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Can't find Root Bridge?


When I issue the command "show spantree (vlan#) active, the output from the switch show something similiar to:


Designated Root 00-d0-14-73-14-00

Designated Root Priority 8192

Designated Root Cost 12

Designated Root Port 3/1-2


But I couldn't locate this mac address "00-d0-14-73-14-00" on all my switches? Can anybody help to explain this?



Re: Can't find Root Bridge?

Designated Root Port points you in the direction of the Root Bridge. In this case, look upstream to what's connected to your interface 3/1-2 (looks like an EtherChannel uplink to me).

Designated Root Cost can also give you an idea how far you are from the Root Bridge. It is the sum of all the Path Costs between the switch in your example, and the Root Bridge. Assuming that they're all Cisco switches, a Root Cost of 12 could be telling you that you are 3 Gigabit Ethernet hops away from the Root Bridge. (GigE Path Cost default is 4.)

Work your way from that switch back toward the Root Bridge; the Designated Root Cost should diminish as you go.

When you get to the switch whose Bridge ID MAC ADDR matches the Designated Root, you will have found yourself the Root Bridge.

Not knowing what switches or routers you're using, it's possible that you may have some sort of bridging functionality enabled on a module within a chassis. But following the path to the Root Bridge in this way will get you closer to it.

For what it's worth, I did a check of the MAC address prefix "00-d0-14" at

Maybe this info will help you identify the device that's your Root Bridge:


Here are the results of your search through the public section of the IEEE Standards OUI database report for 00-d0-14:


00-D0-14 (hex) ROOT, INC.

00D014 (base 16) ROOT, INC.



JAPAN 170-0005



Your attention is called to the fact that the firms and numbers listed may not always be obvious in product implementation. Some manufacturers subcontract component manufacture and others include registered firms' OUIs in their products.


Hope this helps.

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