Cisco 2950G 24 Software Configuration Guide - Page 331
Enabling UplinkFast for Use with Redundant Links
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Chapter 13 Configuring Optional Spanning-Tree Features Configuring Optional Spanning-Tree Features To disable BPDU filtering, use the no spanning-tree portfast bpdufilter default global configuration command. You can override the setting of the no spanning-tree portfast bpdufilter default global configuration command by using the spanning-tree bpdufilter enable interface configuration command. Enabling UplinkFast for Use with Redundant Links UplinkFast cannot be enabled on VLANs that have been configured for switch priority. To enable UplinkFast on a VLAN with switch priority configured, first restore the switch priority on the VLAN to the default value by using the no spanning-tree vlan vlan-id priority global configuration command. Note When you enable UplinkFast, it affects all VLANs on the switch. You cannot configure UplinkFast on an individual VLAN. The UplinkFast feature is supported only when the switch is running PVST. Beginning in privileged EXEC mode, follow these steps to enable UplinkFast: Step 1 Step 2 Step 3 Step 4 Step 5 Command Purpose configure terminal Enter global configuration mode. spanning-tree uplinkfast [max-update-rate Enable UplinkFast. pkts-per-second] (Optional) For pkts-per-second, the range is 0 to 65535 packets per second; the default is 150. If you set the rate to 0, station-learning frames are not generated, and the spanning-tree topology converges more slowly after a loss of connectivity. end Return to privileged EXEC mode. show spanning-tree summary Verify your entries. copy running-config startup-config (Optional) Save your entries in the configuration file. 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 interfaces and VLAN trunks is increased by 3000 (if you change the path cost to 3000 or above, the path cost is not altered). The changes to the switch priority and the path cost reduces the chance 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 defaults. To return the update packet rate to the default setting, use the no spanning-tree uplinkfast max-update-rate global configuration command. To disable UplinkFast, use the no spanning-tree uplinkfast command. 78-14982-01 Catalyst 2950 Desktop Switch Software Configuration Guide 13-17
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