3com WX4400 3CRWX440095A ユーザーズマニュアル

The command applies only to the ports you specify. The port cost on 
other ports remains unchanged.

To reset the cost of ports 3 and 4 in the default VLAN to the default 
value, type the following command:

WX1200# clear spantree portcost 3-4
success: change accepted.

To reset the cost of ports 3 and 4 for VLAN beige, type the following 
command:

WX1200# clear spantree portvlancost 3-4 vlan beige
success: change accepted.

To change the priority of a port, use one of the following commands:

set spantree portpri port-list priority value
set spantree portvlanpri port-list priority value {all | 
vlan vlan-id}

The set spantree portpri command changes the priority for ports in the 
default VLAN (VLAN 1) only. The set spantree portvlanpri command 
changes the priority for ports in a specific other VLAN or in all VLANs. 

Specify a priority from 0 (highest priority) through 255 (lowest priority). 
The default is 128.

The all option applies the change to all VLANs. Alternatively, specify an 
individual VLAN.

To set the priority of ports 3 and 4 in the default VLAN to 48, type the 
following command:

WX1200# set spantree portpri 3-4 priority 48
success: change accepted.

To set the priority of ports 3 and 4 to 48 in VLAN mauve, type the 
following command:

WX1200# set spantree portvlanpri 3-4 priority 48 vlan mauve
success: change accepted.