OSPF Inter-Area Summarization with ABR Area Range

Bundle lab · $29.99

Build a 5-node CML lab to design OSPFv2 across two areas with an ABR that summarizes non-backbone routes using area range. Validate adjacencies, end-to-end reachability, and that the backbone learns a single summary in place of specific inter-area routes. Intentionally introduce an area mismatch, diagnose why the adjacency does not form, and repair it.

Learning objectives

• Design and deploy a multi-area OSPFv2 topology with stable router-ids and passive-interface hygiene.
• Implement ABR summarization using the area range command to aggregate non-backbone prefixes into a single summary.
• Verify that specific inter-area routes are replaced by a single summary in the backbone while reachability to component subnets remains intact.
• Perform end-to-end testing from hosts across multiple areas and confirm symmetric forwarding.
• Troubleshoot an intentional OSPF area mismatch and validate adjacency recovery.

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.