en_ROUTE_v7_Ch01 (3)_Cisco ccna v7..pptx

© 2007 – 2016, Cisco Systems, Inc. All rights reserved. Cisco Public
ROUTE v7 Chapter 1
1
Chapter 1:
Basic Network and Routing
Concepts
CCNP ROUTE: Implementing IP Routing

Chapter 1
2
Chapter 1 Objectives
 Differentiating Between Dynamic Routing Protocols
 How Different Traffic Types, Network Types, and Overlaying
Network Technologies Influence Routing
 Differentiating Between the Various Branch Connectivity
Options and Describing Their Impact on Routing Protocols
 How to Configure Routing Information Protocol Next
Generation (RIPng)

Chapter 1
3
Differentiating
Between
Dynamic Routing
Protocols

Chapter 1
4
Differentiating Between Dynamic Routing Protocols
 Enterprise Network Infrastructure
 Dynamic Routing Protocols in the Enterprise Network
Infrastructure
 Choosing a of Dynamic Routing Protocols
 IGP and EGP Routing Protocols
 Types of Routing Protocols
 Importance of convergence
 Route summarization
 Describe what influences routing protocol scalability

Chapter 1
5
Enterprise network infrastructure
Enterprise Campus
 An enterprise campus provides access to the
network communications services and
resources to end users and devices.
 It is spread over a single geographic location,
spanning a single floor, building, or several
buildings in the same locality.
 The campus is commonly designed using a
hierarchical model — comprising the core,
distribution, and access layers—creating a
scalable infrastructure.
Enterprise Edge
 An enterprise edge provides users at
geographically disperse remote sites with
access to the same network services as users
at the main site.
 The network edge aggregates private WAN
links that are rented from service providers,
and it enables individual users to establish
VPN connections.
 In addition, the network edge also provides
Internet connectivity for campus and branch
users.

Chapter 1
6
Dynamic Routing Protocols in the Enterprise Network
Infrastructure
 It is a best practice that you use one
IP routing protocol throughout the
enterprise, if possible.
 One common example of when
multiple routing protocols are used is
when the organization is multihomed.
 In this scenario, the most commonly
used protocol to exchange routes
with the service provider is Border
Gateway Protocol (BGP), whereas
within the organization, Open
Shortest Path First (OSPF) or
Enhanced Interior Gateway Routing
Protocol (EIGRP) is typically used.
 In a single-homed infrastructures
static routes are commonly used
between the customer and the ISP.

Chapter 1
7
Choosing a of Dynamic Routing Protocols
Input requirements :
 Size of network
 Multivendor support
 Knowledge level of specific protocol
Protocol characteristics :
 Type of routing algorithm
 Speed of convergence
 Scalability

Chapter 1
8
IGP and EGP Routing Protocols
An autonomous system (AS) represents a collection of network devices
under a common administrator.
Routing protocols can be divided based on whether they exchange routes
within an AS or between different autonomous systems:
Interior Gateway Protocols (IGP)
 Support small, medium-sized, and large organizations, but their scalability
has its limits. Fast convergence, and basic functionality is not complex to
configure. The most commonly used IGPs in enterprises are EIGRP,
OSPF and RIP is rarely used. IS-IS is also commonly found as ISP IGP
Exterior Gateway Protocols (EGP)
 Used to exchange routes between different autonomous systems. BGP is
the only EGP that is used today. The main function of BGP is to exchange
a huge number of routes between different autonomous systems.

Chapter 1
9
Types of Routing Protocols
Distance vector protocols
 The distance vector routing approach determines the direction (vector) and distance (such as link
cost or number of hops) to any link in the network. The only information that a router knows about a
remote network is the distance or metric to reach this network and which path or interface to use to
get there. Distance vector routing protocols do not have an actual map of the network topology.
Link-state protocols
 The link-state approach uses the Shortest Path First (SPF) algorithm to create an abstract of the
exact topology of the entire network or at least within its area. A link-state routing protocol is like
having a complete map of the network topology. The map is used to determine best path to a
destination.
Path vector protocols
 Path information is used to determine the best paths and to prevent routing loops. Similar to
distance vector protocols, path vector protocols do not have an abstract of the network topology.
Path vector protocols indicate direction and distance, but also include additional information about
the specific path of the destination.

