From: Eric Phillips (ephillips@squick.cc)
Date: Mon Nov 05 2007 - 14:48:30 ART
Thanks for clarifying that everyone,
I thought I might be overthinking this. I seem to do that a lot. But in
this case it is just strange that since routers never preempt each other, DR
election has more to do with router boot orders then it does priorities,
unless you set the priority to 0.
My main concern was that since the rack is rebooted before grading, you
really have no way of knowing what order the grading proctor will start the
routers; so if DR selection was a requirement, leaving it to chance would
not be good.
Thanks again everyone!
-Eric
On 11/5/07, Herbert Maosa <asawilunda@googlemail.com> wrote:
>
> Given that OSPF does not pre-empt a DR even if a router with higher
> priority comes online, I dont think there is a way to to provide this
> guarantee without setting the other routers' priority to zero as you state.
> Point to note on meshed multi-access networks is that if you set all other
> routers with a priority of zero, and then you lose the DR, you will have no
> adjacencies on the LAN even though the topology is allowing for full mesh
> connectivity.
>
> Keep in mind that when priorities are equal, the OSPF Router ID is the tie
> breaker.
>
> Herbert.
>
>
> On 11/5/07, Eric Phillips < ephillips@squick.cc> wrote:
> >
> > Hey all,
> >
> > I have done quite a bit of Googling and DOC-CD reading, and have not
> > found
> > anyone offering any clever ways to force the election of a certain
> > router as
> > the DR besides setting the priority to 0 on all other routers.
> >
> > For example, if I had a question that asked me to ensure Router1 was
> > always
> > the DR on a certain segment without touching the configuration of
> > Router2
> > and Router3 I can set the priority very high on Router1, but if Router1
> > boots a few seconds later than Router2, Router2 will be the DR even if
> > it
> > has it's default priority of 1. The only way I can think to completely
> > guarantee Router1 is always the DR is to make the priority 0 on all
> > other
> > routers.
> >
> > Am I missing something obvious, or am I over thinking this too much? I
> > have
> > not seen this asked in any practice labs, just theorizing what could
> > happen.
> >
> > -Eric
> >
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