 Gathering traces in CS for z/OS IP
Using trace tools is helpful when you have a concern about what is happening in the flow of
data. Communications Server for z/OS IP provides general trace and application-specific
trace facilities. Included in the general traces are packet trace and event trace. Both use the
Component Trace (CTRACE) facilities of z/OS.
A packet trace captures data packets that flow in or out of the IP stack.
An event trace can capture data flows within the stack, through the application socket
interfaces as well as other network flows, such as the ARP process.
This section deals with the trace facilities that are available to analyze TCP/IP problems on
z/OS servers and clients. It also discusses how to process those traces.
The MVS component trace can be used to diagnose most TCP/IP problems. Some
components of TCP/IP continue to maintain their own tracing mechanisms, for example, the
FTP server. Consult z/OS Communications Server: IP Diagnosis Guide, GC31-8782, and
z/OS MVS Diagnosis: Tools and Service Aids, GA22-7589, for more information about the
various trace options.
The following TCP/IP traces are available using the component trace:
Event trace for TCP/IP stacks (SYSTCPIP)
Packet trace (SYSTCPDA)
Socket data trace
Note: The MAXRECS parameter is now available on the GLOBALCONFIG TCP/IP profile
statement for configuring a default value for the DISPLAY TCPIP,,NETSTAT command’s
MAX parameter. The default value is 100.

OMPROUTE trace (SYSTCPRT)
Resolver trace (SYSTCPRE)
Intrusion detection services trace (SYSTCPIS)
IKE daemon trace (SYSTCPIK)
OSAENTA trace (SYSTCPOT)
Network security services server trace (SYSTCPNS)
Configuration profile trace
Figure 8-3 shows the traces that can be used for debugging. Some applications have their
own internal trace functions. The output from those traces can be to the screen, a file, or to
the syslogd logging function. The data from the z/OS Component Trace is written to either an
external writer or the TCP/IP data space TCPIPDS1.
Figure 8-3 Trace points
Information APAR II12014 is a useful source of information about the TCP/IP component and
packet trace. For general information about the MVS component trace, see z/OS MVS
Diagnosis: Tools and Service Aids, GA22-7589.
8.4.1 Taking a component trace
Component trace data is written to either an external writer or the TCP/IP data space
TCPIPDS1 (the default is to write trace data to the data space). In this section we show the
necessary steps to start a component trace that uses the external writer; this allows you to
store trace data in data sets, which can later be used as input to IPCS.
Trace
files
Syslog
CTWTR
file
Console
z/OS Component Trace Points
Data Link layer
... OSAHiperSocketsMPC
Dataspace
Trace output
Network/Transport layer
Event trace
Packet trace
OSPF UDP TCP ICMP
SYSTCPIP
SYSTCPDA
SYSTCPOT
OMPROUTE Resolver IDS
Application traces
:
TN3270E, FTPD, etc...
NSSIKED
SYSTCPIPSYSTCPNSSYSTCPISSYSTCPRT SYSTCPRE SYSTCPDASYSTCPIK

Before starting the traces, create the external write procedure in the SYS1.PROCLIB library,
which allocates the trace data set. This procedure is activated using the trace command. A
sample procedure named CTWTR is shown in Figure 8-4.
Figure 8-4 sample External Write procedure
Next, follow these steps using the trace command to activate, capture data, and stop the
trace process:
1. Start the external writer (CTRACE writer).
TRACE CT,WTRSTART=ctwrt
Where ctwrt is the name of the procedure created to allocate the trace data set.
2. Start the CTRACE and connect to the external writer.
TRACE CT,ON,COMP=component,SUB=(proc_name)
R xx,OPTION=(valid_options),WTR=ctwrt,END
Where:
– component is the component name of the trace being started and can be any of these:
SYSTCPIP (Event trace)
SYSTCPDA (Packet trace)
SYSTCPDA (Data trace)
SYSTCPIS (Intrusion Detection Services trace)
SYSTCPIK (IKE daemon trace)
SYSTCPOT (OSAENTA trace)
SYSTCPNS (Network security services (NSS) server trace)
SYSTCPRT (OMPROUTE trace)
SYSTCPRE (RESOLVER trace)
Configuration profile trace
– proc_name is the procedure related to the component trace being started, and can be
any of these:
tcpip_proc
iked_proc
nss_proc
omp_proc
– ctwtr is the started procedure name of the external writer.
3. To verify the trace is started, use the display trace command.
DISPLAY TRACE,COMP=component,SUB=(proc_name)
4. Perform the operation you want to trace.
5. Disconnect the external writer.
TRACE CT,ON,COMP=component,SUB=(proc_name)
R xx,WTR=DISCONNECT,END
//CTWTR PROC
//TRCOUT01 DD DSNAME=SYS1.&SYSNAME..CTRACE,
// VOL=SER=COMST2,UNIT=3390,
// SPACE=(CYL,10),DISP=(NEW,CATLG),DSORG=PS
//*

6. Stop the component trace.
TRACE CT,OFF,COMP=component,SUB=(proc_name)
7. Stop the external writer.
TRACE CT,WTRSTOP=ctwrt
The next sections describe each component trace used by z/OS Communications Server -
TCP/IP component for documenting problems. For a detailed explanation for each component
trace, refer to z/OS Communications Server: IP Diagnosis Guide, GC31-8782.
8.4.2 Event trace for TCP/IP stacks (SYSTCPIP)
The TCP/IP event trace, SYSTCPIP, traces TCP/IP stack components such as IP, ARP, TCP,
UDP, TELNET, VTAM, and Socket API (SOCKAPI). It is automatically started at TCP/IP
initialization using the CTRACE parm option in the parms statement of the TCP/IP sack
startup procedure.
z/OS Communications Server provides a default trace options set in the SYS1.PARMLIB
member (CTIEZB00 for SYSTCPIP, and CTIEZBTN for the TN3270 Telnet server). The
options provided can be changed using an alternate member with the desired options (for
example, CTIEZBXX), and then changing the value in the parm CTRACE keyword in your
TCP/IP procedure; see Figure 8-5.
Figure 8-5 Overriding CTIEZB00 with CTIEZBXX
If you want to specify different trace options after TCP/IP initialization, you can execute the
TRACE CT command and either specify the new component trace options file or respond to
prompts from the command.
Note: The buffer size option is defined during TCP/IP startup only, so any change needs to
be done using the CTIEZBxx parmlib member and cannot be reset without restarting the
TCP/IP address space. The default is 8 MB.
//TCPIPC PROC PARMS='CTRACE(CTIEZBXX)'
//*
//TCPIP EXEC PGM=EZBTCPIP,REGION=0M,TIME=1440,
// PARM='&PARMS'

Figure 8-6 shows the status of the component trace for TCP/IP procedure TCPIPA as it has
been initialized using SYS1.PARMLIB member CTIEZB01. Note that we have changed the
default value for BUFSIZE to 4 M.
Figure 8-6 DISPLAY TRACE,COMP=SYSTCPIP,SUB=(TCPIPC) output
The MINIMUM trace option is always active. During minimum tracing, certain exceptional
conditions are being traced so the trace records for these events will be available for easier
debugging in case the TCP/IP address space should encounter an abend condition.
Socket API trace
The SOCKAPI option for the TCP/IP CTRACE component SYSTCPIP is intended to be used
for application programmers to debug problems in their applications. The SOCKAPI option
captures trace information related to the socket API calls that an application might issue.
When you need to trace application-related problems using the SOCKAPI option, it is
recommended that you follow these guidelines:
Trace only one application. Use the job name or ASID option when capturing the trace to
limit the trace data to one application.
Trace only the SOCKAPI option. To get the maximum number of SOCKAPI trace records,
specify only the SOCKAPI option.
Use an external writer. The external writer is recommended to save more trace data.
Trace only one TCP/IP stack.
Activate the data trace only if more data is required. The SOCKAPI trace contains the first
96 bytes of data sent or received, which is usually sufficient.
However, the SOCKET option is primarily intended for use by TCP/IP Service and provides
information meant to be used to debug problems in the TCP/IP socket layer, UNIX System
Services, or the TCP/IP stack. Refer to z/OS CS: IP Diagnosis, GC31-8782, for further details
on the SOCKAPI option.
RESPONSE=SC30
ST=(ON,0256K,00512K) AS=ON BR=OFF EX=ON MO=OFF MT=(ON,024K)
TRACENAME
=========
SYSTCPIP
=====================
OFF HEAD 4
NO HEAD OPTIONS
--------------------------------------------------------------
TCPIPA ON 0004M
ASIDS *NONE*
JOBNAMES *NONE*
OPTIONS MINIMUM
WRITER *NONE*

Sample SYSTCPIP trace
In this section we follow the steps described in 8.4.1, “Taking a component trace” on page 251
to start, get data, and stop a CTRACE for component SYSTCPIP. The TN3270 server
address space also uses the SYSTCPIP event trace. Therefore, all discussions that follow
here where TCP/IP is used also pertain to the Telnet server, with the following exceptions:
The Telnet server does not use a data space for trace data collection; it uses its own
private storage.
A subset of the trace commands are used by Telnet so a new default member, CTIEZBTN,
is created, which provides an indication of the trace options available. This member can
also be overwritten in the same manner as the TCP/IP parmlib member can be
overwritten.
A subset of IPCS commands are used by Telnet.
The resulting messages are shown after each command, as follows:
TRACE CT,WTRSTART=CTWTR
IEF196I IGD100I 8623 ALLOCATED TO DDNAME TRCOUT01 DATACLAS ( )
ITT110I INITIALIZATION OF CTRACE WRITER CTWTR COMPLETE.
2. Connect to the CTRACE external writer and specify trace options.
TRACE CT,ON,COMP=SYSTCPIP,SUB=(TCPIPC)
R 60,JOBNAME=(FTPDC),OPTIONS=(SOCKAPI),WTR=CTWTR,END
IEE600I REPLY TO 060 IS;JOBNAME=(FTPDC),OPTIONS=(SOCKAPI),WTR=CTWTR
3. Display the active component trace options to verify they are correct.
DISPLAY TRACE,COMP=SYSTCPIP,SUB=(TCPIPC)
TRACENAME
=========
SYSTCPIP
=====================
OFF HEAD 3
NO HEAD OPTIONS
--------------------------------------------------------------
TCPIPC ON 0008M
ASIDS *NONE*
Note: If using the Telnet option, do not specify the JOBNAME parm when starting
CTRACE.
Note: You can use the parmlib member CTIEZBxx to provide the same options:
TRACE CT,ON,COMP=SYSTCPIP,SUB=(TCPIPC),PARM=(CTIEZBXX)

JOBNAMES FTPDC
OPTIONS SOCKAPI
WRITER CTWTR
4. Reproduce the failure that you want to trace.
TRACE CT,ON,COMP=SYSTCPIP,SUB=(TCPIPC)
TRACE CT,OFF,COMP=SYSTCPIP,SUB=(TCPIPC)
IEF196I IEF285I SYS1.SC32.CTRACE CATALOGED
After your events trace data is captured, the trace data set created by the external writer
procedure is saved and IPCS is used to format and analyze its contents. Refer to z/OS CS: IP
Diagnosis, GC31-8782, for further details about SYSTCPIP events trace.
8.4.3 Packet trace (SYSTCPDA)
Packet tracing captures IP packets as they enter or leave TCP/IP. You select what you want to
trace using the PKTTRACE statement within the PROFILE.TCPIP, or using the VARY
PKTTRACE command entered from the MVS console. RACF authorization is required to
execute this command.
You can also use the packet trace to capture data traffic going through fast local socket (local
traffic).
With the VARY PKTTRACE command or PKTTRACE statement in PROFILE.TCPIP, you can
specify options such as IP address, port number, discard, and protocol type. If you are
planning to gather a trace for relatively long hours, or if your system experiences heavy traffic,
it is recommended that you specify these filtering options so that TCP/IP does not have to
gather unnecessary packets.

To run a packet trace, follow the steps described in 8.4.1, “Taking a component trace” on
page 251 to activate the component trace for component SYSTCPDA. Then, activate the
packet trace with the desired options and filters. All data in this sample is written to an
external writer:
1. Start the CTRACE external writer.
TRACE CT,WTRSTART=CTWTR
IEF196I IGD100I 8623 ALLOCATED TO DDNAME TRCOUT01 DATACLAS ( )
ITT110I INITIALIZATION OF CTRACE WRITER CTWTR COMPLETE.
2. Start the CTRACE and connect the external writer to the TCP/IP address space.
TRACE CT,ON,COMP=SYSTCPDA,SUB=(TCPIPA)
063 ITT006A SPECIFY OPERAND(S) FOR TRACE CT COMMAND.
R 63,WTR=CTWTR,END
IEE600I REPLY TO 063 IS;WTR=CTWTR,END
3. Check that the trace started successfully.
D TRACE,COMP=SYSTCPDA,SUB=(TCPIPA)
TRACENAME
=========
SYSTCPDA
=====================
OFF HEAD 2
NO HEAD OPTIONS
NO HEAD OPTIONS
--------------------------------------------------------------
TCPIPA MIN 0016M
ASIDS *NONE*
JOBNAMES *NONE*
OPTIONS MINIMUM
WRITER CTWTR
4. Start the trace through the PROFILE.TCPIP statement and the VARY OBEYFILE
command, or through the V TCPIP,,PKT command.
VARY TCPIP,TCPIPA,PKT,ON
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,PKT,ON
EZZ0053I COMMAND VARY PKTTRACE COMPLETED SUCCESSFULLY
The trace options can modify the data that is captured using the VARY command. If both
options IPaddr and PORTNUM are specified in the same command, an AND condition is
created so data is only captured if both conditions are met.

For example, issuing the following VARY command records only the packets with both
IPaddr (10.1.1.1) and Portnum= 23. Example 8-14 shows the output generated by this
command.
Example 8-14 Command to modify the trace options
V TCPIP,TCPIPA,PKTTRACE,IP=10.1.1.1,PORTNUM=23
It can also create an OR condition issuing multiple VARY commands to apply filters
together. For example, if you want to record all packets with destination ports xx OR
source ports yy, use the following commands:
VARY TCPIP,tcpprocname,PKT,DEST=xx
VARY TCPIP,tcpprocname,PKT,SRCP=yy
A new filter option is introduced in z/OS V1R10 Communications Server, called the
DISCARD option, which allows you to filter inbound packets that are discarded by the
stack. You also can filter packet trace collection and formatting by using discard reason
codes. For example, if you want to record all packets that are discarded or filter the
packets with reason code such as 4136, use the commands:
VARY TCPIP,TCPIPA,PKT,DISCARD=*
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,PKT,DISCARD=*
VARY TCPIP,TCPIPA,PKT,DISCARD=4136
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,PKT,DISCARD=4136

5. Check if the package trace options set are correct, using the Netstat dev (-d) command,
we can see the PORTNUM = 23 option 1 , the IPADDR: 10.1.1.1 option 2 and the
Discard Code = 4136 option 3. Figure 8-7 shows a sample package trace setting.
Figure 8-7 Package Trace options setting
6. Perform the operation that you want to trace.
7. Stop the trace.
VARY TCPIP,TCPIPA,PKT,OFF
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,PKT,OFF
8. Disconnect the external writer from TCP/IP.
TRACE CT,ON,COMP=SYSTCPDA,SUB=(TCPIPA)
ITT120I SOME CTRACE DATA LOST, LAST 9 BUFFER(S) NOT WRITTEN
9. Stop the CTRACE.
TRACE CT,OFF,COMP=SYSTCPDA,SUB=(TCPIPA)
WERE SUCCESSFULLY EXECUTED
DEVNAME: LOOPBACK DEVTYPE: LOOPBACK
DEVSTATUS: READY
LNKNAME: LOOPBACK LNKTYPE: LOOPBACK LNKSTATUS: READY
ACTMTU: 65535
PACKET TRACE SETTING:
PROTOCOL: * TRRECCNT: 00000000 PCKLENGTH: FULL
DISCARD: NONE
SRCPORT: * DESTPORT: * PORTNUM: 23 1
IPADDR: * SUBNET: *
IPADDR: 10.1.1.1 SUBNET: * 2
DISCARD: *
SRCPORT: * DESTPORT: * PORTNUM: *
IPADDR: * SUBNET: *
DISCARD: 4136 3
SRCPORT: * DESTPORT: * PORTNUM: *
IPADDR: * SUBNET: *
MULTICAST SPECIFIC:
MULTICAST CAPABILITY: NO

10.Stop the external writer.
Socket data trace
Using the SYSTCPDA component CS for z/OS IP provides a way to capture socket data into
and out of the Physical File System (PFS). It helps to diagnose application data-related
problems. To activate this trace, we follow the same steps we used to activate a packet trace
and change only the command to start and stop the socket data trace:
V TCPIP,tcpproc,DATTRACE,ON
V TCPIP,tcpproc,DATTRACE,OFF
A new PORTNUM parameter is supported on the VARY TCPIP,,DATTRACE command that
you can use to trace only packets that have a source or destination port that matches a
specific port number.
The Socket data trace options can modify the data being captured using the VARY command.
For example, issuing the VARY command records only the data packets with both IPaddr
(10.1.9.11) and Portnum= 21, as shown in Example 8-15.
Example 8-15 V TCPIP,TCPIPB,DAT options
V TCPIP,TCPIPB,DAT,JOBNAME=*,IP=10.1.9.11/32,PORTNUM=21
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPB,DAT,JOBNAME=*,
IP=10.1.9.11/32,PORTNUM=21
EZZ0053I COMMAND VARY DATTRACE COMPLETED SUCCESSFULLY
To verify if the data trace options setting are correct, use the Netstat CONFIG command. See
Example 8-16.
Example 8-16 Netstat CONFIG command shows the options
D TCPIP,TCPIPB,N,CONFIG
TCP CONFIGURATION TABLE:
DEFAULTKEEPALIVE: 00000015 DELAYACK: NO
TTLS: NO
DATA TRACE SETTING:
JOBNAME: * TRRECCNT: 00000000 LENGTH: FULL
IPADDR/PREFIXLEN: 10.1.9.11/32
PORTNUM: *
JOBNAME: * TRRECCNT: 00000000 LENGTH: FULL
IPADDR/PREFIXLEN: 10.1.9.11/32
PORTNUM: 21

8.4.4 OMPROUTE trace (SYSTCPRT)
To diagnose OMPROUTE problems, z/OS Communications Server provides the debug and
trace parameter that can be defined during OMPROUTE initialization. The resulting output is
written to the OMPROUTE log and can cause increased overhead. This performance issue
can be solved by using the CTRACE facility. To do so, we highly recommend that you use the
OMPROUTE option (DEBUGTRC) in the startup procedure, which changes the output
destination of the OMPROUTE trace. In this section we briefly describe how to define and use
CTRACE to debug OMPROUTE problems.
The OMPROUTE CTRACE can be started anytime by using the command TRACE CT, or it
can be activated during OMPROUTE initialization. If not defined, OMPROUTE component
trace is started with a buffer size of 1 MB and the MINIMUM tracing option.
A parmlib member can be used to customize the parameters and to initialize the trace. The
default OMPROUTE Component Trace parmlib member is the SYS1.PARMLIB member
CTIORA00. The parmlib member name can be changed by using the
OMPROUTE_CTRACE_MEMBER environment variable.
In addition to specifying the trace options, you can also change the OMPROUTE trace buffer
size. The buffer size can be changed only at OMPROUTE initialization. The maximum
OMPROUTE trace buffer size is 100 MB. The OMPROUTE REGION size in the OMPROUTE
catalog procedure must be large enough to accommodate a large buffer size.
Here we shown the necessary steps to start the CTRACE for OMPROUTE during
OMPROUTE initialization using the parmlib member CTIORA00 and directing the trace
output to an external writer.
1. Prepare the SYS1.PARMLIB member CTIORA00 to get the desired output data.
Example 8-17 on page 261 shows a sample of CTIORA00 contents.
Example 8-17 CTIORA00 sample
TRACEOPTS
/* ---------------------------------------------------------------- */
/* ---------------------------------------------------------------- */
WTRSTART(CTWTR)
/* ---------------------------------------------------------------- */
/* ---------------------------------------------------------------- */
ON
/* OFF */
/* ---------------------------------------------------------------- */
/* CTRACE buffers reside in OMPROUTE Private storage */
/* which is in the regions address space. */
/* ---------------------------------------------------------------- */
BUFSIZE(50M)
Note: After the packet trace or the socket data is captured, the trace data set that is
created by the external writer procedure is saved. Use IPCS to format and analyze the
saved contents. Refer to z/OS CS: IP Diagnosis, GC31-8782 for further details about these
traces.

WTR(CTWTR)
/* ---------------------------------------------------------------- */
/* ---------------------------------------------------------------- */
/* OPTIONS( */
/* 'ALL ' */
/* ,'MINIMUM ' */
/* ,'ROUTE ' */
/* ,'PACKET ' */
/* ,'OPACKET ' */
/* ,'RPACKET ' */
/* ,'IPACKET ' */
/* ,'SPACKET ' */
,'DEBUGTRC'
/* ) */
2. Start the OMPROUTE procedure using the desired Debug and Trace options, as shown in
Example 8-18.
Example 8-18 OMPROUTE procedure
///OMPC32 PROC STDENV=OMPENC&SYSCLONE
//OMPC32 EXEC PGM=OMPROUTE,REGION=0M,TIME=NOLIMIT,
// 'ENVAR("_BPXK_SETIBMOPT_TRANSPORT=TCPIPC"',
// '"_CEE_ENVFILE=DD:STDENV")/-d1 -t2')1
//STDENV DD DISP=SHR,DSN=TCPIPC.TCPPARMS(&STDENV)
//SYSPRINT DD SYSOUT=*
The description for the tag shown in Example 8-18 is as follows:
– 1The parameters -t (trace) and -d (debug) define how detailed we want the output
data to be. We recommend using -t2 and -d1.
3. Verify that CTRACE has been started as expected, issuing the console command as
shown:
D TRACE,COMP=SYSTCPRT,SUB=(OMPC)
TRACENAME
=========
SYSTCPRT
=====================
OFF HEAD 1
NO HEAD OPTIONS
-------------------------------------------------------------
OMPC ON 0010M
ASIDS *NONE*
JOBNAMES *NONE*
OPTIONS MINIMUM ,DEBUGTRC
WRITER CTWTR

4. You can also use TRACE CT command to define the options we want after OMPROUTE
has been initialized, as shown:
TRACE CT,ON,COMP=SYSTCPRT,SUB=(OMPC)
TRACE CT,ON,COMP=SYSTCPRT,SUB=(OMPC)
TRACE CT,OFF,COMP=SYSTCPRT,SUB=(OMPC)
9. Change the OMPROUTE Debug and Trace level to avoid performance problems using the
MODIFY command, as shown in:
F OMPC,TRACE=0
F OMPC,DEBUG=0
After these steps, the generated trace file must be formatted using the IPCS. For further
information about OMPROUTE diagnosis, refer to z/OS Communications Server: IP
8.4.5 Resolver trace (SYSTCPRE)
z/OS Communications Server provides component trace support for the Resolver. A default
minimum component trace is always started during Resolver initialization. To customize the
parameters used to initialize the trace, update SYS1.PARMLIB member CTIRES00. In
addition to specifying the trace options, you can change the Resolver trace buffer size. Note
that the buffer size can be changed only at Resolver initialization.
After Resolver initialization, you must use the TRACE CT command to change component
trace options.

To gather the component trace for the Resolver, use the commands listed in 8.4.1, “Taking a
component trace” on page 251 and, in step 2 on page 252, specify the comp= parameter with
the resolver component name, SYSTCPRE and the sub= parameter with the Resolver
proc_name.
The generated trace file created after the problem is reproduced must be formatted using the
IPCS. For further information about Resolver diagnosis, refer to z/OS Communications
Server: IP Diagnosis Guide, GC31-8782.
8.4.6 IKE daemon trace (SYSTCPIK)
z/OS Communications Server provides component trace support for the IKE daemon and, as
other components, a default minimum component trace is always started during IKE daemon
initialization. Use a parmlib member to customize the parameters that are used to initialize the
trace. The default IKE daemon component trace parmlib member is the SYS1.PARMLIB
member CTIIKE00. The parmlib member name can be changed using the
IKED_CTRACE_MEMBER environment variable.
After IKE daemon is initialized you can start CTRACE to modify trace options or send data to
a external writer, using the commands listed in 8.4.1, “Taking a component trace” on
page 251 and, in step 2, specify the comp= parameter with the IKE daemon component name,
SYSTCPIK and the sub= parameter with the iked proc_name.
The generated trace file created after the problem is reproduced must be formatted using the
IPCS. For further information about IKE daemon diagnosis, refer to z/OS Communications
8.4.7 Intrusion detection services trace (SYSTCPIS)
When the TCP/IP stack starts, it reads SYS1.PARMLIB member CTIIDS00, which contains
trace options for the SYSTCPIS trace. Packets are traced based on the IDS policy defined in
LDAP. Refer to “Intrusion Detection Services” in z/OS Communications Server: IP
Configuration Guide, SC31-8775, for information about defining policy.
If the EZZ4210I message indicates the parmlib member name CTIIDS00, then the IDS
CTRACE space is set up using the default BUFSIZE of 32 M.
The CTIIDS00 member is used to specify the IDS CTRACE parameters. To eliminate this
message, ensure that a CTIIDS00 member exists within Parmlib and that the options are
correctly specified. A sample CTIIDS00 member is shipped with z/OS Communications
Server.
See z/OS Communications Server: IP Diagnosis Guide, GC31-8782 for details about the
intrusion detection services trace and z/OS Communications Server: IP Configuration Guide,
SC31-8775 for information about defining policy.
Tip: The IKE daemon reads the IKED_CTRACE_MEMBER environment variable only
during initialization. Changes to IKED_CTRACE_MEMBER after daemon initialization
have no affect. After IKE daemon initialization, you must use the TRACE CT command to
change component trace options.

8.4.8 OSAENTA trace (SYSTCPOT)
TCP/IP Services component trace is also available for use with the OSA-Express Network
Traffic Analyzer (OSAENTA) trace facility. The OSAENTA trace is a diagnostic method for
obtaining frames flowing to and from an OSA adapter. You can use the OSAENTA statement
to copy frames as they enter or leave an OSA adapter for an attached host. The host can be
an LPAR with z/OS, VM, or Linux. For more information about OSAENTA, refer to 8.5,
“OSA-Express2 Network Traffic Analyzer” on page 267.
8.4.9 Queued Direct I/O Diagnostic Synchronization
Communications Server provides support for a new Queued Direct I/O Diagnostic
Synchronization (QDIOSYNC) facility. It provides the ability to synchronize OSA-Express2
diagnostic data with host diagnostic data. The QDIOSYNC facility also provides for optional
filtering of the OSA-Express2 diagnostic data. If a filter is specified, the OSA-Express2
adapter honors the filter by limiting the types of diagnostic data collected. Although the
QDIOSYNC trace differs from a traditional VTAM TRACE command, you use the VTAM
MODIFY TRACE and NOTRACE commands to control it. The DISPLAY TRACES command
is modified to show the state of the QDIOSYNC trace.
The QDIOSYNC trace is not a traditional trace in which output is generated based on specific
events. Instead, the QDIOSYNC trace freezes and captures (logs) OSA-Express2 diagnostic
data in a timely manner. In addition to (or instead of) using the hardware management
console (HMC) to manually capture the diagnostic data, you can arm the OSA-Express2
adapter to automatically capture diagnostic data when one of the following occurs:
The OSA-Express2 adapter detects an unexpected loss of host connectivity.
Unexpected loss of host connectivity occurs when the OSA-Express2 adapter receives an
unexpected halt signal from the host or when the host is unresponsive to OSA requests.
The OSA-Express2 adapter receives a CAPTURE signal from the host.
A CAPTURE signal is sent by the host when one of the following occurs:
– The VTAM-supplied message processing facility (MPF) exit (IUTLLCMP) is driven.
– Either the VTAM or TCP/IP functional recovery routine (FRR) is driven with ABEND06F.
(ABEND06F is the result of a SLIP PER trap that specifies ACTION=RECOVERY).
When arming an OSA-Express2 adapter for QDIOSYNC, you can specify an optional filter
that alters what type of diagnostic data is collected by the OSA-Express2 adapter. This
filtering reduces the overall amount of diagnostic data collected, and therefore decreases the
likelihood that pertinent data is lost.
If you have several OSAs to arm, but you do not want to arm all of them, consider first arming
all OSAs and then individually disarm those you do not want armed.
For more information about how to set up the trace, refer to:
z/OS Communications Server: SNA Diagnosis Vol. 1, Techniques and Procedures,
GC31-6850
z/OS Communications Server: SNA Operation, SC31-8779
MVS Installation Exits, SA22-7593
Note: Do not use QDIOSYNC to unconditionally arm an OSA-Express2 adapter when it is
shared by other operating systems and those operating systems might use this function. In
this case, the function should be coordinated between all sharing operating systems.

