Cisco WS-C3560E-24PD-E Command Reference - Page 631
spanning-tree portfast (interface configuration
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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 disable trunk (Optional) Disable the Port Fast feature on the specified interface. (Optional) Enable the Port Fast feature on a trunking interface. 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(19)EA1 Modification This command was introduced. 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. 78-16405-05 Catalyst 3560 Switch Command Reference 2-599