Cisco Catalyst 3550 User Manual

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Catalyst 3550 Multilayer Switch Command Reference
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Chapter 2 Catalyst 3550 Switch Cisco IOS Commands
spanning-tree port-priority
spanning-tree port-priority
Use the spanning-tree port-priority interface configuration command to configure an interface
priority. If a loop occurs, spanning tree can determine which interface to put in the forwarding state. Use
the no form of this command to return to the default setting.
spanning-tree [vlan vlan-id] port-priority priority
no spanning-tree [vlan vlan-id] port-priority
Syntax Description
Defaults The default is 128.
Command Modes Interface configuration
Command History
Usage Guidelines If the variable vlan-id is omitted, the command applies to the spanning-tree instance associated with
VLAN 1.
You can set the priority on a VLAN that has no interfaces assigned to it. The setting takes effect when
you assign the interface to the VLAN.
If you configure an interface with both the spanning-tree vlan vlan-id port-priority priority command
and the spanning-tree port-priority priority command, the spanning-tree vlan vlan-id port-priority
priority command takes effect. only on the range of VLANs specified by that command. On the VLANs
that are not specified by the spanning-tree vlan vlan-id port-priority priority command, the
spanning-tree port-priority priority command takes effect.
Examples This example shows how to increase the likelihood that the interface will be put in the forwarding state
if a loop occurs:
Switch(config)# interface fastethernet0/2
Switch(config-if)# spanning-tree vlan 20 port-priority 0
You can verify your settings by entering the show spanning-tree interface interface-id privileged
EXEC command.
vlan vlan-id (Optional) VLAN range associated with a spanning-tree instance. 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.
priority The range is 0 to 240 in increments of 16. 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. The lower the number, the higher the priority.
Release Modification
12.1(4)EA1 This command was introduced.
12.1(13)EA1 The values for the vlan-id and the priority variables were changed.

Cisco Catalyst 3550 Specifications

General

Category	Switch
QoS	Yes
Form Factor	Rack-mountable
Manageable	Yes
RAM	64 MB
Model	Catalyst 3550
Uplink Ports	2 x GBIC (Gigabit Interface Converter) or SFP (Small Form-factor Pluggable)
Layer Support	Layer 3
VLAN Support	Yes
MAC Address Table Size	12000 entries
Routing Protocol	EIGRP
Features	QoS
Operating Temperature	32 to 113°F (0 to 45°C)
Operating Humidity	10 - 95% (non-condensing)
Ports	24 or 48 10/100 ports