Tuesday, September 20, 2011

CCNP - ENTERPRISE - EIGRP Troubleshooting Targets

For EIGRP issues look to the following:

- If Adjacencies are not forming check:
Timers match, AS number matches
In Frame-Relay topologies check that you have included the 'broadcast' option to allow the multicast packets that are sent to to be forwarded.
Check for any ACL's blocking EIGRP specifically or the subnets in general
Check that the router interfaces are up, you can ping the neighbour ( if it isn't up then troubleshoot the interface config as appropriate)

- If Static/Dynamic routes are not being redistributed in to EIGRP check:
Routes learned by EIGRP are in the Routing Table
Check the EIGRP topology table to see if the route was learned at all
Check the EIGRP config to ensure you are advertising the correct networks
Are there any Distribution Lists filtering your network?
For discontiguous networks check that no auto-summary is applied.

- For the Error 'Not on common Subnet' check:
IP addressing the interfaces that should be forming an adjacency.
Remember EIGRP packets are sourced from the Primary IP address on the interface. As such you can't use a Secondary IP to form the adjacency.

- If Load Balancing does not operate as expected check:
Ensure you have correctly used the Variance command in the Router process (not at the interface)

- Do you get 'Stuck in Active' (SIA) errors?
Check that the router has enough resources to respond to EIGRP updates (#sh processes cpu)
Check the bandwidth parameter on the interface is set correctly
Check #sh interfaces for interface resets, input/output errors.
If you do observe these issues look at hardware upgrades.

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