[Please suggest content for the Short Description, to summarise and introduce this topic.]

1. Document the address details of the suspect route or adjacency.
2. If the problem is not currently ongoing then document the time that it occurred.
3. Check the path being used: Use the show ip route command.
4. Check the state of the interface for that path: Use the show interface command.
5. Examine the protocol-specific state. For example: show ip bgp summary.
6. Check whether the adjacent router can be reached: Use the ping command.
7. Trace the network path that is being used: Use the traceroute command.
8. Investigate events before and after the problem: Use the show journal command.
9. If the problem is ongoing or you expect it to occur again, then:
   1. Increase protocol logging: Use the monitor protocols command.
   2. After the next occurrence, examine the new events: Use the show journal command.