STP on a Switched network

Abrown1966

Question regaurding STP and Root Bridge. If you have a switched network with four or more switches, and you are connected via a console port on a non designated, is it possible to tell which switch is the root bridge using a show command or CDP? I don't have access to a lab at this point so thanks for the help.

MrfixitRight

Abrown1966 wrote:

Question regaurding STP and Root Bridge. If you have a switched network with four or more switches, and you are connected via a console port on a non designated, is it possible to tell which switch is the root bridge using a show command or CDP? I don't have access to a lab at this point so thanks for the help.

Possibly the show-mac-address-table command? The switch with the lowest MAC address is always elected as the Root Bridge. Whether this will show all the switches, not sure.

mikej412

http://www.techexams.net/forums/viewtopic.php?t=21989

Abrown1966

Thanks mikej412. That makes sense too me. MrfixitRight, if I'm not mistaken, the bridge elected root is the bridge with the lowest bridge id, which is made up of the priority with the mac address apended on the end. That would make your statement true, but only if the default value is used for the priority setting on all switches, right?

MrfixitRight

Abrown1966 wrote:

Thanks mikej412. That makes sense too me. MrfixitRight, if I'm not mistaken, the bridge elected root is the bridge with the lowest bridge id, which is made up of the priority with the mac address apended on the end. That would make your statement true, but only if the default value is used for the priority setting on all switches, right?

The switch with the "lowest" switch ID is elected as the root bridge. If all switches have the same priorty, the default, then the switch with the lowest MAC address is elected.