set spantree uplinkfast

Use the set spantree uplinkfast command to enable fast switchover to alternate ports when the root port fails. This command applies to a switch, not to a WAN.

set spantree uplinkfast {enable | disable} [rate station_update_rate]

Syntax Description

enable	Keyword used to enable fast switchover.
disable	Keyword used to disable fast switchover.
rate station_update_rate	(Optional) Keyword rate station_update_rate specifies the number of multicast packets transmitted per 100 ms when an alternate port is chosen after the root port goes down. The default value is 15 packets/100 ms, which is equivalent to a load of 1 percent on a 10-Mbps Ethernet. If this value is specified as 0, the generation of these packets is turned off.

Default

The default rate is 15.

Command Type

Switch command.

Command Mode

Privileged.

Usage Guidelines

This command has the following results:

• Changes the bridge priority to 49152 for all VLANs (allowed VLANs).
• Increases the path cost and portvlancost of all ports to a value greater than 3000.
• On detecting the failure of a root port, an instant cutover occurs to an alternate port selected by Spanning-Tree Protocol.

If you run set spantree uplinkfast enable on a switch that has this feature already enabled, only the station update rate is updated. The rest of the parameters are not modified.

If you run set spantree uplinkfast disable on a switch, the uplinkfast feature is disabled but the switch priority and port cost values are not reset to the factory defaults. To reset the values to the factory defaults, use the clear spantree uplinkfast command.

Example

This example shows how to enable spantree uplinkfast:

Console>(enable) set spantree uplinkfast enable rate 40
VLANs 1-1000 bridge priority set to 49152.
The port cost and portvlancost of all ports increased to above 3000.
Station update rate set to 40 packets/100ms.
uplinkfast turned on for bridge.
  

Related Command

show spantree