Cisco Systems Network Switch Cabling manual Setting the portfast option means

13. Set the remaining interfaces, which are identical, as follows.

If the switches connect to a gateway device through another switch or a device that participates in spanning tree protocol, do not set spanning tree portfast for the link to that device.

At this prompt...	Enter...	Notes
sw01(config)#	interface range GigabitEthernet 1/0/3 – 24	Setting the portfast option means
		that the port starts forwarding
		packets immediately instead of
		waiting for spanning tree protocol
		packets. This allows for less
		dropped packets when a switch
		first is brought online. This
		explanation assumes that none of
		the interfaces are running
		spanning tree. All spanning tree-
		to-spanning tree switches must not
		have spanning-tree portfast
		enabled. If they do have it enabled,
		the interface is automatically
		disabled upon receipt of a
		spanning tree packet.
sw01(config-if-range)#	spanning-tree portfast	Displays the following output:
	%Warning: portfast should only be enabled on ports connected to
	a single host. Connecting hubs, concentrators, switches,
	bridges, etc... to this interface when portfast is enabled, can
	cause temporary bridging loops.
	Use with CAUTION
	%Portfast will be configured in 22 interfaces due to the range
	command but will only have effect when the interfaces are in a
	non-trunking mode.

At this prompt...	Enter...	Notes
sw01(config-if-range)#	switchport mode access
sw01(config-if-range)#	exit
sw01(config)#	interface range GigabitEthernet 2/0/2 – 24
sw01(config-if-range)#	spanning-tree portfast	Displays the following output:

%Warning: portfast should only be enabled on ports connected to a single host. Connecting hubs, concentrators, switches, bridges, etc... to this interface when portfast is enabled, can cause temporary bridging loops.

Use with CAUTION

CASSATT ACTIVE RESPONSE CONTROL NODE AND NETWORK SWITCH CABLING EXAMPLE 28