[c-nsp] Spanning-tree problem

[Matlock, Kenneth L]

The 'cost' has no bearing on which bridge gets elected as the root
bridge.

The first criteria is the priority. On the switch that you want to be
the root, add the "spanning-tree vlan <VLAN_ID> priority <priority>"
command. Just set the priority to something lower than the rest (in
multiples of 4096 if you're running Extended System-ID mode), and STP
will elect that as the root instead.

Setting port costs only determines the ports back to the root, AFTER the
root bridge is elected.

Ken Matlock
Network Analyst
Exempla Healthcare
(303) 467-4671
matlockk at exempla.org


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Renelson Panosky
Sent: Thursday, June 03, 2010 8:10 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] Spanning-tree problem

I have three 6509-E daisy chain together i know that's not the best
design
but it was working fine until this morning.
for some reason the second switch took over as the root bridge
i changed the spanning tree cost to a higher number and it still
claiming to
be the bridge.
i do a sho mac-address-table | include the mac-address i can't find it
can any one please help ?
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