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The document discusses the implementation principles of networks connecting East and West London branches through a headquarters, focusing on scalable routing protocols like TCP/IP, OSPF, and BGP. It also covers the limitations and advancements of various routing protocols such as RIP, and emphasizes the importance of network scalability for large systems. Key concepts include the use of NAT to address IPv4 shortages and various types of network address translation.

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Implemention principles of East ToImplemention principles of East To West NetworksWest Networks Dr Ahmed Alneami British Institute of Technology and E-Commerce email:- drahmed@bite.ac.uk Web:- www.bite.ac.uk
NetworkTechnologyNetworkTechnology Final AssignmentFinal Assignment Submission Date: 6th of Dec. 2010 Configure a new network between East and West London branches through a headquater. East London West LondonHeadquarter
Outcomes of this lecture are:Outcomes of this lecture are: 1. Scalable Routing Protocols and (Scalable network) 2. TCP/IP (Transmission Control Protocol/Internet Protocol) 3. OSPF (Open Shortest Path First) 4. or BGP (Border Gateway Protocol) 5. DHCP (Dynamic Host Configuration Protocol) 6. NAT (Network Address Translation)
Web 2.0 Expo NYC, 16th September 2008 4 Scalability – myths and liesScalability – myths and lies What is scalability not ? ◦ Raw Speed / Performance ◦ HA / BCP ◦ Technology X ◦ ProtocolY
Web 2.0 Expo NYC, 16th September 2008 5 Scalability – myths and liesScalability – myths and lies So what is scalability?
Web 2.0 Expo NYC, 16th September 2008 6 Scalability – myths and liesScalability – myths and lies So what is scalability? ◦ Traffic growth ◦ Dataset growth ◦ Maintainability
Web 2.0 Expo NYC, 16th September 2008 7 TodayToday Two goals of application architecture: Scale HA
Web 2.0 Expo NYC, 16th September 2008 8 TodayToday Three goals of application architecture: Scale HA Performance
Web 2.0 Expo NYC, 16th September 2008 9 ScalabilityScalability Two kinds: ◦ Vertical (get bigger) ◦ Horizontal (get more) Network Scalability it is a a routing protocol developed for IP NKs. i.e Without a scalable routing system, a Nk may suffer from severe peformance penalties and proven by disastorus events in large network.
Web 2.0 Expo NYC, 16th September 2008 10 Big IronsBig Irons Sunfire E20k $450,000 - $2,500,000 36x 1.8GHz processors PowerEdge SC1435 Dualcore 1.8 GHz processor Around $1,500
Web 2.0 Expo NYC, 16th September 2008 11 Cost vs CostCost vs Cost See the uploaded Scalable –Rep file please.
Routing Information ProtocolRouting Information Protocol RIPRIP identify the best path to any given destination address. As IP-based networks became both more numerous and greater in size, it became apparent to the Internet Engineering Task Force (IETF) that RIP needed to be updated. RIP 2 enabled RIP messages to carry more information, which permitted the use of a simple authentication mechanism to secure table updates.
13 Router Router Router Router Router What is an optimal route ? What is an optimal route ? Switch Switch Routing Protocol
RIP Routing Metric •RIP uses a single routing metric (hop count) to measure the distance between the source and a destination network. •The IP address of the sender is used as the next hop. •RIP prevents routing loops from continuing indefinitely by implementing a limit on the number of hops allowed in a path from the source to a destination. Max 16 •RIP uses numerous timers to regulate its performance. These include a routing-update timer, a route-timeout timer, and a route-flush timer.
IP RIP packet format fields Command—Indicates whether the packet is a request or a response. The request asks that a router send all or part of its routing table. •Zero—This field is not actually used by RFC 1058 RIP; it was added solely to provide backward compatibility with prestandard varieties of RIP. Its name comes from its defaulted value: zero. •Address-family identifier (AFI)—Specifies the address family used. Each entry has an address-family identifier to indicate the type of address being specified. •Address—Specifies the IP address for the entry. •Metric—Indicates how many internetwork hops (routers) have been traversed in the trip to the destination. This value is between 1 and 15 for a valid route, or 16 for an unreachable route. •Version number—Specifies the RIP version used. This field can signal different potentially incompatible versions. See the uploaded RIP file please.
More details and slides later
The Open Shortest Path FirstThe Open Shortest Path First (OSPF) protocol(OSPF) protocol How OSPF works and how it can be used to design and build large and complicated networks.
Background InformationBackground Information It was found that Routing Information Protocol (RIP) incabable in serving the large hetrogeneous internetworks.
The Intermediate System-to-The Intermediate System-to- Intermediate System (IS-IS) routingIntermediate System (IS-IS) routing protocolprotocol The (IS-IS) routing protocol is an Interior Gateway Protocol (IGP) standardized by the Internet Engineering Task Force (IETF).  Commonly used in large Service Provider networks. IS-IS may also be deployed in extremely large Enterprise networks. IS-IS is a link-state routing protocol, providing fast convergence and excellent scalability. Like all link-state protocols, IS-IS is very efficient in its use of network bandwidth.
Intermediate Systems-to-Intermediate Systems-to- Intermediate Systems IS-ISIntermediate Systems IS-IS This is dynamic link state routing protocol All Intermediate Systems are routers, Routers are organised into local groups called Areas, Several Areas are grouped together into a “Domain”, IS-IS places area router into layer (no. 1) and the routers that interconnected the areas into layer 2.
Backbone Area (area 0) is the first area that will always exist in any network using OSPF. All other areas are connected to be the backbone either Directly or usingVirtual Links that “tunnel” through other areas. Each area is designated by an area number. All other areas described as having stubbiness
22 Path Determination GraphicPath Determination Graphic
23 Router Router Router Router Router What is an optimal route ? What is an optimal route ? Switch Switch Routing Protocol
24 Routing ProtocolsRouting Protocols Routing protocols includes the following: processes for sharing route information allows routers to communicate with other routers to update and maintain the routing tables Examples of routing protocols that support the IP routed protocol are: RIP, IGRP, OSPF, BGP, and EIGRP.
25 Routed ProtocolsRouted Protocols Protocols used at the network layer that transfer data from one host to another across a router are called routed or routable protocols. The Internet Protocol (IP) and Novell's Internetwork Packet Exchange (IPX) are examples of routed protocols. Routers use routing protocols to exchange routing tables and share routing information. In other words, routing protocols enable routers to route routed protocols.
26 Autonomous System AS 2000 AS 3000 IGP Interior Gateway Protocols are used for routing decisions within an Autonomous System. Exterior Gateway Protocols are used for routing between Autonomous Systems EGP AS 1000 An Autonomous System (AS) is a group of IP networks, which has a single and clearly defined external routing policy. Fig. 48 IGP and EGP (TI1332EU02TI_0004 The Network Layer, 67)
27 IGP Interior Gateway Protocol (IGP) Exterior Gateway Protocol (EGP) EGP EGP EGP Interior Gateway Protocol (IGP) AS 1000 AS 2000 AS 3000 Fig. 49 The use of IGP and EGP protocols (TI1332EU02TI_0004 The Network Layer, 67)
28 IGP and EGPIGP and EGP An autonomous system is a network or set of networks under common administrative control, such as the cisco.com domain.