8.4.10 Network security services server trace (SYSTCPNS)
z/OS Communications Server provides component trace support for the Network Security
Services (NSS) and, as with other components, a default minimum component trace is
always started during NSS server initialization. Use a parmlib member to customize the
parameters that are used to initialize the trace. The default NSS server component trace
parmlib member is the SYS1.PARMLIB member CTINSS00. In addition to specifying the
trace options, you can also change the NSS trace buffer size. The buffer size can be changed
only at NSS initialization and has a maximum of 256 MB.
You can change the parmlib member name using the NSSD_CTRACE_MEMBER
environment variable.
After the NSS server is initialized, you can start CTRACE to modify trace options or send data
to a external writer by using the commands listed in 8.4.1, “Taking a component trace” on
page 251 and, in step 2 on page 252, specify the comp= parameter with the NSS server
component name, SYSTCPNS and the sub= parameter with the nss_proc_name.
The generated trace file created after the problem iss reproduced must be formatted using
the IPCS. For more information about NSS server diagnosis, refer to z/OS Communications
8.4.11 Obtaining component trace data with a dump
If the TCP/IP or user’s address space abends, TCP/IP recovery dumps the home ASID, the
primary ASID, the secondary ASID, and the TCPIPDS1 data space to the data sets defined
within your MVS environment. The TCPIPDS1 data space contains the trace data for
SYSTCPIP, SYSTCPDA, and SYSTCPIS components.
To obtain a dump of the TCP/IP stack when no abend has occurred, use the DUMP
command. Remember to specify the data space name, which is always TCPIPDS1, because
it contains the trace data for the SYSTCPIP, SYSTCPDA, and SYSTCPIS components. Be
sure to include “region” (RGN) in the SDATA dump options, as shown here:
DUMP COMM=(enter_dump_title_here)
Rxx,JOBNAME=tcpproc,DSPNAME=(‘tcpproc’.TCPIPDS1),CONT
Rxx,SDATA=(CSA,LSQA,NUC,PSA,RGN,SQA,SUM,SQA,TRT),END
To obtain a dump of the OMPROUTE, RESOLVER, or TELNET address space (which
contains the trace table), use the DUMP command as shown here:
DUMP COMM=(enter_dump _title_here)
Rxx,JOBNAME=proc_started_task_name,SDATA=(RGN,CSA,ALLPSA,SQA,SUM,TRT,ALLNUC),EN
D
For more information about how to get a dump, refer to z/OS Communications Server: IP
Tip: The NSS server reads the NSSD_CTRACE_MEMBER environment variable only
during initialization. Changes to NSSD_CTRACE_MEMBER after server initialization have
no effect.

8.4.12 Analyzing a trace
You can format component trace records using IPCS panels or a combination of IPCS panels
and the CTRACE command, either from a dump or from external writer files. You can also use
IPCS in batch to print a component trace.
The primary purpose of the component trace is to capture data that the IBM Support Center
can use in diagnosing problems. There is little information in the documentation on
interpreting trace data. If you want to analyze the packet trace or data trace, you can do so by
formatting the trace data using a z/OS tool in TSO called IPCS. For more information about
trace and dump analysis using IPCS, refer to z/OS Communications Server: IP Diagnosis
Guide, GC31-8782.
8.4.13 Configuration profile trace
You can use the ITRACE statement in the PROFILE.TCPIP data set to activate TCP/IP
runtime tracing for configuration, the TCP/IP SNMP subagent, commands, and the autolog
subtask. ITRACE should only be set at the direction of an IBM Service representative. For
more information, refer to z/OS Communications Server: IP Diagnosis Guide, GC31-8782.
8.5 OSA-Express2 Network Traffic Analyzer
When data problems occur in a LAN environment, multiple traces are usually required. A
sniffer trace might be required to see the data as it was received from or sent to the network.
An OSA hardware trace might be required if the problem is suspected in the OSA, and z/OS
Communications Server traces are required to diagnose VTAM or TCP/IP problems.
To assist in problem diagnosis, the OSA-Express network traffic analyzer (OSAENTA)
function provides a way to trace inbound and outbound frames for an OSA-Express2 feature.
The OSAENTA trace function is controlled and formatted by z/OS Communications Server,
but is collected in the OSA at the network port.
This section discusses the steps that are necessary for setting up and using OSAENTA:
Determining the microcode level for OSA-Express2
Defining TRLE definitions
Checking TCPIP definitions
Customizing OSA-Express Network Traffic Analyzer
Defining a resource profile in RACF
Allocating a VSAM linear data set
Starting the OSAENTA trace
Note: To enable the OSA-Express network traffic analyzer, you must be running at least an
IBM System z9 EC or z9 BC and OSA-Express2 feature in QDIO mode (CHPID type
OSD). See the 2094DEVICE Preventive Service Planning (PSP) and the 2096DEVICE
Preventive Service Planning (PSP) buckets for more information about these topics.

8.5.1 Determining the microcode level for OSA-Express2
There are two ways to determine the OSA-Express2 microcode level: from the Hardware
Management Console (HMC), or by issuing the D NET,TRL,TRLE=OSA2080P command.
Each method is discussed in more detail in this section. From the HMC:
1. Select your system.
2. Double-click OSA Advanced Facilities.
3. Select appropriate PCHID.
4. Select View code level.
Figure 8-8 shows the microcode level installed in one of our OSA-Express2 features.
Figure 8-8 View code level
Alternatively, you can issue the D NET,TRL,TRLE=OSA2080P command. Example 8-19
shows the output.
Example 8-19 Output Display TRL
NAME = OSA2080P, TYPE = TRLE 756
TRL MAJOR NODE = OSA2080
STATUS= ACTIV, DESIRED STATE= ACTIV
TYPE = LEASED , CONTROL = MPC , HPDT = YES
MPCLEVEL = QDIO MPCUSAGE = SHARE
PORTNAME = OSA2080 LINKNUM = 0 OSA CODE LEVEL = 087A
HEADER SIZE = 4096 DATA SIZE = 0 STORAGE = ***NA***
WRITE DEV = 2081 STATUS = ACTIVE STATE = ONLINE
READ DEV = 2080 STATUS = ACTIVE STATE = ONLINE
DATA DEV = 2082 STATUS = ACTIVE STATE = N/A
I/O TRACE = OFF TRACE LENGTH = *NA*
ULPID = TCPIPA
IQDIO ROUTING DISABLED
READ STORAGE = 4.0M(64 SBALS)
PRIORITY1: UNCONGESTED PRIORITY2: UNCONGESTED
DEVICEID PARAMETER FOR OSAENTA TRACE COMMAND = 02-03-00-02
UNITS OF WORK FOR NCB AT ADDRESS X'0F4E7010'
P1 CURRENT = 0 AVERAGE = 0 MAXIMUM = 0
TRACE DEV = 2083 STATUS = RESET STATE = N/A

8.5.2 Defining TRLE definitions
Use the D U,,,2080,16 command to ensure that you have defined enough devices, as shown
in Example 8-20.
Example 8-20 Verifying the number of OSA devices
D U,,,2080,16
IEE457I 16.50.55 UNIT STATUS 833
UNIT TYPE STATUS VOLSER VOLSTATE
2080 OSA A-BSY
2081 OSA A
2082 OSA A-BSY
2083 OSA O
2084 OSA O
2085 OSA O
2086 OSA O
2087 OSA O
2088 OSA O
2089 OSA O
208A OSA O
208B OSA O
208C OSA O
208D OSA O
208E OSA O
208F OSAD O-RAL
The OSA-Express2 needs an additional “DATAPATH” statement on the TRL (see
Example 8-21).
Example 8-21 TRL definition
OSA2080P TRLE LNCTL=MPC,
READ=2080,
WRITE=2081,
DATAPATH=(2082-208E),
PORTNAME=OSA2080,
MPCLEVEL=QDIO
8.5.3 Checking TCPIP definitions
An excerpt of TCP/IP profile, displayed in Example 8-22, shows the information that you need
when starting the OSAENTA trace in a later step. Keep this information available.
Example 8-22 TCP/IP definitions
;OSA DEFINITION
DEVICE OSA2080 MPCIPA
LINK OSA2080L IPAQENET OSA2080 VLANID 10
HOME
10.1.2.11 OSA2080L
START OSA2080

After TCP/IP is started, you can also see the OAT entries using OSA/SF (see Example 8-23).
Example 8-23 OAT entries
00(2080)* MPC N/A OSA2080P (QDIO control) SIU ALL
02(2082) MPC 00 No4 No6 OSA2080P (QDIO data) SIU ALL
VLAN 10 (IPv4)
Group Address Multicast Address
01005E000001 224.000.000.001
VMAC IP address
HOME 00096B1A7490 010.001.000.010
HOME 00096B1A7490 010.001.001.010
HOME 00096B1A7490 010.001.002.010
HOME 00096B1A7490 010.001.002.011
REG 00096B1A7490 010.001.002.012
REG 00096B1A7490 010.001.003.011
REG 00096B1A7490 010.001.003.012
REG 00096B1A7490 010.001.004.011
REG 00096B1A7490 010.001.005.011
REG 00096B1A7490 010.001.006.011
REG 00096B1A7490 010.001.007.011
REG 00096B1A7490 010.001.008.010
REG 00096B1A7490 010.001.008.020
03(2083) N/A N/A CSS
8.5.4 Customizing OSA-Express Network Traffic Analyzer
Use this task to select an OSA-Express Network Traffic Analyzer (NTA) support element
control, to customize the OSA-Express NTA settings in Advanced Facilities, or to check the
current OSA-Express NTA authorization.
Customizing OENTA allows the following activities for the support element:
Set up the OSA LAN Analyzer traces and capture data to the support element hard disk
Change authorization to allow host operating systems to enable the NTA traces outside
their own partition
Note: The OSA-Express Network Traffic Analyzer is mutually exclusive with the OSA LAN
Analyzer for tracing on a specified CHPID. Only one or the other can be enabled for a
specified CHPID at any one time.

To accomplish this customization, change the current OSA-Express NTA control. Using the
HMC, follow these steps:
1. Log on to the Support Element (SE) on the Hardware Management Console (HMC)
through Single Object Operations (SOO).
2. Select the CPC you want to work with, as shown in Figure 8-9.
Figure 8-9 From the HMC, log on to SE
3. Select and open the Service task list; see Figure 8-10.
Figure 8-10 OSA-Express NTA
4. Double-click the OSA-Express NTA SE Controls task; see Figure 8-11.
Figure 8-11 OSA NTA Controls
Important: Enabling the OENTA support can allow tracing of sensitive information.
Therefore, the user ID used to do the following steps must have the “Access
Administrator Tasks” role assigned.

5. Select the control to work with:
– Customize OSA-Express Network Traffic Analyzer Settings... provides the capability to
allow or disallow the support element to change authorization to allow host operating
systems to enable the Network Traffic Analyzer to trace outside their own partition.
– Check current OSA-Express Network Traffic Analyzer authorization... allows the
support element to scan all the OSAs and reports back which OSAs are authorized for
NTA to trace outside its own partition.
6. Click OK to change the current OSA-Express NTA control; see Figure 8-12.
Figure 8-12 Change the current OSA-Express NTA control
7. Click Allow the Support Element to allow Host Operating System to enable NTA.
8. Click OK; see Figure 8-13.
Figure 8-13 Command completed
9. Log off from the SE and from the HMC.
10.Log on to the SE on the HMC through SOO (Single Object Operations) using the
SYSPROG user ID.
11.Select Channels work area (on the left side of the screen) Channel Operation (on the
right side of the screen).
12.Select the channel that you want to manage (see Figure 8-14).

Figure 8-14 Channel Operations menu
13.In our case we selected PCHID 0390 (CHPID 02). We double-clicked Advanced
Facilities; see Figure 8-15.
Figure 8-15 Advanced Facilities options

14.Select Card trace/log/dump facilities, then click OK; see Figure 8-16.
Figure 8-16 Card Trace/Log/Dump Facilities
15.Select OSA-Express Host Network Traffic Analyzer Authorization, then click OK; see
Figure 8-17.
Figure 8-17 NTA Authorization
16.If your CHPID is shared between several LPARs, we suggest you take the second option
shown in Figure 8-17, then click OK. Figure 8-18 shows the results.
Figure 8-18 Command completed
17.To verify if the command has been set as required:
– Log off the SYSPROG user ID.
– Log on to the SE on the HMC through SOO; see Figure 8-9 on page 271.

– Select Check current OSA-Express Network Traffic Analyzer Authorization, as
shown in Figure 8-11 on page 271.
– Click OK; see Figure 8-19.
Figure 8-19 OSA-Express NTA controls
18.Figure 8-20 shows that PCHID 0390 is allowed to be traced.
Figure 8-20 PCHID NTA Authorization
8.5.5 Defining a resource profile in RACF
See Example 8-24 for the RACF commands needed to allow users to issue the VARY TCPIP
command.
Example 8-24 RACF commands
RDEFINE OPERCMDS MVS.VARY.TCPIP.OSAENTA UACC(NONE) PERMIT MVS.VARY.TCPIP.OSAENTA
ACCESS(CONTROL) CLASS(OPERCMDS) ID(CS03) SETR GENERIC(OPERCMDS) REFRESH SETR
RACLIST(OPERCMDS) REFRESH
8.5.6 Allocating a VSAM linear data set
Example 8-25 shows how to create the VSAM linear data set. This VSAM linear data set is
optional; however, we recommend its use.
Example 8-25 Allocate VSAM linear data set
//DEFINE EXEC PGM=IDCAMS
//SYSIN DD *
DELETE +
(CS03.CTRACE.LINEAR) +
CLUSTER
DEFINE CLUSTER( +
NAME(CS03.CTRACE.LINEAR) +
LINEAR +
MEGABYTES(10) +
Important: For checking the authorization of OENTA support, the user ID must have
the Access Administrator Tasks role assigned.

VOLUME(CPDLB0) +
CONTROLINTERVALSIZE(32768) +
) +
DATA( +
NAME(CS03.CTRACE.DATA) +
)
LISTCAT ENT(USER41.CTRACE.LINEAR)
ALL
8.5.7 Starting the OSAENTA trace
The OSAENTA statement dynamically defines a QDIO interface to the OSA-Express being
traced, called an OSAENTA interface. That interface is used exclusively for capturing
OSA-Express Network Traffic Analyzer traces.
The OSAENTA statement enables an installation to trace data from other hosts connected to
OSA-Express.
To see the complete syntax of the OSAENTA command, refer to z/OS Communications
Server: IP Configuration Reference, SC31-8776.
Components involved for z/OS CTRACE
The CTRACE component for collecting NTA trace data is called SYSTCPOT. The member in
SYS1.PARMLIB is named CTINTA00. This member is used to define the size of the buffer
space in the TCPIPDS1 data space reserved for OSAENTA CTRACE. The size can range
from 1 M to 624 M, with a default of 64 M.
Using the OSAENTA command
An internal interface is created when PORTNAME is defined on the OSAENTA statement.
The dynamically-defined interface name is EZANTA concatenated with the port name. These
EZANTA interfaces are displayed at the end of the NETSTAT DEV output.
When the ON keyword of the OSAENTA parameter is used, VTAM allocates the next available
TRLE data path associated with the port. This data path is used only for inbound trace data.
When the OFF keyword of the OSAENTA parameter is used (or the trace limits of the TIME,
DATA, or FRAMES keyword are reached), the data path is released.
Important: The trace data collected should be considered confidential and TCP/IP system
dumps and external trace files containing this trace data should be protected.
Note: Update CTINTA00 to set the CTRACE buffer size. Keep in mind that this will use up
auxiliary page space storage.

Setting the OSAENTA traces
You can set the OSAENTA trace in two ways: by coding the OSAENTA statement in the profile
TCP/IP, or by issuing a command in z/OS. These methods are explained in this section.
To code the OSAENTA statement in the profile TCP/IP, see Example 8-26.
Example 8-26 TCP/IP profile
; set up the filters to trace for TCP packets on PORT 2323 with a source
;or destination
; IP address of 10.1.2.11 over MAC address 00096B1A7490
OSAENTA PORTNAME=OSA2080 PROT=TCP IP=10.1.2.11 PORTNUM=2323
OSAENTA PORTNAME=OSA2080 MAC=00096B1A7490
; activate the tracing (the trace will self-deactivate after 20,000 frames)
OSAENTA PORTNAME=OSA2080 ON FRAMES=20000
; deactivate the tracing
OSAENTA OFF PORTNAME=OSA2080
In this case, OSAENTA traces the portname OSA2080 only for traffic matching the
following filters:
– Protocol = UDP
– IP address = 10.1.2.11
– Port number = 2323
There are seven filters available to define the packets to be captured:
– MAC address
– VLAN ID
– Ethernet frame type
– IP address (or range)
– IP protocol
– Device ID
– TCP/UDP
To issue the following command in z/OS:
V TCPIP,TCPIPA,OSAENTA,ON,PORTNAME=OSA2080,IP=10.1.2.11,PORTNUM=2323
The messages you receive in response to this command are shown in Figure 8-21.
Figure 8-21 OSAENTA results
Note: Use filters to limit the trace records to prevent over consummation of the OSA
CPU resources, the LPAR CPU resources, the TCPIPDS1 trace data space,
memory, auxiliary page space and the IO subsystem writing trace data to disk.
RESPONSE=SC30 EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,OSAENTA,ON,
RESPONSE=PORTNAME=OSA2080,IP=10.1.2.11,PORTNUM=2323
RESPONSE=SC30 EZZ0053I COMMAND VARY OSAENTA COMPLETED SUCCESSFULLY

The command NETSTAT DEVLINKS has been enhanced to show the OSAENTA
definition; see Example 8-27.
Example 8-27 Netstat Devlinks command output
OSA-EXPRESS NETWORK TRAFFIC ANALYZER INFORMATION:
OSA PORTNAME: OSA2080 OSA DEVSTATUS: READY
OSA INTFNAME: EZANTAOSA2080 OSA INTFSTATUS: READY
OSA SPEED: 1000 OSA AUTHORIZATION: CHPID
OSAENTA CUMULATIVE TRACE STATISTICS:
DATAMEGS: 0 FRAMES: 0
DATABYTES: 0 FRAMESDISCARDED: 0
FRAMESLOST: 0
OSAENTA ACTIVE TRACE STATISTICS:
DATAMEGS: 0 FRAMES: 0
DATABYTES: 0 FRAMESDISCARDED: 0
FRAMESLOST: 0 TIMEACTIVE: 0
OSAENTA TRACE SETTINGS: STATUS: ON
DATAMEGSLIMIT: 1024 FRAMESLIMIT: 2147483647
ABBREV: 224 TIMELIMIT: 10080
DISCARD: EXCEPTION
OSAENTA TRACE FILTERS: NOFILTER: NONE
DEVICEID: *
MAC: *
VLANID: *
ETHTYPE: *
IPADDR: 10.1.2.11/32
PROTOCOL: * TCP
PORTNUM: * 2323
The NETSTAT display for devices shows the Network Traffic Analyzer interfaces. The
interface name has prefixed the OSA port name with EZANTA.
To display a specific NTA interface, use the INTFName=EZANTAosaportname keyword.
Traces are placed in an internal buffer, which can then be written out using a CTRACE
external writer. The MVS TRACE command must also be issued for component
SYSTCPOT to activate the OSAENTA trace.
Important: If you receive ERROR CODE 0003 it means that an attempt was made to
enable OSA-Express Network Traffic Analyzer (OSAENTA) tracing for a specified OSA, but
the current authorization level does not permit it.
Refer to 8.5.4, “Customizing OSA-Express Network Traffic Analyzer” on page 270 for
directions about how to change the authorization to allow OSAENTA to be used on this
specified OSA. Also read Support Element Operations Guide, SC28-6860, for complete
information about this topic.
Attention: If you receive ERROR CODE 0005 it means that an attempt was made to
enable OSA-Express Network Traffic Analyzer tracing for a specified OSA that already
has either OSAENTA or OSA LAN Analyzer tracing enabled elsewhere on the system
for this OSA.
Only one instance of active tracing (either OSAENTA or LAN Analyzer) for a specified
OSA is permitted on the system at any one time.

When the trace is started from OSA/SF, you can see that another device has been
allocated for trace; see Example 8-28.
Example 8-28 OAT with OSAENTA started
00(2080)* MPC N/A OSA2080P (QDIO control) SIU ALL
VLAN 10 (IPv4)
Group Address Multicast Address
01005E000001 224.000.000.001
VMAC IP address
HOME 00096B1A7490 010.001.000.010
HOME 00096B1A7490 010.001.001.010
HOME 00096B1A7490 010.001.002.010
HOME 00096B1A7490 010.001.002.011
REG 00096B1A7490 010.001.002.012
REG 00096B1A7490 010.001.003.011
REG 00096B1A7490 010.001.003.012
REG 00096B1A7490 010.001.004.011
REG 00096B1A7490 010.001.005.011
REG 00096B1A7490 010.001.006.011
REG 00096B1A7490 010.001.007.011
REG 00096B1A7490 010.001.008.010
REG 00096B1A7490 010.001.008.020
You can also use the D NET,TRL,TRLE=OSA2080 command, as shown in Example 8-29.
Example 8-29 Output Display TRLE
TRL MAJOR NODE = OSA2080
STATUS= ACTIV, DESIRED STATE= ACTIV
TYPE = LEASED , CONTROL = MPC , HPDT = YES
MPCLEVEL = QDIO MPCUSAGE = SHARE
PORTNAME = OSA2080 LINKNUM = 0 OSA CODE LEVEL = 087A
WRITE DEV = 2081 STATUS = ACTIVE STATE = ONLINE
READ DEV = 2080 STATUS = ACTIVE STATE = ONLINE
DATA DEV = 2082 STATUS = ACTIVE STATE = N/A
I/O TRACE = OFF TRACE LENGTH = *NA*
ULPID = TCPIPA
IQDIO ROUTING DISABLED
READ STORAGE = 4.0M(64 SBALS)
DEVICEID PARAMETER FOR OSAENTA TRACE COMMAND = 02-03-00-02
UNITS OF WORK FOR NCB AT ADDRESS X'0F4E7010'
TRACE DEV = 2083 STATUS = ACTIVE STATE = N/A

Starting the CTRACE
To print out the internal trace data, start the CTRACE using these steps:
TRACE CT,WTRSTART=CTWRT
2. Start the CTRACE and connect to the external writer.
TRACE CT,ON,COMP=SYSTCPOT,SUB=(TCPIPA)
R xx,WTR=CTWTR,END
3. Display the active component trace options with this command:
DISPLAY TRACE,COMP=SYSTCPOT,SUB=(TCPIPA)
Example 8-30 shows the output of this command.
Example 8-30 Display Trace output
RESPONSE=SC30
TRACENAME
=========
SYSTCPOT
=====================
OFF HEAD 2
NO HEAD OPTIONS
--------------------------------------------------------------
TCPIPA ON 0128M
ASIDS *NONE*
JOBNAMES *NONE*
OPTIONS MINIMUM
WRITER CTWTR
To display information about the status of the component trace for all active procedures,
issue the following command:
DISPLAY TRACE,COMP=SYSTCPOT,SUBLEVEL,N=8
Example 8-31 displays the output.
Example 8-31 Status of Component Trace
TRACENAME
=========
SYSTCPOT
=====================
OFF HEAD 2
NO HEAD OPTIONS
--------------------------------------------------------------
TCPIPA ON 0128M
ASIDS *NONE*
JOBNAMES *NONE*

OPTIONS MINIMUM
WRITER CTWTR
--------------------------------------------------------------
TCPIP MIN 0016M
ASIDS *NONE*
JOBNAMES *NONE*
OPTIONS MINIMUM
WRITER *NONE*
TRACE CT,ON,COMP=SYSTCPOT,SUB=(TCPIPA)
R xx,WTR=DISCONNECT,END
TRACE CT,OFF,COMP=SYSTCPOT,SUB=(TCPIPA)
TRACE CT,WTRSTOP=CTWRT
Analyzing the trace
You can format the CTRACE using two methods, which we describe in this section.
Use IPCS to format CTRACE
You can format component trace records using IPCS panels or a combination of IPCS panels
and the CTRACE command, either from a dump or from external writer files.
From the IPCS PRIMARY OPTION MENU, select: 0 DEFAULTS - Specify default dump and
options; see Example 8-32 for details.
Example 8-32 IPCS default value
------------------------- IPCS Default Values ---------------------------------
Command ===>
You may change any of the defaults listed below. The defaults shown before
any changes are LOCAL. Change scope to GLOBAL to display global defaults.
Scope ==> LOCAL (LOCAL, GLOBAL, or BOTH)
If you change the Source default, IPCS will display the current default
Address Space for the new source and will ignore any data entered in
the Address Space field.
Source ==> DSNAME('SYS1.SC30.CTRACE')
Address Space ==>
Message Routing ==> NOPRINT TERMINAL
Message Control ==> CONFIRM VERIFY FLAG(WARNING)
Display Content ==> NOMACHINE REMARK REQUEST NOSTORAGE SYMBOL

Modify the DSNAME and OPTIONS to match your environment, then select the following
options:
2 ANALYSIS - Analyze dump contents
7 TRACES - Trace formatting
1 CTRACE - Component trace
D DISPLAY - Specify parameters to display CTRACE entries
Fill in the parameters necessary to format the OSAENTA trace; see Example 8-33.
Example 8-33 CTRACE parameters
-------------------- CTRACE DISPLAY PARAMETERS ------------------------
COMMAND ===>
System ===> (System name or blank)
Component ===> SYSTCPOT (Component name (required))
Subnames ===> TCPIPA
GMT/LOCAL ===> G (G or L, GMT is default)
Start time ===> (mm/dd/yy,hh:mm:ss.dddddd or
Stop time ===> mm/dd/yy,hh.mm.ss.dddddd)
Limit ===> 0 Exception ===>
Report type ===> SHORT (SHort, SUmmary, Full, Tally)
User exit ===> (Exit program name)
Override source ===>
Options ===>
To enter/verify required values, type any character
Entry IDs ===> Jobnames ===> ASIDs ===> OPTIONS ===> SUBS ===>
CTRACE COMP(SYSTCPOT) SUB((TCPIPA)) SHORT
ENTER = update CTRACE definition. END/PF3 = return to previous panel.
S = start CTRACE. R = reset all fields.
On the Command line, enter the S command. Example 8-34 shows the trace formatted by
IPCS.
Example 8-34 TRACE format
COMPONENT TRACE SHORT FORMAT
SYSNAME(SC30)
COMP(SYSTCPOT)SUBNAME((TCPIPA))
z/OS TCP/IP Packet Trace Formatter, (C) IBM 2000-2006, 2007.052
DSNAME('SYS1.SC30.CTRACE')
**** 2007/09/11
RcdNr Sysname Mnemonic Entry Id Time Stamp Description
----- -------- -------- -------- --------------- -----------------------------
------------------------------------------------------------------------------
365 SC30 OSAENTA 00000007 15:01:23.356987 OSA-Express NTA
To Interface : EZANTAOSA2080 Full=86
Tod Clock : 2007/09/11 14:25:44.160269
Sequence # : 0 Flags: Pkt Out Nta Vlan Lpar L3

