Name: Cisco Catalyst 3750-X
Brand: Cisco
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Catalyst 3750-X and 3560-X Switch Command Reference

OL-29704-01

Chapter 2 Catalyst 3750-X and 3560-X Switch Cisco IOS Commands

spanning-tree portfast (interface configuration)

Use the spanning-tree portfast interface configuration command on the switch stack or on a standalone

switch to enable the Port Fast feature on an interface in all its associated VLANs. When the Port Fast

feature is enabled, the interface changes directly from a blocking state to a forwarding state without

making the intermediate spanning-tree state changes. Use the no form of this command to return to the

default setting.

spanning-tree portfast [disable | trunk]

no spanning-tree portfast

Syntax Description

Defaults The Port Fast feature is disabled on all interfaces; however, it is automatically enabled on

dynamic-access ports.

Command Modes Interface configuration

Command History

Usage Guidelines Use this feature only on interfaces that connect to end stations; otherwise, an accidental topology loop

could cause a data packet loop and disrupt switch and network operation.

To enable Port Fast on trunk ports, you must use the spanning-tree portfast trunk interface

configuration command. The spanning-tree portfast command is not supported on trunk ports.

You can enable this feature when the switch is operating in the per-VLAN spanning-tree plus (PVST+),

rapid-PVST+, or the multiple spanning-tree (MST) mode.

This feature affects all VLANs on the interface.

An interface with the Port Fast feature enabled is moved directly to the spanning-tree forwarding state

without the standard forward-time delay.

You can use the spanning-tree portfast default global configuration command to globally enable the

Port Fast feature on all nontrunking interfaces. However, the spanning-tree portfast interface

configuration command can override the global setting.

If you configure the spanning-tree portfast default global configuration command, you can disable

Port Fast on an interface that is not a trunk interface by using the spanning-tree portfast disable

interface configuration command.

disable (Optional) Disable the Port Fast feature on the specified interface.

trunk (Optional) Enable the Port Fast feature on a trunking interface.

Release Modification

12.2(53)SE2 This command was introduced.

Cisco Catalyst 3750-X Command Reference

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