OSPFv2 Multi-Area Capstone: 3-Rtr Line, Auth, LAN Host Intact

Bundle lab

Advanced CCNP OSPFv2 multi-area capstone. Build a three-router line topology with area 10 at the branch, area 0 at the core, and MD5 authentication on the area 0 transit. Advertise all loopbacks and a branch user LAN. Validate end-to-end reachability from the branch host to every router loopback and the core LAN. Includes realistic enterprise management and verification flows.

Learning objectives

• Design and configure multi-area OSPFv2 over a realistic branch-to-core topology with an ABR.
• Implement and verify OSPF MD5 authentication on area 0 transit links.
• Advertise router loopbacks and a branch LAN while keeping user-facing interfaces passive.
• Verify inter-area route exchange from end hosts and troubleshoot common adjacency and reachability issues.

Troubleshooting focus

• No neighbor between RTR-REGIONAL-ABR and RTR-CORE-DC: Check both ends have MD5 enabled with identical key-id and key, and that the interface is in area 0 on both routers.; show ip ospf interface confirms authentication is enabled; show ip ospf neighbor gives the state, which should be FULL.
• No neighbor between RTR-BRANCH-EDGE and RTR-REGIONAL-ABR: check the area IDs (both area 10), the wildcard for 10.0.12.0/30, and that the interface is not passive.
• Routes to loopbacks or LANs are missing: confirm those networks are matched by OSPF network statements. Passive keeps them advertised; it does not withdraw them.
• CLIENT-BRANCH10 pings fail although adjacencies are up: verify host IP/mask/gateway, then that RTR-CORE-DC sees 10.10.10.0/24 and RTR-BRANCH-EDGE sees 10.20.20.0/24.
• Adjacencies never settle or the LSDB is unstable: recheck the router-ids — each must match that router's own Loopback0 and be unique.