From: Chuck Church (cchurch@xxxxxxxxxxxx)
Date: Fri Aug 30 2002 - 11:39:22 GMT-3
But, if a spanning tree root election occurs in the forest, but no other
devices running spanning tree are around to hear the election, did it really
happen?
Chuck Church
CCIE #8776, MCNE, MCSE
Sr. Network Engineer
Magnacom Technologies
140 N. Rt. 303
Valley Cottage, NY 10989
845-267-4000
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Bauer, Rick
Sent: Friday, August 30, 2002 7:53 AM
To: 'Jay Hennigan'; 'ccielab@groupstudy.com'
Subject: RE:
No, setting the priority to 32768 would not full fill the requirement of
"never". That switch could and would become root for the vlans if there are
no other switches connected. Stump or not the switch is still running
spanning tree for the vlan so it will become the root in the absence of
other switches with lower priority.
The question was pretty clear, make sure that this one switch "never"
becomes the root for this one vlan. What does never mean? It means never, so
disable SPT for the vlan.
As for the triangle scenario, YES, I would disable SPT for the vlan on both
switches if the requirement was the neither switch ever become root.
Don't confuse this with a real network example. We are talking about
Commercial Lab challenges.
Rick, #9482
-----Original Message-----
From: Jay Hennigan [mailto:jay@west.net]
Sent: Friday, August 30, 2002 1:15 AM
To: ccielab@groupstudy.com
Subject: RE:
On Wed, 28 Aug 2002, Bauer, Rick wrote:
> But what if the switches with their priority set to zero go away? The
switch
> that you did not want to be root becomes root (that does not equal never).
> The only way to guarantee (in older CAT IOS) that a switch will "never"
> become root for a VLAN is to disable SPT for that VLAN.
If all the other switches go away, you no longer have a spanning tree.
You have a spanning stump. It doesn't span anything.
Suppose your scenario has three switches in a triangle; A, B, and C.
The requirement is that neither B nor C become root. Would you suggest
disabling spanning tree on both of them? I didn't think so. Setting
priority to 32767 would IMHO fulfill the requirement. For small values
of never, it would. :-)
-- Jay Hennigan - CCIE #7880 - Network Administration - jay@west.net NetLojix Communications, Inc. - http://www.netlojix.com/ WestNet: Connecting you to the planet. 805 884-6323
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