OSPF DR BDR election and neighbor adjacencies
- A DR/BDR election will take place on a per segment basis and not on a per OSPF area basis. A segment is a single broadcast domain, that is, a single IP subnet.
- Neighbor adjacencies will form only between the following types of OSPF routers:
- DR and BDR
- DR and DROTHER
- BDR and DROTHER
- DROTHER to DROTHER adjacencies will not form.
- hello and LSA exchanges take place like so:
- from DROTHER to DR/BDR: 18.104.22.168
- from DR/BDR to DROTHER: 22.214.171.124
- In the OSPF DR BDR election process, the BDR is selected first.
Whether OSPF attempts a DR/BDR election depends on the OSPF network types.