CCNP: OSPF Backbone & Area Mismatch Recovery

Archive lab

Advanced multi-area OSPF lab with a realistic two-site design and a WAN ABR. You will deploy OSPF with a backbone (area 0) and a non-backbone area, intentionally create an area mismatch on one transit link to observe the failure, then correct it to restore full reachability. The final build demonstrates solid OSPF hygiene and SSH-only management.

Learning objectives

• Deploy OSPF across a backbone and a non-backbone area with an ABR connecting them
• Pin router-ids, use passive-interface default, and match network statements to real links
• Interpret OSPF neighbor states and LSDB to verify and troubleshoot adjacency issues
• Diagnose and fix an OSPF area mismatch on a transit link
• Restore end-to-end traffic and confirm proper route visibility from hosts and routers

Troubleshooting focus

• Verify every link's interface status and IP addressing (`show ip interface brief`) and correct any interface that is down or misaddressed.
• Confirm each device's running configuration matches the lab objective, and bring any interface, route, or service that is not in its expected state back to health.
• Trace end-to-end reachability with ping/traceroute and isolate the first hop where forwarding fails.