Question

You are troubleshooting a newly configured OSPFv2 adjacency between two IOS XR provider-edge routers, PE1 and PE2, on a directly connected point-to-point link. The neighbors form a relationship but the adjacency never progresses beyond the EXSTART/EXCHANGE state and repeatedly resets. 'show ospf neighbor' shows the neighbor flapping between EXSTART and DOWN. Interface configuration shows PE1 with an MTU of 9000 and PE2 with an MTU of 1500. Which action will bring the adjacency to the FULL state?

Accepted Answer

Match the interface MTU on both routers, or disable OSPF MTU checking with 'mtu-ignore' on the interface

Answer

Change the OSPF network type to broadcast so a DR/BDR is elected on the link

Answer

Configure matching OSPF process IDs on both PE1 and PE2

Answer

Enable OSPF authentication with matching keys on both interfaces