how to determine root bidge in spanning tree protocol

[dannan lin]

hi:

i have a question about spanning tree configuration.

i know we can manually set root priority such as :

Switch(config)#spanning-tree vlan 1 priority 4096

4096 is the lowest number we can use can't we.

now what if i set each switch's priority value as 4096, in that case how switch determine the root bridge? ?

thanks for your help.

[cadet alain]

Hi,

The priority value must be a multiple of 4096 so zero is a valid value and it is the lowest

The tie-breaker is the BID MAC address: each nibble is compared until there is no more match and the lowest value wins.

Regards.

Alain