The OSPF broadcast network type is the default for Ethernet interfaces. It enables dynamic neighbor discovery, uses 10-second hello and 40-second dead timers, and elects a designated router (DR) and backup designated router (BDR) on each segment. section 18.3.2 section 18.5
Understand the operational consequences:
- Elects the DR and BDR during the 2-Way state, using the highest interface priority and then the highest router ID; the default priority is 1. section 18.5
- Forms full adjacencies between every router and the DR or BDR, while routers known as DROthers remain in the 2-Way state with one another. section 18.3.2
Verify the configured network type
Use show ip ospf interface g0/0. Representative output identifies the interface as up, shows its area and process, and reports Network Type BROADCAST. Use show ip ospf neighbor to distinguish FULL/DR, FULL/BDR, and 2WAY/DROTHER relationships.