29 Categories of Routing ProtocolsCategories of Routing Protocols Most routing algorithms can be classified into one of two categories: • distance vector • link-state The distance vector routing approach determines the direction (vector) and distance to any link in the internetwork. The link-state approach, also called shortest path first, recreates the exact topology of the entire internetwork.
30 DistanceVectorDistanceVector Routing ConceptsRouting Concepts
31 2 Hops 1 Hop1 Hop Destination 192.16.1.0 192.16.5.0 192.16.7.0 Distance 1 1 2 Routing table contains the addresses of destinations and the distance of the way to this destination. Flow of routing information Flow of routing information Router B Router CRouter A Router D 192.16.1.0192.16.1.0 192.16.7.0192.16.7.0 192.16.5.0192.16.5.0 Distance Vector Routing (DVR)
32 RoutingTables GraphicRoutingTables Graphic
33 DistanceVectorDistanceVector Topology ChangesTopology Changes
34 Router Metric ComponentsRouter Metric Components
35 RIPv1 Distance Vector Routing Protocol, classful Distribution of Routing Tables via broadcast to adjacent routers Only one kind of metric: Number of Hops Connections with different bandwidth can not be weighted Routing loops can occur -> bad convergence in case of a failure Count to infinity problem (infinity = 16) Maximum network size is limited by the number of hops Fig.59PropertiesofRIPv1(TI1332EU02TI_0004TheNetworkLayer,81)
36 RIP CharacteristicsRIP Characteristics
37 200.14.13.0/24200.14.13.0/24 130.24.13.0/24130.24.13.0/24 Router A Port 2 200.14.13.2/24 Port 2 200.14.13.2/24 Port 1 130.24.13.1/24 Port 1 130.24.13.1/24 130.24.36.0/24130.24.36.0/24 RIP-1: 130.24.36.0 RIP-1: 130.24.36.0 RIP-1: 130.24.0.0 130.24.25.0/24130.24.25.0/24 RIP-1 permits only a Single Subnet Mask Fig. 60 RIP-1 permits only a single subnet mask (TI1332EU02TI_0004 The Network Layer, 83)
38 Router ConfigurationRouter Configuration The router command starts a routing process. The network command is required because it enables the routing process to determine which interfaces participate in the sending and receiving of routing updates. An example of a routing configuration is: GAD(config)#router rip GAD(config-router)#network 172.16.0.0 The network numbers are based on the network class addresses, not subnet addresses or individual host addresses.
39 Configuring RIP ExampleConfiguring RIP Example
40 Verifying RIP ConfigurationVerifying RIP Configuration
41 The debug ip rip CommandThe debug ip rip Command Most of the RIP configuration errors involve an incorrect network statement, discontiguous subnets, or split horizons. One highly effective command for finding RIP update issues is the debug ip rip command. The debug ip rip command displays RIP routing updates as they are sent and received.
42 Problem: Routing LoopsProblem: Routing Loops Routing loops can occur when inconsistent routing tables are not updated due to slow convergence in a changing network.
43 Problem: Counting to InfinityProblem: Counting to Infinity
44 Solution: Define a MaximumSolution: Define a Maximum
45 Solution: Split HorizonSolution: Split Horizon
46 NATNAT Network AddressTranslatorNetwork AddressTranslator Fig. 3 NAT (TI1332EU02TI_0003 New Address Concepts, 7)
47 New addressing concepts Problems with IPv4 Shortage of IPv4 addresses Allocation of the last IPv4 addresses is forecasted for the year 2005 Address classes were replaced by usage of CIDR, but this is not sufficient Short term solution NAT: Network Address Translator Long term solution IPv6 = IPng (IP next generation) Provides an extended address range Fig. 2 Address shortage and possible solutions (TI1332EU02TI_0003 New Address Concepts, 5)
48 NAT: Network Address Translator NAT Translates between local addresses and public ones Many private hosts share few global addresses Public Network Uses public addresses Public addresses are globally unique Private Network Uses private address range (local addresses) Local addresses may not be used externally Fig. 4 How does NAT work? (TI1332EU02TI_0003 New Address Concepts, 9)
49 NAT To be translated exclude reserve pool exclude realm with private addresses NAT Router realm with public addresses map translate Fig. 5 Translation mechanism (TI1332EU02TI_0003 New Address Concepts, 9)
50 free NAT Pool A timeout value (default 15 min) instructs NAT how long to keep an association in an idle state before returning the external IP address to the free NAT pool. Fig. 8 How does NAT know when to return the public IP address to the pool? (TI1332EU02TI_0003 New Address Concepts, 15)
51 NAT Addressing TermsNAT Addressing Terms Inside Local ◦ The term “inside” refers to an address used for a host inside an enterprise. It is the actual IP address assigned to a host in the private enterprise network. Inside Global ◦ NAT uses an inside global address to represent the inside host as the packet is sent through the outside network, typically the Internet. ◦ A NAT router changes the source IP address of a packet sent by an inside host from an inside local address to an inside global address as the packet goes from the inside to the outside network.
52 NAT Addressing TermsNAT Addressing Terms Outside Global ◦ The term “outside” refers to an address used for a host outside an enterprise, the Internet. ◦ An outside global is the actual IP address assigned to a host that resides in the outside network, typically the Internet. Outside Local ◦ NAT uses an outside local address to represent the outside host as the packet is sent through the private enterprise network. ◦ A NAT router changes a packet’s destination IP address, sent from an outside global address to an inside host, as the packet goes from the outside to the inside network.
53 SIEMENSNIXDORF 10.47.10.10 192.50.20.5 WAN Net A Net B SIEMENSNIXDORF LAN LAN 192.50.20.0 10.0.0.0 Router Router RouterRouter Router SA = 10.47.10.10SA = 10.47.10.10 DA = 192.50.20.5DA = 192.50.20.5 SA = 193.50.30.4SA = 193.50.30.4 DA = 192.50.20.5DA = 192.50.20.5 Router A with NATRouter A with NAT Router BRouter B Fig. 7 An example for NAT (TI1332EU02TI_0003 New Address Concepts, 13)
54 WAN 138.76.29.7 SIEMENSNIXDORF Net A 10.0.0.0/8 Router Router Router SA = 10.0.0.10SA = 10.0.0.10 DA = 138.76.29.7DA = 138.76.29.7 SA = 138.76.28.4SA = 138.76.28.4 DA =138.76.29.7DA =138.76.29.7 NAT with WAN interface: 138.76.28.4 NAT with WAN interface: 138.76.28.4 SA = 138.76.29.7SA = 138.76.29.7 DA = 138.76.28.4DA = 138.76.28.4 SA = 138.76.29.7SA = 138.76.29.7 DA = 10.0.0.10DA = 10.0.0.10 10.0.0.10 SIEMENSNIXDORF Fig. 11 An example for NAPT (TI1332EU02TI_0003 New Address Concepts, 21)
55 Types Of NATTypes Of NAT There are different types of NAT that can be used, which are ◦ Static NAT ◦ Dynamic NAT ◦ Overloading NAT with PAT (NAPT)
56 Static NATStatic NAT With static NAT, the NAT router simply configures a one-to-one mapping between the private address and the registered address that is used on its behalf.
