From: Mike Williams (ccie2be@swbell.net)
Date: Thu Jan 15 2004 - 21:13:54 GMT-3
I don't think so. Even if you enable pruning (which we have anyway),
AFAIK that simply keeps any unicast or broadcast traffic for that VLAN
from traveling down a trunk link that has a switch downstream that's not
got a member port of that VLAN, but VTP still propagates the VLAN in the
VTP domain, and the switch learns about the existance of that VLAN. We
even thought of using the "trunk allowed vlan remove" to remove the
unwanted VLANs, but that doesn't stop VTP from propagating them.....
The only real solution we can come up with is to make the switch VTP
transparent (which it goes into that mode upon learning the 69th VLAN),
and then manually running spanning tree only on the VLANs in use on that
particular switch (as well as any VLAN that may be in use by a switch
downstream)......
Mike W.
-----Original Message-----
From: Kenneth Wygand [mailto:KWygand@customonline.com]
Sent: Thursday, January 15, 2004 2:37 PM
To: Kurt Kruegel; Church, Chuck; Mike Williams; CCIELab@Groupstudy.com
Subject: RE: What happens with too many VLANs?
So if you prune off the unused VLANs, does the limitation then become 64
active (or "unpruned") VLAN's per 3500XL series switch?
Kenneth E. Wygand
Systems Engineer, Project Services
CISSP #37102, CCNP, CCDP, ACSP, Cisco IPT Design Specialist, MCP, CNA,
Network+, A+
Custom Computer Specialists, Inc.
"Real Engineers Debug in Binary."
-kw
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Kurt Kruegel
Sent: Thursday, January 15, 2004 3:19 PM
To: Church, Chuck; Mike Williams; CCIELab@Groupstudy.com
Subject: Re: What happens with too many VLANs?
i have personal experience with this.
we are a network with 6500's in the core and cat5000, 3500xl's and
3550's at the edge (collapsed backbone) hsrp between msfc's and each
core's st tuned to the active hsrp. at some point we crossed the line of
64 vlans and nothing was really noticed. we actually still had 2820's at
that time .... we would have the occasional stp loop. when i enabled
pruning i started having bizarre layer 2 problems on certain vlans and
certain switches.. intermittant reachability. when i looked into it
further the problem only occured on a 3500xl switch that had a no
spanning-tree vlan xxx and a had a member port on that switch. this
would only occur on a 3500xl that's missing a stp for a certain vlan. a
workarround was to exempt any vlan having problems from pruning. it
seems the 3500xl accepts the first 64 vlans it sees and won't have a stp
instance for anything >64. i'm replacing 3500xl's as fast as i can with
3550's. there's also a field notice for 3500xl's with certain serial #'s
they can be exchanged for a 3550/48 smi.
kurt
----- Original Message -----
From: "Church, Chuck" <cchurch@wamnetgov.com>
To: "Mike Williams" <ccie2be@swbell.net>; "CCIELab@Groupstudy.com"
<ccielab@groupstudy.com>
Sent: Thursday, January 15, 2004 8:34 AM
Subject: RE: What happens with too many VLANs?
> It means that the VLANs with spanning tree disabled won't run it. No
problem at all as long as it's loop free. If there's loops (or a
possibility of a loop), then you don't want to do it. I'm assuming you
don't need more than 64 VLANs on 1 switch (since there's at most 48
ports), so clear VLANs off of the trunks that you know a certain switch
won't need.
>
> Chuck Church
> CCIE #8776, MCNE, MCSE
> Wam!Net Government Services
> 13665 Dulles Technology Dr. Ste 250
> Herndon, VA 20171
> Office: 703-480-2569
> Cell: 703-819-3495
> cchurch@wamnetgov.com
> PGP key:
http://pgp.mit.edu:11371/pks/lookup?op=index&search=cchurch%40wamnetgov.
com
>
> > -----Original Message-----
> > From: Mike Williams [mailto:ccie2be@swbell.net]
> > Sent: Wednesday, January 14, 2004 11:28 PM
> > To: CCIELab@Groupstudy.com
> > Subject: What happens with too many VLANs?
> >
> >
> > In the production network, we have 2950s that support up to 250
VLANs.
> > But they only support 64 separate VLANs running individual instance
of
> > Spanning Tree....... So my question is what happens when you add
that
> > 65th VLAN? I partially know the answer is that you will see in the
> > config where it says "no spanning-tree vlan <blah>" where <blah> is
> > the # of the VLAN (or VLANs) over 64. But how do the rest of the
switches
> > handle this? Do the switches toward the root treat this switch as
an
> > end-device from a STP perspective?!?!?
> >
> > Any input is appreciated........ just wondering how to plan and what
> > to do to make sure nothing breaks now that we've passed 64 (actually
68)
> > VLANs on the network........
> >
> > Thanks!
> > Mike W.
> >
> > ______________________________________________________________
> > _________
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>
>
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