Reference Guide

Default Enabled
Format spanning-tree tcnguard
Mode Interface Config
no spanning-tree tcnguard
This command resets the TCN guard status of the port to the default value.
Format no spanning-tree tcnguard
Mode Interface Config
spanning-tree transmit
This command sets the Bridge Transmit Hold Count parameter.
Default 6
Format spanning-tree transmit hold-count
Mode Global Config
Parameter Description
hold-count
The Bridge Tx hold-count parameter. The value in an integer between 1 and 10.
spanning-tree uplinkfast
Use this command to configure the rate at which gratuitous frames are sent (in packets per second)
after switchover to an alternate port on PVSTP configured switches and enables uplinkfast on PVSTP
switches. The range is 0-32000; the default is 150. This command has the eect of accelerating
spanning-tree convergence after switchover to an alternate port.
Uplinkfast can be configured even if the switch is configured for MST(RSTP) mode, but it only has an
eect when the switch is configured for PVST mode. Enabling FastUplink increases the priority by
3000. Path costs less than 3000 have an additional 3000 added when uplinkfast is enabled. This
reduces the probability that the switch will become the root switch.
Uplinkfast immediately changes to an alternate root port on detecting a root port failure and changes
the new root port directly to the forwarding state. A TCN is sent for this event.
After a switchover to an alternate port (new root port), uplinkfast multicasts a gratuitous frame on the
new root port on behalf of each attached machine so that the rest of the network knows to use the
secondary link to reach that machine.
PVRSTP embeds support for backbonefast and uplinkfast. There is no provision to enable or disable
these features in PVRSTP configured switches.
Switching Commands
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