After configure OSPF on all routers with the same area (area 0), configure also interface loopback 0 for all routers, and then import route direct into OSPF. However, OSPF routing on NE40-2 can not distribute to NE80E and NE40-1 (see attachment for network topology)
1. On NE80E, ping interface loopback NE40-1 is OK but ping interface loopback NE40-2 failed.
2. When show routing on NE40-1, OSPF routing can learn from NE80E.
3. When show routing on NE40-2, there is no OSPF routing learn from NE80E.
4. Check IP routing on NE80E, OSPF routing can be learn only from NE40-1 but not found OSPF routing from NE40-2
5. Compare OSPF router ID between NE80E and NE40-2, found Router ID are the same
6. So, we change NE40-2 router ID and restart the OSPF process
7. After change NE40-2 Router-id, the OSPF routing still not learn from NE80E, So restart the OSPF process on NE80E again and test ping loopback IP address from NE80E to NE40-1 and NE40-2 successful.
Checking OSPF routing on all router in order to verify the problem. Using several command such as “display ospf 1 brief”, “display ip routing”, “display ospf interface”, etc.
Before enable OSPF routing, check the router ID not conflict with other.