Chapter 2 Catalyst 2960 Switch Cisco IOS Commands
When you map VLANs to an MST instance, the mapping is incremental, and VLANs specified in the
command are added to or removed from the VLANs that were previously mapped. To specify a range,
use a hyphen; for example, instance 1 vlan 1-63 maps VLANs 1 to 63 to MST instance 1. To specify a
series, use a comma; for example, instance 1 vlan 10, 20, 30 maps VLANs 10, 20, and 30 to MST
instance 1.
All VLANs that are not explicitly mapped to an MST instance are mapped to the common and internal
spanning tree (CIST) instance (instance 0) and cannot be unmapped from the CIST by using the no form
of the command.
For two or more switches to be in the same MST region, they must have the same VLAN mapping, the
same configuration revision number, and the same name.
Examples
This example shows how to enter MST configuration mode, map VLANs 10 to 20 to MST instance 1,
name the region region1, set the configuration revision to 1, display the pending configuration, apply the
changes, and return to global configuration mode:
Switch# spanning-tree mst configuration
Switch(config-mst)# instance 1 vlan 10-20
Switch(config-mst)# name region1
Switch(config-mst)# revision 1
Switch(config-mst)# show pending
Pending MST configuration
Name
Revision
Instance
--------
0
1
-------------------------------
Switch(config-mst)# exit
Switch(config)#
This example shows how to add VLANs 1 to 100 to the ones already mapped (if any) to instance 2, to
move VLANs 40 to 60 that were previously mapped to instance 2 to the CIST instance, to add VLAN
10 to instance 10, and to remove all the VLANs mapped to instance 2 and map them to the CIST instance:
Switch(config-mst)# instance 2 vlan 1-100
Switch(config-mst)# no instance 2 vlan 40-60
Switch(config-mst)# instance 10 vlan 10
Switch(config-mst)# no instance 2
You can verify your settings by entering the show pending MST configuration command.
Related Commands
Command
show spanning-tree
78-16882-01
[region1]
1
Vlans Mapped
---------------------
1-9,21-4094
10-20
mst configuration
Description
Displays the MST region configuration.
Catalyst 2960 Switch Command Reference
spanning-tree mst configuration
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