Source : 10.1.2.11
Destination : 224.0.0.5
Source Port : 0 Dest Port: 0 Asid: 0000 TCB: 0000000
Frame: Device ID : 02030002 Sequence Nr: 372 Discard: 0 (OK)
EtherNet II : 8100 IEEE 802.1 Vlan Len: 0x0044 (68
Destination Mac : 01005E-000005 ()
Source Mac : 00096B-1A7490 (IBM)
Vlan_id : 10 Priority: 0 Type: 0800 (Int
IpHeader: Version : 4 Header Length: 20
Tos : 00 QOS: Routine Normal Service
Packet Length : 68 ID Number: 0AFD
Fragment : Offset: 0
TTL : 1 Protocol: OSPFIGP CheckSum: C253
Source : 10.1.2.11
------------------------------------------------------------------------------
Tod Clock : 2007/09/11 14:25:54.163264
Source : 10.1.2.11
EtherNet II : 8100 IEEE 802.1 Vlan Len: 0x0044 (68
Vlan_id : 10 Priority: 0 Type: 0800 (Int
Packet Length : 68 ID Number: 0B07
TTL : 1 Protocol: OSPFIGP CheckSum: C249
Source : 10.1.2.11
------------------------------------------------------------------------------
Use a batch job to format CTRACE
We used a batch job to generate the TRACE file, as shown in Example 8-35.
Example 8-35 CTRACE batch job format
//PKT2SNIF JOB (999,POK),'CS03',NOTIFY=&SYSUID,
// CLASS=A,MSGCLASS=T,TIME=1439,
// REGION=0M,MSGLEVEL=(1,1)
// SET INDUMP='SYS1.SC30.CTRACE'
//IPCSBTCH EXEC PGM=IKJEFT01,DYNAMNBR=30
//IPCSDDIR DD DISP=SHR,DSN=SYS1.DDIR
//IPCSDUMP DD *
//SYSTSPRT DD SYSOUT=*
//INDMP DD DISP=SHR,DSN=&INDUMP.
//IPCSPRNT DD DSN=ENTA.CTRACE.SHORT,UNIT=SYSDA,
// DISP=(NEW,CATLG),LRECL=133,SPACE=(CYL,(10,1)),RECFM=VBS,DSORG=PS

//IPCSTOC DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//SYSTSIN DD *
PROFILE MSGID
IPCS NOPARM
SETD PRINT NOTERM LENGTH(160000) NOCONFIRM FILE(INDMP)
DROPD
CTRACE COMP(SYSTCPOT) SUB((TCPIPA)) SHORT
END
We received the output shown in Example 8-36 from the batch job.
Example 8-36 Output from the batch job
COMPONENT TRACE SHORT FORMAT
SYSNAME(SC30)
COMP(SYSTCPOT)SUBNAME((TCPIPA))
z/OS TCP/IP Packet Trace Formatter, (C) IBM 2000-2006, 2007.052
FILE(INDMP)
**** 2007/09/11
RcdNr Sysname Mnemonic Entry Id Time Stamp Description
----- -------- -------- -------- --------------- -------------------------------
-------------------------------------------------------------------------------
Tod Clock : 2007/09/11 14:25:44.160269
Source : 10.1.2.11
EtherNet II : 8100 IEEE 802.1 Vlan Len: 0x0044 (68)
Vlan_id : 10 Priority: 0 Type: 0800 (Inter
Packet Length : 68 ID Number: 0AFD
TTL : 1 Protocol: OSPFIGP CheckSum: C253 FF
Source : 10.1.2.11
-------------------------------------------------------------------------------
Tod Clock : 2007/09/11 14:25:54.163264
Source : 10.1.2.11
EtherNet II : 8100 IEEE 802.1 Vlan Len: 0x0044 (68)
Vlan_id : 10 Priority: 0 Type: 0800 (Inter

Packet Length : 68 ID Number: 0B07
TTL : 1 Protocol: OSPFIGP CheckSum: C249 FF
Source : 10.1.2.11
-------------------------------------------------------------------------------
8.6 Additional tools for diagnosing CS for z/OS IP problems
IBM and other vendors have developed tools to assist in diagnosing problems in the network
from the perspective of z/OS. The tools often run as GUIs on a workstation, but retrieve their
problem diagnosis information using data from SNMP, SMF, and from MVS control blocks.
Some of these tools also interface with the Network Management Interface API, provided by
IBM.
8.6.1 Network Management Interface API
Figure 8-22 depicts a high level view of the Network Management Interface (NMI) and its
interfaces to network management products.
Figure 8-22 Network Management Interface Architecture
The NMI API can interface with Tivoli® OMEGAMON® XE for Mainframe Networks (or other
products) to provide the following types of functions:
Trace assistance:
– Real-time tracing and formatting for packet and data traces
Information gathering:
– TCP connection initiation and termination notifications
CS z/OS and
components
Remote monitor
Local monitor
Private
protocol
APIs
Commands/Utilities
Exit points
SNMP
SMF and Syslogd
Exit
point
I
n
s
t
r
u
m
e
n
t
a
t
i
o
n
Presentation
IBM Tivoli Software
or other Network
Management vendor
SNMP
z/OS

– API for real-time access to TN3270 server and FTP event data and to IPSec
– APIs to poll information about currently active connections
– TCP listeners (server processes)
– TCP connections (detailed information about individual connections and UDP
endpoints)
– Communications Server storage usage
– API to receive and poll for Enterprise Extender management data
– Information and statistics for IP filtering and IPSec security associations on the local
TCP/IP stacks.
– Information and statistics for IP filtering and IPSec security associations on remote
Network Security Services (NSS) clients when using the NSS server.
Control activities
Control the activation and inactivation of IPSec tunnels
Loading policies for IP filtering and IPSec security associations on the local TCP/IP stacks
– Loading policies for IP filtering and IPSec security associations on remote Network
Security Services (NSS) clients when using the NSS server
– Drop one or multiple TCP connections or UDP endpoints
8.6.2 Systems Management Facilities accounting records
Another technique that is often used to verify the state of the z/OS Communications Server -
TCP/IP component in a stack or even in a Sysplex environment is to list and analyze the
Systems Management Facilities (SMF) records.
In general, SMF records are created for deferred processing and analysis. SMF recording is
generally not used for real-time monitoring purposes. In a TCP/IP environment, real-time
monitoring is implemented using the NMI API and SNMP protocol, but on z/OS a lot of the
information that is written in SMF records is useful from a real-time monitoring perspective.
The objective of the TCP/IP product is to define and generate the lowest level of detail that is
needed by all disciplines. A customer has to use other products such as RMF, Performance
Reporter for z/OS (PR), MVS Information Control System (MICS), or SAS-based tools. In
many cases, there are customer-written programs to generate the reports to collect and
analyze the SMF Records created by TCP/IP.
The contents of SMF records can be used to generate reports in customized formats that help
customers to perform tasks such as:
Performance management:
Customized reports can be generated to verify if the defined service levels are met and, if
not, to identify possible causes. These reports are usually a set of time intervals, ranging
from weeks through days matching the SMF interval. Some examples of potential reports
related to performance management are:
Note: TCP/IP- produced SMF records should not be viewed in isolation. Other
components in MVS produce SMF records for the same purposes as those produced by
TCP/IP. An installation is likely to combine information from a series of subsystems when
performing detailed performance or capacity planning.

– TCP connection elapsed time per server port number per time of day (potentially
broken down by source IP address or netmask).
– Number of TCP connections per server port number per time of day (potentially broken
down by source IP address or netmask).
– Number of inbound/outbound bytes transferred in TCP connections per time of day
(potentially broken down in various ways: by destination or source port, by destination
IP address, netmask, or in total).
Capacity planning:
Capacity planning can be done using the SMF records to generate reports showing trends
for resource utilization of central processing power, memory, channel-based I/O
subsystem, network attachments, and network bandwidth, over a period of time. These
trends can help with planned launches of new applications or use of existing applications,
in order to predict capacity needs in the future. Some examples of potential reports related
to capacity planning are:
– Total number of TCP connections per reserved server port number per day including
analysis of average and variations around average during daily peak periods
– Total number of UDP inbound/outbound UDP datagrams per reserved server port
number per day including average and variations around average during daily peak
periods.
– Number of bytes or packets transferred inbound and outbound per interface (LINK) per
time of day (potentially broken down into unicasts, broadcasts, and multicasts)
Auditing
Auditing involves tasks that are related to identifying and proving that individual events
have taken place. Some examples of potential reports related to auditing are:
– Detailed information about specific TCP connections or UDP sockets, IP addresses,
server/client identification, duration, number of bytes, and so on.
– Details about activity that involves a specific client or server.
– Details about a given application session based on server-specific SMF recording,
such as individual Telnet sessions or FTP sessions.
Accounting
Accounting involves tasks that are related to calculating how much each individual user or
organizational unit should be charged for use of the shared central IS resources. Input for
these reports can be based on CPU cycle use, data quantities, bandwidth usage, and
memory use. For TCP/IP, additional metrics can be defined, such as type of service (FTP,
Web server, TN3270 and so on), and TCP connection-related information (number of
connections, duration, byte transfer counts, and so on).
Some examples of potential reports related to accounting are:
– Aggregated number of connections to a given server from a given source in terms of a
specific client IP address, or netmask
– Accumulated connect time to a given server from a given source in terms of a specific
client IP address, or netmask
– Number of bytes transferred to or from a given source in terms of a specific client IP
address, or netmask
– Amount of data protected by specific manual or dynamic tunnels
– For IKED: Information about IKE tunnels
– For TN3270: Number of sessions and session type (TN3270/TN3270E/LINEMODE)

Depending on the configuration for the z/OS Communications Server - TCP/IP component,
SMF records can be cut at multiple levels in the TCP/IP protocol stack, and the type of
information that can be included depends on where the SMF record is created:
At the IP and interface layer
Information about ICMP activity, IP packet fragmentation and reassembly activity, IP
checksum errors, IGMP activity, and ARP activity. This information is important to
generate reports related either to performance or capacity management.
At the transport protocol layer
Information about IP addresses, port numbers, and host names. It has also information
about TCP connections, such as byte counts, connection times, reliability metrics, and
performance metrics. For UDP-related workload, each UDP datagram is a separate entity;
the only way to aggregate information for UDP is on a UDP socket level, where SMF
records could be created every time a UDP socket is closed.
At the application layer
Currently, application-layer SMF recording is done for the TN3270 Telnet server (Telnet),
the FTP server, and the IKE daemon, but not for any other servers.
SMF record types used by Communications Server for z/OS IP
Communications Server for z/OS IP generates SMF records using two types of records: SMF
record type 118 and SMF record type 119. TCP/IP SMF records written using record type 118
are created to reflect information related to the events shown in Table 8-2.
Table 8-2 Events logged using SMF record type 118
SMF record type 118 provides basic information and does not have information related to the
TCP/IP stack. In a multiple stack environment it is not easy to determine which SMF records
relate to which TCP/IP stack.
SMF record type 119 contain additional values that identify the TCP/IP stack, which solves
the record 118 problem. It also provides other advantages such as uniformity of date and time
(UTC), common record format (self-defining section and TCP/IP identification section), and
support for IPv6 addresses and expanded field sizes (64 bit versus 32 bit) for some counters.
The SMF record type 119 subtype records available are shown in Table 8-3:
Table 8-3 Events logged using SMF record type 119
Events Subtype records
TCP API connection initiation 1
TCP API connection termination 2
FTP client requests 3
Telnet client connection initiation and termination 4
TCP/IP statistics 5
TN3270 server session initiation and termination 20-21
FTP Server related information 70-75
TCP connection initiation 1
TCP connection termination 2

Customizing the SMF records data collection
Depending on the type of information needs to be gathered, You can control the collection of
these records using the SMFCONFIG statements in PROFILE.TCPIP, the SMF statements in
the FTP.DATA for the FTP server configuration, and the SMF119 statement in IKE daemon
configuration file. For more information about configuring those statements, see:
In Appendix B, the section “SMFCONFIG” on page 332
Refer to the following content for more information regarding use of logs, standard
commands, tools, and utilities:
z/OS Communications Server: IP System Administrator’s Commands, SC31-8781
z/OS MVS Diagnosis: Tools and Service Aids, GA22-7589
z/OS Communications Server: SNA Diagnosis Vol. 1, Techniques and Procedures,
GC31-6850
MVS Installation Exits, SA22-7593
Support Element Operations Guide, SC28-6860
You can find information about z/OS Communications Server product support at:
http://www.ibm.com/software/network/commserver/zos/support/
FTP client transfer completion 3
TCP/IP, interface, and server port statistics 5-7
TCP/IP stack start/stop 8
UDP socket close 10
TN3270 server session initiation and termination 20-21
TSO Telnet client session initiation and termination 22-23
FTP server transfer completion 70
FTP server logon failure 72
IKE tunnel activation, refresh, deactivation, and expire 73,74
Dynamic tunnel activation, refresh, installation, and removal 75-78
Manual tunnel activation and deactivation 79,80

For information about IBM Tivoli OMEGAMON XE for Mainframe Networks, go to:
http://publib.boulder.ibm.com/tividd/td/IBMTivoliOMEGAMONXEforMainframeNetworks
1.0.html

Appendix A. IPv6 support
IPv6 has gained greater acceptance in the industry in recent years. IPv6 is attractive because
it resolves some deficiencies of IPv4 in the following areas:
IP address space
Auto-configuration
Security
Quality of service
Anycast and multicast
This appendix discusses the following topics.
A
Section Topic
“Overview of IPv6” on page 292 Basic concepts of IPv6
“Importance of IPv6” on page 292 Key characteristics of IPv6 and why it might be important
in your environment
“Common design scenarios for IPv6” on
page 292
Commonly implemented IPv6 design scenarios, their
dependencies, advantages, considerations, and our
recommendations
“How IPv6 is implemented in z/OS
Communications Server” on page 295
Selected implementation scenarios, tasks, configuration
examples, and problem determination suggestions

Overview of IPv6
Internet Protocol Version 6 (IPv6) is the next generation of the Internet protocol designed to
replace the current Internet Protocol Version 4 (IPv4).
IPv6 was developed to resolve impending problems related to the limitations of IPv4 and the
rapidly-growing demand for IP resources and functionality; the most significant issue is the
diminishing supply and expected shortages of IPv4 addresses.
Using IPv4 32-bit addressing allows for over 4 million nodes, each with a globally unique
address. This current IPv4 space will be unable to satisfy the huge expected increase in the
number of users on the Internet. The expected shortage will be exacerbated by the
requirements of emerging technologies such as PDAs, HomeArea Networks, and
Internet-connected commodities such as automotive and integrated telephone services. IPv6
uses 128-bit addressing and will generate a space large enough to last for the forseeable
future.
Importance of IPv6
IPv6 is important because it addresses the limitations of IPv4, such as:
128-bit addressing
This quadruples the network address bits from 32 to 128, thereby significantly increasing
the number of possible unique IP addresses to comfortably accommodate on the Internet.
This huge address space obviates the need for private addresses and Network Address
Translators (NATs).
Simplified header formats
This allows for more efficient packet handling and reduced bandwidth cost.
Hierarchical addressing and routing
This keeps routing tables small and backbone routing efficient by using address prefixes
rather than address classes.
Improved support for options
This changes the way IP header options are encoded, allowing more efficient forwarding
and greater flexibility.
Address auto-configuration
This allows stateless IP address configuration without a configuration server.
Security
IPv6 brings greater authentication and privacy capabilities through the definition of
extensions.
Quality of Service (QoS)
QoS is provided through a traffic class byte in the header.
Common design scenarios for IPv6
Although as explained, there are predictable improvements over IPv4, the success of any
IPv6 implementation depends on the ability to have IPv6 coexist with IPv4. Because of the

Appendix A. IPv6 support 293
pervasiveness of IPv4, this coexistence will be around for some time. Therefore, the
development of technologies and mechanisms to facilitate coexistence is as important as the
deployment strategy for IPv6. In the following sections we will discuss some of the coexistence
technologies available today.
Tunneling
Tunneling is the transmission of IPv6 traffic encapsulated within IPv4 packets over an IPv4
connection. Tunnels are used primarily to connect remote IPv6 networks, or to simply connect
an IPv6 network over an IPv4 network infrastructure.
Dependencies
All tunnel mechanisms require that the endpoints of the tunnel run in dual-stack mode. A
dual-stack router is a router running both versions of IP. There are other dependencies based
on the tunneling mechanism used.
For example, an IPv6 Manually configured tunnel requires an ISP-registered IP address. The
Automatic tunnel mechanism requires IPv6 prefixes. ISATAP tunnels only require a dual-stack
router, but they are not yet commercially available and 6over4 tunnels are not supported by
vendor router software.
Advantages
Tunneling allows the implementation of IPv6 without any significant upgrades to the existing
infrastructure, and therefore does not risk interrupting the existing services provided by the
IPv4 network.
Considerations
There are various tunneling mechanisms designed to do primarily different things, so you
must give careful consideration to the mechanism you choose. Some are primarily used for
stable and secure links for regular communications. Others are primarily used for single hosts
or small sites, with low data traffic volumes.
Dedicated data links
Network architects can choose a separate ATM, or frame relay PVCs, or separate optical
media, to run IPv6 traffic across. The only requirement is the reconfiguration of the routers
(with IPv6 support). Note that these links can only be used for IPv6 traffic.
Dependencies
Dual-stack routers with IPv6 and IPv4 addresses are required to provide access to the WAN.
Access to a DNS is needed to resolve IPv6 names and addresses.
Advantages
Use of the existing Layer 2 infrastructure makes this implementation less complex and
immediate. This implementation is not disruptive, apart from a schedule change for router
configuration, and therefore there is little impact to the status quo.
Considerations
All routers on the WAN need to support IPv6 over dedicated data links. Additional costs for
the those links will be incurred until the environment is completely migrated over to IPv6.

MPLS backbones
An MPLS IPv4 core network can enable IPv6 domains to communicate over MPLS
backbones. It is therefore primarily used by enterprises and service providers. There are
various implementations of this strategy, ranging from no changes and no impact to changes
and risks. This means that the closer the IPv6 implementation is to the client edge, the less
expensive it becomes. In contrast, the closer the IPv6 implementation is to the service
provider edge, the more expensive it becomes.
Dependencies
Dependencies vary from router configuration to specific hardware requirements to software
upgrades, depending on the service provider solution.
Advantages
Use of this strategy requires minor modifications to the infrastructure and minor
reconfigurations of the core routers. It is therefore a strategy that could have little or no impact
to your environment, involving low costs and low risks.
Considerations
Considerations also vary, depending on the strategy chosen. For example, using the Circuit
Transport over MPLS strategy does not support a mix of IPv4 and IPv6 traffic. IPv6 on service
provider edge routers do not support VPNs or VRF, currently.
Dual-stack backbones
A dual-stack backbone is a core network with all routers configured to support dual-stacks. It
essentially consists of two network types existing side by side. The IPv4 stack routes the IPv4
traffic through the IPv4 network. The IPv6 stack routes the IPv6 traffic through the IPv6
network. This is a very basic approach to routing both IPv4 and IPv6 traffic through a network.
Dependencies
Each site has the appropriate entries in a DNS to resolve both IPv4 and IPv6 names and
IP addresses.
Advantages
This is a basic and simple strategy for routing IPv4 and IPv6 traffic in a network.
Considerations
All routers in the network require a software upgrade to support dual-stack. Having dual-stack
requires additional router management of a dual addressing scheme and additional router
memory.
Dual-mode stack
A dual-mode stack is a stack configured to support both IPv4 and IPv6 protocols. It is a single
stack (not two stacks) configured to support IPv4 and IPv6 simultaneously. Both IPv4 and
IPv6 interfaces are capable of receiving and sending IPv4 and IPv6 packets over
corresponding interfaces.

Dependencies
A z/OS Communications Server V1R4 or later that is configured to support IPv6 requires
OSA-Express ports to be running in QDIO mode.
Advantages
There are no additional software or hardware requirements for users in a z/OS environment
configured with OSA-Express features. Dual-mode allows IPv4 and IPv6 applications to
coexist indefinitely. However, any application can be migrated one at a time or at the user’s
convenience from IPv4 to IPv6. This is therefore an inexpensive, low risk, low impact
deployment strategy.
Considerations
The only link layer protocol that supports IPv6 is MPC+. The devices that use the MPC+
protocol are XCF, MPCPTP, and MPCIPA (for example, OSA-Express in QDIO mode and
HiperSockets on the System z9).
Recommendation
Using dual-mode stacks is the recommended strategy for application migration from IPv4 to
IPv6. Dual-mode is implemented in z/OS Communications Server V1R4 or later.
How IPv6 is implemented in z/OS Communications Server
IPv6 is implemented in the z/OS Communications Server through a series of configuration
tasks. We configure the stack to support IPv6 in a similar fashion to the steps performed for
IPv4 configuration. However, before you start to configure the stack to support IPv6 traffic,
you need to understand a few things about IPv6.
IPv6 addressing
An IPv6 address is a 128-bit number written in colon hexadecimal notation. This scheme is
hexadecimal and consists of eight 16-bit pieces of the address.
Alternate notations described in RFC 2373 are acceptable; for example:
FEDC:BA98:7654:3210:FEDC:BA98:7654:3210
The following conventional forms represent IPv6 addresses as text strings:
The preferred form is xxxxxxxx, where the x’s indicate the hexadecimal value of the eight
16-bit pieces of the address, for example:
FEDC:BA98:7654:3210:FEDC:BA98:7654:3210
1080:0:0:0:8:800:200C:417A
Note: It is not necessary to write the leading zeros in an individual field, but there must
be at least one numeral in every field, except for the case described in the next list item.

Due to some methods of allocating certain styles of IPv6 addresses, it is common for
addresses to contain long strings of zero bits. To simplify the writing of addresses that
contain zero bits, a special syntax is available to compress the zeros. The use of ::
indicates multiple groups of 16 bits of zeros. The :: can appear only once in an address.
The :: can also be used to compress the leading or trailing zeros in an address.
Consider the following addresses:
1080:0:0:0:8:800:200C:417A (unicast address)
FF01:0:0:0:0:0:0:101 (multicast address)
0:0:0:0:0:0:0:1 (loopback address)
0:0:0:0:0:0:0:0 (unspecified addresses)
They can be represented as:
1080::8:800:200C:417A (unicast address)
FF01::101 (multicast address)
::1 (loopback address)
:: (unspecified addresses)
An alternative form that is sometimes more convenient to use when dealing with a mixed
environment of IPv4 and IPv6 nodes is to use x:x:x:x:x:x:d.d.d.d. Here, the x’s are the
hexadecimal values of the six high-order 16-bit pieces of the address. The d’s are the
decimal values of the four low-order 8-bit pieces of the address (standard IPv4
representation).
Consider this example:
0:0:0:0:0:0:13.1.68.3
0:0:0:0:0:FFFF:129.144.52.38
In compressed form, it is written as:
::13.1.68.3
::FFFF:129.144.52.38

IPv6 TCP/IP Network part (prefix)
Designers have defined some address types, known as “address scopes”, and have left room
for future definitions, because unknown requirements might arise. RFC 2373: IP version 6
Addressing Architecture (July 1998) defines the current addressing scheme. Figure A-1
depicts the layout of three types or “scopes” of addresses: the Link-local scope, the Site-local
scope, and the Global scope.
Figure A-1 Unicast IPv6 Addressing Formats
Each address begins with a format or scope prefix of 10 bits, followed by a second field and
then an interface identifier field. Each of these addresses serves a unique purpose:
Link local scope
These are special addresses that are only valid on a link of an interface. Using this
address as the destination, the packet never passes through a router. A packet with a
link-local source or destination address will not leave its originating LAN. A router
receiving the packet will not forward it onto another physical LAN. An address of this type
bears the prefix of fe80.
A link-local address is assigned to each IPv6-enabled interface after stateless
auto-configuration, commonly used in IPv6 implementations. The link-local address is
used for link communications such as:
– Neighbor discovery, that is, discovering whether there is anyone else on this link
– Communication with a neighbor when a router is unnecessary
0 127
10 bits 54 bits 64 bits
Interface ID
1111 1110 10
FE80
0...0 MAC, Other Interface ID
9 63
Link-local
Scope
0 127
54 bits 64 bits
Interface ID
1111 1110 11
FEC0
0...0 MAC, Other Interface ID
9 63
Site-local
Scope
(deprecated)
10 bits
0 127
3 bits 61 bits 64 bits
Interface ID
001
(anything
else)
variable
"subnet"
MAC, Other Interface ID
4 63
Global Scope
RFC 2373
vs.
RFC 3513
Unicast
"Prefix" or "Full Routing Prefix"
Format Prefix
Scope Prefix

Consider the example shown in Figure A-2.
Figure A-2 Link-local addresses and link-local scope zones
Figure A-2 shows a LAN environment separated into two LAN segments, which are
represented by Link scope zone A with three nodes and Link scope zone B with four
nodes. The link local addresses in each zone begin with the prefix “fe80”.
Within a zone, nodes communicate with each other using link-local addresses. Across
zones, nodes must communicate with each other using global scope addresses, which are
discussed later.
Note that Node X has link-local addresses in two zones: in zone A and in zone B. Because
link-local addresses use the same prefix value, it is necessary to understand which zone a
packet should be sent to, particularly when a default route is to be used. So if a route
exists on Node X for any destination address with a prefix of “fe80”, then the routing table
needs to be able to distinguish between “fe80” in zone A and “fe80” in zone B.
Therefore, both the address and the zone index value need to be specified in the routing
table. The zone index is a value assigned by the stack to represent the correct entry (or
interface) in the routing table. If the zone index is not present, then the stack uses the
“default route” for this configuration.
If the default route uses the interface that matches the IPv6 link-local address that was
specified, everything works just fine. If, however, the default route does not use the correct
interface for the specified IPv6 link-local address, then a routing error is encountered and
the application request fails or times out. So the zone index helps the stack to distinguish
whether the routing path should flow into zone A or into zone B.
z/OS Communications Server supports scope zone information about Getaddrinfo and
Getnameinfo invocations, and also on the z/OS Socket APIs that support IPv6, thus
satisfying requirements for IPv6 compliance. In addition, scope zone information can be
included on command line operations and in configuration files for FTP, Ping, Traceroute,
REXEC, orexec, RSH, and orsh.
Link scope
zone A
fe80...
Link scope
zone B
fe80...
fe80...
fe80...
fe80... fe80... fe80...
Node X

Site local address type
These addresses are now deprecated, that is, no longer recommended by the IETF. Use
and deployment difficulties caused by the use of such addresses has led the IETF to
discourage their use.
Originally, site-local addresses were used to communicate across routers or zones within
the same intranet. They were similar to the RFC 1918/Address Allocation for Private
Internets in IPv4 today, such as the address ranges represented by10.0.0.0/8,
172.16.0.0/16 - 172.31.0.0/16, and 192.168.0.0/24. Since their deprecation, they are
treated as global unicast addresses.
This deprecated address scope begins with the following prefixes:
fec0: (most commonly used)
fed0:
fee0:
6bone test addresses
These addresses were the first global addresses defined and used for testing purposes.
They all begin with the following prefix:
3ffe:
6to4 addresses
These addresses were designed for a special tunneling mechanism (RFC
3056/Connection of IPv6 Domains using IPv4 Clouds and RFC 2893/Transition
Mechanisms for IPv6 Hosts and Routers). They encode a given IPv4 address and a
possible subnet. They begin with the following prefix:
2002:
Consider this example, representing 192.168.1.1/5:
2002:c0a8:0101:5::1
Assigned by a provider for hierarchical routing
These addresses are delegated to Internet service providers (ISP) and begin with the
following prefix:
2001:
Multicast addresses
Multicast addresses are used for related services and always begin with the prefix ffxx:.
Here, xx is the scope value.
Anycast addresses
Anycast addresses are special addresses used to cover such items as the nearest
Domain Name System (DNS) server, nearest Dynamic Host Configuration Protocol
(DHCP) server, or similar dynamic groups. Addresses are taken out of the unicast address
space, and can be aggregated globally or site-local at the moment. The anycast
mechanism (client view) is handled by dynamic routing protocols.
A simple example of an anycast address is the subnet-router anycast address. Assuming
that a node has the following global assigned IPv6 address:
3ffe:ffff:100:f101:210:a4ff:fee3:9566/64
Note: Anycast addresses cannot be used as source addresses. They are used only as
destination addresses.

