Filter
Top Products
11-16
Catalyst 2950 Desktop Switch Software Configuration Guide
78-14982-01
Chapter 11 Configuring STP
Configuring Spanning-Tree Features
Note The show spanning-tree 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 [vlan vlan-id] port-priority
interface configuration command. For information on how to configure load sharing on trunk ports by
using spanning-tree port priorities, see the “Load Sharing Using STP” section on page 14-21.
Configuring the Path Cost
The spanning-tree path cost default value is derived from the media speed of an interface. If a loop
occurs, spanning tree 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, spanning tree puts the interface with the lowest interface
number in the forwarding state and blocks the other interfaces.
Spanning tree uses the cost value when the interface is configured as an access port and uses VLAN port
cost values when the interface is configured as a trunk port.
Beginning in privileged EXEC mode, follow these steps to configure the cost of an interface:
Step 3
spanning-tree port-priority priority Configure the port priority for an interface that is an access
port.
For priority, the range is 0 to 255; the default is 128. The
lower the number, the higher the priority.
Step 4
spanning-tree vlan vlan-id port-priority priority Configure the VLAN port priority for an interface that is a
trunk port.
• For vlan-id, the range is 1 to 4094 when the EI is
installed and 1 to 1005 when the SI is installed. Do not
enter leading zeros.
• For priority, the range is 0 to 255; the default is 128.
The lower the number, the higher the priority.
Step 5
end Return to privileged EXEC mode.
Step 6
show spanning-tree interface interface-id
or
show spanning-tree vlan vlan-id
Verify your entries.
Step 7
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 Enter interface configuration mode, and specify an interface to
configure. Valid interfaces include physical interfaces and
port-channel logical interfaces (port-channel
port-channel-number).