Command:

spanning-tree uplinkfast

Mode:

Switch(config)#


Syntax:

spanning-tree uplinkfast [max-update-rate pkts-per-second]

no spanning-tree uplinkfast [max-update-rate pkts-per-second]


Syntax Description:

max-update-rate pkts-per-second

The number of packets per second at which stations address update packets are sent. The range is 0 to 1000.


Command Description:

Use the spanning-tree uplinkfast global configuration command to accelerate the choice of a new root port when a link or switch fails or when Spanning Tree Protocol (STP) reconfigures itself. Use the no form of this command to return to the default value.

When you enable UplinkFast, it is enabled for the entire switch and cannot be enabled for individual VLANs.

When you enable UplinkFast, the bridge priority of all VLANs is set to 49152, and the path cost of all ports and VLAN trunks is increased by 3000. This change reduces the chance that the switch will become the root switch.

When you disable UplinkFast, the bridge priorities of all VLANs and path costs are set to their default values.

Do not enable the root guard on ports that will be used by the UplinkFast feature. With UplinkFast, the backup ports (in the blocked state) replace the root port in the case of a failure. However, if root guard is also enabled, all the backup ports used by the UplinkFast feature are placed in the root-inconsistent state (blocked) and prevented from reaching the forwarding state.


Example:

The following command shows how to enable UplinkFast:

Switch(config)#spanning-tree uplinkfast
 

You can verify the previous command by entering the show spanning-tree command in privileged EXEC mode.


Misconceptions:
None

Related commands:
show spanning-tree

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