EIGRP Configuration Guide

Configuring EIGRP involves enabling the protocol on the router and specifying the networks to be advertised. Here's a basic guide:

Basic EIGRP Configuration:

Router(config)# router eigrp <AS-number>
Router(config-router)# network <network-address> [wildcard-mask]
Router(config-router)# no auto-summary

• <AS-number>: Autonomous System number. All routers in the same EIGRP domain must use the same AS number.
• network <network-address> [wildcard-mask]: Advertises directly connected networks. The wildcard mask is optional but recommended for precise network advertisement.
• no auto-summary: Disables automatic summarization of routes at classful network boundaries. This is highly recommended in modern networks to prevent routing issues.

Passive Interface:

To prevent EIGRP from sending Hello packets and updates out of an interface, but still advertise the network connected to it:

Router(config-router)# passive-interface <interface-type> <interface-number>

EIGRP Authentication:

To secure EIGRP updates, MD5 authentication can be configured:

Router(config)# key chain <key-chain-name>
Router(config-keychain)# key 1
Router(config-keychain-key)# key-string <password>
Router(config-keychain-key)# exit
Router(config-router)# interface <interface-type> <interface-number>
Router(config-if)# ip authentication mode eigrp <AS-number> md5
Router(config-if)# ip authentication key-chain eigrp <AS-number> <key-chain-name>

Verifying EIGRP:

Useful commands to verify EIGRP operation:

• show ip eigrp neighbors: Displays EIGRP neighbors.
• show ip eigrp topology: Shows the EIGRP topology table, including feasible successors.
• show ip route eigrp: Displays EIGRP routes in the routing table.
• show ip protocols: Provides information about active routing protocols.