Administrator Guide

Layer 2 Switching Commands 769
User Guidelines
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.
Example
The following example configures an MST region.
console (config)#spanning-tree mst configuration
console (config-mst)#instance 1 add vlan 10-20
console (config-mst)#name region1
console (config-mst)#revision 1
spanning-tree mst cost
Use the spanning-tree mst cost command in Interface Configuration mode
to configure the internal path cost for multiple spanning tree (MST)
calculations. If a loop occurs, the spanning tree considers path cost when
selecting an interface to put in the forwarding state. To return to the default
port path cost, use the no form of this command.
Syntax
spanning-tree mst instance-id cost cost
no spanning-tree mst instance-id cost
• instance-ID — ID of the spanning -tree instance. (Range: 1-4094)
• cost — The port path cost. (Range: 0–200,000,000)
Default Configuration
The default cost is 0, which signifies that the cost will be automatically
calculated based on port speed.
The default configuration is:
• Ethernet (10 Mbps) — 2,000,000
• Fast Ethernet (100 Mbps) — 200,000
• Gigabit Ethernet (1000 Mbps) — 20,000
• Port-Channel — 20,000