Spanning-Tree Portfast (Interface Configuration) - Cisco Catalyst 3750 Command Reference Manual

Chapter 2 Catalyst 3750 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.
Syntax Description disable
trunk
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 Release
12.1(11)AX
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.
78-16181-03
spanning-tree portfast [disable | trunk]
no spanning-tree portfast
(Optional) Disable the Port Fast feature on the specified interface.
(Optional) Enable the Port Fast feature on a trunking interface.
Modification
This command was introduced.
spanning-tree portfast (interface configuration)
Catalyst 3750 Switch Command Reference
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