Root Bridge - STP

Unanswered Question
Jun 30th, 2007
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Hello everyone,

I have a scenario here with a couple of routers and 5 switches. We have a total of 5 vlans spread apart on all of the switches.

Is there a command/commands which I can perform on one of the switches to deterine which switch is the root bridge for a particular VLAN?


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Overall Rating: 5 (2 ratings)
royalblues Sat, 06/30/2007 - 14:47
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do a sh spanning-tree vlan .

This would show the MAC address of the root bridge.

If the current switch is not the root switch, it would indicate the port through which te root switch will be reachable. Log on to the switch and use the above command.

Continue this procedure till you reach a switch where the Root bridge MAC-ID and the switch MAC-ID are the same.

HTH, rate if it does


danny9797 Sat, 06/30/2007 - 15:30
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Thanks for the reply,

I have a simulation setup and I gave it a try.

I'm assuming it would show under the root id, correct? I'm a bit confused bc theres two sections (root and bridge id)

I have an image of the output for the three switches

It looks like the 000C.1000.4605 is the root bridge or am I wrong? Problem is, I wouldn't know which switch it is or can you tell with emulated switches?


royalblues Sat, 06/30/2007 - 18:21
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Yes, Under the root ID you see details of root bridge.

Bridge ID, is the details of the current switch. If the Switch is the root, then both the root ID and Bridge ID fields are same.

also in your setup, the switch with MAC 000C.1000.4605 is the root.

HTH, rate if it does



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