Cisco Catalyst 3550 Command Reference Manual page 587

Multilayer switch

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Chapter 2 Catalyst 3550 Switch Cisco IOS Commands

Do not enable the root guard on interfaces that will be used by the UplinkFast feature. With UplinkFast,

the backup interfaces (in the blocked state) replace the root port in the case of a failure. However, if root

guard is also enabled, all the backup interfaces used by the UplinkFast feature are placed in the

root-inconsistent state (blocked) and prevented from reaching the forwarding state.

If you set the max-update-rate to 0, station-learning frames are not generated, so the spanning-tree

topology converges more slowly after a loss of connectivity.

This example shows how to enable UplinkFast:

Switch(config)# spanning-tree uplinkfast

You can verify your setting by entering the show spanning-tree summary privileged EXEC command.

Related Commands

show spanning-tree

spanning-tree stack-port

spanning-tree vlan

Displays a summary of the spanning-tree port states.

Enables cross-stack UplinkFast (CSUF) on an interface and

accelerates the choice of a new root port when a link or switch

fails or when spanning tree reconfigures itself.

root primary

Forces this switch to be the root switch.

Catalyst 3550 Multilayer Switch Command Reference

spanning-tree uplinkfast

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