How to implement eigrp on a network topology with three Cisco routers

Enhanced Interior Gateway Routing Protocol, popularly known as EIGRP, is a Cisco proprietary advanced distance vector routing protocol. Eigrp uses the diffusing update algorithm to calculate the shortest path to a network, and speeds up convergence time by keeping the best routes in the routing table and the second best routes in what is known as the eigrp topology table. If your routers are all Cisco routers, then you have no excuse not to use eigrp. In this post, we will look at how to implementation eigrp on a network topology with three Cisco routers.

Before we go into the configuration lab for implementing eigrp on a network topology with three Cisco routers, let’s look at a few key points about eigrp worth committing to memory.

  • Eigrp is Cisco proprietary, though there are talks to make it an industry-standard routing protocol but I am yet to come across it on other vendors routers. I stand to be corrected though.
  • Eigrp has a default administrative distance of 90.
  • Eigrp supports manual route summarization.
  • It supports variable length subnetmask, known as VLSM
  • It’s an advanced distance vector routing protocol. Some authors say it is a hybrid protocol since it also has some features of a link state routing protocol.
  • It has support for neighbor authentication.

Network topology

eigrp on network topology with three cisco routers

Eigrp on a network topology with three Cisco routers

Router0

Router0>en

Router0#conf t

Router0(config)#int s0/3/0

Router0(config-if)#ip add 192.168.4.1 255.255.255.252

Router0(config-if)#desc connection to Router1

Router0(config-if)#no shut

Router0(config-if)#int f0/0

Router0(config-if)#ip add 192.168.0.1 255.255.255.0

Router0(config-if)#desc connection to LAN

Router0(config-if)#no shut

Router0(config-if)#exit

Router0(config)#router eigrp 25

Router0(config-router)#netw 192.168.4.0 0.0.0.3

Router0(config-router)#netw 192.168.0.0 0.0.0.255

Router0(config-router)#no auto

Router0(config-router)#exit

Router0(config)#exit

Router0#copy run start

 

Router1

Router1>en

Router1#conf t

Router1(config)#int s0/3/0

Router1(config-if)#clock rate 64000

Router1(config-if)#ip add 192.168.4.2 255.255.255.252

Router1(config-if)#desc connection to Router0

Router1(config-if)#no shut

Router1(config-if)#int s0/2/0

Router1(config-if)#clock rate 64000

Router1(config-if)#ip add 192.168.4.5 255.255.255.252

Router1(config-if)#desc connection to Router2

Router1(config-if)#no shut

Router1(config-if)#int f0/0

Router1(config-if)#ip add 192.168.1.1 255.255.255.0

Router1(config-if)#desc connection to LAN

Router1(config-if)#no shut

Router1(config-if)#exit

Router1(config)#router eigrp 25

Router1(config-router)#netw 192.168.1.0 0.0.0.255

Router1(config-router)#netw 192.168.4.0 0.0.0.3

Router1(config-router)#netw 192.168.4.4 0.0.0.3

Router1(config-router)#exit

Router1(config)#exit

Router#copy run start

 

Router2

Router2>en

Router2#conf t

Router2(config)#int s0/3/0

Router2(config-if)#ip add 192.168.4.6 255.255.255.252

Router2(config-if)#desc connection to Router2

Router2(config-if)#no shut

Router2(config-if)#int f0/0

Router2(config-if)#ip add 192.168.2.1 255.255.255.0

Router2(config-if)#desc connection to LAN

Router2(config-if)#no shut

Router2(config-if)#exit

Router2(config)#router eigrp 25

Router2(config-router)#netw 192.168.4.4 0.0.0.3

Router2(config-router)#netw 192.168.2.0 0.0.0.255

Router2(config-router)#no auto

Router2(config-router)#exit

Router2(config)#exit

Router2#copy run start

Verification

To verify our configuration, I will use the “show ip eigrp neighbor” and “show ip route” commands on router1 to see the routers it has formed eigrp neighbor relationships with as well as the routes learned. See output from both commands below:

eigrp on network topology with three cisco routers eigrp on network topology with three cisco routers

The first image shows that Router1 has formed neighbor relationships with Router0 and Router2 (192.168.4.1 and 192.168.4.6) and that the LAN networks attached to both routers have been learned via eigrp. In the second image, ping tests to the IP addresses assigned to the f0/0 interfaces of Router0 and Router2 returned successfully, showing that we have full connectivity.

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Timigate

I believe that Africa will advance technologically if knowledge is shared among the living than out of greed, taken to the grave.

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