Chapter 1
10
Importance of Convergence
 The process of when
routers notice change in
the network, exchange
the information about
the change, and perform
necessary calculations
to reevaluate the best
routes.
 To minimize downtime and quickly respond to network
changes, a fast convergence time is desired.

Chapter 1
11
Route Summarization
 Route summarization
reduces routing
overhead and
improve stability and
scalability of routing
by reducing the
amount of routing
information that is
maintained and
exchanged between
routers.
Less frequent and smaller updates, as a result of route
summarization, also lower convergence time.

Chapter 1
12
Routing Protocol Scalability
Scalability factors include:
 Number of routes
 Number of adjacent neighbors
 Number of routers in the network
 Network design
 Frequency of changes
 Available resources (CPU and memory)
 The scalability of the routing protocol and its configuration
options to support a larger network can play an important
role when evaluating routing protocols against each other.

Chapter 1
13
Understanding Network
Technologies

Chapter 1
14
Understanding Network Technologies
 Differentiate traffic types
 Differentiate IPv6 address types
 Describe ICMPv6 neighbor discovery
 Network Types
 NBMA Networks

Chapter 1
15
Differentiate traffic types

Chapter 1
16
Differentiate traffic types
Unicast
 Unicast addresses are used in a one-to-one context. Unicast traffic is exchanged
only between one sender and one receiver.
Multicast
 Multicast addresses identify a group of interfaces across different devices. Traffic
that is sent to a multicast address is sent to multiple destinations at the same time.
 IPv6 reserved multicast addresses 224.0.0.0–239.255.255.255.
 IPv6 reserved multicast addresses have the prefix FF00::/8.
Anycast
 An anycast address is assigned to an interface on more than one node. When a
packet is sent to an anycast address, it is routed to the nearest interface that has
this address. The nearest interface is found according to the measure of distance of
the particular routing protocol.
Broadcast
 IPv4 broadcast addresses are used when sending traffic to all devices in the
subnet. Local broadcast address 255.255.255.255.
 IPv6 does not use a broadcast address, but uses multicast addresses instead

Chapter 1
17
Well-known IPv4 and Assigned IPv6 Multicast Addresses

Chapter 1
18
Differentiate IPv6 address types

Chapter 1
19
Describe ICMPv6 neighbor discovery
Router Solicitation (RS)
 Sent by a device to the all IPv6 routers multicast to request a Router Advertisement
message from the router.
Router Advertisement (RA)
 Sent by an IPv6 router to the all IPv6 devices multicast. Includes link information
such as prefix, prefix-length, and the default gateway address.
 The RA also indicates to the host whether it needs to use a stateless or stateful
DHCPv6 server.
Neighbor Solicitation (NS)
 Sent by a device to the solicited node multicast address when it knows the IPv6
address of a device but not its Ethernet MAC address. This is similar to ARP for
IPv4.
Neighbor Advertisement (NA)
 Sent by a device usually in response to a Neighbor Solicitation message.
Redirect
 This has similar functionality as in IPv4. Sent by a router to inform the source of a
packet of a better next-hop router on the link that is closer to the destination.

Chapter 1
20
Network Types

Chapter 1
21
Network Types
Point-to-point network
 A network that connects a single pair of routers.
 A serial link is an example of a point-to-point connection.
Broadcast network
 A network that can connect many routers along with the capability to
address a single message to all of the attached routers.
 Ethernet is an example of a broadcast network.
Nonbroadcast Multiaccess (NBMA) network
 A network that can support many routers but does not have broadcast
capability.
 The sender needs to create an individual copy of the same packet for
each recipient if it wishes to inform all connected packet can be
transmitted.
 Frame Relay and Asynchronous Transfer Mode (ATM) are examples of an
NBMA network type.

Chapter 1
22
NBMA Networks Issues
Split horizon
 Prevents a routing update that is received on an interface
from being forwarded out of the same interface.

