An interface is configured on a router for OSPF but the command "show router ospf neighbor" does not show any neighbors. Which of the following is NOT a possible cause?
An interface is configured on a router for OSPF but the command "show router ospf neighbor" does not show any neighbors. Which of the following is NOT a possible cause?
An OSPF database description packet has not been received from the neighbor. If there are no neighbors displayed in the OSPF routing table, it means the routers have not even initiated or completed the initial steps of the OSPF neighbor forming process, which starts with sending and receiving Hello packets. Typically, the lack of neighbors is due to not receiving Hello packets, the interface being down, or being in different OSPF areas, rather than not receiving database description packets.
I'm not sure about the given answer. If the command 'show router ospf neighbor' doesn't show any entry, then they have not even sent Hello packets. Usually the command would show any one of the adjacency state. If the port or interface is Admin Down, the show command will not show any output/entry. Like if the neighbor has gone down, but the router is still sending Hello Packets, it will show Down. If there is some kind of mismatch in the Neighbor adjacency during Hello packets, it will show Init. If they have started to send DBD packets and not forming adjacency after that, it probably would be stuck as Exstart. Please correct me if I'm wrong.
My bad. I read the question wrong. I missed the 'NOT' in the second part of the question.