Use the router eigrp autonomous-system command to enable the EIGRP routing process:

R1(config)#router eigrp 100

To exchange routing updates, each router in the EIGRP network must be configured with the same autonomous system number.

Use the router configuration network network-number command to enable interfaces to participate in the EIGRP update process:

R1(config-router)#network 172.30.0.0
R1(config-router)#network 192.168.3.0

Verify EIGRP configuration with the show running-configuration and show ip protocols commands:

R1#show ip protocols

Some possible reasons why EIGRP may not be working correctly are:

• Layer 1 or Layer 2 connectivity issues exist.
• Autonomous system numbers on EIGRP routers are mismatched.
• The link may be congested or down.
• The outgoing interface is down.
• The advertised network interface is down.
• Auto-summarization is enabled on routers with discontiguous subnets.
• Use no auto-summary to disable automatic network summarization.

One of the most common reasons for a missing neighbor is a failure on the actual link. Another possible cause of missing neighbors is an expired holddown timer. Since hellos are sent every 5 seconds on most networks, the hold-time value in a show ip eigrp neighbors command output should normally be a value between 10 and 15.

To effectively monitor and troubleshoot an EIGRP network, use the commands described in Figures - .

Web Links Troubleshooting EIGRP http://www.cisco.com/en/US/tech/ tk826/tk365/technologies_tech_note 09186a0080094613.shtml