The subnet-router anycast address is created by blanking the suffix (least significant 64
bits) completely:
3ffe:ffff:100:f101::/64
IPv6 implementation in z/OS
The z/OS Communications Server provides support for both IPv4 and IPv6 protocols to
coexist. In this book we review how this strategy can be implemented in a z/OS networking
environment.
Further details about configuration options not referenced here are available in z/OS
Communications Server: IP Configuration Reference, SC31-8776 and z/OS Communications
Server: IPv6 Network and Application Design Guide, SC31-8885.
Table A-1 summarizes the z/OS TCP/IP stack-related functions and the level of support,
based on the current release of the z/OS Communications Server. You can use this table to
determine whether a given function is applicable and supported.
Table A-1 z/OS TCP/IP stack function support
z/OS TCP/IP stack
function
IPv4
support
IPv6
support
Comments
Link-layer device support Y Y IPv4 devices are defined with the DEVICE and LINK configuration
statements. In IPv6, interfaces are defined with the INTERFACE
statement.
Ethernet LAN connectivity
using OSA-Express in
QDIO mode
Y Y To define an MPCIPA device for IPv4, use the DEVICE statement
with the MPCIPA parameter and the LINK statement with the
IPAQENET parameter.
For IPv6 traffic, you must configure OSA-Express2 and
OSA-Express features, running in QDIO mode, by using an
INTERFACE statement of type IPAQENET6.
Virtual IP addressing support
Virtual device/interface
configuration
Y Y With IPv4, a static virtual device is configured using DEVICE and
LINK statements with the VIRTUAL parameter.
An IPv6 virtual interface is configured with an INTERFACE
statement of type VIRTUAL6.
Sysplex support
Sysplex support Y Y IP Sysplex functions:
Dynamic VIPA
Sysplex Distributor
SourceVIPA
SNMP MIBs for dynamic VIPA
SysplexPorts
Support does not include these functions:
Sysplex Distributor integration with MNLB
Sysplex Wide Security Association (SWSA)
IP routing functions
Dynamic routing - OSPF
and RIP
Y Y IPv6-related changes were made to OMPROUTE:
RIPng support
OSPFv3 support

Dynamic routing - Auto
Configuration
N Y
Static route configuration
using BEGINROUTES
statement
Y Y Related configuration statement:
BEGINROUTES
Static route configuration
using GATEWAY statement
Y N Related configuration statement:
GATEWAY
Multipath routing groups Y Y Related configuration statements:
IPCONFIG
IPCONFIG6
Multicast Listener
Discovery
N Y MLDv2 supported using Source-Filtered multicast (SFM)
Miscellaneous IP/IF-layer functions
Path MTU discovery Y Y Path MTU discovery is mandatory in IPv6.
Related configuration statements:
IPCONFIG
IPCONFIG6
Link-layer address
resolution
Y Y In IPv4, this is performed using Address Resolution Protocol
(ARP).
In IPv6, this is performed using the neighbor discovery protocol.
DEVICE and LINK (LAN Channel Station and OSA devices)
INTERFACE (IPAQENET6 interfaces)
ARP/Neighbor cache
PURGE capability
Y Y Use the V TCPIP,PURGECACHE command. For information see
z/OS Communications Server: IP System Administrator’s
Commands, SC31-8781.
Datagram forwarding
enable/disable
Y Y Related configuration statements:
IPCONFIG
IPCONFIG6
Transport-layer functions
Fast response cache
accelerator
Y N
Enterprise extender Y Y IPv6 Enterprise Extender support requires a virtual IP address
and IUTSAMEH.
INTERFACE VIRTUAL6 and MPCPTP6
IPCONFIG6 DYNAMICXCF
Server-BIND control Y Y Related configuration statement:
PORT
UDP Checksum
disablement option
Y N UDP checksum is required when operating over IPv6.
Related configuration statement:
UDPCONFIG
Network management and accounting functions
z/OS TCP/IP stack
function
IPv4
support
IPv6
support
Comments

SNMP Y Y SNMP applications can communicate over an IPv6 connection.
IPv6 management data includes added support for the
version-neutral (both IPv4 and IPv6) MIB data in the following
new, IETF Internet drafts:
IP-MIB: draft-ietf-ipv6-rfc2011-update-01.txt
IP-FORWARD-MIB: draft-ietf-ipv6-rfc2096-update-02.txt
TCP-MIB: draft-ietf-ipv6-rfc2012-update-01.txt
Network SLAPM2 subagent Y Y
Policy-based networking Y Y IPv6 support in Policy Agent:
IPv6 source and destination IP addresses are allowed to be
specified in policy rules (LDAP and configuration files).
Interfaces in policy rules and subnet priority TOS masks are
allowed to be specified by name.
– Allowed for both IPv4 and IPv6 interfaces
– IPv6 interfaces must be specified by name
TOS in policy definitions means IPv4 Type of Service or IPv6
Traffic Class.
SMF SMFCONFIG Y Y New Type 119 records are used to collect IPv6-related
information.
Related configuration statement:
SMFCONFIG
Security function
IPSec Y Y Related configuration statements:
IPCONFIG
IPCONFIG6
IP filtering Y Y
NAT traversal Y N
Network access control Y N Related configuration statement:
NETACCESS
Stack and port access
control
Y Y Related configuration statements:
PORT
DELETE
Application transparent TLS Y Y
Intrusion detection services Y N
Server applications
Rpcbind server Y Y IPv6-enabled RPC applications require a Rpcbind server. The
following RPC facilities are not IPv6 enabled, and they do not
support RPC binding protocols Version 3 and Version 4:
rpcgen and orpcgen
rpcinfo and orpcinfo
RPC library for the z/OS Communications Server
environment
RPC library for the z/OS UNIX System Services environment
For more information see z/OS Communications Server: IP
Configuration Guide, SC31-8775
z/OS TCP/IP stack
function
IPv4
support
IPv6
support
Comments

Based on the discussion and recommendation in “Common design scenarios for IPv6” on
page 292, here we concentrate on a single stack environment running in dual-mode. A single
stack environment is one TCP/IP stack running in an LPAR.
Dual-mode stack
As previously discussed, a TCP/IP stack that supports both IPv4 and IPv6 interfaces and is
capable of receiving and sending IPv4 and IPv6 packets over the corresponding interfaces is
referred to as a dual-mode stack. A dual-mode stack is a single stack supporting IPv4 and
IPv6 protocols, which is different from dual-stack mode that uses two TCP/IP stacks running
side by side, each supporting only one of the protocols (either IPv4 or IPv6).
The z/OS Communications Server can be configured to support an IPv4-only stack or a
dual-mode stack (IPv4 and IPv6). There is no support for an IPv6-only stack. By default,
IPv6-enabled applications can communicate with both IPv4 and IPv6 peers in a dual-mode
environment.
A z/OS dual-mode stack is enabled when both AF_INET and AF_INET6 are coded in
SYS1.PARMLIB(BPXPRMxx). You cannot code AF_INET6 without specifying AF_INET, and
doing so will cause the TCP/IP stack initialization to fail.
Note that AF_INET6 support can be dynamically enabled by configuring AF_INET6 in
BPXPRMxx and then issuing the SETOMVS RESE= command to activate the new
configuration.
IPv6 application on a dual-mode stack
An IPv6 application on a dual-mode stack can communicate with IPv4 and IPv6 partners as
long as it does not bind to a native IPv6 address. If it binds to a native IPv6 address, then the
native IPv6 address cannot be converted to an IPv4 address.
If a partner is IPv6, then all communication will use IPv6 packets.
If a partner is IPv4, then the following will occur:
Both source and destination will be IPv4-mapped IPv6 addresses.
On inbound, the transport protocol layer will map the IPv4 address to its corresponding
IPv4-mapped IPv6 address before returning to the application with AF_INET6 addresses.
On outbound, the transport protocol layer will convert the IPv4-mapped address to the
native IPv4 addresses and send IPv4 packets.
An IPv4 application running on a dual-mode stack can communicate with an IPv4 partner.
The source and destination addresses will be native IPv4 addresses and the packet will be an
IPv4 packet.
If a partner is IPv6 enabled and running on an IPv6-only stack, then communication will fail.
The partner only has a native IPv6 address (not an IPv4-mapped IPv6 address). The native
IPv6 address for the partner cannot be converted into a form that the AF_INET application will
understand.
Older AF_INET applications are only able to communicate using IPv4 addresses.
IPv6-enabled applications that use AF_INET6 sockets can communicate using both IPv4 and
IPv6 addresses (on a dual-mode stack). AF_INET and AF_INET6 applications can thus
communicate with one another, but only using IPv4 addresses.

If the socket libraries on the IPv6-enabled host are updated to support IPv6 sockets
(AF_INET6), applications can be IPv6 enabled. When an application on a dual mode stack is
IPv6 enabled, the application is able to communicate with both IPv4 and IPv6 partners. This
is true for both clients and server on a dual-mode stack.
IPv6-enabling both sockets libraries and applications on dual-mode stack therefore becomes
a migration concern. As soon as IPv6-only hosts are being deployed in a network,
applications on those IPv6-only partners cannot communicate with the IPv4-only applications
on the dual mode hosts, unless one of the multiple migration technologies is implemented
either on intermediate nodes in the network or directly on the dual mode hosts.
Table A-2 summarizes the application communication rules when running in dual-mode.
Table A-2 Dual-mode communication
Figure A-3 depicts a dual-mode stack, which is the IPv6 configuration we implemented in our
networking environment. The following sections walk you through the setup.
Figure A-3 Dual-mode TCP/IP stack
Implementation tasks for a dual-mode stack
To implement a dual-mode stack in our networking environment, we modified the following:
BPXPRMxx definitions
VTAM definitions
Partner
Application communication on a dual-mode TCP/IP stack
IPv4 only IPv6 enabled
IPv4-only Yes Yes
IPv6-only No Yes
Dual-mode Stack
IPv4-only
Application
IPv6-enabled
Application
TCP, UDP, and Raw
IPv4 and IPv6
Network Interfaces
IPv6
Network
IPv6
Network

TCP/IP definitions
BPXPRMxx definitions
IPv6 is not enabled, by default. You must specify a NETWORK statement with AF_INET6 in
your BPXPRMxx member.
To support our dual-mode stack (IPv4 and IPv6), we added the NETWORK statement, as
shown in Example A-1, to our BPXPRMxx member.
Example A-1 BPXPRMxx NETWORK statement
NETWORK DOMAINNAME (AF_INET6)
DOMAINNUMBER(19)
MAXSOCKETS(2000)
TYPE(INET)
The TYPE option in our case is INET, because we used a single stack.
For more details about the definitions required in BPXPRMxx to provide a dual- stack, refer to
z/OS Communications Server: IP Configuration Guide, SC31-8775.
VTAM definitions
As previously mentioned, one of the protocols that z/OS Communications Server TCP/IP
supports is MPC+, and the MPC+ protocols are used to define the DLCs for OSA-Express
devices in QDIO. OSA-Express QDIO connections are configured through a TRLE definition.
Because VTAM provides the DLCs for TCP/IP, all TRLEs are defined as VTAM major nodes
(see Example A-2).
Example A-2 TRLE definition
OSA2080P TRLE LNCTL=MPC,
READ=2080,
WRITE=2081,
DATAPATH=(2082-2087),
PORTNAME=OSA2080, 1
MPCLEVEL=QDIO
The PORTNAME 1 is identical to the device name defined in the TCP/IP PROFILE data set
on the INTERFACE statement.
TCP/IP definitions
We added one INTERFACE statement for the OSA-Express2 1000BASE-T port to support
IPv6. This statement merges the DEVICE, LINK, and HOME definitions into a single
statement. Several different parameters are associated with the INTERFACE statement. To
determine which of them best fits your requirements, refer to z/OS Communications Server:
IP Configuration Reference, SC31-8776.
Note: The BPXPRMxx member can be updated dynamically using the z/OS command
SETOMVS RESET=(xx). After the reset, we received the message BPXF203I DOMAIN
AF_INET6 WAS SUCCESSFULLY ACTIVATED. We then recycled the TCP/IP stack to pick up the
change.

We used the following syntax:
INTERFace interfname DEFINE linktype PORTNAME portname IPADDR ipaddr
The syntax is explained here:
interfname specifies a name for the interface with no more than 16 characters in length.
linktype must be IPAQENET6, which is the only DLC that currently supports IPv6.
portname is specified in the VTAM TRLE definition for the QDIO interface.
ipaddr is optional for link type IPAQENET6. If not specified, TCP/IP enables
auto-configuration for the interface. If used, one or more prefixes or full IPv6 addresses
can be specified.
The TCP/IP IPv6 PRFOFILE for a single stack is illustrated in Example A-3 on page 306. The
INTERFACE statement defines the configuration of the OSA-Express device (OSA2080) that
we used for network connectivity. The PORTNAME must be identical to the PORTNAME
defined in the TRLE. The TRLE is defined as a VTAM major node in the VTAM definition data
set.
Example A-3 shows the TCP/IP profile for our environment, using SYSTEM SYMBOLS and
INCLUDE statements. The &sysclone that you see throughout the example will result in a
two-digit value (30 in our example, for system SC30) being inserted. By doing this we can use
the same profile for each of several systems, each time translating to the appropriate system
value (systems 30, 31, and 32). The &sysclone value is defined in SYS1.PARMLIB.
Example A-3 Profile definition with the use of SYSTEM SYMBOLS and INCLUDE
ARPAGE 20
;
GLOBALCONFIG TCPIPSTATISTICS
;
IPCONFIG 1
DATAGRAMFWD
SYSPLEXROUTING
SOURCEVIPA
;
DYNAMICXCF 10.10.20.1&sysclone 255.255.255.0 8
;
IPCONFIG6 2
DATAGRAMFWD
SOURCEVIPA
;
SOMAXCONN 240
;
TCPCONFIG RESTRICTLOWPORTS
;
UDPCONFIG RESTRICTLOWPORTS
;
INCLUDE TCPIPE.TCPPARMS(HOME&SYSCLONE.6)
;
Note: To configure a single physical device for both IPv4 and IPv6 traffic, you must use
DEVICE/LINK/HOME for the IPv4 definition and INTERFACE for the IPv6 definition, so that
the PORTNAME value on the INTERFACE statement matches the device name on the
DEVICE statement.

INCLUDE TCPIPE.TCPPARMS(STAT&SYSCLONE.6)
;
AUTOLOG 5
FTPDE&sysclone JOBNAME FTPDE&sysclone.1
; OMP&sysclone ; OSPF daemon
; SMTP ; SMTP Server
ENDAUTOLOG
;
PORT
20 TCP * NOAUTOLOG ; FTP Server
21 TCP OMVS BIND 10.10.10.210; control port
23 TCP INTCLIEN ; MVS Telnet Server
23 TCP OMVS BIND 10.10.10.210 ;Telnet Server
25 TCP SMTP ; SMTP Server
; 111 TCP PORTMAP ; Portmap Server
; 111 UDP PORTMAP ; Portmap Server
; 443 TCP HTTPS ; http protocol over TLS/SSL
; 443 UDP HTTPS ; http protocol over TLS/SSL
514 UDP OMVS ; UNIX Syslogd daemon
; 3389 TCP MSYSLDAP ; LDAP Server for Mesas
;
SACONFIG ENABLED COMMUNITY public AGENT 161
;
SMFCONFIG
FTPCLIENT TN3270CLIENT
TYPE119 FTPCLIENT TN3270CLIENT
;
INCLUDE TCPIPE.TCPPARMS(TELN&SYSCLONE)
1. Defines the IPv4 environment.
2. Defines the IPv6 environment.
Example A-4 shows the DEVICE, LINK, HOME, INTERFACE, and IPADDR definitions we
used to support IPv4 and IPv6 and their addressing schemes.
Example A-4 Interface and address definitions
DEVICE OSA2080 MPCIPA 1
LINK OSA2080LNK IPAQENET OSA2080 VLANID 10
INTERFACE LNK62080 DEFINE IPAQENET6 PORTNAME OSA2080 1
IPADDR FEC0:0:0:1::3302
FEC0:0:0:1001::3302
;
; Static VIPA definitions
DEVICE STAVIPA1 VIRTUAL 0
LINK STAVIPA1LNK VIRTUAL 0 STAVIPA1
;
HOME
10.10.10.210 STAVIPA1LNK
10.10.2.212 OSA2080LNK
;
START OSA2080
START LNK62080

1. Defines the same device (OSA2080) to support IPv4 and IPv6 addresses.
Example A-5 show static routes in a flat network (no dynamic routing protocol).
Example A-5 Static route definitions
BEGINRoutes
ROUTE FEC0::0/10 = LNK62080 mtu 1492
ROUTE 10.10.2.0 255.255.255.0 = OSA2080LNK mtu 1492
; Default Route - All packets to an unknown destination are routed
;through this route.
; Destination First Hop Link Name Packet Size
ROUTE DEFAULT 10.10.2.1 OSA2080LNK mtu 1492
ENDRoutes
Example A-6 shows our VTAM and Telnet (TN3270) definitions.
Example A-6 Our definitions for TN3270
TelnetParms
Port 23 ; Port number 23 (std.)
TELNETDEVICE 3278-3-E NSX32703 ; 32 line screen -
; default of NSX32702 is 24
TELNETDEVICE 3278-5-E NSX32705 ; 132 column screen-
TELNETDEVICE 3279-5-E NSX32705 ; 132 column screen -
LUSESSIONPEND ; On termination of a Telnet server connection,
; the user will revert to the DEFAULTAPPL
; instead of having the connection dropped
MSG07 ; Sends a USS error message to the client if an
; error occurs during session establishment
; instead of dropping the connection
CodePage ISO8859-1 IBM-1047 ; Linemode ASCII, EBCDIC code pages
Inactive 0 ; Let connections stay around
PrtInactive 0 ; Let connections stay around
TimeMark 600
ScanInterval 120
; SMFinit std
; SMFterm std
; Define logon mode tables to be the defaults shipped with the
; latest level of VTAM
EndTelnetParms
;
BeginVTAM
Port 23
; Define the LUs to be used for general users.

DEFAULTLUS
SC&SYSCLONE.TS01..SC&SYSCLONE.TS30
ENDDEFAULTLUS
LINEMODEAPPL TSO ; Send all line-mode terminals directly to TSO.
ALLOWAPPL SC* DISCONNECTABLE ; Allow all users access to TSO
ALLOWAPPL TSO* DISCONNECTABLE ; Allow all users access to TSO
; applications.
; TSO is multiple applications all beginning with TSO,
; so use the * to get them all. If a session is closed,
; disconnect the user rather than log off the user.
ALLOWAPPL * ; Allow all applications that have not been
; previously specified to be accessed.
RESTRICTAPPL IMS ; Only 3 users can use IMS.
USER USER1 ; Allow user1 access.
LU TCPIMS01 ; Assign USER1 LU TCPIMS01.
USER USER2 ; Allow user2 access from the default LU pool.
USER USER3 ; Allow user3 access from 3 Telnet sessions,
; each with a different reserved LU.
LU TCPIMS31 LU TCPIMS32 LU TCPIMS33
USSTCP USSTEST1
EndVTAM
The messages shown in Example A-7 were written to the z/OS console when the TCP/IP
stack was initializing.
Example A-7 TCP/IP stack initialization
J E S 2 J O B L O G -- S Y S T E M S C 3 0 -- N O D E W T S C P L X 5
--- FRIDAY, 21 OCT 2005 ----
IEF695I START TCPIPE WITH JOBNAME TCPIPE IS ASSIGNED TO USER TCPIP , GROUP
$HASP373 TCPIPE STARTED
IEE252I MEMBER CTIEZB00 FOUND IN SYS1.IBM.PARMLIB
EZZ7450I FFST SUBSYSTEM IS NOT INSTALLED
EZZ0300I OPENED INCLUDE FILE 'TCPIPE.TCPPARMS(HOME306)'
EZZ0300I OPENED INCLUDE FILE 'TCPIPE.TCPPARMS(STAT306)'
EZZ0300I OPENED INCLUDE FILE 'TCPIPE.TCPPARMS(TELN30)'
EZZ0300I OPENED PROFILE FILE DD:PROFILE
EZZ0309I PROFILE PROCESSING BEGINNING FOR DD:PROFILE
EZZ0309I PROFILE PROCESSING BEGINNING FOR TCPIPE.TCPPARMS(HOME306)
EZZ0316IPROFILEPROCESSINGCOMPLETEFORFILE'TCPIPE.TCPPARMS(HOME306)'
EZZ0304I RESUMING PROCESSING OF FILE DD:PROFILE
EZZ0309I PROFILE PROCESSING BEGINNING FOR TCPIPE.TCPPARMS(STAT306)
EZZ0316IPROFILEPROCESSINGCOMPLETEFORFILE'TCPIPE.TCPPARMS(STAT306)'
EZZ0309I PROFILE PROCESSING BEGINNING FOR TCPIPE.TCPPARMS(TELN30)
EZZ0316IPROFILEPROCESSINGCOMPLETEFORFILE'TCPIPE.TCPPARMS(TELN30)'
EZZ0316I PROFILE PROCESSING COMPLETE FOR FILE DD:PROFILE
EZZ0641I IP FORWARDING NOFWDMULTIPATH SUPPORT IS ENABLED
EZZ0350I SYSPLEX ROUTING SUPPORT IS ENABLED
EZZ0351I SOURCEVIPA SUPPORT IS ENABLED
EZZ0624I DYNAMIC XCF DEFINITIONS ARE ENABLED
EZZ0700I IPV6 FORWARDING NOFWDMULTIPATH SUPPORT IS ENABLED 1
EZZ0702I IPV6 SOURCEVIPA SUPPORT IS ENABLED 1

EZZ0338I TCP PORTS 1 THRU 1023 ARE RESERVED
EZZ0338I UDP PORTS 1 THRU 1023 ARE RESERVED
EZZ0613I TCPIPSTATISTICS IS DISABLED
EZZ4202I Z/OS UNIX - TCP/IP CONNECTION ESTABLISHED FOR TCPIPE
EZD1176I TCPIPE HAS SUCCESSFULLY JOINED THE TCP/IP SYSPLEX GROUP
EZB6473I TCP/IP STACK FUNCTIONS INITIALIZATION COMPLETE.
EZAIN11I ALL TCPIP SERVICES FOR PROC TCPIPE ARE AVAILABLE.
EZZ4340I INITIALIZATION COMPLETE FOR INTERFACE LNK62080 2
EZZ4313I INITIALIZATION COMPLETE FOR DEVICE IUTIQDIO
EZZ0400I TELNET/VTAM (SECOND PASS) BEGINNING FOR FILE: DD:PROFILE
EZZ0309I PROFILE PROCESSING BEGINNING FOR TCPIPE.TCPPARMS(HOME306)
EZZ0316IPROFILEPROCESSINGCOMPLETEFORFILE'TCPIPE.TCPPARMS(HOME306)'
EZZ0309I PROFILE PROCESSING BEGINNING FOR TCPIPE.TCPPARMS(STAT306)
EZZ0316IPROFILEPROCESSINGCOMPLETEFORFILE'TCPIPE.TCPPARMS(STAT306)'
EZZ0309I PROFILE PROCESSING BEGINNING FOR TCPIPE.TCPPARMS(TELN30)
EZZ0316IPROFILEPROCESSINGCOMPLETEFORFILE'TCPIPE.TCPPARMS(TELN30)'
EZZ6003I TELNET LISTENING ON PORT 23
EZZ0403I TELNET/VTAM (SECOND PASS) COMPLETE FOR FILE: DD:PROFILE
EZD0011I USE OF SITE LOCAL ADDRESS FEC0::1001:0:0:0:3302 IS NOT RECOMMENDED 3
EZD0011I USE OF SITE LOCAL ADDRESS FEC0::1:0:0:0:3302 IS NOT RECOMMENDED 3
EZZ4313I INITIALIZATION COMPLETE FOR DEVICE IUTSAMEH
EZZ4324I CONNECTION TO 10.30.20.100 ACTIVE FOR DEVICE IUTSAMEH
S FTPDE30
In this example, 1 through 3 indicate that IPv6 support is enabled and that the interface is
initialized with IPv6 addresses.
Verification
Next, we verified our environment. Because the TRLE must be active before the interface is
started, we ensured that the TRLE is in an active state. The results are shown in
Example A-8. You can also verify the OSA-Express code level with this command.
Example A-8 OSA-Express status and code level
IST486I STATUS= ACTIV, DESIRED STATE= ACTIV 1
IST1716I PORTNAME = OSA2080 LINKNUM = 0 OSA CODE LEVEL = 0804 4
IST1221I WRITE DEV = 2081 STATUS = ACTIVE STATE = ONLINE 2
IST1221I READ DEV = 2080 STATUS = ACTIVE STATE = ONLINE 2
IST1221I DATA DEV = 2082 STATUS = ACTIVE STATE = N/A 3
IST1717I ULPID = TCPIPE

1 indicates the state of the TRLE major node.
2 and 3 are the desired and required states.
4 indicates the OSA code level, which is a four-digit number that relates to a specific
microcode engineering change (EC) and patch level (MCL).
Example A-9 displays the HOME addresses after initialization.
Example A-9 HOME addresses displayed
D TCPIP,TCPIPE,N,HOME
EZD0101I NETSTAT CS V1R8 TCPIPE 617 617
HOME ADDRESS LIST:
LINKNAME: STAVIPA1LNK
ADDRESS: 10.10.10.210
FLAGS: PRIMARY
LINKNAME: OSA2080LNK 1
ADDRESS: 10.10.2.212
FLAGS:
ADDRESS: 10.10.20.130
FLAGS:
LINKNAME: IQDIOLNK0A0A1482
ADDRESS: 10.10.20.130
FLAGS:
LINKNAME: LOOPBACK
ADDRESS: 127.0.0.1
FLAGS:
INTFNAME: LNK62080 2
ADDRESS: FEC0:0:0:1::3302
TYPE: SITE_LOCAL
FLAGS:
ADDRESS: FEC0:0:0:1001::3302 2
TYPE: SITE_LOCAL
FLAGS:
ADDRESS: FE80::9:6B00:21A:7490 3
TYPE: LINK_LOCAL
FLAGS: AUTOCONFIGURED
INTFNAME: LOOPBACK6 4
ADDRESS: ::1
TYPE: LOOPBACK
FLAGS:
1. This is the IPv4 address assigned to the OSA Express device (OSA2080).
2. These are the IPv6 addresses assigned to the same OSA Express device (OSA2080)
defined with the INTERFACE statement. However, these SITE_LOCAL addresses are not
generally recommended.
3. This is an auto-configured LINK_LOCAL address for the same OSA Express device.
4. This is the IPv6 Loopback address.

Example A-10 shows the output of NETSTAT DEV, with the IPv6 Loopback and device
interfaces shown as READY.
Example A-10 Device display, using Netstat
D TCPIP,TCPIPE,N,DEV
EZD0101I NETSTAT CS V1R8 TCPIPE 627 627
DEVNAME: LOOPBACK DEVTYPE: LOOPBACK
DEVSTATUS: READY
LNKNAME: LOOPBACK LNKTYPE: LOOPBACK LNKSTATUS: READY
ACTMTU: 65535
MULTICAST SPECIFIC:
LINK STATISTICS:
BYTESIN = 17662
OMMAND INPUT ===> SCR
BYTESOUT = 17662
INTFNAME: LOOPBACK6 INTFTYPE: LOOPBACK6 INTFSTATUS: READY 1
ACTMTU: 65535
MULTICAST SPECIFIC:
BYTESIN = 0
INBOUND PACKETS = 0
BYTESOUT = 0
DEVSTATUS: READY
LNKNAME: OSA2080LNK LNKTYPE: IPAQENET LNKSTATUS: READY 2
ACTMTU: 1492
SECCLASS: 255

MULTICAST SPECIFIC:
GROUP REFCNT
----- ------
224.0.0.1 0000000001
LINK STATISTICS:
BYTESIN = 52142
BYTESOUT = 366
INTFNAME: LNK62080 INTFTYPE: IPAQENET6 INTFSTATUS: READY 3
NETNUM: N/A QUESIZE: 0 SPEED: 0000000100
MACADDRESS: 00096B1A7490
DUPADDRDET: 1
CFGMTU: NONE ACTMTU: 1500
MULTICAST SPECIFIC:
REFCNT GROUP
------ -----
0000000002 FF02::1:FF00:3302
0000000001 FF02::1:FF1A:7490
0000000001 FF01::1
0000000001 FF02::1
BYTESIN = 0
INBOUND PACKETS = 0
BYTESOUT = 1304
If the device does not have a LnkStatus or IntfStatus of Ready (as with 1, 2, and 3), you must
resolve this before you continue. There are several factors that might cause the LnkStatus or
IntfStatus to not be ready. For example, the device cannot be varied online or defined to z/OS
correctly, or the device cannot be defined in the TCP/IP profile correctly, and so on.

