CCNA Foundations: OSPF Day 2 — Router IDs & Neighbor States

Archive lab

Build a two-router OSPFv2 lab, assign deterministic router-ids using loopbacks, form a clean adjacency from Down through Exchange to FULL, and verify neighbor state and router-ids. End-to-end reachability is validated from real hosts across an enterprise-clean topology.

Learning objectives

• Configure OSPFv2 with deterministic router-ids sourced from Loopback0 addresses
• Enable OSPF on specific interfaces using exact network/wildcard statements
• Apply OSPF hygiene: passive-interface default, and selectively enable transit links
• Observe and verify OSPF neighbor states and the peer router-id using show ip ospf neighbor
• Validate end-to-end forwarding between hosts across the OSPF domain

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.