Administrator Guide

Layer 2 Switching Commands 774
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 value 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
Command Mode
Interface Configuration (gigabitethernet, port-channel, tengigabitethernet,
fortygigabitethernet) mode
User Guidelines
MST instance id 0 is the common internal spanning tree instance (CIST).
Example
The following example configures the MSTP instance 1 path cost for
interface 1/0/9 to 4.
console(config)#interface gigabitethernet 1/0/9
2CSNXXX_SWUM204.book Page 774 Monday, January 25, 2016 1:25 PM