Cisco Catalyst 4500 Series Administration Guide

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Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
OL_28731-01
Chapter 25 Configuring Optional STP Features
Enabling UplinkFast
Figure 25-3 UplinkFast After Direct Link Failure
Enabling UplinkFast
UplinkFast increases the bridge priority to 49,152 and adds 3000 to the spanning tree port cost of all
interfaces on the switch, making it unlikely that the switch becomes the root switch. The
max_update_rate value represents the number of multicast packets transmitted per second (the default
is 150 packets per second [pps]).
UplinkFast cannot be enabled on VLANs that have been configured for bridge priority. To enable
UplinkFast on a VLAN with bridge priority configured, restore the bridge priority on the VLAN to the
default value by entering a no spanning-tree vlan vlan_ID priority command in global configuration
mode.
Note When you enable UplinkFast, it affects all VLANs on the switch. You cannot configure UplinkFast on
an individual VLAN.
To enable UplinkFast, perform this task:
This example shows how to enable UplinkFast with a maximum update rate of 400 pps:
Switch(config)# spanning-tree uplinkfast max-update-rate 400
Switch(config)# exit
Switch#
This example shows how to verify which VLANS have UplinkFast enabled:
Switch# show spanning-tree uplinkfast
UplinkFast is enabled
L1
L2 L3
Switch C
Switch A
(Root)
Switch B
UplinkFast transitions port
directly to forwarding state
Link failure
11242
Command Purpose
Step 1
Switch(config)# [no] spanning-tree uplinkfast
[max-update-rate max_update_rate]
Enables UplinkFast.
Use the no keyword to disable UplinkFast and restore the
default rate, use the command.
Step 2
Switch(config)# end
Exits configuration mode.
Step 3
Switch# show spanning-tree vlan vlan_ID
Verifies that UplinkFast is enabled on that VLAN.

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