There was an interesting post on IEOC yesterday in regards to an OSPF virtual link. Below is the original post and questions to win at the bottom of this post.
Okay, I have never came across anything like this before. On R2 and R3 connected via serial with HDLC. OSPF network type default to P2P. I configured VL using the OSPF RIDs of both routers. R3 VL comes up and R2 VL is down. I changed just about every option which makes logical sense and nothing works. I reboot and clear process and still nothing. Out of shear desperation I changed the network-types to P2MP on both sides and voila it works. I tried testing broadcast and that doesn’t work. Only difference I can find is the mask changed from /24 to /32 in the LSA…as it should. But I am not sure why this has any bearing on the VL coming up.
Rack1R2#show ip ospf vir
Virtual Link OSPF_VL8 to router 184.108.40.206 is down
Rack1R3#show ip ospf vir
Virtual Link OSPF_VL0 to router 220.127.116.11 is up
Rack1R2(config-if)#ip ospf network p
Rack1R2(config-if)#ip ospf network point-to-m
*May 9 15:28:40.599: %OSPF-5-ADJCHG: Process 1, Nbr 18.104.22.168 on Serial0/1/0 from FULL to DOWN, Neighbor Down: Interface down or detached
*May 9 15:28:41.007: %OSPF-5-ADJCHG: Process 1, Nbr 22.214.171.124 on Serial0/1/0 from LOADING to FULL, Loading Done
*May 9 15:28:46.815: %OSPF-5-ADJCHG: Process 1, Nbr 126.96.36.199 on OSPF_VL8 from LOADING to FULL, Loading Done
Tags: ccie ospf, ospf virtual link