750 Configuring the Spanning Tree Protocol
Configuring MSTP Interface Settings

Beginning in Privileged EXEC mode, use the following commands to

configure MSTP settings for the switch.

Command Purpose
configure Enter global configuration mode.
interface
interface
Enter interface configuration mode for the specified interface.
The
interface
variable includes the interface type and number,
for example tengigabitethernet 1/0/3 or port-channel 4.
You can also specify a range of interfaces with the interface
range command, for example, interface range
tengigabitethernet 1/0/8-12 configures interfaces 8, 9, 10, 11,
and 12. The range keyword is also valid for LAGs (port-
channels).
spanning-tree mst 0
external-cost
cost
Set the external cost for the common spanning tree. (Range:
0–200000000)
spanning-tree mst
instance-id
cost
cost
Configure the path cost for MST calculations. If a loop occurs,
the spanning tree considers path cost when selecting an
interface to put in the forwarding state.
•

instance-ID —

ID of the spanning -tree instance. (Range: 1-
4094)
•

cost —

The port path cost. (Range: 0–200,000,000)
spanning-tree mst
instance-id
port-
priority
priority
Specify the priority of the port.
The priority value is used to determine which ports are put in
the forwarding state and which ports are put in the blocking
state. A port with a lower priority value is more likely to be put
into a forwarding state.
•

instance-ID —

ID of the spanning tree instance. (Range: 1-
4094)
•

priority —

The port priority. (Range: 0–240 in multiples of 16)
CTRL + Z Exit to Privileged EXEC mode.
show spanning-tree
interface
instance
instance-id
View MST configuration information for the specified port or
LAG (port-channel) and instance.