EIGRP is one of the routing protocols you must master if you want to pass the Cisco CCNA exam. In this lesson, I’ll walk you through the configuration. If you have no idea what EIGRP is or how it works, you should read my Introduction to EIGRP first. This is the topology that we will use:
In the topology above, I have four routers. All interfaces are FastEthernet with the exception of the link between R1 and R2. That’s where we use an Ethernet link. Behind R4, there is a loopback interface.
Let’s start by configuring EIGRP between R1 and R3:
R1(config)#router eigrp 1 R1(config-router)#no auto-summary R1(config-router)#network 192.168.13.0
R3(config)#router eigrp 1 R3(config-router)#no auto-summary R3(config-router)#network 192.168.13.0
Configuring EIGRP is similar to RIP. The “1” is the AS number, and it has to be the same on all routers! We require the no auto-summary command because by default EIGRP behaves classful, and we want it to be classless.
no auto-summaryis enabled by default since IOS 15.
After typing in these commands, this is what you will see:
R1# %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 192.168.13.3 (FastEthernet0/0) is up: new adjacency
R3# %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 192.168.13.1 (FastEthernet0/0) is up: new adjacency
Our routers have become EIGRP neighbors. We can also verify this with a command:
R1#show ip eigrp neighbors IP-EIGRP neighbors for process 1 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 0 192.168.13.3 Fa0/0 12 00:11:58 1275 5000 0 3
R3#show ip eigrp neighbors IP-EIGRP neighbors for process 1 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 0 192.168.13.1 Fa0/0 14 00:11:47 15 200 0 3
show ip eigrp neighbors to verify that we have a working EIGRP neighbor adjacency. This seems to be the case.
Let’s configure all the network commands, so all routers become EIGRP neighbors and advertise their networks: