Specifications

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Catalyst 4500 Series Switch Cisco IOS Command Reference—Release IOS XE 3.3.0XO(15.1(1)XO)
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Chapter 2 Cisco IOS Commands for the Catalyst 4500 Series Switches
spanning-tree portfast (interface configuration mode)
spanning-tree portf ast (interface configurat ion mode)
To enable PortFast mode, where the interface is immediately put into the forwarding state upon linkup
without waiting for the timer to expire, use the spanning-tree portfast command. To return to the
default setting, use the no form of this command.
spanning-tree portfast {disable | trunk}
no spanning-tree portfast
Syntax Description
Defaults P ortFast mode is disable d.
Command Modes Interface configuration mode
Usage Guidelines You should use this feature only with interfaces that conne ct to end stations; othe rwise, an accidental
topology loop could cause a data packet loop and disrupt th e Catalyst 4500 series switch and ne twork
operation.
An interface with PortFast mode enabled is moved directly to the spanning-tree forwarding state when
linkup occurs without waiting for the standard forward-time delay.
Be careful when using the no spanning-tree portfast command. This command does not disable
PortFast if the spanning-tree portfast default command is ena bled.
This command has four states:
• spanning-tree portfast—This command enables PortFast unconditionally on the given port.
• spanning-tree portfast disable—This command explicitly disables PortFast for the given port. The
configuration line shows up in the running-configuration as it is not the default.
• spanning-tree portfast trunk—This command allows you to configure PortFast on trunk port s.
Note If you enter the spanning-tree portfast trunk command, the port is configured for PortFast
even when in the access mode.
• no spanning-tree portfast—This command implicitly enables PortFast if the spanning-tree
portfa st de faul t command is defined in globa l configuration and if the port is not a trunk port. If
you do not configure P ortFast globa lly, the no spanning-tree portfast command is equivalent to the
spanning-tree portfast disable command.
Examples This exampl e shows how to enable PortFast mode:
Switch(config-if)# spanning-tree portfast
Switch(config-if)
disable Disables PortFast on the interface.
trunk Enables PortFast on the interface even while in the trunk mode.