Spanning Tree

Show spanning tree info

SW1>show spanning-tree

VLAN0001
Spanning tree enabled protocol ieee
Root ID    Priority    16385
            Address     0015.2b2e.2600
            This bridge is the root
            Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

Bridge ID  Priority    16385  (priority 16384 sys-id-ext 1)
            Address     0015.2b2e.2600
            Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
            Aging Time 150

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa1/0/1          Desg FWD 19        128.3    P2p
Fa1/0/20         Desg FWD 19        128.22   P2p
Fa1/0/47         Desg FWD 19        128.51   P2p

Change spanning tree mode

SW1(config)#spanning-tree mode rapid-pvst

Change port priority

SW1(config-if)#spanning-tree port-priority 128

Priority ranges from 0 to 240, by increments of 16. Default is 128.

Change port cost

SW1(config-if)#spanning-tree cost 18

Refer to the link cost table for more info on the default port cost.