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Catalyst4500 Series SwitchCiscoIOS Command Reference—Release 12.2(18)EW
78-16201-01
Chapter2Cisco IOS Commands for the Catalyst 4500 Series Switches
spanning-tree uplinkfast
spanning-tree uplinkfast
To enable the UplinkFast feature, use the spanning-tree uplinkfast command. To disable UplinkFast,
use the no form of the command.
spanning-tree uplinkfast [max-update-rate packets-per-second]
no spanning-tree uplinkfast [max-update-rate]
Syntax Description
Defaults The default settings are as follows:
• Disabled.
• Maximum update rate is 150.
Command Modes Global configuration
Command History
Usage Guidelines This command should be used only on access switches.
When UplinkFast is configured, the bridge priority is changed to 49,152 so that this switch will not be
selected as root. All interface path costs of all spanning tree interfaces belonging to the specified
spanning tree instances are also increased by 3000.
When spanning tree detects that the root interface has failed, the UplinkFast feature causes an immediate
switchover to an alternate root interface, transitioning the new root interface directly to the forwarding
state. During this time, a topology change notification is sent. To minimize the disruption caused by the
topology change, a multicast packet is sent to 01-00-0C-CD-CD-CD for each station address in the
forwarding bridge except for those associated with the old root interface.
Use the spanning-tree uplinkfast max-update-rate command to enable UplinkFast (if not already
enabled) and change the rate at which update packets are sent. Use the no form of the command to return
the default rate of 150 packets per second.
Examples This example shows how to enable UplinkFast and set the maximum rate to 200 packets per second:
Switch(config)# spanning-tree uplinkfast
Switch(config)# spanning-tree uplinkfast max-update-rate 200
max-update-rate
packets_per_second
(Optional) Specifies the maximum rate (in packets per second) at which update
packets are sent; valid values are from 0 to 65535.
Release Modification
12.1(8a)EW Support for this command was introduced on the Catalyst 4500 series switch.
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