Chapter 1
23
Neighbor discovery
 OSPF over NBMA neighbors are not automatically discovered.
 You can statically configure neighbors, but an additional
configuration is required to manually configure the hub as a
Designated Router (DR).
 OSPF treats an NBMA network like Ethernet by default
Broadcast replication
 With routers that support multipoint connections over a single
interface that terminates at multiple PVCs, the router must
replicate broadcast packets.
 These replicated broadcast packets consume bandwidth and
cause significant latency variations in user traffic.

Chapter 1
24
Point-to-point subinterfaces
 Each subinterface, which provides connectivity between two
routers, uses its own subnet for addressing.
Point-to-multipoint subinterfaces
 One subnet is shared between all virtual circuits.
 Both EIGRP and OSPF need additional configuration to
support this underlying technology.

Chapter 1
25
Connecting Remote
Locations with
Headquarters

Chapter 1
26
Connecting Remote Locations with
Headquarters
 Identify options for connecting branch offices and remote
locations
 Describe the use of static and default static routes
 Describe basic PPP configuration on point-to-point serial links
 Describe basic Frame Relay on point-to-point serial links
 Explain VRF Lite
 Describe the interaction of routing protocols over MPLS VPNs
 Explain the use of GRE for branch connectivity
 Describe Dynamic Multipoint virtual private networks
 Describe multipoint GRE tunnels
 Describe the Next Hop Resolution Protocol
 Identify the role of IPsec in DMVPN solutions

Chapter 1
27
Principles of Static Routing
A static route can be used in the following circumstances
 When it is undesirable to have dynamic routing updates
forwarded across slow bandwidth links, such as a dialup link.
 When the administrator needs total control over the routes used
by the router.
 When a backup to a dynamically recognized route is necessary.
 When it is necessary to reach a network accessible by only one
path (a stub network).
 When a router connects to its ISP and needs to have only a
default route.
 When a router is underpowered and does not have the CPU or
memory resources necessary to handle a dynamic routing
protocol.

Chapter 1
28
Configuring an IPv4 Static Route
ip route prefix mask { address | interface [ address ]} [ dhcp ] [ distance ]
[ name next-hop-name ] [ permanent | track number ] [ tag tag ]

Chapter 1
29
Configuring a Static Default Route

Chapter 1
30
Basic PPP Overview
 Point-to-Point Protocol (PPP) has several advantages over
its predecessor High-Level Data Link Control (HDLC).
• Authentication
• Multi-link
• Compression
• Quality

Chapter 1
31
PPP Authentication Overview
Router(config-if)# ppp authentication { chap | chap pap |
pap chap | pap } [ if-needed ][ list-name | default ] [ callin ]

Chapter 1
32
PPP Configuration Example

Chapter 1
33
PPPoE

Chapter 1
34
Basic Frame Relay Overview
 Frame Relay provides several benefits over traditional point-to-point
leased lines
• No need for separate physical interface per connection on the router
• Bandwidth cost is much more flexible
 Frame Relay is a switched WAN technology where virtual circuits (VCs)
are created by a service provider (SP) through the network.
• The VCs are typically PVCs that are identified by a data-link connection identifier
(DLCI)
 By default, a Frame Relay network is an NBMA network.
• To emulate the LAN broadcast capability that is required by IP routing protocols Cisco
IOS implements pseudo-broadcasting
• Dynamic maps always allow pseudo-broadcasting.
 Dynamic maps created via Frame Relay Inverse Address Resolution
Protocol (INARP) for IPv4 or Frame Relay Inverse Neighbor Discovery
(IND) for IPv6
 Split horizon is disabled by default on Frame Relay physical interfaces.

Chapter 1
35
Frame Relay Topologies

Chapter 1
36
Basic Frame Relay Configuration

Chapter 1
37
VPN Connectivity Overview
 MPLS-based VPNs
 Tunneling VPNs
• GRE
• Ipsec
• DMVPN

Chapter 1
38
L3 MPLS VPNs
 Traffic forwarding through the MPLS backbone is based on
labels that are previously distributed among the core routers.
 With a Layer 3 MPLS VPN, the service provider participates
in customer routing.
 The service provider establishes routing peering between the
PE and CE routers.
 Then customer routes that are received on the PE router are
redistributed into MP-BGP and conveyed over the MPLS
backbone to the remote PE router.
 On the remote PE, these customer routes are redistributed
back from MP-BGP into a remote PE-CE routing protocol.
 Routing protocols between PE-CE routers on the local and
remote sites may be totally different.