57 Dynamic NATDynamic NAT Like static NAT, the NAT router creates a one-to-one mapping between an inside local and inside global address and changes the IP addresses in packets as they exit and enter the inside network. However, the mapping of an inside local address to an inside global address happens dynamically.
58 Dynamic NATDynamic NAT Dynamic NAT sets up a pool of possible inside global addresses and defines criteria for the set of inside local IP addresses whose traffic should be translated with NAT. The dynamic entry in the NAT table stays in there as long as traffic flows occasionally. If a new packet arrives, and it needs a NAT entry, but all the pooled IP addresses are in use, the router simply discards the packet.
59 PATPAT Port Address TranslatorPort Address Translator Fig. 9 NAPT (TI1332EU02TI_0003 New Address Concepts, 17)
60 WAN 138.76.29.7 SIEMENSNIXDORF Net A 10.0.0.0/8 Router Router Router SA = 10.0.0.10, sport = 3017SA = 10.0.0.10, sport = 3017 DA = 138.76.29.7, dpor t= 23DA = 138.76.29.7, dpor t= 23 SA = 138.76.28.4, sport = 1024SA = 138.76.28.4, sport = 1024 DA =138.76.29.7, dpor t= 23DA =138.76.29.7, dpor t= 23 NAPT with WAN interface: 138.76.28.4 NAPT with WAN interface: 138.76.28.4 SA = 138.76.29.7, spor t= 23SA = 138.76.29.7, spor t= 23 DA = 138.76.28.4, dport = 1024DA = 138.76.28.4, dport = 1024 SA = 138.76.29.7, spor t= 23SA = 138.76.29.7, spor t= 23 DA = 10.0.0.10, dport = 3017DA = 10.0.0.10, dport = 3017 10.0.0.10 SIEMENSNIXDORF Fig. 11 An example for NAPT (TI1332EU02TI_0003 New Address Concepts, 21)
61 WAN private IP network (e.g. SOHO) registered IP @, assigned TU port # local IP @, local TU port # single public IP address mapping pool of TU port numbers PAT with e.g. a single public IP addressPAT with e.g. a single public IP address TU....TCP/UDP Fig. 10 NAPT (TI1332EU02TI_0003 New Address Concepts, 19)
62 NAT&PATNAT&PAT Network Address Translation &Network Address Translation & Port Address TransationPort Address Transation Fig. 3 NAT (TI1332EU02TI_0003 New Address Concepts, 7)
63 New addressing concepts Problems with IPv4 Shortage of IPv4 addresses Allocation of the last IPv4 addresses is forecasted for the year 2006 Address classes were replaced by usage of CIDR, but this is not sufficient Short term solution NAT: Network Address Translator Long term solution IPv6 = IPng (IP next generation) Provides an extended address range Fig. 2 Address shortage and possible solutions (TI1332EU02TI_0003 New Address Concepts, 5)
64 NAT: Network Address Translator NAT Translates between local addresses and public ones Many private hosts share few global addresses Public Network Uses public addresses Public addresses are globally unique Private Network Uses private address range (local addresses) Local addresses may not be used externally Fig. 4 How does NAT work? (TI1332EU02TI_0003 New Address Concepts, 9)
65 NAT To be translated exclude reserve pool exclude private addresses NAT Router public addresses map translate Fig. 5 Translation mechanism (TI1332EU02TI_0003 New Address Concepts, 9)
66 free NAT Pool A timeout value (default 15 min) instructs NAT how long to keep an association in an idle state before returning the external IP address to the free NAT pool. Fig. 8 How does NAT know when to return the public IP address to the pool? (TI1332EU02TI_0003 New Address Concepts, 15)
67 NAT Addressing TermsNAT Addressing Terms Inside Local “Private address” ◦ The term “inside” refers to an address used for a host inside an enterprise. It is the actual IP address assigned to a host in the private enterprise network. Inside Global “Public address” ◦ NAT uses an inside global address to represent the inside host as the packet is sent through the outside network, typically the WAN. ◦ A NAT router changes the source IP address of a packet sent by an inside host from an inside local address to an inside global address as the packet goes from the inside to the outside network. Fig. 2 Address shortage and possible solutions (TI1332EU02TI_0003 New Address Concepts, 5)
OSPF (Open Shortest Path First) Protocol © 2003, Cisco Systems, Inc. All rights reserved. 68
69 OSPF is a Link-OSPF is a Link-SState Routing Protocolstate Routing Protocols ◦ Link-state (LS) routers recognize much more information about the network than their distance-vector counterparts,Consequently LS routers tend to make more accurate decisions. ◦ Link-state routers keep track of the following:  Their neighbours  All routers within the same area  Best paths toward a destination
70 Link-Link-SState Data Structurestate Data Structures ◦ Neighbor table:  Also known as the adjacency database (list of recognized neighbors) ◦ Topology table:  Typically referred to as LSDB (routers and links in the area or network)  All routers within an area have an identical LSDB ◦ Routing table:  Commonly named a forwarding database (list of best paths to destinations)
71 OSPF vs. RIPOSPF vs. RIP RIP is limited to 15 hops, it converges slowly, and it sometimes chooses slow routes because it ignores critical factors such as bandwidth in route determination. OSPF overcomes these limitations and proves to be a robust and scalable routing protocol suitable for the networks of today.
72 OSPFTerminologyOSPFTerminology The next several slides explain various OSPF terms -one per slide.
73 OSPFTerm: LinkOSPFTerm: Link
74 OSPFTerm: Link StateOSPFTerm: Link State
75 OSPFTerm: AreaOSPFTerm: Area
76 OSPFTerm: Link CostOSPFTerm: Link Cost
77 OSPFTerm: Forwarding DatabaseOSPFTerm: Forwarding Database
78 OSPFTerm: Adjacencies DatabaseOSPFTerm: Adjacencies Database
79 OSPFTerms: DR & BDROSPFTerms: DR & BDR
80 LLink-ink-SStatetate Data StructureData Structure:: Network HierarchyNetwork Hierarchy Link-state routing requires a hierachical network structure that is enforced by OSPF. This two-level hierarchy consists of the following:  Transit area (backbone or area 0)  Regular areas (nonbackbone areas)
81 OSPF Areas
82 Area Terminology
83 LS Data StructureLS Data Structuress:: AdjacencyAdjacency DatabaseDatabase ◦ Routers discover neighbors by exchanging hello packets. ◦ Routers declare neighbors to be up after checking certain parameters or options in the hello packet. ◦ Point-to-point WAN links:  Both neighbors become fully adjacent. ◦ LAN links:  Neighbors form an adjacency with the DR and BDR.  Maintain two-way state with the other routers (DROTHERs). ◦ Routing updates and topology information are only passed between adjacent routers.
