Spanning-Tree Mst Port-Priority - Cisco Catalyst 3550 Command Reference Manual

Chapter 2 Catalyst 3550 Switch Cisco IOS Commands

spanning-tree mst port-priority

Use the spanning-tree mst port-priority interface configuration command to configure an interface
priority. If a loop occurs, the Multiple Spanning Tree Protocol (MSTP) can determine which interface
to put in the forwarding state. Use the no form of this command to return to the default setting.
Syntax Description
instance-id
priority
Defaults The default is 128.
Command Modes
Interface configuration
Command History Release
12.1(9)EA1
12.1(13)EA1
12.2(25)SEC
Usage Guidelines
You can assign higher priority values (lower numerical values) to interfaces that you want selected first
and lower priority values (higher numerical values) that you want selected last. If all interfaces have the
same priority value, the MST puts the interface with the lowest interface number in the forwarding state
and blocks other interfaces.
Examples
This example shows how to increase the likelihood that the interface associated with spanning-tree
instance 20 is placed into the forwarding state if a loop occurs:
Switch(config)# interface fastethernet0/2
Switch(config-if)# spanning-tree mst 20 port-priority 0
You can verify your settings by entering the show spanning-tree mst interface interface-id privileged
EXEC command.
OL-8566-01
spanning-tree mst instance-id port-priority priority
no spanning-tree mst instance-id port-priority
Range of spanning-tree instances. You can specify a single instance, a range of
instances separated by a hyphen, or a series of instances separated by a comma. The
range is 0 to 4094.
The range is 0 to 240 in increments of 16. Valid priority values are 0, 16, 32, 48, 64,
80, 96, 112, 128, 144, 160, 176, 192, 208, 224, and 240. All other values are
rejected. The lower the number, the higher the priority.
Modification
This command was introduced.
The values for the instance-id and the priority variables were changed.
The instance-id range changed to 1 to 4094.
Catalyst 3550 Multilayer Switch Command Reference
spanning-tree mst port-priority
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