Chapter 1
39
L2 MPLS VPNs
 A Layer 2 MPLS VPN CE router interconnects with the PE
router at Layer 2 using any Layer 2 protocol with Ethernet
being the most common.
 Layer 2 traffic is sent between PE routers, over a pre-
established pseudowire.
 Pseudowire emulates a wire between PE routers that carries
Layer 2 frames across the IP-MPLS backbone.
 There are two basic Layer 2 MPLS VPN service architectures.
• Virtual Private Wire Service (VPWS) is a point-to-point technology that
allows the transport of any Layer 2 protocol at the PE.
• The second type of Layer 2 MPLS VPN is Virtual Private LAN Service
(VPLS), which emulates an Ethernet multiaccess LAN segment over the
MPLS core and provides multipoint- to-multipoint service.

Chapter 1
40
Tunneling VPNs
GRE
 Tunneling protocol developed by Cisco that enables encapsulation of
arbitrary Layer 3 protocols inside a point-to-point, tunnel-over-IP network.
 Traffic that is transported over the GRE tunnel is not encrypted
 GRE traffic is usually encapsulated within IPsec.
IPsec
 Is a framework that uses a set of cryptographic protocols to secure traffic
at Layer 3.
DMVPN
 This solution offers the capability to dynamically establish hub-to-spoke
and spoke-to-spoke IPsec tunnels, thus reducing latency and optimizing
network performance.
 DMVPN supports dynamic routing protocols between hub and spokes as
well as IP multicast. It is also suitable for environments with dynamic IP
addresses on physical interfaces such as DSL or cable connections.

Chapter 1
41
Routing Across MPLS VPNs
 The Layer 2 MPLS VPN backbone solution is providing the Layer 2
service across the backbone, where R1 and R2 are connected
together directly using the same IP subnet.
 If you deploy a routing protocol over the Layer 2 MPLS VPN,
neighbor adjacency is established between your R1 and R2
routers. The figure presents the connectivity through the
backbone, which can be illustrated as one big switch.

Chapter 1
42
Routing Across MPLS VPNs
 The Layer 3 MPLS VPN backbone solution is providing the Layer 3
service across the backbone, where R1 and R2 are connected to
ISP edge routers.
 A separate IP subnet is used on each side. If you deploy a routing
protocol over this VPN, service providers need to participate in it.
 Neighbor adjacency is established between your R1 and the closest
PE router and between your R2 and it’s closest PE router.

Chapter 1
43
Routing Over GRE Tunnel
 A passenger protocol or encapsulated protocol, such as
IPv4 or IPv6 that is being encapsulated.
 A carrier protocol, GRE in this example, that is defined by
Cisco as a multiprotocol carrier protocol.
 A transport protocol, such as IP, that carries the
encapsulated protocol.

Chapter 1
44
Dynamic Multipoint Virtual Private Network

Chapter 1
45
DMVPN
The primary benefits of DMVPNs follow:
 Hub router configuration reduction
• Traditionally, the individual configuration of a GRE tunnel and IPsec would need to
be defined for each individual spoke router. The DMPVN feature enables the
configuration of a single mGRE tunnel interface and a single IPsec profile on the
hub router to manage all spoke routers
 Automatic IPsec initiation
• GRE uses NHRP to configure and resolve the peer destination address. This
feature allows IPsec to be immediately triggered to create point-to-point GRE
tunnels without any IPsec peering configuration.
 Support for dynamically addressed spoke routers
• When using point-to-point GRE and IPsec hub-and-spoke VPN networks, it is
important to know the physical interface IP address of the spoke routers when
configuring the hub router.
• DMVPN enables spoke routers to have dynamic physical interface IP addresses
and uses NHRP to register the dynamic physical interface IP addresses of the
spoke routers with the hub router.

