CCNA Foundations: OSPF Day 5 — Multi-Area OSPF & the ABR

Archive lab

Build and verify a compact, enterprise-clean multi-area OSPF network with an ABR. Configure area 0 and a non-backbone area, advertise loopbacks and LANs, enforce OSPF hygiene (passive LANs, explicit router-ids), and verify O IA inter-area routes from the endpoints.

Learning objectives

• Configure OSPFv2 across two areas with an ABR on the boundary
• Assign stable router-ids from loopbacks and advertise LAN and transit networks
• Apply passive-interface default and selectively enable OSPF hellos on transit links
• Verify OSPF adjacencies and inter-area (O IA) routes
• Prove end-to-end host reachability across areas with ping and traceroute

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.