Enhanced Interior Gateway Routing Protocol (EIGRP) is a routing protocol used to select the best suitable route for packets within a network. Basically EIGRP is the enhanced version of IGRP protocols and developed by Cisco Systems. EIGRP uses a bandwidth and delay method to calculate the metric of a network route.
In its configuration, EIGRP may help you to enable authentication protect routing table. In this case, we will try to configure two different routers with routing protocol EIGRP and then perform the authentication between them using the IP authentication key-chain eigrp interface command.
We will use network topology of two different class network in given figure:
Configuration to Enable EIGRP on Router A:
A (config# router eigrp 210 // Enable EIGRP protocol and 20 is Autonomous number.
A (config-router)# network 172.16.15.4 //Advertised router A Serial Network 40.0.0.0.
A (config-router)# network 200.10.4.0 //Advertised router A Ethernet Network 210.100.10.0.
Configuration to Enable EIGRP on Router B:
B (config) # router eigrp 210 //Enable EIGRP protocol and 20 is Autonomous number.
B (config-router) # network 172.16.15.4 //Advertised router B Serial Network 40.0.0.0.
B (config-router) # network 200.10.50.0 //Advertised router B Ethernet Network 210.100.30.0 .
Now Configure EIGRP Authentication on Router A
A (config) # key chain myKey //Create the key chain name, eg. myKey.
A (config-keychain) # key 1 //Set the key number, eg. 1.
A (config-keychain-key) # key-string ironman //Set the key string, eg. “ironman”.
A (config-keychain-key) # end
Now specify the interface that you want to configure EIGRP message authentication.
A (config) # interface serial 0/0/0
A (config-if) # ip authentication key-chain eigrp 1 myKey
A (config-if) # ip authentication mode eigrp 1 md 5
A (config-if) # end
Now Configure EIGRP Authentication on Router B
B (config) # key chain myKey //Create the key chain name, eg. myKey.
B (config-keychain) # key 1 //Set the key number, eg. 1.
B (config-keychain-key) # key-string ironman //Set the key string, eg. “ironman”.
B (config-keychain-key) # end
Now specify the interface that you want to configure EIGRP message authentication.
B (config) # interface serial 0/0/0
B (config-if) # ip authentication key-chain eigrp 1 myKey
B (config-if) # ip authentication mode eigrp 1 md 5
B (config-if) # end
