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Catalyst 3560 Switch Command Reference
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Chapter 2 Catalyst 3560 Switch Cisco IOS Commands
spanning-tree portfast (interface configuration)
spanning-tree portfast (interface configuration)
Use the spanning-tree portfast interface configuration command 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
12.1(19)EA1 This command was introduced.
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