Chapter 1
46
Multipoint GRE
The main characteristics of the mGRE configuration are as follows:
 Only one tunnel interface needs to be configured on a router to support
multiple remote GRE peers
 To learn the IP addresses of other peer, devices using mGRE require
NHRP to build dynamic GRE tunnels.
 mGRE interfaces also support unicast, multicast, and broadcast traffic.

Chapter 1
47
NHRP

Chapter 1
48
NHRP

Chapter 1
49
IPsec
IPsec provides four important security services:
 Confidentiality (encryption)
• No one can eavesdrop on the communication. If the communication is
intercepted, it cannot be read.
 Data integrity
• The receiver can verify that the data was transmitted through the path
without being changed or altered in any way.
 Authentication
• Authentication ensures that the connection is made with the desired
communication partner. IPsec uses Internet Key Exchange (IKE) to
authenticate users and devices that can carry out communication
independently.
 Antireplay protection
• Antireplay protection verifies that each packet is unique and not duplicated.

Chapter 1
50
Routing and
TCP/IP
Operations

Chapter 1
51
Routing and TCP/IP Operations
 MSS, Fragmentation, and PMTUD
 IPv4 Fragmentation and PMTUD
 Bandwidth Delay Product
 TCP Starvation
 Latency
 ICMP Redirect

Chapter 1
52
MSS, Fragmentation, and PMTUD
 An IPv4 packet has a maximum size of 65,535 bytes
 An IPv6 packet with a hop-by-hop extension header and the
jumbo payload option can support up to 4,294,967,295
bytes
 However, most transmission links enforce a smaller
maximum packet length called the maximum transmission
unit (MTU).
 When a router receives an IPv4 packet larger than the MTU
of the egress or outgoing interface, it must fragment the
packet unless the DF (Don’t Fragment) bit is set in the IPv4
header.

Chapter 1
53
MSS, Fragmentation, and PMTUD
Fragmentation causes several issues including the
following:
 CPU and memory overhead in fragmentation of the packet
 CPU and memory overhead in destination devices during
reassembly of packets
 Retransmission of the entire packet when one fragment is
dropped
 Firewalls that do Layer 4 through Layer 7 filtering may have
trouble processing IPv4 fragments correctly

Chapter 1
54
IPv4 Fragmentation and PMTUD
 TCP Maximum Segment Size (MSS) defines the largest amount
of data that the receiving device is able to accept in a single TCP
segment.
 To avoid fragmentation of an IPv4 packet, the selection of the
TCP MSS is the minimum buffer size and MTU of the outgoing
interface minus 40 bytes. The 40 bytes take into account the 20-
byte IPv4 header and the 20-byte TCP header.
 The TCP MSS helps avoid fragmentation at the two ends of the
TCP connection but it does not prevent fragmentation due to a
smaller MTU on a link along the path.
 Path MTU Discovery (PMTUD) was developed for the purpose
of determining the lowest MTU along a path from the packet’s
source to destination.
 PMTUD is only supported by TCP.

Chapter 1
58
ICMP Redirect
 ICMPV4 Redirect messages are used by routers to notify the sender of
a packet that there is a better route available for a particular destination.
 Similar to IPv4, R1 will forward the IPv6 packet to PCB, but unlike ICMP
for IPv4, it will send an ICMPv6 redirect message to PCA informing the
source of the better route. PCA can now send subsequent IPv6 packets
directly to PCB even though it is on a different IPv6 network.

Chapter 1
59
Implementing RIPng
 Describe general RIP characteristics
 Describe how to configure and verify basic RIPng
 Describe how to configure RIPng to share default routes
 Analyze the RIPng database

Chapter 1
60
RIP Overview
 RIP is an IGP that is used in smaller networks.
 It is a distance vector routing protocol that uses hop count
as a routing metric.
 There are three versions of RIP: RIPv1, RIPv2, and RIPng.
RIPv1 and RIPv2 route in IPv4 networks.
 RIPng routes in IPv6 networks.
 RIP is a standardized IGP routing protocol that works in a
mixed-vendor router environment.

