19-20
Cisco IE 3000 Switch Software Configuration Guide
OL-13018-03
Chapter 19 Configuring MSTP
Configuring MSTP Features
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 MSTP path cost default value is derived from the media speed of an interface. If a loop occurs, the
MSTP 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, the MSTP puts the interface with the lowest interface number in the
forwarding state and blocks the other interfaces.
Beginning in privileged EXEC mode, follow these steps to configure the MSTP cost of an interface. This
procedure is optional.
Step 3
spanning-tree mst
instance-id
port-priority
priority
Configure 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
end
Return to privileged EXEC mode.
Step 5
show spanning-tree
mst
interface
interface-id
or
show spanning-tree mst
instance-id
Verify your entries.
Step 6
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Command
Purpose
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
interface
interface-id
Specify an interface to configure, and enter interface
configuration mode. Valid interfaces include physical ports and
port-channel logical interfaces. The port-channel range is 1 to 6.