Configuring Spanning Tree
MSTP Configurations
User Guide
333
Step 3
spanning-tree mst instance
instance-id
{[ port-priority
pri
] | [ cost
cost
]}
Configure the priority and path cost of ports in the specified instance.
instance-id:
Specify the instance ID, the valid values ranges from 1 to 8.
pri:
Specify the Priority for the port in the corresponding instance. The value should be an
integral multiple of 16, ranging from 0 to 240. The default valueis 128. The port with lower value
has the higher priority. When the root path of the port is the same as other ports’, the switch
will compare the port priorities between these ports and select a root port with the highest
priority.
cost:
Enter the value of the path cost in the corresponding instance. The valid values are from
0 to 2000000. The default setting is Auto, which means the port calculates the external path
cost automatically according to the port’s link speed. The port with the lowest root path cost
will be elected as the root port of the switch.
Step 4
show spanning-tree mst
{
configuration
[
digest
] |
instance
instance-id
[
interface
[
fastEthernet
port
|
gigabitEthernet
port
|
port-channel
lagid |
ten-gigabitEthernet
port ] ] }
(Optional) View the related information of MSTP Instance.
digest:
Specify to display the digest calculated by instance-vlan map.
instance-id:
Specify the Instance ID desired to view, ranging from 1 to 8.
port:
Specify the port number.
lagid:
Specify the ID of the LAG.
Step 5
end
Return to privileged EXEC mode.
Step 6
copy running-config startup-config
Save the settings in the configuration file.
This example shows how to configure the priority as 144, the path cost as 200 of port 1/0/3
in instance 5:
Switch#configure
Switch(config)#interface gigabitEthernet
1/0/3
Switch(config-if)#spanning-tree mst instance
5
port-priority
144
cost
200
Switch(config-if)#show spanning-tree interface gigabitEthernet
1/0/3
MST-Instance 0 (CIST)
Interface State Prio Ext-Cost Int-Cost Edge P2p Mode Role Status LAG
---------- ------ ---- -------- -------- ---- --------- ----- ---- -------- ---
Gi1/0/3 Enable 32 Auto Auto No No(auto) N/A N/A LnkDwn N/A
MST-Instance 5
Downloaded from
