PLANET XGS3-24042 - Manual (Page 265)

14-111
For the aggregation ports, the default costs are as below:
Port Type Allowed Number Of Aggregation
Ports
Default Port Cost
10Mbps N 2000000/N
100Mbps N 200000/N
1Gbps N 20000/N
10Gbps N 2000/N
Usage Guide:
By setting the port cost, users can control the cost from the current port to the root bridge in order to
control the elections of root port and the designated port of the instance.
Example:
On the port1/0/2, set the MSTP port cost in the instance 2 to 3000000.
Switch(Config-If-Ethernet1/0/2)#spanning-tree mst 2 cost 3000000
14.1.21 spanning-tree mst loopguard
Command:
spanning-tree [mst <instance-id>] loopguard
no spanning-tree [mst <instance-id>] loopguard
Function:
Enable the loopguard function for specified instance, the no command disables this function.
Parameter:
<instance-id>: MSTP instance ID.
Command mode:
Port Mode
Default:
Disable loopguard function.
Usage Guide:
The command can avoid root port or alternate port to be changed as designated port due to invalid
unilateralism link. When the receiving timer is time, the configured port with loopguard is set as
block state.
Example:
Configure port 1/0/2 as loopguard mode for instance 0.
Switch(Config)#interface ethernet 1/0/2
Switch(Config-Ethernet-1/0/2)#spanning-tree mst 0 loopguard