No OSPF neighbor relationship established
Symptom
No OSPF neighbor relationship can be established.
Analysis
If the physical link and lower layer protocols work well, verify OSPF parameters configured on interfaces. Two neighbors must have the same parameters, such as the area ID, network segment, and mask (a P2P or virtual link may have different network segments and masks).
Solution
Use the display ospf peer command to display OSPF neighbor information.
Use the display ospf interface command to display OSPF interface information.
Ping the neighbor router's IP address to verify connectivity.
Verify OSPF timers. The dead interval on an interface must be at least four times the hello interval.
Use the peer ip-address command to specify the neighbor manually on an NBMA network.
On an NBMA or a broadcast network, at least one connected interface must have a router priority higher than 0.