4 Command Line Interface

The recommended range is -

-Ethernet: 200,000-20,000,000

-Fast Ethernet: 20,000-2,000,000

-Gigabit Ethernet: 2,000-200,000

-10 Gigabit Ethernet: 200-20,000

Default Setting

By default, the system automatically detects the speed and duplex mode used on each port, and configures the path cost according to the values shown below. Path cost “0” is used to indicate auto-configuration mode.

•Ethernet – half duplex: 2,000,000; full duplex: 1,000,000; trunk: 500,000

•Fast Ethernet – half duplex: 200,000; full duplex: 100,000; trunk: 50,000

•Gigabit Ethernet – full duplex: 10,000; trunk: 5,000

•10 Gigabit Ethernet – full duplex: 1000; trunk: 500

Command Mode

Interface Configuration (Ethernet Ports 1-8, Port Channel)

Command Usage

•Each spanning-tree instance is associated with a unique set of VLAN IDs.

•This command is used by the multiple spanning-tree algorithm to determine the best path between devices. Therefore, lower values should be assigned to interfaces attached to faster media, and higher values assigned to interfaces with slower media.

•Path cost takes precedence over interface priority.

Example

Console(config)#interface ethernet ethernet 1/5

Console(config-if)#spanning-tree mst 1 cost 50

Console(config-if)#

Related Commands

spanning-tree mst port-priority(4-164)

spanning-tree mst port-priority

This command configures the interface priority on a spanning instance in the Multiple Spanning Tree. Use the no form to restore the default.

Syntax

spanning-tree mst instance_id port-priority priority no spanning-tree mst instance_id port-priority

•instance_id - Instance identifier of the spanning tree. (Range: 0-4094, no leading zeroes)

•priority - Priority for an interface. (Range: 0-240 in steps of 16)

Default Setting

128

4-164