User Guide

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Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
78-14099-04
Chapter 15 Configuring STP and IEEE 802.1s MST
Configuring IEEE 802.1s MST
Configuring MST Instance Parameters
To configure MST instance parameters, perform these tasks:
This example shows how to configure MST instance parameters:
Router(config)# spanning-tree mst 1 priority ?
<0-61440> bridge priority in increments of 4096
Router(config)# spanning-tree mst 1 priority 1
% Bridge Priority must be in increments of 4096.
% Allowed values are:
0 4096 8192 12288 16384 20480 24576 28672
32768 36864 40960 45056 49152 53248 57344 61440
Router(config)# spanning-tree mst 1 priority 49152
Router(config)#
Router(config)# spanning-tree mst 0 root primary
mst 0 bridge priority set to 24576
mst bridge max aging time unchanged at 20
mst bridge hello time unchanged at 2
mst bridge forward delay unchanged at 15
Router(config)# ^Z
Router#
Router# show spanning-tree mst
###### MST00 vlans mapped: 11-4094
Bridge address 00d0.00b8.1400 priority 24576 (24576 sysid 0)
Root this switch for CST and IST
Configured hello time 2, forward delay 15, max age 20, max hops 20
Interface Role Sts Cost Prio.Nbr Status
---------------- ---- --- --------- -------- --------------------------------
Fa4/4 Back BLK 1000 160.196 P2p
Fa4/5 Desg FWD 200000 128.197 P2p
Fa4/48 Desg FWD 200000 128.240 P2p Bound(STP)
###### MST01 vlans mapped: 1-10
Bridge address 00d0.00b8.1400 priority 49153 (49152 sysid 1)
Root this switch for MST01
Interface Role Sts Cost Prio.Nbr Status
---------------- ---- --- --------- -------- --------------------------------
Fa4/4 Back BLK 1000 160.196 P2p
Fa4/5 Desg FWD 200000 128.197 P2p
Fa4/48 Boun FWD 200000 128.240 P2p Bound(STP)
Router#
Command Purpose
Step 1
Router(config)# spanning-tree mst X priority Y
Configures the priority for an MST instance
Step 2
Router(config)# spanning-tree mst X root [primary
| secondary]
Configures the bridge as root for an MST instance.
Step 3
Router# show spanning-tree mst
Verifies the configuration.