3Com WX4400 Command Reference Manual page 463

set spantree uplinkfast 463
History —Introduced in MSS Version 3.0.
Usage — The uplink fast convergence feature is applicable to bridges
that are acting as access switches to the network core (distribution layer)
but are not in the core themselves. Do not enable the feature on WX
switches that are in the network core.
Examples — The following command enables uplink fast convergence:
WX4400# set spantree uplinkfast enable
success: change accepted.
See Also
display spantree uplinkfast on page 452