Example A-11 shows the FTPD server 1 and the Internal Telnet server (TN3270) 2 bound to
the IPv6 address. They can now be accessed by another IPv6-enabled client across an IPv4
network.
Example A-11 Sockets in the stack
D TCPIP,TCPIPE,N,SOCKETS
EZD0101I NETSTAT CS V1R8 TCPIPE 643
SOCKETS INTERFACE STATUS:
NAME: DCD1DIST SUBTASK: 007D0988
TYPE: STREAM STATUS: LISTEN CONN: 00000045
BOUNDTO: 0.0.0.0..38241
CONNTO: 0.0.0.0..0
NAME: DCD1DIST SUBTASK: 007D21C0
BOUNDTO: 0.0.0.0..38240
CONNTO: 0.0.0.0..0
NAME: FTPDE301 SUBTASK: 007FF540
BOUNDTO: ::FFFF:10.10.10.210..21 1
CONNTO: ::FFFF:0.0.0.0..0
NAME: TCPIPE SUBTASK: 007D2D80
TYPE: STREAM STATUS: LISTEN CONN: 0000001E
BOUNDTO: ::..23 2
CONNTO: ::..0
NAME: TCPIPE SUBTASK: 007E4BE8
TYPE: STREAM STATUS: ESTBLSH CONN: 00000019
BOUNDTO: 127.0.0.1..1025
CONNTO: 127.0.0.1..1024
NAME: TCPIPE SUBTASK: 007E6370
TYPE: STREAM STATUS: ESTBLSH CONN: 0000001A
BOUNDTO: 127.0.0.1..1024
CONNTO: 127.0.0.1..1025
BOUNDTO: 127.0.0.1..1024
CONNTO: 0.0.0.0..0
END OF THE REPORT
We used the ping command from various hosts within the network to verify connectivity for
IPv4 and IPv6 (see Example A-12).
Example A-12 Results of the ping command
TSO PING FEC0:0:0:1001::3302
CS V1R8: Pinging host FEC0:0:0:1001::3302
TSO PING FE80::9:6B00:21A:7490
CS V1R8: Pinging host FE80::9:6B00:21A:7490
TSO PING 10.10.2.232 (TCP tcpipe

Appendix B. Additional parameters and
functions
This appendix contains examples and a discussion of the following topics:
MVS System symbols
Reusable Address Space ID (REUSASID) function
PROFILE.TCPIP parameters
TCP/IP built-in security functions
B

MVS System symbols
One of the many strengths of the z/OS technology is that it allows multiple TCP/IP stacks
(instances) to be configured in the same MVS system or across multiple MVS systems. If you
need to run many stacks, you need to ensure that each profile configuration data set is
unique. For example, if you are running your TCP/IP stacks in a sysplex, you would need to
maintain one configuration for each stack on each of the systems. As more systems are
added to the sysplex, more TCP/IP configuration files need to be maintained and
synchronized.
In our case, we used MVS System symbols to enable us to share the definitions for our
TCP/IP stacks across LPAR SC30, SC31, SC32, and SC33. MVS System symbols are used
in creating shared definitions for systems that are in a sysplex. With this facility, you use the
symbols defined during system startup as variables in configuring your TCP/IP stack. This
means that you only need to create and maintain a template file for all the systems in the
sysplex.
MVS System symbols processing
Use of MVS system symbols in the following files or environment variables is automatically
supported:
PROFILE.TCPIP file
Resolver SETUP file
TCPIP.DATA file
OMPROUTE configuration file
Resolver environment variables, such as RESOLVER_CONFIG and RESOLVER_TRACE
For the use of MVS system symbols in other configuration files, use the symbol translator
utility, EZACFSM1. EZACFSM1 reads an input file which includes the system symbols, and
creates an output file with the symbols translated to the system-specific values. This process
is done before the files are read by TCP/IP.
The sample JCL for EZACFSM1 utility is included in hlq.SEZAINST(CONVSYM), as shown in
Example B-1.
Example B-1 JCL for EZACFSM1
//CONVSYM JOB (accounting,information),programmer.name,
// MSGLEVEL=(1,1),MSGCLASS=A,CLASS=A
//*
//STEP1 EXEC PGM=EZACFSM1,REGION=0K
//SYSIN DD DSN=TCP.DATA.INPUT,DISP=SHR
//*SYSIN DD PATH='/tmp/tcp.data.input'
//* The input file can be either an MVS data set or an z/OS
//* UNIX file.
//*
//*
//*
//SYSOUT DD DSN=TCP.DATA.OUTPUT,DISP=SHR
//*SYSOUT DD PATH='/tmp/tcp.data.output',PATHOPTS=(OWRONLY,OCREAT),
//* PATHMODE=(SIRUSR,SIWUSR,SIRGRP,SIWGRP)
The input to EZACFSM1 is your template data set that contains the system symbols and the
definitions that you need. The output data set will be the parameter files, such as
TCPIP.DATA, that the TCP/IP stack or CS for z/OS IP application will use during its startup

Appendix B. Additional parameters and functions 317
and operation. You need to run the utility on each of the systems where you need to have the
symbols translated.
Symbols definitions
The variable &SYSCLONE is defined in the IEASYMxx member of SYS1.PARMLIB. As
shown in Example B-2, the value for &SYSCLONE is derived from &SYSNAME. The variable
&SYSNAME could be defined either in the IEASYSxx member or in the LOADxx member
used during IPL. In our case, &SYSNAME was defined in IEASYSxx, which we used to IPL
our MVS images. Refer to Example B-3 for a sample of the IEASYSxx that we used for the
startup of SC30. You can find further information about system symbols in z/OS
V1R1.0-V1R2.0 MVS Initialization and Tuning Guide, SA22-7591.
Example B-2 &SYSCLONE definition in SYS1.PARMLIB
SYSDEF SYSCLONE(&SYSNAME(3:2)) 1
SYMDEF(&SYSR2='O37RZ1')
SYMDEF(&SYSR3='&SYSR2(1:5).2')
SYMDEF(&SYSR4='&SYSR2(1:5).3')
1. The value of SYSCLONE is defined as two characters starting from the third character of
SYSNAME. Our SYSNAME is SC30, so SYSCLONE resolves to 30.
Example B-3 IEASYSxx definition
COUPLE=00,
OMVS=7A,
PROD=01,
PROG=(A0,S0,D0,C1,L0), Authorization list
SMF=00,
SMS=00,
SYSNAME=SC30, 1
SSN=00,
VAL=00,
1. The SYSNAME is defined as SC30 in this LPAR (LPAR A23).
You can also define and use your own variable in configuring CS for z/OS IP, aside from
&SYSNAME or &SYSCLONE. Refer to z/OS Communications Server: IP Configuration
Guide, SC31-8775, for information about creating symbols output data set.
Include files
Together with the MVS System symbols support, we also used a facility (INCLUDE) to help us
organize and share our stack configuration. By using the include configuration statement, we
were able to structure our configuration better by putting different sections of
PROFILE.TCPIP in separate files. During the stack's initialization, the contents of the file
pointed to by the include statement are read and processed. These include statements are
treated as though they were coded in PROFILE.

Sample PROFILE.TCPIP definition using MVS System symbols
Example B-4 shows the use of MVS system symbols in TCP/IP profile. Because
&SYSCLONE is unique in each system, it ensures that the files and IDs that will be generated
when the stacks initialize are also unique.
In our environment, all stacks across LPARs shared the same OSAs and used the same
HiperSockets interfaces. We could share the device-related definitions: DEVICE, LINK,
BEGINROUTES, and START. We could not share the definitions for HOME and VIPADynamic
statements because they are unique in each TCP/IP stack, so we made them into separate
members and used the INCLUDE statement. We used the SYSCLONE value to point to
those members (the members name must include SYSCLONE).
Example B-4 Use of system symbols in our TCP/IP profile
.....
;***************************************************************
; Include the stack-specific Dynamic VIPA definitions
;***************************************************************
INCLUDE TCPIPA.TCPPARMS(DVIPA&SYSCLONE) 1
;
;***************************************************************
; Include the stack-specific HOME definitions
;***************************************************************
INCLUDE TCPIPA.TCPPARMS(HOME&SYSCLONE) 1
;
......................................................................... Lines
deleted
;***************************************************************
; start the ftp daemon in each of the A stack
;***************************************************************
AUTOLOG 5
FTPD&SYSCLONE JOBNAME FTPD&SYSCLONE.1 2
; OMP&SYSCLONE ; OSPF daemon
; SMTP ; SMTP Server
ENDAUTOLOG
;***************************************************************
; Include the stack-specific PORT definitions
;***************************************************************
INCLUDE TCPIPA.TCPPARMS(PORT&SYSCLONE) 1
....
START OSA2080I
START OSA20C0I
START OSA20E0I
START OSA20A0I
START IUTIQDF4
START IUTIQDF5
START IUTIQDF6
Important: The system symbols are stored in upper case by MVS. Because you can code
the TCP/IP configuration statements in either upper case or lower case, you must ensure
that you code the system symbol name in upper case.

1. Include file for system-specific device definitions.
2. Defines the AUTOLOG with unique FTP server daemon Jobname.
Example B-5 shows the sample definition of a separate member for a stack-specific
statement. It contains only the HOME statement for system SC30, called HOME30. This
member is included in the PROFILE.TCPIP file in SC30 system. Likewise, define separate
members for other LPARs.
Example B-5 Included device file HOME30 for SC30
;**************************************************************
; TCPIPA.TCPPARMS(HOME30)
; HOME definitions for stack on SC30 image
;**************************************************************
HOME
10.1.1.10 VIPA1L
10.1.2.11 OSA2080I
10.1.3.11 OSA20C0I
10.1.3.12 OSA20E0I
10.1.2.12 OSA20A0I
10.1.4.11 IUTIQDF4L
10.1.5.11 IUTIQDF5L
10.1.6.11 IUTIQDF6L
10.1.2.10 VIPA2L
10.1.&SYSCLONE..10 VIPA3L
Reusable Address Space ID (REUSASID) function examples
In this section, we detail sample definitions of the REUSASID function and results of its
usage. Example B-6 shows how to enable this function in PARMLIB.
Example B-6 Sample DIAGXX member in PARMLIB
002800 VSM TRACK CSA(ON) SQA(ON)
002900 VSM TRACE GETFREE(OFF)
003000 REUSASID(YES) 1
In Example B-6, the number corresponds to the following information:
1. Parameter to code in member DIAGxx of PARMLIB to enable REUSASID
Example B-7 Enabling the new DIAGXX definition
T DIAG=88
IEE252I MEMBER DIAG88 FOUND IN SYS1.IBM.PARMLIB
IEE536I DIAG VALUE 88 NOW IN EFFECT
Note: A dot (.) is needed at the end of &SYSCLONE because the next character is not a
space.

Example B-8 Without REUSASID TCPIP the old ASID is unavailable and a new ASID is assigned
D A,TCPIPA
IEE115I 14.42.09 2008.298 ACTIVITY 318
JOBS M/S TS USERS SYSAS INITS ACTIVE/MAX VTAM OAS
00004 00024 00003 00034 00019 00003/00030 00022
TCPIPA TCPIPA TCPIPA NSW SO A=0082 PER=NO SMC=000 1
PGN=N/A DMN=N/A AFF=NONE
CT=000.223S ET=333.691S
WUID=STC09685 USERID=TCPIP
WKL=SYSTEM SCL=SYSSTC P=1
RGP=N/A SRVR=NO QSC=NO
ADDR SPACE ASTE=062B7080
DSPNAME=00000EDC ASTE=093D7500
DSPNAME=TCPIPDS1 ASTE=7EE44C00
P TCPIPA
EZZ4201I TCP/IP TERMINATION COMPLETE FOR TCPIPA
IEF352I ADDRESS SPACE UNAVAILABLE 2
$HASP395 TCPIPA ENDED
S TCPIPA 3
$HASP100 TCPIPA ON STCINRDR
IEF695I START TCPIPA WITH JOBNAME TCPIPA IS ASSIGNED TO USER
D A,TCPIPA
IEE115I 14.43.10 2008.298 ACTIVITY 446
00004 00023 00002 00034 00019 00002/00030 00021
CT=000.107S ET=030.909S
1. TCPIPA ASID=0082.
2. Without REUSASID, the address space is unavailable.
3. TCPIPA restarted without REUSASID parameter.
4. TCPIPA new ASID=0085.

Example B-9 With REUSASID enabled the old ASID is available and reused
S TCPIPA,REUSASID=YES 1
D A,TCPIPA
IEE115I 14.49.38 2008.298 ACTIVITY 711
00004 00023 00002 00034 00019 00002/00030 00021
CT=000.121S ET=069.808S
P TCPIPA
EZZ4201I TCP/IP TERMINATION COMPLETE FOR TCPIPA 3
$HASP395 TCPIPA ENDED
S TCPIPA,REUSASID=YES 4
D A,TCPIPA
IEE115I 14.56.01 2008.298 ACTIVITY 868
00004 00023 00001 00034 00019 00001/00030 00021
CT=000.111S ET=028.495S
1. TCPIPA started with REUSASID parameter.
2. TCPIPA using ASID=0085.
3. When TCPIPA is terminated the message ADDRESS SPACE UNAVAILABLE is no longer
issued.
4. TCPIPA restarted with REUSASID parameter.
5. The old ASID=0085 is being reused.

PROFILE.TCPIP statements
In this section we show PROFILE.TCPIP statements that are not always necessary, but are
important. For detailed descriptions of statement, refer to z/OS Communications Server: IP
Configuration Guide, SC31-8775. The syntax for the statement in the PROFILE can be found
in z/OS Communications Server: IP Configuration Reference, SC31-8776.
IPCONFIG statements
This section provides information about IPCONFIG statements.
SOURCEVIPA
When the packet is sent to the destination host, the source IP address is included in the
packet. In most cases the source IP address of the packet is used as the destination IP
address of the returning packet from the other host. For the inbound traffic, z/OS
Communications Server sets the destination IP address of the incoming packet to the source
IP address of the return packet. However, for outbound traffic, the source IP address is
determined by several parameters.
By default (IPCONFIG NOSOURCEVIPA), z/OS Communications Server sets the IP address
of the interface which is used to send out a packet to a specific destination as the source IP
address. The sending interface is selected depending on the routing table of the TCP/IP
stack.
When IPCONFIG SOURCEVIPA is set, outbound datagrams use the virtual IP address
(VIPA) for the source IP address of the packet instead of the physical interface IP address. By
using VIPA as the source IP address, and therefore the destination IP address of the return
packets from other hosts, SOURCEVIPA provides the tolerance of device and adapter
failures.
The order of the HOME list is important if SOURCEVIPA is specified. The source IP address
is the first static VIPA listed above the interface chosen for sending the packet. In
Example B-10, if OSA20C0 2 is chosen as the actual physical interface for sending the
outbound packet, then the IP address of the first VIPA above the HOME list, 10.1.2.10, is the
source IP address.
Example B-10 Source IP Address selection with IPCONFIG SOURCEVIPA
....
IPCONFIG SOURCEVIPA
HOME
10.1.1.10 VIPA1L
10.1.2.10 VIPA2L 1
10.1.2.11 OSA2080I
10.1.3.11 OSA20C0I 2
....
Note: The source IP address selection can be overridden with SRCIP statement. Refer to
“SRCIP” on page 339 for details.
SOURCEVIPA has no effect on OSPF or RIP route information exchange packets
generated by the OMPROUTE routing daemon, which means that it is only applicable for
data diagrams.

MULTIPATH
With the IPCONFIG MULTIPATH statement, packets can be load balanced on routes that
have been defined to be of equal cost. These routes could either be learned dynamically or
defined statically in your routing program (OMPROUTE). With multipath enabled, TCP/IP will
select a route to that destination network or host on a round-robin basis. TCP/IP can select a
route on a per-connection or per-packet basis, but we recommend that you do not use the
per-packet basis because it requires high CPU processing for reassembly of out-of-order
packets at the receiver. See Chapter 5, “Routing” on page 153 for details about this topic.
By default (IPCONFIG NOMULTIPATH), there is no multipath support and all connections use
the first active route to the destination network or host even if there are other, equal-cost
routes available.
PATHMTUDISCOVERY
Coding IPCONFIG PATHMTUDISCOVERY prevents the fragmentation of datagrams. It tells
TCP/IP to discover dynamically the Path Maximum Transfer Unit (PMTU), which is the
smallest of the MTU sizes of each hop in the path between two hosts.
When a connection is established, TCP/IP uses the minimum MTU of the sending host as the
starting segment size and sets the Don't Fragment (DF) bit in the IP header. Any router along
the route that cannot process the MTU will return an ICMP message requesting
fragmentation and will inform the sending host that the destination is unreachable. The
sending host can then reduce the size of its assumed PMTU. You can find more information
about PMTU discovery in RFC 1191, Path MTU Discovery.
The default is IPCONFIG NOPATHMTUDISCOVERY. Aside from enabling PMTU during stack
initialization, you could also enable or disable PMTU discovery by using VARY OBEYFILE.
IQDIOROUTING
When IPCONFIG IQDIOROUTING is configured, the inbound packets that are to be
forwarded by this TCP/IP stack use HiperSockets (also known as Internal Queued Direct I/O
or iQDIO) and Queued Direct I/O (QDIO) directly and bypass the TCP/IP stack. This type of
routing is called HiperSockets Accelerator because it allows you to concentrate external
network traffic over a single OSA-Express QDIO connection and then accelerates the routing
over a HiperSockets link, bypassing the TCP/IP stack. The default is NOIQDIOROUTING. For
further information about HiperSockets, see Chapter 4, “Connectivity” on page 109.
ARPTO
IPCONFIG ARPTO and ARPAGE statements have the same function: they specify the time
interval between the creation or revalidation and deletion of an entry in the ARP table. The
value of IPCONFIG ARPTO is specified in seconds, and the value of ARPAGE is specified in
minutes. ARP cache entries for MPCIPA and MPCOSA are not affected by ARPTO or
ARPAGE because they use the ARP offload function. The ARP cache timer for ARP offload is
set to 20 minutes. It is hard-oded and not configurable. For more information about devices
that are affected by ARPTO, refer to z/OS Communications Server: IP Configuration Guide,
SC31-8775.
The UNIX shell command onetstat -R displays the current ARP cache entries. The upper
case R in the option is required for this display. A third parameter can be coded that would
specify the IP address of the entry you want to display, as the NETSTAT ARP ip_addr command
does from TSO. If you want to display the entire ARP cache, you can specify the third
parameter with the reserved word ALL (again, all in upper case letters). If you do not specify in
upper case letters, the reserved word is not recognized (see Example B-11).

Example B-11 ARP display
D TCPIP,TCPIPA,N,ARP
INTERFACE: OSA2080I ETHERNET: 00145E749924
INTERFACE: OSA20A0I ETHERNET: 020054749661
INTERFACE: OSA20A0I ETHERNET: 020055749661
INTERFACE: OSA20C0I ETHERNET: 0014F1464600
INTERFACE: OSA20C0I ETHERNET: 02000374979B
INTERFACE: OSA20E0I ETHERNET: 00145E74979B

INTERFACE: OSA20E0I ETHERNET: 0014F1464600
INTERFACE: OSA20E0I ETHERNET: 020003749A7F
END OF THE REPORT
GLOBALCONFIG statements
This section provides information about GLOBALCONFIG statements.
TCPIPSTATISTICS
This statement prints the values of several TCP/IP counters to the output data set designated
by the CFGPRINT JCL statement. These counters include the number of TCP
retransmissions and the total number of TCP segments sent from the MVS TCP/IP system.
These TCP/IP statistics are written to the designated output data only during termination of
the TCP/IP address space.
The TCPIPSTATISTICS parameter is confirmed by the message:
EZZ0613I TCPIPSTATISTICS IS ENABLED
This parameter should be specified in the GLOBALCONFIG section. Note that the
SMFCONFIG TCPIPSTATISTICS parameter serves a different purpose; it requests that SMF
records of subtype 5 containing TCP/IP statistics be created.
SEGMENTATIONOFFLOAD
When sending or receiving packets over OSA-Express in QDIO mode with checksum offload
support, TCP/IP offloads most IPv4 (outbound and inbound) checksum processing (IP
header, TCP, and UDP checksums) to the OSA. The TCP/IP stack still performs checksum
processing in the cases where checksum cannot be offloaded.
When sending packets over OSA-Express in QDIO mode with TCP segmentation offload
support, TCP/IP offloads most IPv4 outbound TCP segmentation processing to the OSA. The
TCP/IP stack still performs TCP segmentation processing in the cases where segmentation
cannot be offloaded.
Tip: Applications that use large TCP send buffers will obtain the most benefit from TCP
segmentation offload. The size of the TCP receive buffer on the other side of the TCP
connection also affects the negotiated buffer size.
You can control the size of these buffers using the TCPSENDBFRSIZE and
TCPRCVBUFRSIZE parameters on the TCPCONFIG statement to set the default TCP
send/receive buffer size for all applications. However, an application can use the
SO_SNDBUF socket option to override the default TCP send buffer sizes (example FTP).

The segmentation offload feature decreases host CPU utilization and increases data transfer
efficiency for IPv4 packets. The z/OS Communications Server provides the Offloads feature
for IPv4 segmentation processing to OSA-Express2 in QDIO mode. This enhances the data
transfer efficiency of IPv4 packets while decreasing host CPU utilization.
The OFFLOAD feature is supported by OSA-Express in QDIO mode.
Example B-12 displays the Netstat Devlinks of an OSA-Express that has
SegmentationOffload enabled.
Example B-12 Segmentation Offload enabled
D TCPIP,TCPIPA,N,DE
......................................................................... Lines
deleted
SPEED: 0000001000
ARPOFFLOAD: YES 1 ARPOFFLOADINFO: NO 1
IPADDR: 10.1.2.11/24
CHECKSUMOFFLOAD: YES 1 SEGMENTATIONOFFLOAD: YES 1
......................................................................... Lines
deleted
1. Indicates the enabled features of ARP, Segmentation and Checksum Offload.
IQDMULTIWRITE | NOIQDMULTIWRITE
This statement allows the HiperSockets to move multiple buffers of data with a single write
operation. HiperSockets multiple write can reduce CPU use and increase throughput for
outbound streaming-type workloads, such as FTP transfers.
This parameter applies to all HiperSockets interfaces, including IUTIQDIO and IQDIOINTF6
interfaces created for Dynamic XCF.
NOIQDIOMULTIWRITE | IQDIOMULTIWRITE
This statement tells to TCP/IP should displace CPU cycles for HiperSockets multiple write
workload to a zIIP. Example B-13 shows the output of z/OS command Netstat Config.
Example B-13 Output of Display Netstat Config
DEFAULTKEEPALIVE: 00000120 DELAYACK: YES

TTLS: NO
UDP CONFIGURATION TABLE:
CHECKSUM: YES
RESTRICTLOWPORT: NO UDPQUEUELIMIT: YES
IP CONFIGURATION TABLE:
FORWARDING: YES TIMETOLIVE: 00064 RSMTIMEOUT: 00060
IPSECURITY: NO
ARPTIMEOUT: 01200 MAXRSMSIZE: 65535 FORMAT: LONG
IGREDIRECT: YES SYSPLXROUT: YES DOUBLENOP: NO
STOPCLAWER: NO SOURCEVIPA: NO
MULTIPATH: NO PATHMTUDSC: NO DEVRTRYDUR: 0000000090
DYNAMICXCF: YES
IPADDR: 10.1.7.11 SUBNET: 255.255.255.0 METRIC: 01
SECCLASS: 255
IQDIOROUTE: NO
TCPSTACKSRCVIPA: NO
MLSCHKTERM: NO XCFGRPID: IQDVLANID: 0
SEGOFFLOAD: NO SYSPLEXWLMPOLL: 060 MAXRECS: 100
EXPLICITBINDPORTRANGE: 00000-00000 IQDMULTIWRITE: YES 1
SYSPLEX MONITOR:
ZIIP:
IPSECURITY: NO IQDIOMULTIWRITE: YES 2
1. Indicates the enabled features of Hipersocket Multi Write is “on.”
2. Indicates the enabled features of zIIP Assisted Hipersocket Multiple Write is “on.”
PORT statement
This section discusses uses of the PORT statement.
Port sharing (TCP only)
If you want to run multiple instances of a listener for performance reasons, you can share the
same port between them. TCP/IP will select the listener with the fewest connections (both
active and in the backlog) at the time when a client request comes in. A typical application
using this feature is the Internet Connection Secure Server. If the load gets high, additional
servers are started by the Workload Manager.
An example of a shared port is:
PORT
80 TCP WEBSRV1 SHAREPORT
80 TCP WEBSRV2
80 TCP WEBSRV3

BIND control for INADDR_ANY
The BIND option associates the server job name with a specific IP address when the server
binds to INADDR_ANY. This new function can be used to change the BIND for INADDR_ANY
to a BIND for a specific IP address.
Telnet, for example, is a server that binds to INADDR_ANY. Previously, an client that wants to
access both Telnet servers, TN3270 and UNIX Telnet, would connect to different ports or
different TCP/IP stacks, depending on which Telnet server it wanted to connect to. This led to
cases where either one server used a different, nonstandard port, or multiple TCP/IP stacks
had to be used. With this function you do not need to have two different ports or TCP/IP
stacks. You use the same port 23 for both TN3270 and UNIX Telnet. All that is needed is to
code the BIND keyword in the PORT statement for each server:
PORT
23 TCP TN3270A BIND 10.1.1.10
23 TCP OMVS BIND 10.1.1.20
In this case, the TN3270A is a jobname for TN3270 server. When it BINDs to port 23 and
INADDR_ANY, it is associated with IP address 10.1.1.10. The OMVS job name identifies any
UNIX server, including the UNIX Telnet server. When UNIX Telnet Server BINDs to port 23
and INADDR_ANY, it is associated with IP address 10.1.1.20.
Both IP addresses can be dynamic VIPA addresses, static VIPA addresses, or real interface
addresses. You also can code a wild card for the job name. Note that this function will work
only for servers that bind to INADDR_ANY, and it is not valid with the PORTRANGE
statement.
TCPCONFIG/UDPCONFIG RESTRICTLOWPORTS
Port numbers that are not specified on a PORT profile statement are considered unreserved
ports. You can restrict the use of unreserved ports below 1024 to programs that are
APF-authorized or have OMVS superuser authority. You might decide not to explicitly reserve
all well-known ports by defining the UNRESTRICTLOWPORTS option on the TCPCONFIG
and UDPCONFIG statements. This would allow any socket application to acquire a
well-known port. See Example B-14.
Example B-14 PROFILE.TCPIP UNRESTRICTLOWPORTS statement
UDPCONFIG UNRESTRICTLOWPORTS
If you want the well-known ports to be used only by predefined application processes or
superuser-authorized application processes, then you can define the RESTRICTLOWPORTS
option on the TCPCONFIG and UDPCONFIG statements. This prevents any non-authorized
socket application from acquiring a well-known port.
PORT
The PORT reservations that are defined in the PROFILE data set are the ports that are used
by specific applications. You control access to particular ports by port number, by reserving
the port using the PORT or PORTRANGE profile statements. You can also use the optional
SAF parameter to provide additional access control.
You then need to explicitly define PORT statements to reserve each port or define the
process with superuser authority in RACF. The reserved ports indicate that the port is not
available for use by any user. However, the unreserved port numbers from 1024 through
65535 are available for use by any application that issues an explicit bind to a specific

unreserved port. These port numbers are also used by the stack to provide stack-selected
ephemeral ports.
Controlling access to unreserved ports
You can also use the PORT statement to control application access to unreserved ports by
configuring one or more PORT statements in which the port number is replaced by the
keyword UNRSV. The UNRSV keyword refers to any unreserved port (any port number that
has not been reserved by a PORT or PORTRANGE statement). If you configure the
RESTRICTLOWPORTS parameter on the TCPCONFIG or UDPCONFIG profile statement,
PORT UNRSV statements for the corresponding protocol control access only to unreserved
ports above port 1023. If you do not configure the RESTRICTLOWPORTS parameter, PORT
UNRSV statements control access to all unreserved ports in the range 1 to 65535.
This new type of entry is identified by the keyword ‘UNRSV’ and it too is used to specify the
jobname or user IDs that are allowed to run applications that use an application-specified
unreserved port.
You reserve the ports with PORT, PORTRANGE, and UNRSV commands using the keyword
OMVS with a job name of the process or a wild card job name such as *. UNIX applications.
The job can fork() another address space with a different name (for example, inetd or FTP
server). Example B-15 shows the access control to the ports.
Example B-15 PROFILE.TCPIP: PORT, PORTRANGE and UNRSV
TCPCONFIG
RESTRICTLOWPORTS
UDPCONFIG
RESTRICTLOWPORTS
PORT
20 TCP OMVS NOAUTOLOG ; FTP Server 1
21 TCP FTPDA1 BIND 10.1.1.10 ; FTP Server 2
23 TCP TN3270A ; Telnet Server
514 UDP OMVS ; UNIX SyslogD Server 3
520 UDP OMPA NOAUTOLOG ; OMPROUTE RIP IPv4
521 UDP OMPA NOAUTOLOG ; OMPROUTE RIP IPv6
PORTRANGE 10000 2000 TCP OMVS ; TCP 10000 - 11999 4
PORTRANGE 10000 2000 UDP OMVS ; UDP 10000 - 11999 4
PORT UNRSV UDP * DENY 5
Normally you can specify either OMVS or the job name in the PORT statement. However,
certain daemons have special considerations on this matter.
When the FTP server starts, it forks the listener process to run in the background, requiring
that the name of the forked address space (FTPDA1, in this example), not the original
procedure name, be used on the PORT statement of the control connection 2. You must
specify OMVS as the name on the PORT for FTP's PORT 20 1, which is used for the data
connection managed by the child process. If you specify the forked name on the data
connection (Port 20), the data connections will fail.
Note that you can also reserve UDP port 514 3 to OMVS. This port is used by the SyslogD
server in OMVS to receive log messages from other SyslogD servers in the TCP/IP network.
Note: this new control (UNRSV) does not affect the use of ports that are selected by the
stack either as a local ephemeral port or as a sysplex-wide port for a distributed DVIPA.

