From: Wright, Jeremy (JA_WRIGHT@xxxxxxxxxxxx)
Date: Fri Oct 12 2001 - 10:57:01 GMT-3
One addition to the problem....my boss put the wrong trap manager address in
2 of the switches that were actually causing the TCN's. So now we have the
problem fixed. Thanks for everyone's advice/help. I can't believe all of
this mess could have been resolved by putting the correct ip address of the
trap manager on the switch, but you know my boss is all knowing and
configures everything perfect.....rrrright (in my Dr. Evil voice). I guess
the plus side to this is that I am stronger now on BPDU/TCN's topic. Thanks
team for all of the info.....Jeremy
-----Original Message-----
From: Mas Kato [mailto:loomis_towcar@speedracer.com]
Sent: Wednesday, October 10, 2001 7:04 PM
To: JA_WRIGHT@admworld.com
Cc: ccielab@groupstudy.com
Subject: RE: BPDU/Topology Changes
Jeremy,
Other culprits could include interface resets (any way to
track them?) and perhaps network diameter-related timer settings either
being mismatched or too low, or actual diameter too big for legal topology,
etc.
Do any of the C'trons keep track of where the last 'Topology
Change Notification' BPDU came from? Or perhaps your sniffer can filter on
them? Might lead to a smoking gun...
Regards,
Mas Kato
https://ecardfile.com/id/mkato
> "Wright, Jeremy" <JA_WRIGHT@admworld.com>Cc:
ccielab@groupstudy.com
> RE: BPDU/Topology ChangesDate: Wed, 10 Oct 2001 12:24:25
-0500
>Reply-To: "Wright, Jeremy" <JA_WRIGHT@admworld.com>
>
>Thanks for the info....no I don't see any topology changes
during off hours.
>We see them sparatically through the day but more towards
the beginning of
>the day and the end which makes me think that it has to do
with people
>booting up and shutting down there computer and something
is generating
>topology changes.
>
> -----Original Message-----
> From: Craig King [mailto:cking007@hotmail.com]
> Sent: Wednesday, October 10, 2001 12:15 PM
> To: Wright, Jeremy
> Cc: ccielab@groupstudy.com
> Subject: Re: BPDU/Topology Changes
>
> Have you taken a look at the utilization/traffic
patterns of
>your network?
> You don't mention anything about your topology except
the
>1000-user base.
> If your network is suffering from congestion problems,
the
>switches could be
> adjusting the topology because BPDUs are delayed and
the
>switches think that
> certain links are down. Do you see any topology
changes in
>offhours? If
> not, then it could be related to network traffic
patterns
>throughout the
> day.
>
> Take a look at other stats that might indicate a
>oversaturated or problem
> link (collisions, errors, delay exceeded, etc...).
This
>might help isolate
> the problem to a specific portion of your network.
>
> HTH,
>
> CK
>
> ----- Original Message -----
> From: "Wright, Jeremy" <JA_WRIGHT@admworld.com>
> To: <jezerski@broadcom.com>; "'Chris Allen'"
><chris.allen@callisma.com>;
> "Wright, Jeremy" <JA_WRIGHT@admworld.com>
> Cc: <ccielab@groupstudy.com>
> Sent: Wednesday, October 10, 2001 11:03 AM
> Subject: RE: BPDU/Topology Changes
>
>
> > Thanks for the advice....I have defined the root and
>secondary bridge
> > before, so I don't think that is an issue. My uplink
ports
>are also not in
> > port fast. We haven't had to power cycle or add any
new
>switches
> > recently.I'm just having trouble tracking down the
>device(s) that are
> > causing the topology change. If we had Cisco devices
I
>could find it...but
> > since my boss loves his Cabletron and the
prices...we are
>now paying for
> it.
> > I have been suggesting Cisco since I got here and
what's
>funny is, my boss
> > asked "do you know of any good Cisco switches".....I
would
>hate for him to
> > actually take my advice for once. Thanks a lot for
the
>input...anymore
> would
> > be appreciated...
> >
> > -----Original Message-----
> > From: Joseph Ezerski [mailto:jezerski@broadcom.com]
> > Sent: Wednesday, October 10, 2001 10:49 AM
> > To: 'Chris Allen'; 'Wright, Jeremy'
> > Cc: ccielab@groupstudy.com
> > Subject: RE: BPDU/Topology Changes
> >
> > I might also add that you do not want a portfast
type of
> > technology on your
> > trunk links between switches. At least, in the
Cisco
>world,
> > turning on
> > Portfast bypasses MAXAGE and the Forward Delay
timers and
> > goes right into
> > Forwarding, thus effectively ignoring Spanning Tree.
I
> > would venture to say
> > that you might still have STP loops but are not
noticing
> > them, since
> > enjoying the blissful peace of non-convergence.
> >
> > In a corrrectly functioning network, you should have
NO
> > topolgy changes
> > unless you added more switches, changed the root
bridge,
>or
> > changed the path
> > costs.
> >
> > Do what Chris suggests. Set your root and secondary
> > bridges. Don't leave
> > those to chance. It could be as simple as that. It
is a
> > good start. Then
> > work your way down from there.
> >
> > I had an example where a Cat 3548XL, in a lab no
less,
>that
> > had a better MAC
> > and BID than my core 6509s and was assuming the
duties of
> > the root bridge
> > (this was before I set my root priorities).
Everytime
>that
> > switch was
> > rebooted or unplugged we had a convergence.
Needless to
> > say, it sucked,
> > until I set my root bridge priority to 0 and my
secondary
>to
> > 1. Now, the
> > only way someone can assume root is if they have a 0
> > priority and a better
> > MAC, which is highly unlikely. Add to that a newer
>feature
> > from Cisco
> > called RootGuard that will eliminate even that
slight
> > chance.
> >
> > I hope this helps.
> >
> > -Joe
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com
>[mailto:nobody@groupstudy.com]On
> > Behalf Of
> > Chris Allen
> > Sent: Wednesday, October 10, 2001 8:27 AM
> > To: Wright, Jeremy
> > Cc: ccielab@groupstudy.com
> > Subject: RE: BPDU/Topology Changes
> >
> >
> > Are you forcing Root and Secondary Bridge
Elections??? If
> > not I would....
> > Also you can make the network even more predictable
and
> > stable by manually
> > configuring port costs to force a certain path....
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com
>[mailto:nobody@groupstudy.com]On
> > Behalf Of
> > Wright, Jeremy
> > Sent: Wednesday, October 10, 2001 10:18 AM
> > To: 'cisco@groupstudy.com'
> > Cc: 'ccielab@groupstudy.com'
> > Subject: BPDU/Topology Changes
> >
> >
> > My network recently was having a lot of topology
changes.
>I
> > then used
> > fastforwarding (Cabletron's version of port fast,
and no I
> > don't make the
> > decision on what hardware to purchase, I just
configure)
>and
> > it reduced the
> > number of changes tremendously. We are still having
>several
> > per day, we have
> > about a 1000 users here. I'm running Sniffer with a
filter
> > on BDPU's and was
> > wondering if there were any suggestions on a better
way to
> > track the
> > topology changes down. Also, I would like to know
what is
> > the recommended
> > min/max number of topology changes. I realize it is
>specific
> > to your network
> > but I just want to get a general feel. Thanks team
> >
> >
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