From: Nawaz, Ajaz (Ajaz.Nawaz@bskyb.com)
Date: Fri Feb 07 2003 - 08:16:16 GMT-3
I disagree.
DR and BDR's are chosen per interface, if the interface happens to be part
of a multiacess segment.
This means for example, if a router is connected to 10 ethernet segments and
OSPF is switched on for all those interfaces - then DR/BDR election process
will take place 10 times separately - this will result in 10DR's and
10BDR's.
-----------------------------------------------------------------------
RFC 1245 quotes:
* Designated router. A Designated Router is elected on all multi-access
networks (e.g., ethernets or X.25 PDNs). The network's Designated
-----------------------------------------------------------------------
quote from OSPF Design Guide available from Cisco.com:
"Remember that the DR and BDR concepts are per multiaccess segment. "
I think it's important to conclude a router can be designated for one
segment and BDR for another. It could also be a drother for another segment.
These segment would in most cases be separate IP subnets.
ajaz
-----Original Message-----
From: Evgeny Tantsura [mailto:ivgen@castel.nl]
Sent: 07 February 2003 10:19
To: Joe Chang
Cc: Jeongwoo Park; ccielab@groupstudy.com
Subject: Re: OSPF - Can a router have two DR's?
Hi,
DR is chosen per IP subnet.
> Hi Jeongwoo,
>
> Your diagram is somewhat hard to understand, but from looking at the
> adjacency table on R3 nothing seems to be wrong. You have two neighbors in
> two different areas, so it is possible to have two DRs.
>
> ----- Original Message -----
> From: "Jeongwoo Park" <jpark@wams.com>
> To: <ccielab@groupstudy.com>
> Sent: Friday, February 07, 2003 1:02 AM
> Subject: OSPF - Can a router have two DR's?
>
>
> > Hi all
> > Can a router have two DR's?
> > I have a layout as following.
> >
-----------------------r6-------------------------r3----------------------
> --
> > ---r5
> > area 2 area1 area0
> >
> > area 1 is a transit area where the virtual link are going through.
> > r3 has a config "ip ospf priority 0" not to be DR.
> > In this layout, r3 seems to have two DR's( r6 and r5) as following.
> >
> > r3#sh ip ospf nei
> > Neighbor ID Pri State Dead Time Address
> Interface
> > 170.100.51.5 1 FULL/DR 00:01:38 170.100.1.5
> Serial0/0
> > 170.100.66.6 1 FULL/DR 00:00:38 170.100.55.6
> > Ethernet0/1
> >
> > And both r6 and r5 get priority 1 each.
> >
> > Is this normal behavior for r3.
> >
> > One more thing is that from r5's point of view, r3 is DROTHER, and from
> r6's
> > point of view r3 is BDR.
> >
> > Are these normal behavior?
> >
> > Thanks a lot.
> >
> > JP
> > .
> .
With kind regards/ met vriendelijke groeten,
------------------------------------------------
E. Tantsura
Network Developer
Essent Kabelcom N.V.
Dr.van Deenweg 84
8025BN Zwolle, The Netherlands
Tel: +31-(0)38-850-7642
Fax: +31-(0)38-850-7410
Mob: +31-(0)6-290-80458
------------------------------------------------
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