The PORTRANGE statements 4 reserve a range of ephemeral TCP and UDP ports for UNIX
System Services and the PORT UNRSV statement 5 denies UDP explicit bind access to
application-specified unreserved ports by any job.
In Example B-15 on page 329, ports 10000 to 11999 are reserved. The range must match the
INADDRANYPORT and INADDRANYCOUNT in your BPXPRMxx member 6 (see
Example B-16).
Example B-16 INADDRANYPORT and INADDRANYCOUNT in BPXPRMxx member
NETWORK DOMAINNAME(AF_INET)
DOMAINNUMBER(2)
MAXSOCKETS(10000)
TYPE(INET)
INADDRANYPORT(10000) 6
INADDRANYCOUNT(2000) 6
NETWORK DOMAINNAME(AF_INET6)
DOMAINNUMBER(19)
MAXSOCKETS(10000)
TYPE(INET)
To display the PORT reservation list, use the TSO/E command NETSTAT PORTL, the MVS
command D TCPIP,procname,NETSTAT PORTL command, or the UNIX shell command
onetstat -p procname -o. Example B-17 shows these MVS commands.
Example B-17 Viewing port reservation list
D TCPIP,TCPIPA,N,PORTL
PORT# PROT USER FLAGS RANGE SAF NAME
UNRSV UDP * XL
20 TCP OMVS D
21 TCP FTPDA1 DABU
BINDSPECIFIC: 10.1.1.10
23 TCP TN3270A DA 500 UDP IKED DA
520 UDP OMPROUTE D
521 UDP OMPROUTE D
4500 UDP IKED DA
END OF THE REPORT
TCPCONFIG TCPSENDBFRSIZE
TCPCONFIG TCPSENDBFRSIZE specifies the TCP send buffer size. This value is used as
the default send buffer size for those applications that do not explicitly set the buffer size using
SETSOCKOPT(). The default is 16384 (16 000).
TCPCONFIG TCPRCVBUFRSIZE
TCPCONFIG TCPRCVBUFRSIZE specifies the TCP receive buffer size. This value is used
as the default receive buffer size for those applications that do not explicitly set the buffer size
using SETSOCKOPT(). You can specify value from 256 and TCPMAXRCVBUFRSIZE. The
default is 16384 (16 000).

TCPCONFIG TCPMAXRCVBUFRSIZE
TCPCONFIG TCPMAXRCVBUFRSIZE specifies the TCP maximum receive buffer size an
application can set as its receive buffer size using SETSOCKOPT(). You can use this
parameter to limit the receive buffer size that an application can set. The minimum value you
can specify is TCPRCVBUFRSIZE, and the maximum is 512 KB. The default is 256 KB.
TCPCONFIG FINWAIT2TIME
TCPCONFIG FINWAIT2TIME parameter allows you to specify the number of seconds a TCP
connection should remain in the FINWAIT2 state. When this time limit is reached, the system
waits a further 75 seconds before dropping the connection. The default is 600 seconds, but
you can specify a value as low as 60 seconds, which will reduce the time a connection
remains in the FINWAIT2 status, and thereby free up resources for future connections.
TCPCONFIG TCPTIMESTAMP
The TCP time stamp option is exchanged during connection setup. This option is enabled (by
default) using the TCPCONFIG TCPTIMESTAMP parameter. Enabling the TCP time stamp
allows TCP/IP to better estimate the Route Trip Response Time (RTT), which helps avoid
unnecessary retransmissions and helps protect against the wrapping of sequence numbers.
IDYNAMICXCF
You have the option of either defining the DEVICE, LINK, HOME, and START statements for
MPC XCF connections to another z/OS, or letting TCP/IP dynamically define them for you.
Dynamic XCF devices and links, when activated, appear to the stack as though they had
been defined in the TCP/IP profile. They can be displayed using standard commands, and
they can be stopped and started. For multiple stack environments, IUTSAMEH links are
dynamically created for same-LPAR links. Refer to Communications Server for z/OS V1R9
TCP/IP Implementation Volume 3: High Availability, Scalability, and Performance,
SG24-7534, for further details.
SACONFIG (SNMP subagent)
The SACONFIG statement provides subagent support for SNMP. Through the subagent
support you can manage an ATM OSA network interface. Refer to the SNMP subagent
chapter of Communications Server for z/OS V1R9 TCP/IP Implementation Volume 2:
Standard Applications, SG24-7533, for further information. Example B-18 shows an example
of this statement.
Example B-18 The SACONFIG statement
SACONFig
COMMUNity public ; Community string
OSASF 760 ;OSASF port number
; AGENT 161 ;Agent port number
ENABLed
SETSENAbled
ATMENabled
Note: The FTP server and client applications override the default settings and use 64 KB
as the TCP window size and 180 KB for send/recv buffers. No changes are required in the
TCPCONFIG statement for the FTP server and client.

SMFCONFIG
The SMFCONFIG statement is used to turn on SMF logging. It defines the type 118 and type
119 records to be collected (the default format is type 118). The Example below shows the
SMFCONFIG statement to provide SMF logging for TCP stack activity, TCP connection
initialization, TCP connection termination TCP/IP statistics, when a IPSEC dynamic tunnel is
added and removed and when a IPSEC manual tunnel is activated or deactivated:
SMFCONFIG TYPE119 TCPSTACK TCPINIT TCPTERM TCPIPSTATISTICS IPSECURITY
The SMFPARMS statement can also be used to turn on SMF logging. However, you are
encouraged to migrate to SMFCONFIG, which has the following advantages over the
SMFPARMS statement:
Using SMFCONFIG means that SMF records are written using standard subtypes. With
SMFPARMS, you have to specify the subtypes to be used.
SMFCONFIG allows you to record both type 118 and type 119 records. With SMFPARMS,
only type 118 records can be collected.
SMFCONFIG enables you to record a wider variety of information.
By using SMFCONFIG, you gain support for dynamic reconfiguration, for all environments
under which CS for z/OS IP is executing (SRB mode, reentrant, XMEM mode, and so on),
and you can avoid duplicate SMF exit processes.
In the following example, type 118 FTP client records, type 119 TN3270 client records, and
type 119 IPSEC records are collected:
SMFCONFIG TYPE118 FTPCLIENT
TYPE119 TN3270CLIENT IPSECURITY
The preceding example can also be coded this as shown here, because type 118 records are
collected by default:
SMFCONFIG FTPCLIENT
TYPE119 TN3270CLIENT IPSECURITY
SMFCONFIG is coded in the PROFILE.TCPIP, but it has related entries in both Telnet and in
FTP. (See Communications Server for z/OS V1R9 TCP/IP Implementation Volume 2:
Standard Applications, SG24-7533.)
We use the Netstat CONFIG command to check if the SMFCONFIG setup above is right, the
Example B-19 shows it.
Example B-19 Output Netstat CONFIG
D TCPIP,TCPIPA,N,CONFIG
SMF PARAMETERS:
TYPE 118:
TCPINIT: 00 TCPTERM: 00 FTPCLIENT: 00
TN3270CLIENT: 00 TCPIPSTATS: 00
TYPE 119:
TCPINIT: YES TCPTERM: YES FTPCLIENT: YES
TCPIPSTATS: YES IFSTATS: NO PORTSTATS: NO
STACK: YES UDPTERM: NO TN3270CLIENT: YES
IPSECURITY: YES

The only SMF exit supported in CS for z/OS IP is the FTP server SMF exit, FTPSMFEX. This
exit is only called for type 118 records. If you need to access type 119 FTP SMF records, use
the standard SMF exit facilities, IEFU83, IEFU84, and IEFU85.
For further information about TCP/IP SMF record layouts and standardized subtype numbers,
refer to z/OS Communications Server: IP Configuration Reference, SC31-8776.
INTERFACE statement
You can use the INTERFACE statement to define either IPv4 or IPv6. If used for IPv4, the
statement combines the definitions of the DEVICE/LINK/HOME statements. See
Example B-20.
Example B-20 INTERFACE statement to define IPv4 interfaces
INTERFACE OSA20A0I 1
DEFINE IPAQENET 2
PORTNAME OSA20A0 3
IPADDR 10.1.2.12/24 4
MTU 1492 5
VLANID 20 6
VMAC 7
SOURCEVIPAINT VIPA2L 8
;
INTERFACE OSA20A0X 1
DEFINE IPAQENET
PORTNAME OSA20A0 3
IPADDR 10.1.10.16/24 4
MTU 1492
VLANID 21 6
VMAC 7
1. The INTERFACE statement replaces the DEVICE and LINK statements. The INTERFACE
statement label must be unique.
2. In IPv4 the INTERFACE statement can be used for IPAQENET devices only.
3. The PORTNAME operand as defined in TRL node. For multiple VLAN configurations the
same PORTNAME can be defined several times.
4. The IPADDR operand replaces the HOME statement. The optional subnetmask definition
replaces similar definition coded in BEGINROUTES.
5. The optional MTU operand replaces similar definition coded in BSDROUTINGPARMS.
6. The optional VLANID operand is required when defining multiple VLANs.
7. The optional VMAC operand, with or without set values, is required when defining VLANs.
8. SOURCEVIPAINT defines VIPA associated with this INTERFACE.
Example B-21 Display Netstat dev (-d)
D TCPIP,TCPIPA,N,DE
Note: If SOURCEVIPAINT is coded, the whole INTERFACE definition block must be
defined in PROFILE after the VIPA DEVICE and LINK statements are defined.

........................................................................ Lines
deleted
DEVNAME: OSA2080 1 DEVTYPE: MPCIPA
DEVSTATUS: READY
LNKNAME: OSA2080I 2 LNKTYPE: IPAQENET LNKSTATUS: READY
SPEED: 0000001000
ACTMTU: 8992
MULTICAST SPECIFIC:
........................................................................ Lines
deleted
INTFNAME: OSA20A0I 3 INTFTYPE: IPAQENET INTFSTATUS: READY
PORTNAME: OSA20A0 4 DATAPATH: 20A2 5 DATAPATHSTATUS: READY
SPEED: 0000001000
VMACADDR: 020012749661 VMACORIGIN: OSA 6 VMACROUTER: ALL
IPADDR: 10.1.2.12/24 7
MULTICAST SPECIFIC:
........................................................................ Lines
deleted
INTFNAME: OSA20A0X 3 INTFTYPE: IPAQENET INTFSTATUS: READY
PORTNAME: OSA20A0 4 DATAPATH: 20A3 5 DATAPATHSTATUS: READY
SPEED: 0000001000
VMACADDR: 020013749661 VMACORIGIN: OSA 6 VMACROUTER: ALL
IPADDR: 10.1.10.16/24 7
MULTICAST SPECIFIC:

Compare resulting displays of resources defined with the DEVICE/LINK/HOME statement to
resources defined with the INTERFACE statement. In this example, the numbers correspond
to the following information:
1. Device and link names.
2. Device and link names.
3. Interface name.
4. PORTNAME in use matching the TRLE PORTNAME definition. The same PORTNAME is
defined several times for multiple VLANs (that is not possible with DEVICE/LINK).
5. DATAPATH device address in use. One DATAPATH device is needed per each
INTERFACE defined on the same physical OSA port.
6. Virtual MAC address (VMAC) dynamically assigned by OSA.
7. IP Address and subnet mask.
Example B-22 OBEYFILE definition to delete an INTERFACE
INTERFACE OSA20A0I
DELETE 1
1. Parameter to code to delete an INTERFACE. Note syntax differences from DEVICE/LINK
deletion coding.
Example B-23 Process to delete an INTERFACE
V TCPIP,TCPIPA,STOP,OSA20A0I 1
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,STOP,OSA20A0I
D TCPIP,TCPIPA,N,DE,INTFN=OSA20A0I 2
INTFNAME: OSA20A0I INTFTYPE: IPAQENET INTFSTATUS: NOT ACTIVE 2
PORTNAME: OSA20A0 DATAPATH: UNKNOWN DATAPATHSTATUS: NOT ACTIVE 2
........................................................................ Lines
deleted
LANGROUP: 00002
NAME STATUS ARPOWNER VIPAOWNER
---- ------ -------- ---------
OSA2081L ACTIVE OSA2081L YES
OSA20A0I 2 NOT ACTIVE OSA2081L NO
END OF THE REPORT
V TCPIP,TCPIPA,O,TCPIPA.TCPPARMS(OBDELINT) 3
EZZ0060I PROCESSING COMMAND: VARY TCPIP,TCPIPA,O,TCPIPA.TCPPARMS(OBDELINT)
EZZ0300I OPENED OBEYFILE FILE 'TCPIPA.TCPPARMS(OBDELINT)'
EZZ0309I PROFILE PROCESSING BEGINNING FOR 'TCPIPA.TCPPARMS(OBDELINT)'
EZZ0316I PROFILE PROCESSING COMPLETE FOR FILE 'TCPIPA.TCPPARMS(OBDELINT)'
Note: The Netstat dev (-d) always return the resources defined with the DEVICE/LINK
statements first and the resources defined with the INTERFACE statement later.

D TCPIP,TCPIPA,N,DE,INTFN=OSA20A0I 4
0 OF 0 RECORDS DISPLAYED 4
END OF THE REPORT
1. Stop the interface.
2. Check that the interface is not active.
3. Enter the OBEYFILE command.
4. Check that the interface has been deleted.
Example B-24 TRL nodes definition in VTAMLST for OSA-Express 3
READ=20A0, 1 *
WRITE=20A1, 1 *
DATAPATH=(20A2-20A7), 1 2 *
PORTNAME=OSA20A0, 3 *
PORTNUM=0, 4 *
MPCLEVEL=QDIO
READ=20A8, 1 *
WRITE=20A9, 1 *
DATAPATH=(20AA-20AE), 1 2 *
PORTNAME=OSA20A1, 3 *
PORTNUM=1, 4 *
MPCLEVEL=QDIO
1. OSA-Express 3 devices defined on the same CHPID (see Example B-27 on page 338).
2. Multiple DATAPATH device addresses to allow for multiple INTERFACE statements.
3. PORTNAME to be referenced in VTAM TRL node.
4. Port to be used on OSA-Express 3.
Example B-25 Display TRL nodes
D NET,TRL,TRLE=OSA20A0P
IST075I NAME = OSA20A0P, TYPE = TRLE
IST2263I PORTNAME = OSA20A0 PORTNUM = 0 1 OSA CODE LEVEL = 0707
IST1221I WRITE DEV = 20A1 STATUS = ACTIVE 2 STATE = ONLINE
Note: The two TRLE resources associated with the two ports defined on the same CHPID
can be defined on either the same or different TRL major nodes.

IST1221I READ DEV = 20A0 STATUS = ACTIVE 2 STATE = ONLINE
IST1221I DATA DEV = 20A2 STATUS = ACTIVE 2 STATE = N/A
........................................................................ Lines
deleted
IST1221I DATA DEV = 20A3 STATUS = ACTIVE 2 STATE = N/A
........................................................................ Lines
deleted
IST1221I DATA DEV = 20A4 STATUS = RESET 3 STATE = N/A
........................................................................ Lines
deleted
IST314I END
D NET,TRL,TRLE=OSA20A1P
IST075I NAME = OSA20A1P, TYPE = TRLE
IST2263I PORTNAME = OSA20A1 PORTNUM = 1 1 OSA CODE LEVEL = 0707
IST1221I WRITE DEV = 20A9 STATUS = ACTIVE 2 STATE = ONLINE
IST1221I READ DEV = 20A8 STATUS = ACTIVE 2 STATE = ONLINE
IST1221I DATA DEV = 20AA STATUS = ACTIVE 2 STATE = N/A
........................................................................ Lines
removed
IST1221I DATA DEV = 20AB STATUS = ACTIVE 2 STATE = N/A
........................................................................ Lines
removed
IST1221I DATA DEV = 20AC STATUS = ACTIVE 2 STATE = N/A
........................................................................ Lines
removed
IST1221I DATA DEV = 20AD STATUS = RESET 3 STATE = N/A
........................................................................ Lines
removed
IST314I END
1. OSA-Express 3 Port number.
2. Read, Write and Datapath device addresses in use. Multiple DATAPATH devices are
needed if multiple INTERFACEs and multiple VLANs are defined on the same OSA port.
3. Datapath device not in use.
Example B-26 Display OSA-Express 3 devices online and allocated by NET
D U,,,20A0,16
IEE457I 09.34.57 UNIT STATUS 249

UNIT TYPE STATUS VOLSER VOLSTATE
20A0 OSA A-BSY
20A1 OSA A
20A2 OSA A-BSY
20A3 OSA A-BSY
20A4 OSA O
20A5 OSA O
20A6 OSA O
20A7 OSA O
20A8 OSA A-BSY
20A9 OSA A
20AA OSA A-BSY
20AB OSA A-BSY
20AC OSA A-BSY
20AD OSA O
20AE OSA O
20AF OSAD O-RAL
Example B-27 Display OSA-Express 3 CHPID
D M=CHP(03)
IEE174I 14.59.34 DISPLAY M 586
CHPID 03: TYPE=11, DESC=OSA DIRECT EXPRESS, ONLINE
DEVICE STATUS FOR CHANNEL PATH 03
0 1 2 3 4 5 6 7 8 9 A B C D E F
020A + + + + + + + + + + + + + + + +
SWITCH DEVICE NUMBER = NONE
PHYSICAL CHANNEL ID = 0581
DEVICE AND LINK statements
Device and Link statements now support features to support VLAN IDs and OFFLOAD
processing to the OSA-Express adapter.
VLAN ID
Support is provided for virtual local area network standard IEEE 802.1q (VLAN).
Implementing VLAN allows a physical LAN to be logically subdivided into separate logical
LANs. With VLANID specified, the TCP/IP stacks that share an OSA can have an IP address
assigned from different IP subnets.
It is configured and implemented in the z/OS environment through the LINK definitions in the
PROFILE.TCPIP for OSA-Express in QDIO mode. VLANs support ARP takeover in a flat
network (no routing protocol) when connected appropriately. Refer to Chapter 4,
“Connectivity” on page 109 for more information about this implementation.
Example B-28 shows a link definition example of OSA2080I attached to virtual LAN 10.
Example B-28 Link definition example
INTERFACE OSA2080I
Note: All devices OSA-Express 3 of either port 0 and port 1 are defined under the same
CHPID. Additional device addresses can be defined through HCD if required (see
OSA-Express Customer’s Guide and Reference, SA22-7935).

DEFINE IPAQENET
PORTNAME OSA2080
IPADDR 10.1.2.11/24
MTU 1492
VLANID 10
VMAC
Example B-29 displays the Netstat Devlinks display of an OSA-Express that has VLAN ID
enabled.
Example B-29 VLAN ID enabled
D TCPIP,TCPIPA,N,DE
........................................................................ Lines
deleted
SPEED: 0000001000
ARPOFFLOAD: YES ARPOFFLOADINFO: NO
IPADDR: 10.1.2.11/24
........................................................................ Lines
deleted
1. VLAN tagging is enabled on this device (VLAN 10).
SRCIP
For inbound packets, the source IP address of a returning packet is always the destination IP
address of a receiving packet. For outbound packets, the default source IP address is the
HOME IP address of the interface chosen for sending the packet according to the routing
table. If you specify IPCONFIG SOURCEVIPA, the source IP address is the first static VIPA
listed above the interface chosen for sending the packet.
Alternatively you can designate the source IP addresses to be used for outbound TCP
connections initiated by specified jobs or destined for specified IP addresses, networks, or
subnets, by using the SRCIP statement, as described here:
Job-specific source IP addressing by using the JOBNAME option in the SRCIP statement
Destination-specific source IP addressing by using the DESTINATION option in the
SRCIP statement
These source IP address definitions override any other source IP address specification in
TCP/IP profile. However, the use of SRCIP can also be overridden directly by an application
through the use of specific socket API options.

A distributed DVIPA cannot be specified as the source IP address on the DESTINATION
statement. The TCP/IP client application issues a connect() socket call to start a TCP/IP
connection, and optionally issues a bind() socket call prior to connect(). A problem occurs
when a client application issues an explicit bind() socket call with INADDR_ANY and port 0
to have a port assigned prior to connect(). Until a connect() socket call that includes the
destination IP address is issued, z/OS Communications Server is unable to determine the
source IP address and therefore fails to choose which sysplex port pool the port should be
assigned from.
You can relieve this restriction by adding the option EXPLICITBINDPORTRANGE. Unlike the
sysplexport pools for which each pool is associated with a specific distributed DVIPA, the port
range specified by EXPLICITBINDPORTRANGE is not associated with any specific
distributed DVIPA, and can be used for any distributed DVIPA.
The EZBEPORTvvtt structure in the Coupling Facility, where vv is the 2-character VTAM
group ID suffix specified on the XCFGRPID start option and tt is the TCP group ID suffix
specified on the GLOBALCONFIG statement in the TCP/IP profile, coordinates this port
range among all members of the sysplex. The port range should be identical in all members
of the sysplex.
Example B-30 shows a sample definition of the SRCIP statement.
Example B-30 SRCIP definition
GLOBALCONFIG EXPLICITBINDPORTRANGE 7000 1024 3
SRCIP
JOBNAME * 10.1.1.10 CLIENT 1
JOBNAME CUST* 10.1.2.10 SERVER 1
DESTINATION 10.1.2.240 10.1.1.10 2
DESTINATION 10.1.2.0/24 10.1.2.10 2
DESTINATION 10.1.100.0/24 10.1.8.10 3
ENDSRCIP
1. This is a sample definition of a job-specific source IP address. The the SERVER option
listens to server applications while the CLIENT option indicates support for client
applications, and is the default.
2. This is a sample definition of a destination-specific source IP address feature. The most
specific match is applied.
3. This example uses a distributed DVIPA for the source IP address on the DESTINATION
option. Define GLOBALCONFIG EXPLICITBINDPORTRANGE to reserve 1024 ports
starting from 7000 for any distributed DVIPAs that are to be the source IP addresses.
Ensure that the ports specified for EXPLICITBINDPORTRANGE are same among all
sysplex members and do not overlap with any other port reservations: PORT,
PORTRANGE, SYSPLEXPORTS, or BPXPRMxx INADDRANYPORT.
We used the NETSTAT,SRCIP command to verify our configuration, as shown in
Example B-31.
Note: The use of EXPLICTBINDPORTRANGE has a restriction in CINET environment. It
is only available when the application has an affinity to a specific TCPIP stack, or when
only one stack is managed by CINET.

Example B-31 NETSTAT SRCIP display
D TCPIP,TCPIPA,N,SRCIP
SOURCE IP ADDRESS BASED ON JOB NAME:
JOB NAME TYPE FLG SOURCE
-------- ---- --- ------
* IPV4 C 10.1.1.10
CUST* IPV4 S 10.1.2.10
SOURCE IP ADDRESS BASED ON DESTINATION
DESTINATION: 10.1.100.0/24
SOURCE: 10.1.8.10
DESTINATION: 10.1.2.240
SOURCE: 10.1.1.10
DESTINATION: 10.1.2.0/24
SOURCE: 10.1.2.10
END OF THE REPORT
To verify the destination-specific source IP address feature functions correctly, we issued the
TSO Telnet command with an IP address configured in an L3 Switch. Example B-32 shows
results of the show tcp brief command issued for the L3 Switch.
Example B-32 show tcp brief commands
telnet 10.1.2.240
Router1#sh tcp bri
TCB Local Address Foreign Address (state)
46303D58 10.1.2.240.23 10.1.1.10.1036 ESTAB
telnet 10.1.2.220
Router2#sh tcp bri
TCB Local Address Foreign Address (state)
423B1414 10.1.2.220.23 10.1.2.10.1037 ESTAB
We see a different source IP address is used for each specific destination IP address.
TCP/IP built-in security functions
z/OS Communications Server has built-in security functions that can be activated and used to
control specific areas:
Simple Mail Transfer Protocol (SMTP) provides a secure mail gateway option that allows
an installation to create a database of registered network job entry (NJE) users who are
allowed to send mail through SMTP to a TCP/IP network recipient.
The FTP server gives you the opportunity to code security exits, in which you can extend
control over the functions performed by the FTP server. Using these exits you can control:
– The use of the FTP server based on IP addresses and port numbers
– The use of the FTP server based on user IDs
– The use of individual FTP subcommands
– The submission of batch jobs through the FTP server
z/OS V1R10 Communications Server enhances FTP server logins in the following ways:

– You can configure the FTP server to restrict the users that can log in to the FTP server
to only those users who are granted READ access to a resource profile in the
SERVAUTH class.
– When logging into the FTP server using the protected port (the port defined by the
TLSPORT configuration statement), the FTP server and client initiate a TLS
handshake without using the AUTH command. In previous releases, the FTP server
had interoperability issues with non-z/OS FTP clients that connect to the protected
port. With this enhancement, you can configure the FTP server to support non-z/OS
FTP clients that connect to the protected port.
z/OS Communications Server provides an SNMP agent that supports community-based
security such as SNMPv1 and SNMPv2C, and user-based security such as SNMPv3. If
you are concerned about sending SNMP data in a less secure environment, consider
implementing SNMPv3, whose messages have data integrity and data origin
authentication.
Both the IMS sockets and CICS sockets support provide a user exit that you can use to
validate each IMS or CICS transaction received by the Listener function. How you code this
exit, and what data you require to be present in the transaction initiation request, is your
decision.

