Content

| 5.6 |  | Troubleshooting EIGRP |
| 5.6.2 |  | Mismatched AS number |

EIGRP will not form any neighbor relationships with routers that have different autonomous system numbers. If the AS numbers are mismatched, no adjacency is formed. This problem is usually caused by misconfiguration on the routers.

Figure shows two routers running EIGRP.

Debugs and Verification
Figure shows the configurations of both routers. Because the two routers have different AS numbers, using the command show ip eigrp neighbors on both RTR A and RTB B would show an empty list.

Solution
The solution is to modify one of the two routers so the AS numbers are the same. Figure shows both routers configured with the same AS number, EIGRP AS 1. At this point, both routers will be able to establish a neighbor relationship and exchange routing information.