From: Wright, Jeremy (JA_WRIGHT@xxxxxxxxxxxx)
Date: Wed Oct 10 2001 - 14:24:25 GMT-3
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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