EIGRP and OSPF Chapter 9 Objectives Enhanced IGRP

EIGRP and OSPF

Chapter 9 Objectives • Enhanced IGRP – EIGRP tables – Configuring EIGRP – Verifying EIGRP • Open Shortest Path First – Configuring OSPF – Verifying OSPF – Configuring OSPF with wildcards 2

What Is Enhanced IGRP (EIGRP)? • Supports IP and IPv 6 (and other routed protocols) via protocol dependent modules • Considered classless • Support for VLSM/CIDR • Support for summaries and discontiguous networks • Efficient neighbor discovery • Communication via Reliable Transport Protocol (RTP) • Best path selection via Diffusing Update Algorithm (DUAL)

EIGRP for IP • Route updates sent only when a change occurs – multicast on 224. 0. 0. 10 • Hello messages sent to neighbors every 5 seconds (60 seconds in most WANs) Enhanced IGRP EIGRP hello

EIGRP Terminology Neighbor Table—IP Next Hop Interface Router Topology Table—IP Destination 1 Successor Destination 1 Feasible Successor Routing Table—IP Destination 1 Successor Note: A feasible successor is a backup route and stored in the Topology table

EIGRP Tables • The neighbor table and topology table are held in RAM and are maintained through the use of hello and update packets. Enhanced IGRP EIGRP hello To see all feasible successor routes known to a router, use the show ip eigrp topology command

Successor routes • Successor route is used by EIGRP to forward traffic to a destination • A successor routes may be backed up by a feasible successor route • Successor routes are stored in both the topology table and the routing table Topology Table—IP Destination 1 Successor Destination 1 Feasible Successor Routing Table—IP Destination 1 Successor

Choosing Routes IP Apple. Talk A T 1 IPX B 19. 2 T 1 Apple. Talk IPX T 1 C IP D • EIGRP uses a composite metric to pick the best path: bandwidth and delay of the line • EIGRP can load balance across six unequal cost paths to a remote network (4 by default)

Configuring EIGRP for IP AS=10 A 10. 1. 0 B C 172. 16. 10. 0 192. 168. 0. 0 Enable EIGRP Router(config)#router eigrp 10 Assign networks Router(config-router)#network 10. 0 Router(config-router)#network 172. 16. 0. 0

Route Path Assuming all default parameters, which route will RIP (v 1 and v 2) take, and which route will EIGRP take? T 1 56 K 10 Base. T 100 Base. T

Verifying EIGRP Operation show ip route Shows the entire routing table show ip route eigrp Shows only EIGRP entries in the routing table show ip eigrp neighbors Shows all EIGRP neighbors show ip eigrp topology Shows entries in the EIGRP topology table show ip protocols Shows routing protocols configuration debug eigrp packet Shows Hello packets sent/received debug ip eigrp events Shows EIGRP changes and updates

Show IP Route P 1 R 1#sh ip route [output cut] Gateway of last resort is not set D 192. 168. 30. 0/24 [90/2172] via 192. 168. 20. 2, 00: 04: 36, Serial 0/0 C 192. 168. 10. 0/24 is directly connected, Fast. Ethernet 0/0 D 192. 168. 40. 0/24 [90/2681] via 192. 168. 20. 2, 00: 04: 36, Serial 0/0 C 192. 168. 20. 0/24 is directly connected, Serial 0/0 D 192. 168. 50. 0/24 [90/2707] via 192. 168. 20. 2, 00: 04: 35, Serial 0/0 P 1 R 1# D is for “Dual” [90/2172] is the administrative distance and cost of the route. The cost of the route is a composite metric comprised from the bandwidth and delay of the line

Introducing OSPF • • Open standard Shortest path first (SPF) algorithm Link-state routing protocol (vs. distance vector) Can be used to route between AS’s

OSPF Hierarchical Routing • Consists of areas and autonomous systems • Minimizes routing update traffic • Supports VLSM • Unlimited hop count

Link State Vs. Distance Vector Link State: • • Provides common view of entire topology Calculates shortest path Utilizes event-triggered updates Can be used to route between AS’s Distance Vector: • Exchanges routing tables with neighbors • Utilizes frequent periodic updates

Types of OSPF Routers Area 1 Backbone Area 0 Area 2 ABR and Backbone/ Router Internal Routers ASBR and Backbone Router • External AS ABR and Backbone Router

OSPF Terminology • Neighbor • Adjacency Neighbors ABR DR Adjacencies Non-DR Cost=6 BDR

