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Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide
—
Release 8.1
78-15486-01
Chapter 7 Configuring Spanning Tree
Configuring MST
Bridge ID MAC ADDR 00-10-7b-bb-2f-00
Bridge ID Priority 32770 (bridge priority:32768, sys ID ext:
2)
Port State Role Cost Prio Type
------------------------ ------------- ---- -------- -----------------------
6/1 forwarding BDRY 10000 20 P2P,
Boundary(PVST)
6/2 blocking BDRY 20000 32 P2P,
Boundary(PVST)
Console> (enable)
Mapping and Unmapping VLANs to an MST Instance
Note
See
Chapter 10, “Configuring VLANs”
for details on using VLANs.
By default, all VLANS are mapped to IST (instance 0). For an MST instance (MSTI) 1 through 15 to be
active, you must map at least one VLAN to that MSTI. IST will always be active whether VLANs are
mapped to IST or not. There are no VLAN mapping conflicts because of separate regions in MST.
Follow these guidelines for mapping and unmapping VLANS to an MST instance:
•
You can only map Ethernet VLANs to MST instances.
•
At least one VLAN in the instance must have an active port in order for MST to be active.
•
You can map as many Ethernet VLANs as you wish to an MST instance.
•
You cannot map a VLAN to more than one MST instance.
•
The Hello Time, Maximum Age timer, and Forward Delay timer set for mode and all spanning trees
are used globally by MST.
To map a VLAN to an MST instance, perform this task in privileged mode:
This example shows how to map a VLAN to MST instance 1 and verify the mapping:
Console> (enable) show spantree mst config
Current (NVRAM) MST Region Configuration:
Configuration Name:cisco Revision:1
Instance VLANs
-------- --------------------------------------------------------------
IST 1,51-4094
1 2-20
2 21-30
3 31-40
4 41-50
5 -
6 -
7 -
8 -
9 -
Task
Command
Step 1
Map a VLAN to an MST instance.
set spantree mst instance vlan vlan
Step 2
Make the new region mapping effective.
set spantree mst config commit
Step 3
Verify that the VLAN is mapped.
show spantree mst [instance] [active] mod/port
