How is the MAC address identified in a Vlan's Bridge ID?

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Jan 16th, 2009
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In spanning-tree, Bridge ID includes the priority and the device' MAC address. For each VLAN on the switch, what MAC address is used here?

A related question: "sh spanning-tree bridge" tells the MAC of the root bridge. How can I find out which switch has that MAC easily?

Thanks a lot

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royalblues Fri, 01/16/2009 - 13:44
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Each switch has a pool of Mac-addresses which are used to define the spanning-tree bridge ID based on the vlan...

But when we use the extended system ID, the same mac-address is used for all vlans and the vlan number differentiates the instances

When you issue the Sh spanning-tree command, it shows the bridge ID of the root bridge along with the port that leads to it. Using this along with CDP you can reach to the switch acting as the root



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