OSPF DR and BDR election notes

NOTE – on point-to-point links a DR and BDR are not elected since only two routers are directly connected.

On LANs, DR and BDR have to be elected. Two rules are used to elect a DR and BDR:
1. Router with the highest OSPF priority will become a DR. By default, all routers have a priority of 1.
2. If there is a tie, a router with the highest router ID wins the election.
3. If there is a tie again, a router with the highest loopback interface address wins the election.
4. If there is still a tile, a router with the highest active physical interface address wins the election.
***The router with the second highest OSPF priority or router ID will become a BDR.

By vichhaiy Posted in Cisco

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