84 OSPF Adjacencies Routers build logical adjacencies between each other using the Hello Protocol. Once an adjacency is formed: • LS database packets are exchanged to synchronize each other’s LS databases. • LSAs are flooded reliably throughout the area or network using these adjacencies.
85 Open Shortest Path FirstOpen Shortest Path First CalculationCalculation Routers find the best paths to destinations by applying Dijkstra’s SPF algorithm to the link-state database as follows: ◦ Every router in an area has the identical link-state database. ◦ Each router in the area places itself into the root of the tree that is built. ◦ The best path is calculated with respect to the lowest total cost of links to a specific destination. ◦ Best routes are put into the forwarding database.
86 OSPF Packet Types
87 OSPF Packet Header Format
88 Neighborship
89 Establishing Bidirectional Communication
90 Establishing Bidirectional Communication (Cont.)
91 Establishing Bidirectional Communication (Cont.)
92 Establishing Bidirectional Communication
93 Discovering the Network Routes
94 Discovering the Network Routes
95 Adding the Link-State Entries
96 Adding the Link-State Entries (Cont.)
97 Adding the Link-State Entries
98 Maintaining Routing Information • Router A notifies all OSPF DRs on 224.0.0.6
99 Maintaining Routing Information (Cont.) • Router A notifies all OSPF DRs on 224.0.0.6 • DR notifies others on 224.0.0.5
100 Maintaining Routing Information (Cont.) • Router A notifies all OSPF DRs on 224.0.0.6 • DR notifies others on 224.0.0.5
101 Maintaining Routing Information • Router A notifies all OSPF DRs on 224.0.0.6 • DR notifies others on 224.0.0.5
102 router ospf process-idrouter ospf process-id Router(config)# • Turns on one or more OSPF routing processes in the IOS software. Configuring Basic OSPF: Single AreaConfiguring Basic OSPF: Single Area network address inverse-mask area [area-id]network address inverse-mask area [area-id] Router(config-router)# • Router OSPF subordinate command that defines the interfaces (by network number) that OSPF will run on. Each network number must be defined to a specific area.
103 Configuring OSPF on Internal Routers of a Single Area
104 show ip protocolsshow ip protocols Router# • Verifies the configured IP routing protocol processes, parameters and statistics Verifying OSPF OperationVerifying OSPF Operation show ip route ospfshow ip route ospf Router# • Displays all OSPF routes learned by the router show ip ospf interfaceshow ip ospf interface Router# • Displays the OSPF router ID, area ID and adjacency information
105 show ip ospfshow ip ospf Router# • Displays the OSPF router ID, timers, and statistics Verifying OSPF Operation (Cont.)Verifying OSPF Operation (Cont.) show ip ospf neighbor [detail]show ip ospf neighbor [detail] Router# • Displays information about the OSPF neighbors, including Designated Router (DR) and Backup Designated Router (BDR) information on broadcast networks
106 The show ip route ospf CommandThe show ip route ospf Command RouterA# show ip route ospf Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP, D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area, E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP, i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default Gateway of last resort is not set 10.0.0.0 255.255.255.0 is subnetted, 2 subnets O 10.2.1.0 [110/10] via 10.64.0.2, 00:00:50, Ethernet0
107 The show ip ospf interface CommandThe show ip ospf interface Command RouterA# show ip ospf interface e0 Ethernet0 is up, line protocol is up Internet Address 10.64.0.1/24, Area 0 Process ID 1, Router ID 10.64.0.1, Network Type BROADCAST, Cost: 10 Transmit Delay is 1 sec, State DROTHER, Priority 1 Designated Router (ID) 10.64.0.2, Interface address 10.64.0.2 Backup Designated router (ID) 10.64.0.1, Interface address 10.64.0.1 Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:04 Neighbor Count is 1, Adjacent neighbor count is 1 Adjacent with neighbor 10.64.0.2 (Designated Router) Suppress hello for 0 neighbor(s)
108 The show ip ospf neighbor CommandThe show ip ospf neighbor Command RouterB# show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.64.1.1 1 FULL/BDR 00:00:31 10.64.1.1 Ethernet0 10.2.1.1 1 FULL/- 00:00:38 10.2.1.1 Serial0
109 show ip protocolshow ip protocol show ip route
110 show ip ospf neighbor detailshow ip ospf neighbor detail show ip ospf database
111 OSPF NetworkTypes - 1OSPF NetworkTypes - 1
112 Point-to-Point Links • Usually a serial interface running either PPP or HDLC • May also be a point-to-point subinterface running Frame Relay or ATM • No DR or BDR election required • OSPF autodetects this interface type • OSPF packets are sent using multicast 224.0.0.5
113 Multi-access Broadcast Network • Generally LAN technologies like Ethernet and Token Ring • DR and BDR selection required • All neighbor routers form full adjacencies with the DR and BDR only • Packets to the DR use 224.0.0.6 • Packets from DR to all other routers use 224.0.0.5
114 Electing the DR and BDR • Hello packets are exchanged via IP multicast. • The router with the highest OSPF priority is selected as the DR. • Use the OSPF router ID as the tie breaker. • The DR election is nonpreemptive.
115 Setting Priority for DR ElectionSetting Priority for DR Election ip ospf priority numberip ospf priority number • This interface configuration command assigns the OSPF priority to an interface. • Different interfaces on a router may be assigned different values. • The default priority is 1. The range is from 0 to 255. • 0 means the router is a DROTHER; it can’t be the DR or BDR. Router(config-if)#
116 OSPF NetworkTypes - 2OSPF NetworkTypes - 2
117 Creation of AdjacenciesCreation of Adjacencies RouterA# debug ip ospf adj Point-to-point interfaces coming up: No election %LINK-3-UPDOWN: Interface Serial1, changed state to up OSPF: Interface Serial1 going Up OSPF: Rcv hello from 192.168.0.11 area 0 from Serial1 10.1.1.2 OSPF: End of hello processing OSPF: Build router LSA for area 0, router ID 192.168.0.10 OSPF: Rcv DBD from 192.168.0.11 on Serial1 seq 0x20C4 opt 0x2 flag 0x7 len 32 state INIT OSPF: 2 Way Communication to 192.168.0.11 on Serial1, state 2WAY OSPF: Send DBD to 192.168.0.11 on Serial1 seq 0x167F opt 0x2 flag 0x7 len 32 OSPF: NBR Negotiation Done. We are the SLAVE OSPF: Send DBD to 192.168.0.11 on Serial1 seq 0x20C4 opt 0x2 flag 0x2 len 72
118 Creation of Adjacencies (Cont.)Creation of Adjacencies (Cont.) RouterA# debug ip ospf adj Ethernet interface coming up: Election OSPF: 2 Way Communication to 192.168.0.10 on Ethernet0, state 2WAY OSPF: end of Wait on interface Ethernet0 OSPF: DR/BDR election on Ethernet0 OSPF: Elect BDR 192.168.0.12 OSPF: Elect DR 192.168.0.12 DR: 192.168.0.12 (Id) BDR: 192.168.0.12 (Id) OSPF: Send DBD to 192.168.0.12 on Ethernet0 seq 0x546 opt 0x2 flag 0x7 len 32 <…> OSPF: DR/BDR election on Ethernet0 OSPF: Elect BDR 192.168.0.11 OSPF: Elect DR 192.168.0.12 DR: 192.168.0.12 (Id) BDR: 192.168.0.11 (Id)

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ConfigureTwo networks principle

  • 1. Implemention principles of East ToImplemention principles of East To West NetworksWest Networks Dr Ahmed Alneami British Institute of Technology and E-Commerce email:- [email protected] Web:- www.bite.ac.uk
  • 2. NetworkTechnologyNetworkTechnology Final AssignmentFinal Assignment Submission Date: 6th of Dec. 2010 Configure a new network between East and West London branches through a headquater. East London West LondonHeadquarter
  • 3. Outcomes of this lecture are:Outcomes of this lecture are: 1. Scalable Routing Protocols and (Scalable network) 2. TCP/IP (Transmission Control Protocol/Internet Protocol) 3. OSPF (Open Shortest Path First) 4. or BGP (Border Gateway Protocol) 5. DHCP (Dynamic Host Configuration Protocol) 6. NAT (Network Address Translation)
  • 4. Web 2.0 Expo NYC, 16th September 2008 4 Scalability – myths and liesScalability – myths and lies What is scalability not ? ◦ Raw Speed / Performance ◦ HA / BCP ◦ Technology X ◦ ProtocolY
  • 5. Web 2.0 Expo NYC, 16th September 2008 5 Scalability – myths and liesScalability – myths and lies So what is scalability?
