Cisco Catalyst 4500 Series Configuration Guide

23-7
Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
OL-25340-01
Chapter 23 Configuring Optional STP Features
Enabling PortFast
unit (BPDU), spanning tree does not place the port into the blocking state. Spanning tree sets the port’s
operating state to non-port fast even if the configured state remains port fast and starts participating in
the topology change.
Note Because the purpose of PortFast is to minimize the time that access ports must wait for spanning tree to
converge, it is most effective when used on access ports. If you enable PortFast on a port connecting to
another switch, you risk creating a spanning tree loop.
Enabling PortFast
Caution Use PortFast only when connecting a single end station to a Layer 2 access port. Otherwise, you might
create a network loop.
To enable PortFast on a Layer 2 access port to force it to enter the forwarding state immediately, perform
this task:
This example shows how to enable PortFast on Fast Ethernet interface 5/8:
Switch(config)# interface fastethernet 5/8
Switch(config-if)# spanning-tree portfast
Switch(config-if)# end
Switch#
This example shows how to verify the configuration:
Switch# show running-config interface fastethernet 5/8
Building configuration...
Current configuration:
!
interface FastEthernet5/8
no ip address
switchport
switchport access vlan 200
switchport mode access
spanning-tree portfast
end
Switch#
Command Purpose
Step 1
Switch(config)# interface {{fastethernet |
gigabitethernet | tengigabitethernet} slot/port}
| {port-channel port_channel_number}
Specifies an interface to configure.
Step 2
Switch(config-if)# [no] spanning-tree portfast
Enables PortFast on a Layer 2 access port connected to a
single workstation or server.
Use the no keyword to disable PortFast.
Step 3
Switch(config-if)# end
Exits configuration mode.
Step 4
Switch# show running interface {{fastethernet |
gigabitethernet | tengigabitethernet} slot/port}
| {port-channel port_channel_number}
Verifies the configuration.

Cisco Catalyst 4500 Series Specifications

General

Series	Catalyst 4500 Series
Category	Switch
Layer Support	Layer 2, Layer 3
Form Factor	Modular chassis
Stackable	No
Chassis Slots	3, 6, 7, 10
Power Supply Options	AC, DC
Redundancy	Power supply, Supervisor engine
Network Management	Cisco IOS Software CLI, SNMP, Cisco Prime Infrastructure
Features	Security, QoS
Port Density	Up to 384 ports per chassis
Security Features	802.1X, ACLs, DHCP Snooping, Dynamic ARP Inspection, IP Source Guard
Supervisor Engine	8-E