From: alex (ecralar@hotmail.com)
Date: Tue Feb 07 2006 - 15:32:39 GMT-3
OSPFv2 section 9.4 is the one You are looking for. Remember that every
router listens WaitTimer=RouterDeadInterval for the purposes of avoiding
DR/BDR reelection, also existing DR/BDR are considered earlier in election
algorithm/have advantage as per section 9.4 step (3). Local router can only
declare itself DR/BDR at step (5) so existing DR/BDR are 2 steps ahead :-)
HTH
Cheers
Alex
----- Original Message -----
From: "Redden Jeremiah" <Jeremiah.Redden@HCAhealthcare.com>
To: <ccielab@groupstudy.com>
Sent: Tuesday, February 07, 2006 5:40 PM
Subject: OSPF DR and BDR Election Process
>I am wondering about the OSPF DR and BDR election process. Let's say I have
> a broadcast segment consisting of four routers. I configure routerA with
> an
> ip ospf priority of 255, routerB has an ip ospf priority of 250, and the
> remaining two routers have a default ip ospf priority of 1. So routerA is
> the DR and routerB is the BDR. A link failure causes routerA to enter
> interface down state, which in turns causes routerB to now become the DR.
> A
> new election will take place and the two remaining routers having the same
> ip ospf priority of 1, will now use the highest router ID to become the
> BDR.
> Moments later, the interface for routerA comes back up. Is it correct to
> say
> that there will be no new election taking place so routerA will not become
> the DR again (no ip ospf priority preempt?) I would like the stability of
> the network (routing database) to be routerA for DR and routerB for BDR
> becuase these two routers have more CPU processing cycles as oppose to the
> remaining 2 routers.
>
> I have searched through last years emails to see if there was anything on
> this topic so that there isn't any overlap, but I couldn't find anything
> there. I have also looked at RFC 2328, cisco.com/univercd, and numerous
> Cisco Press CCIE books to no avail. I would appreciate any help with this
> question.
>
>
> Jeremiah Redden (J.R.)
>
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