Configuring Stp Port Priority - Cisco Catalyst 2950 Software Manual

Configuring Basic STP Features

Configuring STP Port Priority

In the event of a loop, STP considers 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, STP puts the interface with the lowest interface number in the forwarding state
and blocks other interfaces. The priority range is 0 to 255; the default is 128.
Cisco IOS uses the port priority value when the interface is configured as an access port and uses VLAN
port priority values when the interface is configured as a trunk port.
Beginning in privileged EXEC mode, follow these steps to configure the STP port priority of an
interface:
Command
Step 1
configure terminal
Step 2
interface interface-id
Step 3
spanning-tree port-priority priority
Step 4
spanning-tree vlan vlan-id port-priority priority
Step 5
end
Step 6
show spanning-tree interface interface-id
or
show spanning-tree vlan vlan-id
Step 7 copy running-config startup-config
The show spanning-tree interface interface-id interface configuration command only displays
Note
information if the port is in a link-up operative state and is configured for Dynamic Trunking Protocol
(DTP). Otherwise, you can use the show running-config interface interface configuration 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.
Catalyst 2950 Desktop Switch Software Configuration Guide
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Purpose
Enter global configuration mode.
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).
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.
Configure the VLAN port priority for an interface that is a
trunk port.
For vlan-id, the range is 1 to 1005. Do not enter leading
zeroes.
For priority, the range is 0 to 255; the default is 128. The
lower the number, the higher the priority.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Chapter 9 Configuring STP
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