  • 6. Web 2.0 Expo NYC, 16th September 2008 6 Scalability – myths and liesScalability – myths and lies So what is scalability? ◦ Traffic growth ◦ Dataset growth ◦ Maintainability
  • 7. Web 2.0 Expo NYC, 16th September 2008 7 TodayToday Two goals of application architecture: Scale HA
  • 8. Web 2.0 Expo NYC, 16th September 2008 8 TodayToday Three goals of application architecture: Scale HA Performance
  • 9. Web 2.0 Expo NYC, 16th September 2008 9 ScalabilityScalability Two kinds: ◦ Vertical (get bigger) ◦ Horizontal (get more) Network Scalability it is a a routing protocol developed for IP NKs. i.e Without a scalable routing system, a Nk may suffer from severe peformance penalties and proven by disastorus events in large network.
  • 10. Web 2.0 Expo NYC, 16th September 2008 10 Big IronsBig Irons Sunfire E20k $450,000 - $2,500,000 36x 1.8GHz processors PowerEdge SC1435 Dualcore 1.8 GHz processor Around $1,500
  • 11. Web 2.0 Expo NYC, 16th September 2008 11 Cost vs CostCost vs Cost See the uploaded Scalable –Rep file please.
  • 12. Routing Information ProtocolRouting Information Protocol RIPRIP identify the best path to any given destination address. As IP-based networks became both more numerous and greater in size, it became apparent to the Internet Engineering Task Force (IETF) that RIP needed to be updated. RIP 2 enabled RIP messages to carry more information, which permitted the use of a simple authentication mechanism to secure table updates.
  • 13. 13 Router Router Router Router Router What is an optimal route ? What is an optimal route ? Switch Switch Routing Protocol
  • 14. RIP Routing Metric •RIP uses a single routing metric (hop count) to measure the distance between the source and a destination network. •The IP address of the sender is used as the next hop. •RIP prevents routing loops from continuing indefinitely by implementing a limit on the number of hops allowed in a path from the source to a destination. Max 16 •RIP uses numerous timers to regulate its performance. These include a routing-update timer, a route-timeout timer, and a route-flush timer.
  • 15. IP RIP packet format fields Command—Indicates whether the packet is a request or a response. The request asks that a router send all or part of its routing table. •Zero—This field is not actually used by RFC 1058 RIP; it was added solely to provide backward compatibility with prestandard varieties of RIP. Its name comes from its defaulted value: zero. •Address-family identifier (AFI)—Specifies the address family used. Each entry has an address-family identifier to indicate the type of address being specified. •Address—Specifies the IP address for the entry. •Metric—Indicates how many internetwork hops (routers) have been traversed in the trip to the destination. This value is between 1 and 15 for a valid route, or 16 for an unreachable route. •Version number—Specifies the RIP version used. This field can signal different potentially incompatible versions. See the uploaded RIP file please.
  • 17. The Open Shortest Path FirstThe Open Shortest Path First (OSPF) protocol(OSPF) protocol How OSPF works and how it can be used to design and build large and complicated networks.
  • 18. Background InformationBackground Information It was found that Routing Information Protocol (RIP) incabable in serving the large hetrogeneous internetworks.
  • 19. The Intermediate System-to-The Intermediate System-to- Intermediate System (IS-IS) routingIntermediate System (IS-IS) routing protocolprotocol The (IS-IS) routing protocol is an Interior Gateway Protocol (IGP) standardized by the Internet Engineering Task Force (IETF).  Commonly used in large Service Provider networks. IS-IS may also be deployed in extremely large Enterprise networks. IS-IS is a link-state routing protocol, providing fast convergence and excellent scalability. Like all link-state protocols, IS-IS is very efficient in its use of network bandwidth.
  • 20. Intermediate Systems-to-Intermediate Systems-to- Intermediate Systems IS-ISIntermediate Systems IS-IS This is dynamic link state routing protocol All Intermediate Systems are routers, Routers are organised into local groups called Areas, Several Areas are grouped together into a “Domain”, IS-IS places area router into layer (no. 1) and the routers that interconnected the areas into layer 2.
  • 21. Backbone Area (area 0) is the first area that will always exist in any network using OSPF. All other areas are connected to be the backbone either Directly or usingVirtual Links that “tunnel” through other areas. Each area is designated by an area number. All other areas described as having stubbiness
  • 22. 22 Path Determination GraphicPath Determination Graphic
  • 23. 23 Router Router Router Router Router What is an optimal route ? What is an optimal route ? Switch Switch Routing Protocol
  • 24. 24 Routing ProtocolsRouting Protocols Routing protocols includes the following: processes for sharing route information allows routers to communicate with other routers to update and maintain the routing tables Examples of routing protocols that support the IP routed protocol are: RIP, IGRP, OSPF, BGP, and EIGRP.
  • 25. 25 Routed ProtocolsRouted Protocols Protocols used at the network layer that transfer data from one host to another across a router are called routed or routable protocols. The Internet Protocol (IP) and Novell's Internetwork Packet Exchange (IPX) are examples of routed protocols. Routers use routing protocols to exchange routing tables and share routing information. In other words, routing protocols enable routers to route routed protocols.
  • 26. 26 Autonomous System AS 2000 AS 3000 IGP Interior Gateway Protocols are used for routing decisions within an Autonomous System. Exterior Gateway Protocols are used for routing between Autonomous Systems EGP AS 1000 An Autonomous System (AS) is a group of IP networks, which has a single and clearly defined external routing policy. Fig. 48 IGP and EGP (TI1332EU02TI_0004 The Network Layer, 67)
  • 27. 27 IGP Interior Gateway Protocol (IGP) Exterior Gateway Protocol (EGP) EGP EGP EGP Interior Gateway Protocol (IGP) AS 1000 AS 2000 AS 3000 Fig. 49 The use of IGP and EGP protocols (TI1332EU02TI_0004 The Network Layer, 67)
  • 28. 28 IGP and EGPIGP and EGP An autonomous system is a network or set of networks under common administrative control, such as the cisco.com domain.
