abr Dr and bdr question ospf

hitmen

Hi,

I understand that all internal routers need to connect to the Dr and bdr.

How ever, does the abr need to be connected to the Dr and bdr separately?

Thanks

TechGuru80

Are you asking as far as redundancy? Because for that it would be a good idea.

hitmen

TechGuru80 wrote: »

Are you asking as far as redundancy? Because for that it would be a good idea.

Normally is there redundancy for abr
?

hitmen

I mean is there only one abr between areas? It is dangerous if it goes down? Normally is the Dr connected to the abr? Or is it both the Dr and the bdr that is connected to the abr?

tomtom1

Remember that a ABR router is a router that connects another area to area 0. However, per area (depending on the OSPF network type), a DR and a BDR might be elected. However, a device that is the DR or BDR for a given area can also be the ABR for an area. And depending on the entire design, when the ABR goes down, it might pose problems since, for example, the LSA type 3 (summary LSA) generated by that ABR will not be flooded through the backbone anymore.

hitmen

OK. May I should rephrase. How many abr can be placed between 2 areas?

Heero

There isn't a limit to how many ABRs an area can contain.

And DR and BDR is a completely separate concept.