ospf issue

Unanswered Question
Sep 11th, 2007

hi all,

consider multiaccess domain, I've 5 router configured with ospf.

1st is dr, 2nd is bdr, and all other routers.

what happens when at same time both dr &bdr goes down.

I'll be thankfull if some one post problem they have faced on ospf and how they troubleshoot it.

thanking you,


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Jon Marshall Tue, 09/11/2007 - 06:30

Hi Prashanth

If you lose both the BDR and the DR then a new election would be held. First the BDR would be elected, then as there is no DR the BDR would be promoted to a DR and another election would be held for another BDR.



Kevin Dorrell Tue, 09/11/2007 - 07:32

As Jon says, a new election will take place. Provided of course that you have not set the priorities of the other routers to 0 in an attempt to stop them becoming DR. I would give, say, priority 100 to the router you want to become DR, 90 to the one you want to be BDR, and leave the rest at 1.

Kevin Dorrell


The RID and priority values only matter when there's an election and the values will not preempt an already elected B/DR. So if your high priority routers come online *after* your lowbies, a lowbie will still be B/DR. You'll have to 'clear ip ospf ' on the lowbie B/DR in the right order to make sure the high priority routers get back B/DR status.


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