  • 29. 29 Categories of Routing ProtocolsCategories of Routing Protocols Most routing algorithms can be classified into one of two categories: • distance vector • link-state The distance vector routing approach determines the direction (vector) and distance to any link in the internetwork. The link-state approach, also called shortest path first, recreates the exact topology of the entire internetwork.
  • 31. 31 2 Hops 1 Hop1 Hop Destination 192.16.1.0 192.16.5.0 192.16.7.0 Distance 1 1 2 Routing table contains the addresses of destinations and the distance of the way to this destination. Flow of routing information Flow of routing information Router B Router CRouter A Router D 192.16.1.0192.16.1.0 192.16.7.0192.16.7.0 192.16.5.0192.16.5.0 Distance Vector Routing (DVR)
  • 35. 35 RIPv1 Distance Vector Routing Protocol, classful Distribution of Routing Tables via broadcast to adjacent routers Only one kind of metric: Number of Hops Connections with different bandwidth can not be weighted Routing loops can occur -> bad convergence in case of a failure Count to infinity problem (infinity = 16) Maximum network size is limited by the number of hops Fig.59PropertiesofRIPv1(TI1332EU02TI_0004TheNetworkLayer,81)
  • 37. 37 200.14.13.0/24200.14.13.0/24 130.24.13.0/24130.24.13.0/24 Router A Port 2 200.14.13.2/24 Port 2 200.14.13.2/24 Port 1 130.24.13.1/24 Port 1 130.24.13.1/24 130.24.36.0/24130.24.36.0/24 RIP-1: 130.24.36.0 RIP-1: 130.24.36.0 RIP-1: 130.24.0.0 130.24.25.0/24130.24.25.0/24 RIP-1 permits only a Single Subnet Mask Fig. 60 RIP-1 permits only a single subnet mask (TI1332EU02TI_0004 The Network Layer, 83)
  • 38. 38 Router ConfigurationRouter Configuration The router command starts a routing process. The network command is required because it enables the routing process to determine which interfaces participate in the sending and receiving of routing updates. An example of a routing configuration is: GAD(config)#router rip GAD(config-router)#network 172.16.0.0 The network numbers are based on the network class addresses, not subnet addresses or individual host addresses.
  • 41. 41 The debug ip rip CommandThe debug ip rip Command Most of the RIP configuration errors involve an incorrect network statement, discontiguous subnets, or split horizons. One highly effective command for finding RIP update issues is the debug ip rip command. The debug ip rip command displays RIP routing updates as they are sent and received.
  • 42. 42 Problem: Routing LoopsProblem: Routing Loops Routing loops can occur when inconsistent routing tables are not updated due to slow convergence in a changing network.
  • 43. 43 Problem: Counting to InfinityProblem: Counting to Infinity
  • 44. 44 Solution: Define a MaximumSolution: Define a Maximum
  • 46. 46 NATNAT Network AddressTranslatorNetwork AddressTranslator Fig. 3 NAT (TI1332EU02TI_0003 New Address Concepts, 7)
  • 47. 47 New addressing concepts Problems with IPv4 Shortage of IPv4 addresses Allocation of the last IPv4 addresses is forecasted for the year 2005 Address classes were replaced by usage of CIDR, but this is not sufficient Short term solution NAT: Network Address Translator Long term solution IPv6 = IPng (IP next generation) Provides an extended address range Fig. 2 Address shortage and possible solutions (TI1332EU02TI_0003 New Address Concepts, 5)
  • 48. 48 NAT: Network Address Translator NAT Translates between local addresses and public ones Many private hosts share few global addresses Public Network Uses public addresses Public addresses are globally unique Private Network Uses private address range (local addresses) Local addresses may not be used externally Fig. 4 How does NAT work? (TI1332EU02TI_0003 New Address Concepts, 9)
  • 49. 49 NAT To be translated exclude reserve pool exclude realm with private addresses NAT Router realm with public addresses map translate Fig. 5 Translation mechanism (TI1332EU02TI_0003 New Address Concepts, 9)
  • 50. 50 free NAT Pool A timeout value (default 15 min) instructs NAT how long to keep an association in an idle state before returning the external IP address to the free NAT pool. Fig. 8 How does NAT know when to return the public IP address to the pool? (TI1332EU02TI_0003 New Address Concepts, 15)
  • 51. 51 NAT Addressing TermsNAT Addressing Terms Inside Local ◦ The term “inside” refers to an address used for a host inside an enterprise. It is the actual IP address assigned to a host in the private enterprise network. Inside Global ◦ NAT uses an inside global address to represent the inside host as the packet is sent through the outside network, typically the Internet. ◦ A NAT router changes the source IP address of a packet sent by an inside host from an inside local address to an inside global address as the packet goes from the inside to the outside network.
  • 52. 52 NAT Addressing TermsNAT Addressing Terms Outside Global ◦ The term “outside” refers to an address used for a host outside an enterprise, the Internet. ◦ An outside global is the actual IP address assigned to a host that resides in the outside network, typically the Internet. Outside Local ◦ NAT uses an outside local address to represent the outside host as the packet is sent through the private enterprise network. ◦ A NAT router changes a packet’s destination IP address, sent from an outside global address to an inside host, as the packet goes from the outside to the inside network.
  • 53. 53 SIEMENSNIXDORF 10.47.10.10 192.50.20.5 WAN Net A Net B SIEMENSNIXDORF LAN LAN 192.50.20.0 10.0.0.0 Router Router RouterRouter Router SA = 10.47.10.10SA = 10.47.10.10 DA = 192.50.20.5DA = 192.50.20.5 SA = 193.50.30.4SA = 193.50.30.4 DA = 192.50.20.5DA = 192.50.20.5 Router A with NATRouter A with NAT Router BRouter B Fig. 7 An example for NAT (TI1332EU02TI_0003 New Address Concepts, 13)
  • 54. 54 WAN 138.76.29.7 SIEMENSNIXDORF Net A 10.0.0.0/8 Router Router Router SA = 10.0.0.10SA = 10.0.0.10 DA = 138.76.29.7DA = 138.76.29.7 SA = 138.76.28.4SA = 138.76.28.4 DA =138.76.29.7DA =138.76.29.7 NAT with WAN interface: 138.76.28.4 NAT with WAN interface: 138.76.28.4 SA = 138.76.29.7SA = 138.76.29.7 DA = 138.76.28.4DA = 138.76.28.4 SA = 138.76.29.7SA = 138.76.29.7 DA = 10.0.0.10DA = 10.0.0.10 10.0.0.10 SIEMENSNIXDORF Fig. 11 An example for NAPT (TI1332EU02TI_0003 New Address Concepts, 21)
  • 55. 55 Types Of NATTypes Of NAT There are different types of NAT that can be used, which are ◦ Static NAT ◦ Dynamic NAT ◦ Overloading NAT with PAT (NAPT)
  • 56. 56 Static NATStatic NAT With static NAT, the NAT router simply configures a one-to-one mapping between the private address and the registered address that is used on its behalf.
