The EIGRP (Enhanced Interior Gateway Routing Protocol) protocol is sometimes referred to as a hybrid routing protocol because it got features of both link-state and distance vector routing protocols. So, with a growing network, the EIGRP also continues to perform along with it but the scalability may bring complexity in design, configuration, and maintenance.
The main characteristic of troubleshooting routing protocols is ensuring that communication flows between two routers. It is important to follow a defined methodology or flow for troubleshooting a networking protocol. The basic EIGRP connectivity test can be done using the ping command to check if you get any response. There are other major components to consider for EIGRP troubleshooting mentioned below.
- EIGRP Neighbor Relationships: In this step, we troubleshoot neighbor relationships using the commands –
- show ip eigrp neighbors – It displays output that shows a successful neighbor relationship exists between the two routers.
- show ip interface interface – For routers to form a neighbor relationship they must share a directly connected IP subnet. So this command helps to verify the IP address of the interface.
- show ip protocols – This command helps to verify the EIGRP routing protocol is configured and working on the router interfaces.
- show ip eigrp interfaces – It displays EIGRP is running on which interfaces and the number of neighbors that can be seen on each interface.
- debug eigrp packets – It checks if the hello packet information is mismatched between the neighbors that are the autonomous system(AS) number and K values.
- EIGRP Routes in the Routing Table: In this step, we troubleshoot issues in the EIGRP routes established between neighbors in the routing table. So, the commands are –
- ip route – It shows the current state of the routing table and we can verify that if we got the routing protocols required to establish the neighbor relationships.
- show ip eigrp topology – It indicates the EIGRP router ID that is assigned from the highest IP address in the loopback interface.
- show ip protocols – This command checks if any filter lists are applied to EIGRP and also shows if network summarization is achieved.
- EIGRP Authentication: In this last step the EIGRP authentication issues are checked if configured. The commands used are –
- debug eigrp packets – It helps to troubleshoot if the router interface got any MD5 authentication mismatch problems between neighbors and helps to verify that the EIGRP authentication is successful or not.
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