spanning-tree vlan 1,10,20,30 priority 24576

Unanswered Question
Oct 23rd, 2007


I have this command in my switch config, however there are several VLANS that are no in this listing. These VLANs are only at this 1 Location. Do they need to be added to the command above? Thanks for your help.

I have this problem too.
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Kevin Dorrell Tue, 10/23/2007 - 06:11

Not necessarily. This means that your switch is the (primary) root for those VLAN. You will probably have another switch that has the value 28K, which is the secondary root.

By default, the bridge priority is 32K, and if it is set to this value is will not appear in the listing.

It is a good idea to designate a root switch for each VLAN. Do a show spanning-tree n for one of the VLANs that is not mentioned. If the root priority is not 32K, then you should consider appointing one of your switches as root for that VLAN. spanning-tree vlan n root primary. That will autometically set the priority to 24K, as well as doing some other stuff that will help the Spanning Tree structure.

The VLAN will still work without it, but you could end up with a better topology.

Oh, BTW, do that operation outside normal working time. Each VLAN will be interrupted for about 80 seconds following the change.

Kevin Dorrell



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