Dynamic neighbor discovery lets OSPF routers identify connected neighbors through Hello messages instead of manually configured neighbor IP addresses. Broadcast and point-to-point networks use it with 10-second Hello and 40-second dead timers. section 18.3.2
Operational points:
- OSPF-enabled interfaces send Hello messages at 10-second intervals to discover neighbors. section 18.3.2
- OSPF removes a neighbor after 40 seconds without a Hello when the interface remains up; a down/down interface removes it immediately. section 18.3.2
Verify discovered neighbors
Use show ip ospf neighbor to inspect neighbor IDs, states, dead timers, addresses, and interfaces. A FULL/BDR or FULL/DR entry identifies the designated-router relationship on a broadcast segment.
