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Chapter 5
Using Spanning Tree with VLANs
You can verify the UplinkFast configuration with the show spantree
uplinkfast
command:
Todd5000> (enable) show spantree uplinkfast
Station update rate set to 15 packets/100ms.
uplinkfast all-protocols field set to off.
VLAN port list
-----------------------------------------------
1 1/1(fwd)
2 1/1(fwd)
3 1/1(fwd)
4 1/1(fwd)
Todd5000> (enable)
Notice that all four VLANs are changed and that we were not asked which
VLANs to run UplinkFast on.
To configure UplinkFast on a 1900 switch, use the command uplink-
fast
in global configuration mode:
1900A#config t
1900A(config)#uplink-fast
1900A(config)#exit
To verify that UplinkFast is configured and running, use the commands
show uplink-fast
and show uplink-fast statistics:
1900A#show uplink-fast
Uplink fast Enabled
Uplink fast frame generation rate 15
1900A#show uplink-fast statistics
Uplink fast Transitions 0
Uplink fast Station Learning Frames 0
1900A#
The default frame generation rate is 15, which is displayed with the show
uplink-fast
command. The next command used to help STP maintain a
consistent network is BackboneFast.
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