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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 13 Configuring STP
Configuring Spanning-Tree Features
To return the switch to its default setting, use the no spanning-tree vlan vlan-id root global
configuration command.
Configuring the Port Priority
If a loop occurs, spanning tree uses the port priority when selecting an interface to put into the
forwarding state. You can assign higher priority values (lower numerical values) to interfaces that you
want selected first and lower priority values (higher numerical values) that you want selected last. If all
interfaces have the same priority value, spanning tree 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 port priority of an interface.
This procedure is optional.
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 interfaces and
port-channel logical interfaces (port-channel
port-channel-number).
Step 3
spanning-tree port-priority priority Configure the port priority for an interface.
For priority, the range is 0 to 240 in increments of 16. The
default is 128. The lower the number, the higher the
priority.
Valid 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
spanning-tree vlan vlan-id port-priority priority Configure the VLAN port priority for an interface.
• For vlan-id, you can specify a single VLAN identified
by VLAN ID number, a range of VLANs separated by
a hyphen, or a series of VLANs separated by a comma.
The range is 1 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.
Valid 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 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.