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Catalyst2950 Desktop Switch Software Configuration Guide
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Chapter11 Configuring RSTP and MSTP Configuring RSTP and MSTP Features
Specifying the MST Region Configuration and Enabling MSTP
For two or more switches to be in the same MST region, they must have the same VLAN-to-instance
mapping, the same configuration revision number, and the same name.
A region can have one member or multiple members with the sam e M ST co nfigurat ion; ea c h m embe r
must be capable of processing RSTP BPDUs. There is no limit t o the numb er of MS T regi on s in a
network, but each region can support up to 16 spanning-tree instances. You can assign a VLAN to only
one spanning-tree instance at a time.
Beginning in privileged EXEC mode, follow these steps to specify the MST region configuration and
enable MSTP. This procedure is required.
To return to the default MST region configuration, use the no spanning-tree mst configuration global
configuration command. To return to the default VLAN-to-instan ce map, use the no instance instance-id
[vlan vlan-range] MST configuration command. To return to the default name, use the no name MST
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 spanning-tree mst configuration Enter MST configuration mode.
Step3 instance instance-id vlan vlan-range Map VLANs to an MST instance.
•For instance-id, the range is 1 to 15.
•For vlan vlan-range, the range is 1 to 4094.
When you map VLANs to an MST instance, the mapping is incremental,
and the range of VLANs specified is added or removed to the existing
ones.
To specify a range, use a hyphen; for example, instance 1 vlan 1-63 maps
VLANs 1 through 63 to MST instance 1.
To specify a series, use a comma; for e xample , instance 1 vlan 10, 20, 30
maps VLANs 10, 20, and 30 to MST instance 1.
Step4 name name Specify the configuration name. The name string has a maximum length
of 32 characters and is case sensitive.
Step5 revision version Specify the configuration revision number. The range is 0 to 65535.
Step6 show pending Verify your configuration by displaying the pending configuration.
Step7 exit Apply all changes, and return to global configuration mode.
Step8 spanning-tree mode mst Enable MSTP. RSTP is also enabled.
Caution Changing spanning-tree modes can disrupt traffic because all
spanning-tree instances are stopped for the previous mode and
restarted in the new mode.
You cannot run both MSTP and PVST at the same time.
Step9 end Return to privileged EXEC mode.
Step10 show running-config Verify your entries.
Step11 copy running-config startup-config (Optional) Save your entries in the configuration file.