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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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Chapter 22 Configuring Optional Spanning-Tree Features Configuring Optional Spanning-Tree Features
Note If you use BackboneFast, you must enable it on all switches in the network. BackboneFast is not
supported on Token Ring VLANs. This feature is supported for use with third-party switches.
You can configure the BackboneFast feature for rapid PVST+ or for the MSTP, but the feature remains
disabled (inactive) until you change the spanning-tree mode to PVST+.
Beginning in privileged EXEC mode, follow these steps to enable BackboneFast. This procedure is
optional.
To disable the BackboneFast feature, use the no spanning-tree backbonefast global configuration
command.
Enabling EtherChannel Guard
You can enable EtherChannel guard to detect an EtherChannel misconfiguration if your switch is
running PVST+, rapid PVST+, or MSTP.
Beginning in privileged EXEC mode, follow these steps to enable EtherChannel guard. This procedure
is optional.
To disable the EtherChannel guard feature, use the no spanning-tree etherchannel guard misconfig
global configuration command.
You can use the show interfaces status err-disabled privileged EXEC command to show which switch
ports are disabled because of an EtherChannel misconfiguration. On the remote device, you can enter
the show etherchannel summary privileged EXEC command to verify the EtherChannel configuration.
After the configuration is corrected, enter the shutdown and no shutdown interface configuration
commands on the port-channel interfaces that were misconfigured.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 spanning-tree backbonefast Enable BackboneFast.
Step 3 end Return to privileged EXEC mode.
Step 4 show spanning-tree summary Verify your entries.
Step 5 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 spanning-tree etherchannel guard
misconfig Enable EtherChannel guard.
Step 3 end Return to privileged EXEC mode.
Step 4 show spanning-tree summary Verify your entries.
Step 5 copy running-config startup-config (Optional) Save your entries in the configuration file.