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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 13 Configuring Optional Spanning-Tree Fea tures Configuring Optional Spanning-Tree Features
To disable BPDU filtering, use the no spanning-tree portfast bpdufilter default global configura tio n
comm an d.
You ca n overrid e the s et ti ng o f the no spanning- tree portfast bpdufilter default global configuration
comm and by u s ing the spanning- tree bpdufilter enable interfac e configuration comma nd.

Enabling UplinkFast for Use with Redundant Links

UplinkFas t cannot be en abled on VLANs that have been configur ed for switc h priori ty. To enable
UplinkF ast on a VLAN w ith swit ch p ri ority c onfigu red , fir st r estor e the swi tch pr iority on the VL AN to
the default value by using the no spanning-tree vlan vlan-id priority global con figuration co mmand .
Note When you enable UplinkFast, it affects all VLANs on the switch. You cannot configure UplinkFast on
an individual VLAN.
The Upl inkFast feature is supporte d only when th e switch is runni ng PVST.
Beginning in privileged EXEC mode, follow these steps to enable UplinkFast:
When UplinkFast is enabled, the switch priority of all VLANs is set to 49152. If you change the path
cost to a value less than 3000 and you enable UplinkFast or UplinkFast is already enabled, the path cost
of all inter faces and VLA N trunks is increased by 3000 (if you change the pat h cost to 3000 or above,
the pa th co st is not alter ed). Th e ch an g es to t he s witc h prio r ity an d th e pa th co st r edu ces th e c ha nce that
the switch will become the root switch.
When UplinkFast is disabled, the switch priorities of all VLANs and path costs of all interfaces are set
to default values if you did not modify them from their defa ults.
To return the update packet rate to the default setting, use the no spanning-tree uplinkfast
max-update-rate global configurat ion comm and. To disa ble Upl inkFast, use the no spanning-tree
uplinkfast command.
Command Purpose
Step 1 configure terminal Enter g l obal c onfigura tion m od e.
Step 2 spanning-tree uplinkfast [max-update-rate
pkts-per-second]Enable UplinkFast.
(Optional) For pkts-per-second, the range is 0 to 65535 pa ckets per
second ; the default is 150.
If you se t the r ate t o 0, st atio n-le arni ng fra mes are not g ener ated,
and the sp an ning- tree topo logy c onve rges mor e sl owly after a loss
of connectivity.
Step 3 end Return to privileged EXEC mode.
Step 4 show spanning-tree summary Verify yo ur entr ies.
Step 5 copy running-config startup-config (Optio nal) Save your e ntr ies in the con figurati on file.