Appendix C. Examples used in our
environment
This appendix provides the examples that we used in the configuration of our environment.
C

Resolver
This section discusses how to set up the Resolver.
Resolver cataloged procedure
Example C-1 The Resolver cataloged procedure
/*****************************************
/* SYS1.PROCLIB(RESOLV30)
/*****************************************
//RESOLV30 PROC PARMS='CTRACE(CTIRES00)'
//EZBREINI EXEC PGM=EZBREINI,REGION=0M,TIME=1440,PARM=&PARMS
//* SETUP contains Resolver setup parameters.
//* See the section on "Understanding Resolvers" in the
//* IP Configuration Guide for more information. A sample of
//* Resolver setup parameters is included in member RESSETUP
//* of the SEZAINST data set.
//*
//SETUP DD DSN=TCPIPA.TCPPARMS(RESOLV&SYSCLONE),DISP=SHR,FREE=CLOSE
BPXPRMxx
Example C-2 Specifying the Resolver procedure to be started
/*****************************************
/* SYS1.PARMLIB(BPXPRM00)
/*****************************************
/* RESOLVER_PROC is used to specify how the resolver address space */
/* is processed during Unix System Services initialization. */
/* The resolver address space is used by Tcp/Ip applications */
/* for name-to-address or address-to-name resolution. */
/* In order to create a resolver address space, a system must be */
/* configured with an AF_INET or AF_INET6 domain. */
/* RESOLVER_PROC(procname|DEFAULT|NONE) */
/* procname - The name of the address space for the resolver. */
/* In this case, this is the name of the address */
/* space as well as the procedure member name */
/* in SYS1.PROCLIB. procname is 1 to 8 characters */
/* long. */
/* DEFAULT - An address space with the name RESOLVER will */
/* be started. This is the same result that will */
/* occur if the RESOLVER_PROC statement is not */
/* specified in the BPXPRMxx profile. */
/* */
/* NONE - Specifies that a RESOLVER address space is */
/* not to be started. */
/* @DAA*/
/********************************************************************/
RESOLVER_PROC(RESOLV30)

Appendix C. Examples used in our environment 345
Resolver SETUP data set
Example C-3 Resolver address space SETUP data set
; *****************************************
; TCPIPA.TCPPARMS(RESOLV30)
; *****************************************
GLOBALTCPIPDATA('TCPIPA.TCPPARMS(GLOBAL)')
DEFAULTTCPIPDATA('TCPIPA.TCPPARMS(DEFAULT)')
GLOBALIPNODES('TCPIPA.TCPPARMS(IPNODES)')
COMMONSEARCH
Global TCPIP.DATA file
Example C-4 Global TCPIP.DATA file
; *****************************************
; *****************************************
NSPORTADDR 53
RESOLVEVIA UDP
RESOLVERTIMEOUT 10
LOOKUP LOCAL DNS
Default TCPIP.DATA file
Example C-5 Default TCPIP.DATA file
; *****************************************
; TCPIPA.TCPPARMS(DEFAULT)
; *****************************************
TCPIPJOBNAME TCPIP
HOSTNAME WTSC30
Global ETC.IPNODES data set
Example C-6 GLOBALIPNODES data set
; *****************************************
; TCPIPA.TCPPARMS(IPNODES)
; *****************************************
10.12.6.7 OURDNS
10.1.1.10 WTSC30A
10.1.1.20 WTSC31B
10.1.1.30 WTSC32C
10.1.2.240 router1

TCP/IP stack
This section lists some examples that define the TCP/IP stack.
TCPIPA stack started procedure
Example C-7 TCPIPA procedure
/*****************************************
/* SYS1.PROCLIB(TCPIPA)
/*****************************************
//TCPIPA PROC PARMS='CTRACE(CTIEZB00),IDS=00',
// PROFILE=PROFA&SYSCLONE.,TCPDATA=DATAA&SYSCLONE
// PARM=('&PARMS',
// 'ENVAR("RESOLVER_CONFIG=//''TCPIPA.TCPPARMS(&TCPDATA)''")')
//PROFILE DD DISP=SHR,DSN=TCPIPA.TCPPARMS(&PROFILE.)
TCPIP.DATA file for TCPIPA stack
Example C-8 TCPIP.DATA file DATAA30
; *****************************************
; *****************************************
TCPIPJOBNAME TCPIPA
HOSTNAME WTSC30A
MESSAGECASE MIXED
PROFILE.TCPIP (for static routing)
Example C-9 PROFILE.TCPIP (for static routing)
; This profile is for static routing
ARPAGE 20
;
GLOBALCONFIG NOTCPIPSTATISTICS IQDMULTIWRITE ZIIP IQDIOMULTIWRITE
GLOBALCONFIG SEGMENTATIONOFFLOAD
GLOBALCONFIG EXPLICITBINDPORTRANGE 7000 3
GLOBALCONFIG XCFGRPID 21 IQDVLANID 21
GLOBALCONFIG SYSPLEXMONITOR DELAYJOIN RECOVERY TIMERSECS 60
;
IPCONFIG
ARPTO 1200
SOURCEVIPA
IGNOREREDIRECT
DATAGRAMFWD
SYSPLEXROUTING
MULTIPATH PERCONNECTION
PATHMTUDISCOVERY

DYNAMICXCF 10.1.7.11 255.255.255.0 8
;
;
UDPCONFIG UNRESTRICTLOWPORTS UDPSENDBFRSIZE 65535 UDPRCVBUFRSIZE 65535
UDPCONFIG NOUDPQUEUELIMIT
;
NETMONITOR SMFSERVICE
;
SOMAXCONN 10
;
;OSA definitions
;TRL MAJ NODE: OSA2080,OSA20A0,OSA20C0,and OSA20E0
;
INTERFACE OSA2080I
DEFINE IPAQENET
PORTNAME OSA2080
IPADDR 10.1.2.11/24
MTU 1492
VLANID 10
VMAC
;
INTERFACE OSA20A0I
DEFINE IPAQENET
PORTNAME OSA20A0
IPADDR 10.1.2.12/24
MTU 1492
VLANID 10
VMAC
;
INTERFACE OSA20C0I
DEFINE IPAQENET
PORTNAME OSA20C0
IPADDR 10.1.3.11/24
MTU 1492
VLANID 11
VMAC
;
INTERFACE OSA20E0I
DEFINE IPAQENET
PORTNAME OSA20E0
IPADDR 10.1.3.12/24
MTU 1492
VLANID 11
VMAC
;
;HiperSockets definitions

;
;Static VIPA definitions
;
;Dynamic VIPA definitions
VIPADYNAMIC
VIPADEFINE MOVE IMMED 255.255.255.0 10.1.8.25 ;FTP
VIPADISTRIBUTE DEFINE SYSPLEXPORTS DISTMETHOD BASEWLM
10.1.8.25 PORT 20 21
DESTIP 10.1.7.11
10.1.7.21
VIPADEFINE MOVE IMMED 255.255.255.0 10.1.8.21 ;General
VIPADISTRIBUTE DEFINE SYSPLEXPORTS DISTMETHOD ROUNDROBIN
10.1.8.21 PORT 992 20 21 23
DESTIP 10.1.7.11
10.1.7.21
10.1.8.44 PORT 4444
DESTIP 10.1.7.11
10.1.7.21
VIPADEFINE MOVE IMMED 255.255.255.0 10.1.8.22 ;Admin
10.1.8.22 PORT 992 20 21
DESTIP 10.1.7.11
10.1.7.21
VIPADEFINE MOVE IMMED 255.255.255.0 10.1.8.23 ; Payrol
VIPADISTRIBUTE DEFINE SYSPLEXPORTS DISTMETHOD SERVERWLM
10.1.8.23 PORT 992 20 21
DESTIP 10.1.7.11
10.1.7.21
VIPABACKUP 200 MOVE IMMED 255.255.255.0 10.1.8.24 ; EXTRAS
10.1.8.24 PORT 20 21
DESTIP 10.1.7.11
10.1.7.21
VIPAROUTE DEFINE 10.1.7.11 10.1.1.10 ; sc30's static vipa
ENDVIPADYNAMIC
;
HOME
10.1.1.10 VIPA1L
10.1.2.10 VIPA2L
10.1.4.11 IUTIQDF4L
10.1.5.11 IUTIQDF5L
10.1.6.11 IUTIQDF6L
;
PRIMARYINTERFACE VIPA1L
;
BEGINRoutes
; Direct Routes - Routes that are directly connected to the interfaces
ROUTE 10.10.4.0 255.255.255.0 = IUTIQDF4L mtu defaultsize repl

ROUTE 10.10.4.0/24 = IUTIQDF5L mtu defaultsize repl
ROUTE 10.10.5.0/24 = IUTIQDF6L mtu defaultsize repl
; Default Route - All packets to an unknown destination are routed
; through this route.
; Destination First Hop Link Name Packet Size
ROUTE DEFAULT 10.10.2.1 OSA2080I mtu defaultsize repl
ROUTE DEFAULT 10.10.3.1 OSA20A0I mtu defaultsize repl
ROUTE DEFAULT 10.10.2.2 OSA20C0I mtu defaultsize repl
ROUTE DEFAULT 10.10.3.2 OSA20E0I mtu defaultsize repl
ENDRoutes
;
AUTOLOG 5
FTPDA JOBNAME FTPDA1
OMPA
ENDAUTOLOG
;
PORT
21 TCP FTPDA1 BIND 10.1.1.10 ; control port
500 UDP IKED ; @ADI
514 UDP OMVS ; Remote Execution Server
520 UDP OMPA NOAUTOLOG ; OMPROUTE RIPV2 port
4500 UDP IKED
; ; @ADI
PORTRANGE 10000 2000 TCP OMVS ; TCP 10000 - 11999
PORTRANGE 10000 2000 UDP OMVS ; UDP 10000 - 11999
;
PORT UNRSV TCP * DENY
;
SACONFIG ENABLED COMMUNITY j0s9m2ap AGENT 161
SMFCONFIG TYPE119 TCPINIT TCPTERM TCPIPSTATISTICS TN3270CLIENT
FTPCLIENT
;
START OSA2080I
START OSA2081I
START OSA20A0I
START OSA20C0I
START OSA20E0I
START IUTIQDF4
START IUTIQDF5
START IUTIQDF6
PROFILE.TCPIP (for OMPROUTE dynamic routing)
Example C-10 PROFILE.TCPIP (for OMPROUTE dynamic routing)
; This profile is for static routing
ARPAGE 20
;
GLOBALCONFIG NOTCPIPSTATISTICS IQDMULTIWRITE ZIIP IQDIOMULTIWRITE
GLOBALCONFIG SEGMENTATIONOFFLOAD
GLOBALCONFIG EXPLICITBINDPORTRANGE 7000 3
GLOBALCONFIG XCFGRPID 21 IQDVLANID 21

GLOBALCONFIG SYSPLEXMONITOR DELAYJOIN RECOVERY TIMERSECS 60
;
IPCONFIG
ARPTO 1200
SOURCEVIPA
IGNOREREDIRECT
DATAGRAMFWD
SYSPLEXROUTING
MULTIPATH PERCONNECTION
PATHMTUDISCOVERY
DYNAMICXCF 10.1.7.11 255.255.255.0 8
;
;
UDPCONFIG UNRESTRICTLOWPORTS UDPSENDBFRSIZE 65535 UDPRCVBUFRSIZE 65535
UDPCONFIG NOUDPQUEUELIMIT
;
NETMONITOR SMFSERVICE
;
SOMAXCONN 10
;
;OSA definitions
;TRL MAJ NODE: OSA2080,OSA20A0,OSA20C0,and OSA20E0
;
INTERFACE OSA2080I
DEFINE IPAQENET
PORTNAME OSA2080
IPADDR 10.1.2.11/24
MTU 1492
VLANID 10
VMAC
;
INTERFACE OSA20A0I
DEFINE IPAQENET
PORTNAME OSA20A0
IPADDR 10.1.2.12/24
MTU 1492
VLANID 10
VMAC
;
INTERFACE OSA20C0I
DEFINE IPAQENET
PORTNAME OSA20C0
IPADDR 10.1.3.11/24
MTU 1492
VLANID 11
VMAC
;
INTERFACE OSA20E0I
DEFINE IPAQENET
PORTNAME OSA20E0
IPADDR 10.1.3.12/24
MTU 1492

VLANID 11
VMAC
;
;HiperSockets definitions
;
;Static VIPA definitions
;
;Dynamic VIPA definitions
VIPADYNAMIC
VIPADEFINE MOVE IMMED 255.255.255.0 10.1.8.25 ;FTP
10.1.8.25 PORT 20 21
DESTIP 10.1.7.11
10.1.7.21
10.1.8.21 PORT 992 20 21 23
DESTIP 10.1.7.11
10.1.7.21
10.1.8.44 PORT 4444
DESTIP 10.1.7.11
10.1.7.21
VIPADEFINE MOVE IMMED 255.255.255.0 10.1.8.22 ;Admin
10.1.8.22 PORT 992 20 21
DESTIP 10.1.7.11
10.1.7.21
VIPADEFINE MOVE IMMED 255.255.255.0 10.1.8.23 ; Payrol
10.1.8.23 PORT 992 20 21
DESTIP 10.1.7.11
10.1.7.21
VIPABACKUP 200 MOVE IMMED 255.255.255.0 10.1.8.24 ; EXTRAS
10.1.8.24 PORT 20 21
DESTIP 10.1.7.11
10.1.7.21
VIPAROUTE DEFINE 10.1.7.11 10.1.1.10 ; sc30's static vipa
ENDVIPADYNAMIC
;
HOME
10.1.1.10 VIPA1L
10.1.2.10 VIPA2L

10.1.4.11 IUTIQDF4L
10.1.5.11 IUTIQDF5L
10.1.6.11 IUTIQDF6L
;
PRIMARYINTERFACE VIPA1L
;
AUTOLOG 5
FTPDA JOBNAME FTPDA1
OMPA
ENDAUTOLOG
;
PORT
21 TCP FTPDA1 BIND 10.1.1.10 ; control port
500 UDP IKED ; @ADI
514 UDP OMVS ; Remote Execution Server
4500 UDP IKED
; ; @ADI
PORTRANGE 10000 2000 TCP OMVS ; TCP 10000 - 11999
PORTRANGE 10000 2000 UDP OMVS ; UDP 10000 - 11999
;
PORT UNRSV TCP * DENY
;
SACONFIG ENABLED COMMUNITY j0s9m2ap AGENT 161
SMFCONFIG TYPE119 TCPINIT TCPTERM TCPIPSTATISTICS TN3270CLIENT
FTPCLIENT
;
START OSA2080I
START OSA2081I
START OSA20A0I
START OSA20C0I
START OSA20E0I
START IUTIQDF4
START IUTIQDF5
START IUTIQDF6
OMPROUTE dynamic routing
These are the complete examples that we used in our environment and discussed in
Chapter 5, “Routing” on page 153.
OMPROUTE cataloged procedure
Example C-11 OMPROUTE cataloged procedure
//OMPA30 PROC STDENV=OMPENA&SYSCLONE
//OMPA30 EXEC PGM=OMPROUTE,REGION=0M,TIME=NOLIMIT,
// '"_CEE_ENVFILE=DD:STDENV")/')

//STDENV DD DISP=SHR,DSN=TCPIP.SC&SYSCLONE..STDENV(&STDENV)
//OMPCFG DD DSN=TCPIPA.TCPPARMS(OMPA&SYSCLONE.),DISP=SHR
OMPROUTE environment variables
Example C-12 OMPROUTE environment variables
; *****************************************
; TCPIP.SC30.STDENV(OMPENA30)
; *****************************************
RESOLVER_CONFIG=//'TCPIPA.TCPPARMS(DATAA&SYSCLONE.)'
;OMPROUTE_FILE=//'TCPIPA.TCPPARMS(OMPA30)'
OMPROUTE_DEBUG_FILE=/etc/omproute/debug30a
OMPROUTE_DEBUG_FILE_CONTROL=100000,5
TCPIP.DATA file
Example C-13 Global TCPIP.DATA file
; *****************************************
; *****************************************
NSPORTADDR 53
RESOLVEVIA UDP
RESOLVERTIMEOUT 10
LOOKUP LOCAL DNS
Example C-14 Local TCPIP.DATA file
; *****************************************
; *****************************************
TCPIPJOBNAME TCPIPA
HOSTNAME WTSC30A
MESSAGECASE MIXED
Syslogd configuration file
Example C-15 Syslogd configuration file
##**********************************************************************
#* *
#* syslog.conf - Defines the actions to be taken for the specified *
#* facilities/priorities by the syslogd daemon. *
#* *
*.OMPA*.*.err /tmp/syslog/ompa.err.log

OMPROUTE configuration file
Example C-16 OMPROUTE configuration file
Area Area_Number=0.0.0.2
Stub_Area=YES
Authentication_type=None
Import_Summaries=Yes;
OSPF
RouterID=10.1.30.10
Comparison=Type2
DR_Max_Adj_Attempt = 10
Demand_Circuit=YES;
Global_Options
Ignore_Undefined_Interfaces=YES;
;
; Static vipa
name=VIPA1L
cost0=10
mtu=65535;
name=VIPA2L
cost0=10
mtu=65535;
; OSA Qdio VLAN10
Router_Priority=0
Cost0=100
MTU=1492;
; OSA Qdio VLAN11
Router_Priority=0
Cost0=100
MTU=1492;
Router_Priority=1
Cost0=90
MTU=8192;
Router_Priority=1

Cost0=90
MTU=8192;
Router_Priority=1
Cost0=90
MTU=8192;
;Dynamic XCF
interface ip_address=10.1.7.*
mtu=65535;
cost0=10
mtu=65535;
cost0=10
mtu=65535;
Router configuration
Example C-17 Router configuration
interface Loopback1
ip address 10.1.200.1 255.255.255.0
!
interface Vlan10
ip address 10.1.2.240 255.255.255.0
ip ospf cost 100
!
interface Vlan11
ip address 10.1.3.240 255.255.255.0
ip ospf cost 100
!
router ospf 100
router-id 10.1.3.240
log-adjacency-changes
area 2 stub no-summary
network 10.1.2.0 0.0.0.255 area 2
network 10.1.3.0 0.0.0.255 area 2
network 10.1.100.0 0.0.0.255 area 2
network 10.200.1.0 0.0.0.255 area 0
default-information originate always metric-type 1

© Copyright IBM Corp. 2009 357
Appendix D. Our implementation environment
We wrote the four z/OS Communications Server TCP/IP Implementation books at the same
time. Given the complexity of this project, we needed to be creative in organizing the test
environment so that each team could work with minimal coordination and interference from
the other teams. In this appendix, we show the complete environment that we used for the
four books as well as the environment that we used for this book.
D

The environment used for all four books
To enable concurrent work on each of the four books, we set up and shared the test
environment illustrated in Figure D-1.
Figure D-1 Our implementation environment
We wrote our books (and ran our implementation scenarios) using four logical partitions
(LPARs) on an IBM System z10 EC (referred to as LPARs A23, A24, A25, and A29). We
implemented and started one TCP/IP stack on each LPAR. Each LPAR shared the following
resources:
HiperSockets inter-server connectivity
Coupling Facility connectivity (CF38 and CF39) for Parallel Sysplex scenarios
Eight OSA-Express3 1000BASE-T Ethernet ports connected to a switch
Finally, we shared four Windows workstations, representing corporate network access to the
z/OS networking environment. The workstations are connected to the switch. For verifying our
scenarios, we used applications such as TN3270 and FTP.
The IP addressing scheme that we used allowed us to build multiple subnetworks so that we
would not impede ongoing activities from other team members.
z/OS LPAR: A23 z/OS LPAR: A24 z/OS LPAR: A25 z/OS LPAR: A29
VTAM
SC30 (NN)
TSO
SC30TS
VTAM
SC31 (NN)
TSO
SC31TS
VTAM
SC32 (NN)
TSO
SC32TS
VTAM
SC33 (NN)
TSO
SC33TS
TCPIPA
10.1.x.x
10.1.x.x
10.1.100.22410.1.100.22310.1.100.22210.1.100.221
TCPIPB
10.1.x.x
TCPIPC
10.1.x.x
TCPIPD
10.1.x.x
HiperSockets
CHPID F4 Devices E800-E81F IPADDR 10.1.4.x
CHPID F5 Devices E900-E91F IPADDR 10.1.5.x
CHPID F6 Devices EA00-EA1F IPADDR 10.1.6.x
CHPID F7 Devices EB00-EB1F (DYNAMICXCF) IPADDR 10.1.7.x
CF38
CF LPAR: A2E
CHPID 05
OSA20E0
10.1.3.x
Devices 20E0-F
OSA-Express
1000BASE-T
CF39
CF LPAR: A2F
CHPID 02
OSA2080
10.1.2.x
Devices 2080-F
CHPID 03
OSA20A0
10.1.2.x
Devices 20A0-F
CHPID 04
OSA20C0
10.1.3.x
Devices 20C0-F
TCPIPE
192168.x.x
OSA2080
192.168.x.x
Devices 2080-F
Switch
10.1.x.240
Windows XP
with PCOM
192.168.x.x

Appendix D. Our implementation environment 359
VLANs were also defined to isolate the TCP/IP stacks and portions of the LAN environment
(see Figure D-2).
Figure D-2 LAN configuration: VLAN and IP addressing
OSA2080
TCPIPA TCPIPB
Router
OSA20E0
TCPIPC TCPIPD
OSA20A0 OSA20C0
TCPIPE
OSA2080
VLAN 30
10.1.2.240 10.1.3.240
10.1.100.240
TRUNK
CS01TEST CS02TEST CS04TEST
10.1.100.221 10.1.100.222
CS03TEST
10.1.100.223 10.1.100.224
VLAN 12
192.168.2.240
RR
TRUNK TRUNK TRUNKTRUNK
VLAN 11VLAN 10

Our focus for this book
Figure D-3 depicts the environment that we worked with, as required for our basic function
implementation scenarios.
Figure D-3 Our environment for this book
A23 (SC30)
TCPIPA
PROFA30 (dynamic routes)
PROFAS30 (static routes)
VIPA3L 10.1.30.10/24
VIPA1L 10.1.1.10/24
VIPA2L 10.1.2.10/24
OSA2080I 10.1.2.11/24
OSA20A0I 10.1.2.12/24
OSA20C0I 10.1.3.11/24
OSA20E0I 10.1.3.12/24
IUTIQDF4L 10.1.4.11/24
IUTIQDF5L 10.1.5.11/24
IUTIQDF6L 10.1.6.11/24
XCF 10.1.7.11/24
(10.1.9.10-19)
TCPIPB
PROFB31 (dynamic routes)
PROFBS31 (static routes)
VIPA3L 10.31.0.10/24
VIPA1L 10.1.1.20/24
VIPA2L 10.1.2.20/24
OSA2080I 10.1.2.21/24
OSA20A0I 10.1.2.22/24
OSA20C0I 10.1.3.21/24
OSA20E0I 10.1.3.22/24
IUTIQDF4L 10.1.4.21/24
IUTIQDF5L 10.1.5.21/24
IUTIQDF6L 10.1.6.21/24
XCF 10.1.7.21/24
(10.1.9.20-29)
A24 (SC31) A25 (SC32)
TCPIPC
PROFC32 (dynamic routes)
PROFCS32 (static routes)
VIPA1L 10.1.1.30/24
VIPA2L 10.1.2.30/24
OSA2080I 10.1.2.31/24
OSA20A0I 10.1.2.32/24
OSA20C0I 10.1.3.31/24
OSA20E0I 10.1.3.32/24
IUTIQDF4L 10.1.4.31/24
IUTIQDF5L 10.1.5.31/24
IUTIQDF6L 10.1.6.31/24
XCF 10.1.7.31/24
(10.1.9.20-29)
A29 (SC33)
TCPIPD
PROFD33 (dynamic routes)
PROFDS33 (static routes)
VIPA1L 10.1.1.40/24
VIPA2L 10.1.2.40/24
OSA2080I 10.1.2.41/24
OSA20A0I 10.1.2.42/24
OSA20C0I 10.1.3.41/24
OSA20E0I 10.1.3.42/24
IUTIQDF4L 10.1.4.41/24
IUTIQDF5L 10.1.5.41/24
IUTIQDF6L 10.1.6.41/24
XCF 10.1.7.41/24
(10.1.9.40-49)
VLAN 10
10.1.2.240
VLAN 11
10.1.3.240
SWITCH 1
CHPID 02
OSA2080
10.1.2.x1
2080-208F
CHPID 03
OSA20A0
10.1.2.x2
20A0-20AF
CHPID 04
OSA20C0
10.1.3.x1
20C0-20CF
CHPID 05
OSA20E0
10.1.3.x2
20E0-2E0F
XCF
10.1.7.x1

Related publications
We consider the publications that we list in this section particularly suitable for a more
detailed discussion of the topics that we cover in this book.
IBM Redbooks publications
For information about ordering these publications, see “How to get IBM Redbooks
publications” on page 363. Note that some of the documents referenced here might be
available in softcopy only.
Communications Server for z/OS V1R9 TCP/IP Implementation Volume 1: Base
Functions, Connectivity, and Routing, SG24-7532
Migrating Subarea Networks to an IP Infrastructure Using Enterprise Extender,
SG24-5957
TCP/IP Tutorial and Technical Overview, GG24-3376
IP Network Design Guide, SG24-2580
OSA-Express Implementation Guide, SG24-5948
SNA in a Parallel Sysplex Environment, SG24-2113
z/OS Infoprint Server Implementation, SG24-6234
z/OS 1.6 Security Services Update, SG24-6448
Other publications
These publications are also relevant as further information sources:
z/OS XL C/C++ Run-Time Library Reference, SA22-7821
z/OS MVS IPCS Commands, SA22-7594
z/OS MVS System Commands, SA22-7627
z/OS TSO/E Command Reference, SA22-7782
z/OS UNIX System Services Command Reference, SA22-7802
z/OS Communications Server: CSM Guide, SC31-8808
z/OS Communications Server: New Function Summary, GC31-8771
z/OS Communications Server: Quick Reference, SX75-0124

z/OS Communications Server: IP System Administrator’s Commands, SC31-8781
z/OS Communications Server: IP Messages Volume 1 (EZA), SC31-8783
z/OS Communications Server: IP Messages Volume 2 (EZB, EZD), SC31-8784
z/OS Communications Server: IP Messages Volume 3 (EZY), SC31-8785
z/OS Communications Server: IP Messages Volume 4 (EZZ, SNM), SC31-8786
z/OS Communications Server: IP Programmer’s Guide and Reference, SC31-8787
z/OS Communications Server: IP Sockets Application Programming Interface Guide and
Reference, SC31-8788
z/OS Communications Server: IP User’s Guide and Commands, SC31-8780
z/OS Communications Server: IPv6 Network and Application Design Guide, SC31-8885
OSA-Express Customer’s Guide and Reference, SA22-7935
z/OS Communications Server: SNA Network Implementation, SC31-8777
z/OS Communications Server: SNA Resource Definition, SC31-8778
z/OS TSO/E Command Reference, SA22-7782
z/OS UNIX System Services Programming: Assembler Callable Services Reference,
SA22-7803
z/OS UNIX System Services Command Reference, SA22-7802
z/OS UNIX System Services File System Interface Reference, SA22-7808
z/OS UNIX System Services Parallel Environment: Operation and Use, SA22-7810
z/OS UNIX System Services Programming Tools, SA22-7805
z/OS UNIX System Services Planning, GA22-7800
z/OS UNIX System Services User’s Guide, SA22-7801
IBM Health Checker for z/OS: User’s Guide, SA22-7994

Related publications 363
Online resources
These Web sites are also relevant as further information sources:
z/OS Communications Server product support
http://www-306.ibm.com/software/network/commserver/zos/support/
Mainframe networking
http://www.ibm.com/servers/eserver/zseries/networking/
z/OS Communications Server product overview
http://www.ibm.com/software/network/commserver/zos/
z/OS Communications Server publications
http://www-03.ibm.com/systems/z/os/zos/bkserv/r9pdf/#commserv
How to get IBM Redbooks publications
You can search for, view, or download Redbooks, Redpapers, Technotes, draft publications
and Additional materials, as well as order hardcopy Redbooks publications, at this Web site:
ibm.com/redbooks
Help from IBM
IBM Support and downloads
ibm.com/support
IBM Global Services
ibm.com/services