Chapter 1
61
RIP Overview
 RIP uses hop count, the number of routers, as the metric.
 If a device has two paths to the destination network, the path
with fewer hops will be chosen as the path to forward traffic.
 If a network is 16 or more hops away, the router considers it
unreachable.

Chapter 1
62
RIP Overview
 As a routing loop-prevention technique, RIP implements
split horizon. Split horizon prevents routing information from
being sent out the same interface from which it was
received.
 Split horizon with poison reverse is a similar technique but
sends the update with a metric of 16, which is considered
unreachable by RIP.
 RIP is also capable of load balancing traffic over equal-cost
paths.
 The default is four equal-cost paths.
 If the maximum number of paths is set to one, load
balancing is disabled.

Chapter 1
63
Comparing Features in RIPv2 and RIPng

Chapter 1
64
RIPv2 Configuration

Chapter 1
65
RIPv2 Configuration
 By default, RIPv2 automatically summarizes networks at major
network boundaries, summarizing routes to the classful
network address
 When route summarization is disabled, the software sends
subnet routing information across classful network boundaries.
Router(config-router)# no auto-summary
 The ip summary-address rip ip-address network-mask
interface command is used to summarize an address or
subnet under a specific interface.
Router(config-if)# ip summary-address rip 10.2.0.0 255.255.0.0

Chapter 1
66
Configuring RIPng
R2(config)# ipv6 router rip CCNP_RIP

Chapter 1
67
Verify RIPng Configuration

Chapter 1
68
RIPng Summarization

Chapter 1
69
Propagating a Default Route
R1(config-if)# ipv6 rip name default-information originate | only

Chapter 1
70
RIPng Verification Commands

Chapter 1
71
RIPng Verification Commands

Chapter 1
72
Investigating the RIPng Database
 The RIP process (there can be multiple RIPng processes on a single router).
 The route prefix.
 The route metric, in which RIPng uses hop count as a metric. In the example, all three routes
have a metric of 2. This means the destination network is 2 hops away, counting itself as a hop.
 Installed and expired, in which the keyword “installed” means the route is in the routing table. If
a network becomes unavailable, the route will become “expired” after the dead timer expires. An
expired route value (in seconds), during which the route will be advertised as expired, is listed.
 Expires in, in which if the countdown timer reaches 0, the route is removed from the routing
table and marked expired. This timer, the dead timer, is by default three times the hello timer—
180 seconds.

Chapter 1
73
Chapter 1 Summary
 The role of static routes and dynamic routing protocols in enterprise networks.
 The differences between IGP and EGP routing protocols.
 The three types of routing protocols: distance vector, link-state and path vector.
 The importance of convergence time and how route summarization reduced convergence time and
improves scalability.
 The four traffic types: unicast, multicast, anycast, and broadcast.
 The differences between point-to-point, broadcast, and NBMA networks.
 How point-to-point subinterfaces are used to overcome the limitations of NBMA networks.
 How VPNs are used to provide security of a public Internet.
 Common types of VPNs: MPLS-based VPNs, GRE+IPsec, and DMVPN.
 How a customer establishes connectivity with a service provider using a routing protocol and a layer
3 MPLS VPN.
 How static GRE tunnels can establish virtual point-to-point links and support dynamic routing
protocols.
 Using DMVPN to provide fully meshed VPN connectivity with a simple hub-andspoke configuration.
 How DMVPN relies on NHRP, mGRE, and IPsec.
 The differences and similarities between RIPv2 and RIPng.
 How to configure RIPng.
 How to propagate a default route in RIPng.

Chapter 1
74
 CCNPv7_ROUTE_Lab1-1_RIPng
Chapter 1 Labs

Chapter 1
75

Chapter 1
76
Acknowledgment
• Some of images and texts are from Implementing Cisco IP Routing (ROUTE)
Foundation Learning Guide by Diane Teare, Bob Vachon and Rick Graziani
(1587204568)
• Copyright © 2015 – 2016 Cisco Systems, Inc.
• Special Thanks to Bruno Silva

en_ROUTE_v7_Ch01 (3)_Cisco ccna v7..pptx

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