Re: About DR election after ospf graceful restart

Sanjay BM <sanjaybm@GMAIL.COM> Tue, 29 June 2004 23:06 UTC

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Date: Tue, 29 Jun 2004 16:06:06 -0700
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From: Sanjay BM <sanjaybm@GMAIL.COM>
Subject: Re: About DR election after ospf graceful restart
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Thanx Acee.

On Tue, 29 Jun 2004 17:48:00 -0400, Acee Lindem <acee@redback.com> wrote:
>
> Hi Sanjay,
>
> ----- Original Message -----
> From: "Sanjay BM" <sanjaybm@GMAIL.COM>
> To: <OSPF@PEACH.EASE.LSOFT.COM>
> Sent: Tuesday, June 29, 2004 5:14 PM
> Subject: About DR election after ospf graceful restart
>
> > Hi,
> >
> > I had couple of questions regarding DR election on helpers after a
> > OSPF graceful restart.
> >
> > RFC3623 states the following:
> > ---
> > When Router Y exits helper mode for X on a given network segment, it
> >    reoriginates its LSAs based on the current state of its adjacency to
> >    Router X over the segment.  In detail, Y takes the following actions:
> >
> >       a) Y recalculates the Designated Router for the segment,
> >
> >       b) Y reoriginates its router-LSA for the segment's OSPF area,
> >
> >       c) if Y is Designated Router for the segment, it reoriginates the
> >          network-LSA for the segment and
> >
> >       d) if the segment was a virtual link, Y reoriginates its router-
> >          LSA for the virtual link's transit area.
> > ---
> >
> > Question 1:
> > Should Router Y (helpers) recalculate the DR for the segment even when
> > it exits helper mode successfully i.e, when grace LSAs were flushed
> > before grace period expiry.
>
> There may be an optimization where in some cases it is unnecessary.
> However, the algorithm is such that the existing DR should remain DR.  Also,
> unless you have "lots" of neighbors on the subnet, it isn't all that expensive
> to run.
>
> >
> > Question 2:
> > Assume Router X is of higher priority than Router Y and that Router X
> > was the BDR before going through a graceful restart. Should Router X
> > become the new DR for the segment when Router Y runs the DR election
> > after exiting helper mode?
>
> No. Unless other events come into play, whoever was DR prior to X's
> restart should remain DR.
>
> >
> > Thanx,
> > Sanjay
>

About DR election after ospf graceful restart Sanjay BM
Re: About DR election after ospf graceful restart Acee Lindem
Re: About DR election after ospf graceful restart Sanjay BM