Index
Symbols
/etc/hosts 79
/etc/resolv.conf 77
Numerics
127.0.0.1 69, 73
14.0.0.0 69, 73
6bone test address 299
6to4 address 299
A
Access mode 217
access port 217
Accessing the z/OS UNIX shells 14
accounting 287
ACTIVE State 310
Address Resolution Protocol (ARP) 301
address resolution protocol (ARP) 221
address space 9, 31, 63, 325
abends 266
child process 11
name 329
adjacent router 164, 170
router advertisements 170
Advantages 34, 44, 53–54, 293–295
AF_INET 14–15
AF_INET addressing family 15
AF_INET socket 15–16
AF_INET transport provider 16
AF_UNIX 14
AF_UNIX addressing family 15
AF_UNIX socket 15
ALGPRINT 65
anchor configuration data set 77
Anycast address 299
simple example 299
APF authorization 59
APIs 8, 70
APPC/MVS 11
application program interface (API) 11
Application programming interfaces 8
ARP cache 149, 323
ARPTO 331
Assigning user IDs to started tasks 57
attached TCP/IP network
other TCP/IP server host 66
auditing 287
Authorized Program Facility (APF) 59
AUTOLOG consideration 73
AUTOLOG considerations 73
AUTOLOG statement 190
OMPROUTE start procedure 190
procedure name 75
B
Base function
common design scenarios 52
base function 51
base functions
Basic concepts 2, 52, 110, 154
batch job 2, 11, 52, 341
BeginRoutes 174
BEGINROUTES statement 301
BIND control for INADDR_ANY 328
BPXPRMxx 60, 65
BPXPRMxx definitions 305
BPXPRMxx member 11, 55, 305
incorrect value 65
BPXPRMxx, CINET 17
BPXTIINT 65
BSDROUTINGPARMS statement 119, 135, 161
BUFFERPOOL statements 323
C
canonical mode 14
capacity planning 287
CEEDUMP 65
certain periodic updates (CPU) 53, 159
channel-to-channel (CTC) 110
CHPID 133
CICS 342
CINET 16–17
C-INET pre-router 31
CMD 196
command TRACE (CT) 204, 261
Common INET Physical File System (CINET) 17
Common Link Access to Workstation (CLAW) 110
Common Storage 323
Common Storage Manager (CSM) 2, 99
complete detail xi
COMPONENT TRACE
Status 49, 206
TALLY Report 50
component trace 250, 285
primary purpose 267
Component trace (CT) 150, 204, 250, 261
configuration data set
selecting 55
configuration data set names 70
Configuration examples 40
configuration statement 24, 161, 300, 317
Configure the default TCPIP.DATA data set statements
40
Configure the setup data set 38
Configuring the SITE table (HOSTS.LOCAL) 79
Configuring z/OS TCP/IP 70
connected stacks 31

connectivity 110
connectivity status
Verifying 129, 135, 140
Considerations 44, 53–54, 125, 134, 139, 173, 181,
293–295
Controlling the device definitions 144
cookbook for creating multiple stacks 80
CPU cycle 18, 35, 53–54, 121, 159
CPU resources 56
cron 12
Cross-System Coupling Facility (XCF) 8
CSA 64, 323
CTIEZB00 95, 250, 285
CTIEZBxx 255
CTRACE 250, 285
CTRACE -- RESOLVER (SYSTCPRE) 48
CTRACE command 267, 281
CTWTR procedure 48, 204
Customization levels of UNIX System Services 11
D
Daemons 11
Data Facility Storage Management Subsystem (DFSMS)
3, 52
Data Link Control (DLC) 5, 110, 306
data set 10, 59–60, 183, 251
configuration 55
trace data 251
DATASETPREFIX 70, 77
DD card 37–38
DDVIPA 212
Dedicated data links 293
Default destination address selection 32
default directory path 68
Default Route 155, 308
Default search path and symbolic links 68
default user 13
Dependencies 53–54, 125, 133, 138, 180, 293–295
design scenario 109, 173
designated router (DR) 165–166
destination address 32, 146, 156, 299
device
adding, changing, and deleting 102
DEVICE AND LINK 338
DEVICE and LINK statements for each OSA-Express port
127
DEVICE and LINK statements for HiperSockets CHPID
134
device OSA2080 77, 85, 307
DEVICE statement 306
device status in TCP/IP stack
Verifying 129, 135, 140
device type 113
DEVICE/LINK statement 222
Diagnosing a OMPROUTE problem 202
Diagnosing the Resolver address space environment 44
Differences between RIPng and RIP-2 171
Direct Memory Access
processor system memory 8
Direct Memory Access (DMA) 7, 112
Direct Route 155, 308
Directed mode 211
Dispatch mode 211
Display status of devices 98
Display Storage usage 99
Displaying TCP/IP device resources in VTAM 130, 136
Displaying the TCP/IP Configuration 96
distance vector algorithm 168
Domain Name
Services 10, 293
System 22, 299
DOMAINORIGIN 24
Dual-mode stack 294
dual-mode stack 303
Implementation 304
dual-mode TCP/IP
Application communication 304
dual-stack backbones 294
Dynamic Host Configuration Protocol (DHCP) 299
dynamic route 162
Dynamic VIPA 3, 300
address 328
DYNAMIC XCF
IPCONFIG definition 331
Dynamic XCF 118
device 119, 331
support 119
dynamic XCF 112, 118
additional information 120
Dynamic XCF connectivity 138
DYNAMICXCF implementation 139
DynVLANRegCap 312
E
EDNS0 33
engineering change (EC) 311
Enterprise Extender (EE) 301
ENTRYPOINT 65
ENVAR 77
Ephemeral Ports 55
ETC.IPNO Des 31
IPv4 addresses 32
ETC.IPNODES data set 40
Exclusive DLCs 7
explicit data set allocation 70
extended common service area
maximum amount 99
extended common service area (ECSA) 99
Extension Mechanism for DNS (EDNS0) 33
exterior gateway protocols 154
external gateway protocol (EGP) 169
external writer 48, 150, 204, 251
file 267, 281
procedure CTWTR 207
EZAZSSI 63–64
EZAZSSI JCL procedure 65
EZBPFINI 65
EZZ0053I Command 145
EZZ0309I PROFILE PROCESSING Beginning 309

Index 367
EZZ0316I Profile 309
EZZ4203I 65
EZZ4313I Initialization 145, 310
EZZ4324I Connection 310
F
FILE DD
PROFILE 309
For additional information 18, 50, 208
forked address spaces 11
FTP
security 341
FTP Server
3 329
4 329
FTP server
TCPCONFIG statement 331
full-function mode 10, 52
full-function, UNIX System Services 11
Functional Overview 4
G
Generic Resource Encapsulation (GRE) 210
Generic Server 55
generic server 31
getmain 64
GID 13, 57
Gigabit Ethernet 3, 111
global TCPIP.DATA
statement 23
graphical mode 14
GRE 212
group ID 13, 57
Groups 57
H
Health Checker 106
HFS 12
Hierarchical File System 12
high level qualifier (HLQ) 70
High Performance Data Transfer (HPDT) 7, 123
High Performance Native Socket (HPNS) 16
High-bandwidth and high-speed networking technologies
112
HiperSockets 227, 323
microcode
description 112
multiple write facility 117
HiperSockets (Internal Queued Direct I/O - iQDIO) 115
HiperSockets (MPCIPA) 115
HiperSockets Accelerator 117, 323
HiperSockets connectivity 133
HiperSockets DYNAMICXCF connectivity 120
HiperSockets implementation 134
HOME 73
HOME address to each defined LINK 128, 135
HOME Statement 73
host name resolution 79
hostname 24, 78
hosts file
hosts file 79
HOSTS.LOCA L
IPv4 addresses 32
HOSTS.LOCAL 79
HPDT
displaying TCP/IP device resources in VTAM 130,
136, 141
http protocol 307
hybrid mode 218
I
IBM System
z9 110
identity, MVS 13
identity, UNIX 13
IDYNAMICXCF 331
IEASYS00 60
IEASYSxx 64
IEE839I St 49, 206
IKJTSOxx 64
implementation scenario xi
Implementation tasks 36
implicit data set allocation 70
Important and commonly used interfaces 112
IMS 342
INADDRANYPORT 65
Inbound Packet 312
inbound packet 114
include files 317
INCLUDE statement 101
indirect route 155
individual parameter xi
INET 16
inetd 12
Information Management System (IMS) 9
Input/Output flow process 5
installation
DATASETPREFIX 70
explicit data set allocation 70
high level qualifier (HLQ) 70
implicit data set allocation 70
LNKLST 62
LPALST 62
node name 63
PARMLIB 66
SCHEDxx 63
Integrated Sockets PFS definitions 61
Interactive Problem Control System (IPCS) 150
INTERFACE statement 72, 161, 300
PORTNAME value 306
interior gateway protocols 154
Internal Queued Direct I/O, (IQDIO) 8
Internet Protocol 112, 154, 292
next generation 292
Internet Protocol (IP) 109, 153
IP 250
IP address 16, 22, 56, 120, 154, 256, 291
configured name server 23

server jobname 328
IP network 2, 110, 154
large number 154
IP offload 113
IP packet
forwarding processing 117
IP route 158
IP routing
IP routing algorithm 156
IP traffic 112
IPCONFIG 76
IPCONFIG DYNAMICXCF 119
IPCONFIG6 76
IPCS command 49, 255
IPv4 address 32, 292
303
IPv6
implementation 295, 300
importance 292
IPV6 address 32, 295
IPv6 address 306
certain styles 296
IPv6 addressing 295
303
IPv6 changes to Resolver processing 31
IPv6 dynamic routing 170
IPv6 dynamic routing using OMPROUTE 171
IPv6 dynamic routing using router discovery 170
IPv6 implementation in z/OS 300
IPv6 network 170, 293
connectivity 14
IPv6 traffic 294
prefix 171
IPv6 Resolver statements 34
IPv6 RIP
protocol 171
route 171
UDP port 184
IPv6 support 14, 31, 61, 293, 300
IPv6 TCP/IP Network part (prefix) 297
IPv6 traffic 293
IQD CHPID 116, 133
F7 138
hexadecimal value 134
iQD chpid 116
IQDCHPID 234
iQDIO 115
IQDIOROUTING 323
IQDVLANID 231
ISHELL 3, 10, 58
IST075I Name 310
IST087I Type 310
IST097I Display 310
IST1715I MPCLEVEL 310
IST1716I PORTNAME 310
IST1717I ULPID 310
IST1724I I/O Trace 310
IST1954I TRL MAJOR Node 310
IUTiQDIO device 138
IUTSAMEH 227
IUTSAMEH device 138
IVTPRMxx 64
J
Job log versus syslog as diagnosis tool 106
jobname 57, 318
L
LAN Channel Station (LCS) 7, 301
LAN connections 110
LCS 7
line mode 14
link local address type 297
Link state
algorithm 160
database 164
link state (LS) 158
Link State Advertisement (LSA) 164, 167
Link state database 167
Link state routing 166
LINK statement 300
Link statement 77, 98, 114, 127, 338
LINK statement using BSDROUTINGPARMS 128, 135
Link Statistic 312
LNKLST 62
Load Balancing Advisor (LBA) 3, 229
Local Area Network (LAN) 110, 165
local hosts file 79
local name resolution with TESTSITE
Verifying 100
local settings in a multiple stack environment 29
local settings in a single stack environment 34
Locating PROFILE.TCPIP 76
Logical File System (LFS) 8
login name 13
LOOPBACK 73
loopback 69
LPALST 62
LPAR 53, 303
LPARs
data traffic flow 139
M
Management Information Base (MIB) 4
Maximum Transfer Unit (MTU) 323
maximum transmission unit (MTU) 56
MAXRECS 250
Message types
where to find them 106
message types 106
messages 106
mid-level qualifier (MLQ) 71
Modifying a device 103
Modifying characteristics of a device 145

Index 369
Modifying OMPROUTE 196
MPC
displaying resources 130, 136, 141
MPLS backbones 294
MTU
recommendation 56
MTU size 128, 135, 312
multicast address 296, 299
Multicast Capability 312
MULTIPATH 323
Multipath Channel
I/O process 7
Multi-Path Channel (MPC) 4, 76, 295
Multipath Channel+ (MPC+) 7
multiple AF_INET transport providers 16
multiple security zones 226
Multiple stack 17–18, 35, 52–54, 120–121, 228
separate workload 54
Multiple Stacks
_iptcpn() 55
cookbook 80
Ephemeral ports 55
Generic Server 55
setibmopt() socket call 55
Multiple stacks 54
multiple TCP/IP
stack 17–18, 34–35, 56, 121, 161, 316
multiple TCP/IP stack 305
multiple write assist with IBM zIIP 117
MVPTSSI 63
MVS identity 13
MVS image 15, 116
AF_INET transport providers 17
N
Name and address resolution functions 32
name resolution 79
name server 31
NAT 212
NETSTAT command 58, 129, 135, 140
Network Address Translation (NAT) 210
NETWORK DOMAINNAME 61, 305, 330
network job entry (NJE) 341
network management
programming interface 4
tool 4
networking connectivity
diagnose problems 200
next step 127
NMI API 285
non-canonical mode 14
NONRouter 212
NSPORTADDR 53 39, 183, 345, 353
O
OAT 212
OBEYFILE and security 66
OBEYFILE command 66, 101, 146, 176, 257
Oct 11 196
OFFLOAD 325
OMEGAMON 285
OMPROUTE 181
OMPROUTE configuration file 185, 354
OMPROUTE CTRACE 204
OMPROUTE in a z/OS environment 179
OMPROUTE management 190
OMPROUTE procedure 182
OMVS segment 13, 57
RACF user IDs 58
OMVS shell 3, 67
interface 67
Open Shortest Path First (OSPF) 8, 158, 163
Operating environment 5
Operating mode 14
OPERCMDS, generic class 66
OSA 218
Express 121
OSA Address Table (OAT) 112, 210
OSA address Table (OAT) 222
OSA device 301
OSAENTA 267
OSA-Express (MPCIPA) 113
OSA-Express connectivity 123
OSA-Express device 76, 103, 145, 305
DLC layer 76
OSA-EXPRESS feature 81, 112, 295
OSA-Express implementation with VLAN ID 125
OSA-Express port 82, 118, 123, 200, 295
link statements 127
OSA-Express QDIO
connection 76, 305
interface 112
OSA-Express router support 114
OSA-Express VLAN support 113, 117
OSI model 110
OSPF 161
OSPF area 164
network topology 166
OSPF for IPv6 171
OSPF network 163
other areas 167
RIP routes 164
OSPF terminology 163
outbound connections 31
Outbound Packet 312
P
packet trace 256
PARMLIB 66
Pascal API 9
Path Maximum Transfer Unit (PMTU) 323
Path Maximum Transmission Unit
RFC 1191 331
PATHMTUDISCOVERY 331
performance management 286
permission bits 13, 68
PFS 16
Physical File

System 2, 87, 260
System transport provider 16
Physical File System (PFS) 16, 53
Physical File System transport provider 16
Physical File System transport providers 16
Physical network types 167
PING and TRACERTE
Verifying interfaces 100
PING command 146, 314
Ping command (TSO or z/OS Unix) 243
PKTTRACE 256
PMTU 245
PORT 65
Port management 55
Port Sharing 327
Port sharing (TCP only) 327
PORT Statement 72
PORTNUM 260
Primary differences between IPv6 OSPF and IPv4
OSPFv2 172
PRIRouter 210, 212
Problem determination 146, 179, 198
Problems with the home directory 67
process 11
procname 197
PROFILE.TCPI P 53, 256, 315
configuration file 72
data 190, 267
definition 74
different sections 317
file 100
OBEY statement 102
parameter 322
PKTTRACE statement 256
statement 257
PROFILE.TCPIP 71
Verifying 100
PROFILE.TCPIP and TCPIP.DATA
Verifying using HOMETEST 100
PROFILE.TCPIP parameters 72
PROGnn 63
program properties table (PPT) 63
Protocols and devices 7
Q
QDIO mode 3, 295, 325
OSA-Express port 125
Quality of Service (QOS) 292
Queued Direct I/O (QDIO) 4, 112, 323
R
RACF 57
RACF authorize user IDs for starting OMPROUTE 184
RACF definition 57
RACF environment 57
RACF facility classes 57
RACF implementation 57
RACF profiles 57
RACF resources 57
RACF security environment 58
RACF with z/OS Communications Server TCP/IP 59
raw mode 14
Recommendation 56
Recommendations 181, 295
Reconfiguring the system with z/OS commands 101
Redbooks Web site 363
Contact us xiv
resolv.conf 77
RESOLVE_VIA_LOOKUP compile symbol 79
Resolver address space 21
global definitions 29
Resolver configuration data sets 77
Resolver CTRACE
analysis 50
initialization PARMLIB member 48
Resolver problems
diagnosing 44
Resource Access Control Facility (RACF) 3, 52
resource profiles 13
restartable platform 63
Reusable Address Space ID (REUSASID) 6
REXX sockets 10
RIP 161
RIP V1
implementation 170
limitation 169
packet 170
system 170
RIP v1 159
RIP V1 limitations 169
RIP V2
extension 170
message 170
packet 170
protocol extension 169
system 170
RIP v2 159
RIP Version 1 169
RIP Version 2 169
RIPng or RIP next generation 171
Root file system 12
ROUTE 10.10.3.0 174
Route Trip Response Time (RTT) 331
router 154
Router configuration statements 189, 355
Routing daemons 161
Routing Information
Protocol 158
Routing Information Protocol (RIP) 158, 168
routing protocol 8, 154, 159, 338
main characteristics 159
routing table 119, 154, 156
network routes 170
static definition 157
static routes 174
S
S806, abend code 65
SACONFIG (SNMP subagent) 331

Index 371
same LPAR 120
same VLAN 82
SAMEHOST 7
SCHEDxx 63
search order 76
SECRouter 212
SECRouters 210
security 57
CICS 342
client 66
FTP 341
IMS 342
server 66
SMTP 341
SNMP 342
segment
OMVS 57
server
generic 31
Server Application State Protocol
outboard load balancers 3
Server Application State Protocol (SASP) 3
set of messages show (SMS) 69
Setting up the Resolver procedure 36
Shared DLCs 7
Sharing Resolver between multiple stacks 54
shell 10
shell access 14
shell interface 11
shell, ISHELL 10
shell, OMVS 10
shortest path first (SPF) 172
Simple Mail Transfer Protocol (SMTP) 341
single AF_INET transport provider 16
Single stack 53
site local address type 299
SMF 286
SMFCONFIG 332
SMTP, security 341
SNMP subagent 331
SNMP, security 342
SNMPv1 342
SNMPv2C 342
SNMPv2u 342
socket address 14
socket addressing families 14
Socket addressing families in UNIX System Services 14
SOURCEVIPA 322, 331
spawned address spaces 11
SQA 64
Stack affinity 55
stacks
connected 31
START statement 119, 144
Start syslogd 184
Started task user IDs 58
Starting a device 144
Starting z/OS Communications Server IP 86
Starting z/OS TCP/IP after IPL 95
Static and dynamic routing 157
static route 154, 162
Static routing scenario 174
static routing table
Managing 176
step-by-step checklist xi
Stopping a device 145
structure
names 233
Stub area
default routes 162
subchannel device 116
maximum number 116
subnet mask 128, 135
SubnetMask 312
subnet-router anycast address 299
subnetwork 120, 157
subplexing 225, 229
superuser 13, 66
Superuser mode 66
Supported routing applications 8
switch port 200
network traffic 200
switch port configuration
verifying 125
symbolic links 68
SYMDEF 317
SYS1.PARM LIB member
CTIEZB00 253
CTIEZB01 254
CTIORA00 204, 261
CTIRES00 48, 263
SYS1.PARMLIB 60, 65
SYSCLONE system variable
definition 317
SYSDEF 317
Sysplex Distributor 3, 119, 210, 300
SYSTCPD DD name 77
System symbol 306
further information 317
System Symbolics
definition 317
System z File System 12
System z9 7, 109, 295
compute-intensive functions 8
memory speed 112
server-to-server traffic 115
system memory 133
SYSx.PARMLIB updates
62
T
TCP INTCLIEN 307
TCP PORTMAP 307
TCP structures 233
TCP/IP 1, 21, 51, 154, 250, 297, 300, 315
TCP/IP address space 2, 58, 257, 325
TCP/IP application
server 3
TCP/IP Base Functions
HOSTS.LOCAL 79

TCPIP.DATA 77
TCP/IP client functions 66
TCP/IP component 71, 251
TCP/IP configuration
data 53
data set 70
file 316
parameter 72
statement 318
Verifying 96
TCP/IP configuration data set names 77
TCP/IP data set names 70
TCP/IP definition 305
TCP/IP definitions 305
TCP/IP network 8, 171, 341
RIP router 171
workstation connectivity 3
TCP/IP profile 70, 119, 138, 305, 318
DYNAMICXCF definition 138
required connectivity definitions 144
START statement 144
TCP/IP server functions 66
TCP/IP socket
APIs 8
layer 254
TCP/IP socket APIs 9
TCPCONFIG 72
TCPIP 145, 197, 257, 301, 330
TCPIP.DATA 77
Testing 78
TCPIP.DATA file 55
TCPIP.DATA statement values in USS
Verifying 100
TCPIP.DATA statement values in z/OS
Verifying 100
TCPIPE.TCPP Arm 76, 306, 318
TCPIPJOBNAME 77
TCPIPSTATISTICS 325
TELNETDEVICE 3278 308
TELNETDEVICE 3279 308
test environment 36, 183
Thread 11
time-to-live (TTL) 201
TNF 63
TRACE Ct 48, 206, 252, 263
trace option 203, 250
trace resolver 46
TRACEROUTE command
202, 246
TRANSACTION TRACE (TT) 49, 206
Transport Layer Security (TLS) 4
transport providers 16
Transport Resource List
Element 123, 305
Transport Resource List (TRL) 123
Transport Resource List Element (TRLE) 130, 136, 141
TRL 130, 136, 141
TRLE 123, 130, 136, 141
displaying 142
TRLE definition 77, 125, 306
PORTNAME value 125
TRLE in VTAM to represent each OSA-Express port 126
trunk mode 217
trunk port 217
TSO clients 55
TSO command 176
TSO logon procedures
PROCLIB 65
TT CMD 49, 206
Tunneling 293
Type of Service (TOS) 302
Types of IP routing 155
U
UDP datagram 32
UDP datagrams 31
UDPCONFIG 72
UDPCONFIG statement 328
UID 13, 57
UNIX client functions 66
UNIX Hierarchical File System 12
UNIX identity 13
UNIX permission bits 67–68
UNIX shell 3
UNIX System Service 2, 52
UNIX System Services
Common errors 66
full-function mode 11
minimum mode 11
z/OS UNIX file system interaction 11
UNIX System Services communication 14
UNIX System Services concepts 11
UNIX System Services Verification 87
UNIX Systems Services 10
Update the Resolver configuration file 183, 353
user ID 13, 57
BPXROOT 94
OMVSKERN 58
user Id 13, 57, 184, 316
user IDs
RACF definitions 57
user IDs defined (UID) 13, 53
user name 13
USS
z/OS customization 66
V
V TCPIP,PURGECACHE command 301
VARY 257
VARY TCPIP command 101
Verification 41, 176, 310
Verification checklist 69
VIPA route 161
Virtual IP
Address 3
Virtual IP Address 331
Virtual IP Addressing
virtual LAN (VLAN) 217

Index 373
virtual local area network (VLAN) 109, 333, 338
Virtual MAC 210
virtual MAC (VMAC) 210
Virtual Medium Access Control (VMAC) 209
VLAN and primary/secondary router support 115
VLAN ID 98, 200
tag 218
value 113
VLAN IDs
port assignment 125
VLAN number 127
VLAN support of Generic Attribute Registration Protocol -
GVRP 114
VLANpriority 312
VMCF 63
VTAM 130, 136, 141
VTAM definition 305
VTAM definitions 305
VTAM Resource 76
W
Web server 12
Workload Manager 327
Workstation Operating Mode 14
X
XCF links 227
XCFGRPID 231
Z
z/OS Communications Server 1, 24, 52, 110, 159, 161,
295
component product 1
configure OMPROUTE 181
dual-mode stack dependencies 295
IP routing-related terms 154
IPv6 router discovery 170
tightly coupled design 54
z/OS Communications Server applications 10
z/OS Communications Server IP 70, 106
implementation 4
importance 3
z/OS Communications Server TCP/IP
RACF 59
z/OS environment 1, 16, 52, 121, 153, 295, 338
connectivity scenario 121
dynamic routing 162
feature information 65
important data set 60
UNIX concepts 56
Using OMPROUTE 179
z/OS image 8, 41, 138
z/OS IP 1, 163
z/OS shell 10, 182
ef command 196
issue 196
superuser ID 196
z/OS system 3, 57, 110
link list 62
space 14, 58
TCP/IP application availability 3
z/OS TCP/IP 2, 52, 59, 113, 180, 300, 305
environment 70
RACF 52
z/OS UNIX 2, 46, 52
address space 15
administrator 5
APIs 8
assembler callable service 9
C socket 9
C sockets APIs 9
design components 61
element 9
environment 5, 52, 146
file system 3, 10, 52
file system data 12
file system data set 12
file system file 12, 78, 146, 203–204
file system file system dependancy 4
file system home directory 58
file system interaction 11
function 9
group 53
identity 13
initialization member BPXPRM7A 317
initialization time 60
interface 9
logon service 10
onetstat 100
operating system 13
resource 13
service 12, 52
shell 14
shell traceroute/otracert command 179, 195, 201
sockets programming 9
system 3
Systems Services environment 89
user identification 13
version 9
z/OS UNIX APIs 9
z/OS UNIX file system definitions in BPXPRMxx 12
z/OS UNIX user identification 13
z/OS V1R7.0 Communications Server 150
z/OS VARY TCPIP commands 58

IBMz/OSV1R10CommunicationsServerTCP/IPImplementationVolume1:BaseFunctions,Connectivity,andRouting
IBMz/OSV1R10Communications
ServerTCP/IPImplementationVolume
ServerTCP/IPImplementation
Volume1:BaseFunctions,
IBMz/OSV1R10CommunicationsServerTCP/IPImplementationVolume1:Base

®
SG24-7696-00 ISBN 0738432563
INTERNATIONAL
TECHNICAL
SUPPORT
ORGANIZATION
BUILDING TECHNICAL
INFORMATION BASED ON
PRACTICAL EXPERIENCE
IBM Redbooks are developed
by the IBM International
Technical Support
Organization. Experts from
IBM, Customers and Partners
from around the world create
timely technical information
based on realistic scenarios.
Specific recommendations
are provided to help you
implement IT solutions more
effectively in your
environment.
For more information:
ibm.com/redbooks
®
IBM z/OS V1R10 Communications
Server TCP/IP Implementation
Volume 1: Base Functions,
Connectivity, and Routing
Discusses important
z/OSCommunications
Server TCP/IP base
function capabilities
Includes z/OS
Communications
Server base function
implementation
examples
Provides useful
verification
techniques
For more than 40 years, IBM mainframes have supported an
extraordinary portion of the world’s computing work, providing
centralized corporate databases and mission-critical enterprise-wide
applications. The IBM System z provides world class and
state-of-the-art support for the TCP/IP Internet protocol suite.
The convergence of IBM mainframe capabilities with Internet
technology, connectivity, and standards (particularly TCP/IP) is
changing the face of information technology dramatically and is driving
requirements for even more secure, scalable, and highly available
mainframe TCP/IP implementations.
The z/OS Communications Server TCP/IP Implementation series of IBM
Redbooks publications provide understandable, step-by-step guidance
about how to enable the most commonly used and important functions
of z/OS Communications Server TCP/IP.
This IBM Redbooks publication provides an introduction to z/OS
Communications Server TCP/IP and discusses the System Resolver. It
also presents implementation scenarios for TCP/IP Base functions,
Connectivity, Routing, Virtual MAC support, and sysplex subplexing.
For more specific information about z/OS Communications Server
standard applications, high availability, and security, refer to the other
volumes in the series.
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