DR and BDR

- [Narrator] In this lesson, we are going to discuss…the OSPF designated router and backup designated router.…Now, the designated router allows OSPF…to centralize communication of LSAs…in a multi-access situation.…Now, this allows us to form many fewer neighborships,…saving us on overall communication overhead.…We will basically elect a router representative…of multiple routers that share a single link.…This means that they are basically connected by a switch.…

So here we can see a diagram of what I'm talking about.…We have five routers that are connected together…over a switch, and it could even be…multiple switches if you like.…Now this means that they are sharing the same subnet.…And for our purposes, from a router perspective,…it is almost as if they are sharing the same segment.…Now, they aren't, but from a Layer 3 perspective…it does look that way.…Now notice that we have one DR here…that's going to be in this environment.…And we could have multiple DRs in an area.…

Remember that DRs are elected per multi-access environment.…