  • 57. 57 Dynamic NATDynamic NAT Like static NAT, the NAT router creates a one-to-one mapping between an inside local and inside global address and changes the IP addresses in packets as they exit and enter the inside network. However, the mapping of an inside local address to an inside global address happens dynamically.
  • 58. 58 Dynamic NATDynamic NAT Dynamic NAT sets up a pool of possible inside global addresses and defines criteria for the set of inside local IP addresses whose traffic should be translated with NAT. The dynamic entry in the NAT table stays in there as long as traffic flows occasionally. If a new packet arrives, and it needs a NAT entry, but all the pooled IP addresses are in use, the router simply discards the packet.
  • 59. 59 PATPAT Port Address TranslatorPort Address Translator Fig. 9 NAPT (TI1332EU02TI_0003 New Address Concepts, 17)
  • 60. 60 WAN 138.76.29.7 SIEMENSNIXDORF Net A 10.0.0.0/8 Router Router Router SA = 10.0.0.10, sport = 3017SA = 10.0.0.10, sport = 3017 DA = 138.76.29.7, dpor t= 23DA = 138.76.29.7, dpor t= 23 SA = 138.76.28.4, sport = 1024SA = 138.76.28.4, sport = 1024 DA =138.76.29.7, dpor t= 23DA =138.76.29.7, dpor t= 23 NAPT with WAN interface: 138.76.28.4 NAPT with WAN interface: 138.76.28.4 SA = 138.76.29.7, spor t= 23SA = 138.76.29.7, spor t= 23 DA = 138.76.28.4, dport = 1024DA = 138.76.28.4, dport = 1024 SA = 138.76.29.7, spor t= 23SA = 138.76.29.7, spor t= 23 DA = 10.0.0.10, dport = 3017DA = 10.0.0.10, dport = 3017 10.0.0.10 SIEMENSNIXDORF Fig. 11 An example for NAPT (TI1332EU02TI_0003 New Address Concepts, 21)
  • 61. 61 WAN private IP network (e.g. SOHO) registered IP @, assigned TU port # local IP @, local TU port # single public IP address mapping pool of TU port numbers PAT with e.g. a single public IP addressPAT with e.g. a single public IP address TU....TCP/UDP Fig. 10 NAPT (TI1332EU02TI_0003 New Address Concepts, 19)
  • 62. 62 NAT&PATNAT&PAT Network Address Translation &Network Address Translation & Port Address TransationPort Address Transation Fig. 3 NAT (TI1332EU02TI_0003 New Address Concepts, 7)
  • 63. 63 New addressing concepts Problems with IPv4 Shortage of IPv4 addresses Allocation of the last IPv4 addresses is forecasted for the year 2006 Address classes were replaced by usage of CIDR, but this is not sufficient Short term solution NAT: Network Address Translator Long term solution IPv6 = IPng (IP next generation) Provides an extended address range Fig. 2 Address shortage and possible solutions (TI1332EU02TI_0003 New Address Concepts, 5)
  • 64. 64 NAT: Network Address Translator NAT Translates between local addresses and public ones Many private hosts share few global addresses Public Network Uses public addresses Public addresses are globally unique Private Network Uses private address range (local addresses) Local addresses may not be used externally Fig. 4 How does NAT work? (TI1332EU02TI_0003 New Address Concepts, 9)
  • 65. 65 NAT To be translated exclude reserve pool exclude private addresses NAT Router public addresses map translate Fig. 5 Translation mechanism (TI1332EU02TI_0003 New Address Concepts, 9)
  • 66. 66 free NAT Pool A timeout value (default 15 min) instructs NAT how long to keep an association in an idle state before returning the external IP address to the free NAT pool. Fig. 8 How does NAT know when to return the public IP address to the pool? (TI1332EU02TI_0003 New Address Concepts, 15)
  • 67. 67 NAT Addressing TermsNAT Addressing Terms Inside Local “Private address” ◦ The term “inside” refers to an address used for a host inside an enterprise. It is the actual IP address assigned to a host in the private enterprise network. Inside Global “Public address” ◦ NAT uses an inside global address to represent the inside host as the packet is sent through the outside network, typically the WAN. ◦ A NAT router changes the source IP address of a packet sent by an inside host from an inside local address to an inside global address as the packet goes from the inside to the outside network. Fig. 2 Address shortage and possible solutions (TI1332EU02TI_0003 New Address Concepts, 5)
  • 68. OSPF (Open Shortest Path First) Protocol © 2003, Cisco Systems, Inc. All rights reserved. 68
  • 69. 69 OSPF is a Link-OSPF is a Link-SState Routing Protocolstate Routing Protocols ◦ Link-state (LS) routers recognize much more information about the network than their distance-vector counterparts,Consequently LS routers tend to make more accurate decisions. ◦ Link-state routers keep track of the following:  Their neighbours  All routers within the same area  Best paths toward a destination
  • 70. 70 Link-Link-SState Data Structurestate Data Structures ◦ Neighbor table:  Also known as the adjacency database (list of recognized neighbors) ◦ Topology table:  Typically referred to as LSDB (routers and links in the area or network)  All routers within an area have an identical LSDB ◦ Routing table:  Commonly named a forwarding database (list of best paths to destinations)
  • 71. 71 OSPF vs. RIPOSPF vs. RIP RIP is limited to 15 hops, it converges slowly, and it sometimes chooses slow routes because it ignores critical factors such as bandwidth in route determination. OSPF overcomes these limitations and proves to be a robust and scalable routing protocol suitable for the networks of today.
  • 72. 72 OSPFTerminologyOSPFTerminology The next several slides explain various OSPF terms -one per slide.
  • 79. 79 OSPFTerms: DR & BDROSPFTerms: DR & BDR
  • 80. 80 LLink-ink-SStatetate Data StructureData Structure:: Network HierarchyNetwork Hierarchy Link-state routing requires a hierachical network structure that is enforced by OSPF. This two-level hierarchy consists of the following:  Transit area (backbone or area 0)  Regular areas (nonbackbone areas)
  • 83. 83 LS Data StructureLS Data Structuress:: AdjacencyAdjacency DatabaseDatabase ◦ Routers discover neighbors by exchanging hello packets. ◦ Routers declare neighbors to be up after checking certain parameters or options in the hello packet. ◦ Point-to-point WAN links:  Both neighbors become fully adjacent. ◦ LAN links:  Neighbors form an adjacency with the DR and BDR.  Maintain two-way state with the other routers (DROTHERs). ◦ Routing updates and topology information are only passed between adjacent routers.
  • 84. 84 OSPF Adjacencies Routers build logical adjacencies between each other using the Hello Protocol. Once an adjacency is formed: • LS database packets are exchanged to synchronize each other’s LS databases. • LSAs are flooded reliably throughout the area or network using these adjacencies.
