From: Jay Greenberg (groupstudylist@execulink.com)
Date: Sun Sep 22 2002 - 12:54:59 GMT-3
I don't see how poison reverse has anything to do with this at all.
Besides, since when do you have to tweak spanning tree for everyone to
be able to agree on the root bridge? It is fair to tweak to select the
root bridge, but the book says nothing about tweaking to establish *any*
root bridge whatsover.
If 3 bridges are configured, and they cannot agree on a root bridge,
then something else must be wrong. Tweaking it would just cause
problems with frame transport.
On Sat, 2002-09-21 at 21:37, Hansang Bae wrote:
> At 05:33 PM 9/21/2002 -0400, Jay Greenberg wrote:
> >RE: CCIE Practical Studies pg 944, Figure 13-45
> >Ok, I've been trying to figure this out for days now. My "wolf" router
> >is running IOS Version 12.0(21a), and I have also tried a different
> >router running 12.1(1a)T1 as "wolf". There is nothing whatsoever I can
> >do to get routers wolf, lon_rhino, and trashman to agree on the root
> >bridge. The following configuration on the wolf will work:
> >
> >int ser0.1
> > frame interface-dlci 110
> > bridge-group 1
> >int ser0.2
> > frame interface-dlci 130
> > bridge-group 1
> >
> >I.E., in this configuration, all 3 routers agree on the root bridge.
> >
> >However, if I use a multipoint interface config, as the lab requires,
> >
> >int ser0.1 multi
> > frame map bridge 110 broad
> > frame map bridge 130 broad
> > bridge-group 1
> >
> >with the above config, both lone_rhino and trashman think they are the
> >root!
> >Whats going on here? Is this an IOS version problem, or am I doing
> >something wrong?
>
>
> Think of it as poison-reverse problem for BPDUs, if you will (at wolf's MP interface). You should manually adjust the portcost on the other links so that everyone will agree who will become root.
>
> hsb
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