19-22
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 19 Configuring Standard-Compliant IEEE MST
Configuring MST
Note
The
show spanning-tree mst interface
interface_id
privileged EXEC command displays information
only if the port is in a link-up operative state. Otherwise, you can use the
show running-config interface
privileged EXEC command to confirm the configuration.
To return the interface to its default setting, use the
no spanning-tree mst
instance_id
port-priority
interface configuration command.
Configuring Path Cost
The MST path cost default value is derived from the media speed of an interface. If a loop occurs, MST
uses cost when selecting an interface to put in the forwarding state. You can assign lower cost values to
interfaces that you want selected first and higher cost values that you want selected last. If all interfaces
have the same cost value, MST puts the interface with the lowest interface number in the forwarding state
and blocks the other interfaces.
To configure the MST cost of an interface, perform this task:
Step 3
Router(config-if)#
spanning-tree mst
instance_id
port-priority
priority
Configures the port priority.
•
For
instance_id
, 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.
•
For
priority
, the range is 0 to 240 in increments of 16.
The default is 128. The lower the number, the higher
the priority.
The 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.
Step 4
Router(config-if)#
end
Returns to privileged EXEC mode.
Step 5
Router#
show spanning-tree
mst
interface
interface_id
or
Router#
show spanning-tree mst
instance_id
Verifies your entries.
Step 6
Router#
copy running-config startup-config
(Optional) Saves your entries in the configuration file.
1.
type
=
ethernet
,
fastethernet
,
gigabitethernet
, or
tengigabitethernet
Command
Purpose
Command
Purpose
Step 1
Router#
configure terminal
Enters global configuration mode.
Step 2
Router(config)#
interface
{{
type
1
slot/port
} |
{
port-channel
number
}}
(Optional) Specifies an interface to configure, and enters
interface configuration mode.
