OSPFv2: Router IDs, Neighbor States, and Loopback Adjacency

Bundle lab · $29.99

Deploy OSPFv2 across three routers with unique, loopback-derived router-ids. Observe OSPF neighbor state transitions, advertise loopbacks and LANs, and troubleshoot an adjacency failure caused by a duplicate router-id. Validate full end-to-end reachability from client hosts after fixing the issue.

Learning objectives

• Configure explicit OSPFv2 router-ids and understand how IOS selects the router-id.
• Advertise loopbacks and client LANs in OSPFv2 while keeping host-facing interfaces passive.
• Describe and verify the OSPFv2 neighbor states: Down, Init, 2-Way, ExStart, Exchange, Full.
• Diagnose an OSPF adjacency failure due to a duplicate router-id and restore to Full.
• Validate the routing table and OSPF LSDB contents after correcting the fault.

Troubleshooting focus

• Identify OSPF neighbor state stalls (Init, 2-Way, ExStart) and causes.
• Detect and correct duplicate/misconfigured router-ids that block adjacency.
• Use targeted show and debug commands to confirm LSDB sync and route installation.