  • 85. 85 Open Shortest Path FirstOpen Shortest Path First CalculationCalculation Routers find the best paths to destinations by applying Dijkstra’s SPF algorithm to the link-state database as follows: ◦ Every router in an area has the identical link-state database. ◦ Each router in the area places itself into the root of the tree that is built. ◦ The best path is calculated with respect to the lowest total cost of links to a specific destination. ◦ Best routes are put into the forwarding database.
  • 96. 96 Adding the Link-State Entries (Cont.)
  • 98. 98 Maintaining Routing Information • Router A notifies all OSPF DRs on 224.0.0.6
  • 99. 99 Maintaining Routing Information (Cont.) • Router A notifies all OSPF DRs on 224.0.0.6 • DR notifies others on 224.0.0.5
  • 100. 100 Maintaining Routing Information (Cont.) • Router A notifies all OSPF DRs on 224.0.0.6 • DR notifies others on 224.0.0.5
  • 101. 101 Maintaining Routing Information • Router A notifies all OSPF DRs on 224.0.0.6 • DR notifies others on 224.0.0.5
  • 102. 102 router ospf process-idrouter ospf process-id Router(config)# • Turns on one or more OSPF routing processes in the IOS software. Configuring Basic OSPF: Single AreaConfiguring Basic OSPF: Single Area network address inverse-mask area [area-id]network address inverse-mask area [area-id] Router(config-router)# • Router OSPF subordinate command that defines the interfaces (by network number) that OSPF will run on. Each network number must be defined to a specific area.
  • 103. 103 Configuring OSPF on Internal Routers of a Single Area
  • 104. 104 show ip protocolsshow ip protocols Router# • Verifies the configured IP routing protocol processes, parameters and statistics Verifying OSPF OperationVerifying OSPF Operation show ip route ospfshow ip route ospf Router# • Displays all OSPF routes learned by the router show ip ospf interfaceshow ip ospf interface Router# • Displays the OSPF router ID, area ID and adjacency information
  • 105. 105 show ip ospfshow ip ospf Router# • Displays the OSPF router ID, timers, and statistics Verifying OSPF Operation (Cont.)Verifying OSPF Operation (Cont.) show ip ospf neighbor [detail]show ip ospf neighbor [detail] Router# • Displays information about the OSPF neighbors, including Designated Router (DR) and Backup Designated Router (BDR) information on broadcast networks
  • 106. 106 The show ip route ospf CommandThe show ip route ospf Command RouterA# show ip route ospf Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP, D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area, E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP, i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default Gateway of last resort is not set 10.0.0.0 255.255.255.0 is subnetted, 2 subnets O 10.2.1.0 [110/10] via 10.64.0.2, 00:00:50, Ethernet0
  • 107. 107 The show ip ospf interface CommandThe show ip ospf interface Command RouterA# show ip ospf interface e0 Ethernet0 is up, line protocol is up Internet Address 10.64.0.1/24, Area 0 Process ID 1, Router ID 10.64.0.1, Network Type BROADCAST, Cost: 10 Transmit Delay is 1 sec, State DROTHER, Priority 1 Designated Router (ID) 10.64.0.2, Interface address 10.64.0.2 Backup Designated router (ID) 10.64.0.1, Interface address 10.64.0.1 Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:04 Neighbor Count is 1, Adjacent neighbor count is 1 Adjacent with neighbor 10.64.0.2 (Designated Router) Suppress hello for 0 neighbor(s)
  • 108. 108 The show ip ospf neighbor CommandThe show ip ospf neighbor Command RouterB# show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.64.1.1 1 FULL/BDR 00:00:31 10.64.1.1 Ethernet0 10.2.1.1 1 FULL/- 00:00:38 10.2.1.1 Serial0
  • 109. 109 show ip protocolshow ip protocol show ip route
  • 110. 110 show ip ospf neighbor detailshow ip ospf neighbor detail show ip ospf database
  • 111. 111 OSPF NetworkTypes - 1OSPF NetworkTypes - 1
  • 112. 112 Point-to-Point Links • Usually a serial interface running either PPP or HDLC • May also be a point-to-point subinterface running Frame Relay or ATM • No DR or BDR election required • OSPF autodetects this interface type • OSPF packets are sent using multicast 224.0.0.5
  • 113. 113 Multi-access Broadcast Network • Generally LAN technologies like Ethernet and Token Ring • DR and BDR selection required • All neighbor routers form full adjacencies with the DR and BDR only • Packets to the DR use 224.0.0.6 • Packets from DR to all other routers use 224.0.0.5
  • 114. 114 Electing the DR and BDR • Hello packets are exchanged via IP multicast. • The router with the highest OSPF priority is selected as the DR. • Use the OSPF router ID as the tie breaker. • The DR election is nonpreemptive.
  • 115. 115 Setting Priority for DR ElectionSetting Priority for DR Election ip ospf priority numberip ospf priority number • This interface configuration command assigns the OSPF priority to an interface. • Different interfaces on a router may be assigned different values. • The default priority is 1. The range is from 0 to 255. • 0 means the router is a DROTHER; it can’t be the DR or BDR. Router(config-if)#
  • 116. 116 OSPF NetworkTypes - 2OSPF NetworkTypes - 2
  • 117. 117 Creation of AdjacenciesCreation of Adjacencies RouterA# debug ip ospf adj Point-to-point interfaces coming up: No election %LINK-3-UPDOWN: Interface Serial1, changed state to up OSPF: Interface Serial1 going Up OSPF: Rcv hello from 192.168.0.11 area 0 from Serial1 10.1.1.2 OSPF: End of hello processing OSPF: Build router LSA for area 0, router ID 192.168.0.10 OSPF: Rcv DBD from 192.168.0.11 on Serial1 seq 0x20C4 opt 0x2 flag 0x7 len 32 state INIT OSPF: 2 Way Communication to 192.168.0.11 on Serial1, state 2WAY OSPF: Send DBD to 192.168.0.11 on Serial1 seq 0x167F opt 0x2 flag 0x7 len 32 OSPF: NBR Negotiation Done. We are the SLAVE OSPF: Send DBD to 192.168.0.11 on Serial1 seq 0x20C4 opt 0x2 flag 0x2 len 72
  • 118. 118 Creation of Adjacencies (Cont.)Creation of Adjacencies (Cont.) RouterA# debug ip ospf adj Ethernet interface coming up: Election OSPF: 2 Way Communication to 192.168.0.10 on Ethernet0, state 2WAY OSPF: end of Wait on interface Ethernet0 OSPF: DR/BDR election on Ethernet0 OSPF: Elect BDR 192.168.0.12 OSPF: Elect DR 192.168.0.12 DR: 192.168.0.12 (Id) BDR: 192.168.0.12 (Id) OSPF: Send DBD to 192.168.0.12 on Ethernet0 seq 0x546 opt 0x2 flag 0x7 len 32 <…> OSPF: DR/BDR election on Ethernet0 OSPF: Elect BDR 192.168.0.11 OSPF: Elect DR 192.168.0.12 DR: 192.168.0.12 (Id) BDR: 192.168.0.11 (Id)