Specifications

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Catalyst 4500 Series Switch Cisco IOS Command Reference—Release IOS XE 3.3.0XO(15.1(1)XO)
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Chapter 2 Cisco IOS Commands for the Catalyst 4500 Series Switches
spanning-tree uplinkfast
spanning-tree u plinkfast
To enable the UplinkFast feature, use the spanning-tree uplinkfast command. To disable UplinkFast,
use the no form of this command.
spanning-tree uplinkfast [max-update-rate packets-per-second]
no spanning-tree uplinkfast [max-update-rate]
Syntax Description
Defaults T he default settings are as follows:
• Disabled.
• Maximum update rate is 150.
Command Modes Global c onfiguratio n mode
Usage Guidelines T his command should be used only on access switche s.
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 instanc es 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 notificatio n is sent. To minimize the disruption caused by the
topology change, a multica st packet is sent to 01-00-0 C-CD-CD-CD for each st ation 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 the update packets are sent. Use the no form of this command to
return the default rate of 150 packe ts 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
Related Commands
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.
Command Description
spanning-tree cost Calculates the path cost of STP on an interface.
spanning-tree port-priority Prioritizes an interface when two bridges compete for
position as the root bridge.
spanning-tree portfast default E nables PortFast by default on all access ports.