Symptom:
Snmpwalk of ospfNbrTable for a neighbor fails when the neighbor undergoes a router-id change.

Conditions:
R1---------R2

1. Router-ID of the neighbor R2 is changed  (RTRID-R2 changed to RTDID-R2']) either explicitly or implicitly (if inheriting from IP address of loopback or physical interface).
2. Do a snmpwalk of the neighbor R2 on DUT (R1) and it fails.

Recovery:
- Do a "clear ip ospf neighbor <NEIGHBORRID>" for the neighbor that goes missing during snmpwalk on the DUT R1, where snmpwalk is being is done