Need a good reference for Spanning Tree

From: SEAN (nyboi@xxxxxxxxxx)
Date: Fri Feb 01 2002 - 16:16:20 GMT-3


   
Can anyone recommend a good reference to how spanning tree chooses which
ports to go up to the root bridge?

Basically, I have the following set up - two catalyst 5500 switches with
two trunks between them:
Switch A port 1/1 to Switch B port 1/1
Switch A port 2/1 to Switch B port 2/1

Seems the switch always wants to use 1/1 as the spanning tree root
(unless it's not available). If 1/1 is disabled, and 2/1 is forwarding
fine, and I reenable 1/1, spanning tree recalculates, and 1/1 becomes
forwarding again.

These are supervisor III's, and I was thinking that it probably wants to
use the ports with the lowest mac address? But if I do show mod, both
supervisor modules show the same mac address range.

Can anyone recommend a good resource on how spanning tree chooses ports?

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