OSFP Neighbors • OSPF uses hello packets to create adjacencies and maintain connectivity with neighbor routers • OSPF uses the multicast address 224. 0. 0. 5 Hello? 224. 0. 0. 5 • Hello packets provides dynamic neighbor discovery • Hello Packets maintains neighbor relationships • Hello packets and LSA’s from other routers help build and maintain the topological database

Configuring Single Area OSPF Router(config)#router ospf process-id Defines OSPF as the IP routing protocol Note: The process ID is locally significant and is needed to identify a unique instance of an OSPF database Router(config-router)#network address mask area-id Assigns networks to a specific OSPF area

OSPF Example R 2 10. 1. 3. 0 R 1 R 3 Area 0 10. 5. 5. 0 10. 1. 2. 0 10. 1. 1. 0 hostname R 3 hostname R 2 hostname R 1 router ospf 10 network 10. 1. 2. 3 0. 0 area 0 network 10. 1. 3. 1 0. 0 area 0 router ospf 20 network 10. 0 0. 255 area 0 router ospf 30 network 10. 1. 0. 0. 255 area 0 network 10. 5. 5. 1 0. 0 area 0

Configuring Wildcards If you want to advertise a partial octet (subnet), you need to use wildcards. – 0. 0 means all octets match exactly – 0. 0. 0. 255 means that the first three match exactly, but the last octet can be any value After that, you must remember your block sizes….

Wildcard The wildcard address is always one less than the block size…. – – 192. 168. 10. 8/30 = 0. 0. 0. 3 192. 168. 10. 48/28 = 0. 0. 0. 15 192. 168. 10. 96/27 = 0. 0. 0. 31 192. 168. 10. 128/26 = 0. 0. 0. 63

Wildcard Configuration of the Lab_B Router

Verifying the OSPF Configuration Router#show ip protocols Verifies that OSPF is configured Router#show ip route Displays all the routes learned by the router Router#show ip ospf interface Displays area-ID and adjacency information Router#show ip ospf neighbor Displays OSPF-neighbor information on a per-interface basis

Electing the DR and BDR Multicast Hellos are sent and compared Router with Highest Priority is Elected as DR Router with 2 nd Highest Priority is Elected as BDR • OSPF sends Hellos which elect DRs and BDRs • Router form adjacencies with DRs and BDRs in a multiaccess environment

Router ID (RID) Each router in OSPF needs to be uniquely identified to properly arrange them in the Neighbor tables.

Configuring Loopback Interfaces Router ID (RID): – Number by which the router is known to OSPF – Default: The highest IP address on an active interface at the moment of OSPF process startup – Can be overridden by a loopback interface: Highest IP address of any active loopback interface – also called a logical interface

Interface Priorities What is the default OSPF interface priority? Router# show ip ospf interface ethernet 0/0 Ethernet 0 is up, line protocol is up Internet Address 192. 168. 1. 137/29, Area 4 Process ID 19, Router ID 192. 168. 1. 137, Network Type BROADCAST, Cost: 10 Transmit Delay is 1 sec, State DR, Priority 1 Designated Router (ID) 192. 168. 1. 137, Interface address 192. 168. 1. 137 No backup designated router on this network Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00: 06 Index 2/2, flood queue length 0 Next 0 x 0(0)/0 x 0(0) Last flood scan length is 0, maximum is 0 Last flood scan time is 0 msec, maximum is 0 msec Neighbor Count is 0, Adjacent neighbor count is 0 Suppress hello for 0 neighbor(s)

Specifying a DR What options can you configure that will ensure that R 2 will be the DR of the LAN segment?

Summary Routes EIGRP Core(config)#router eigrp 10 Core(config-router)#network 192. 168. 10. 0 Core(config-router)#network 10. 0 Core(config-router)#no auto-summary Core(config-router)#interface ethernet 0 Core(config-if)#ip summary-address eigrp 10 192. 168. 10. 64 255. 224

Summary Routes OSPF Core#config t Core(config)#router ospf 1 Core(config-router)#network 192. 168. 10. 64 0. 0. 0. 3 area 1 Core(config-router)#network 192. 168. 10. 68 0. 0. 0. 3 area 1 Core(config-router)#network 10. 10. 0. 0. 255 area 0 Core(config-router)#area 1 range 192. 168. 10. 64 255. 224

Summary • Go through all the written and review questions • Go over the answers with the class 32