spanning-tree priority


spanning-tree priority <PRIORITY-MULTIPLIER>

no spanning-tree priority [<PRIORITY-MULTIPLIER>]


Configures the switch (bridge) priority for the designated region in which the switch resides.

The switch compares this priority with the priorities of other switches in the same region to determine the root switch for the region. The lower the priority value, the higher the priority.

The no form of this command sets the bridge priority to the default of 8. The default priority value is derived by multiplying 8 by 4096.

Command context




Specifies the priority as a multiplier. Default: 8. Range: 0-15.

The priority range for an MSTP switch is 0-61440. However, this command specifies the priority as a multiplier (0 - 15) of 4096. That is, when you specify a priority multiplier value of 0 - 15, the actual priority assigned to the switch is: (priority-multiplier) x 4096. For example, with 2 as the priority-multiplier on a given MSTP switch, the switch priority setting is 8,192.




Every switch running an instance of MSTP has a Bridge Identifier, which is a unique identifier that helps distinguish this switch from all others. The switch with the lowest Bridge Identifier is elected as the root for the tree. The Bridge Identifier is composed of a configurable priority component (2 bytes) and the bridge's MAC address (6 bytes). You can change the priority component provides flexibility in determining which switch will be the root for the tree, regardless of its MAC address.


Setting the priority multiplier to 12:

switch(config)# spanning-tree priority 12

Setting the priority multiplier to the default of 8:

switch(config)# no spanning-tree priority