10-37
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-03
Chapter 10 Configuring STP
Configuring Advanced STP Features
Enabling EtherChannel Guard
Use the EtherChannel guard feature to detect a misconfigured EtherChannel when Catalyst 3550 switch
interfaces are configured as an EtherChannel while interfaces on the remote device are not, or not all the
interfaces on the remote device are in the same EtherChannel.
Beginning in privileged EXEC mode, follow these steps to enable EtherChannel guard:
To disable the EtherChannel guard feature, use the no spanning-tree etherchannel guard misconfig
global configuration command.
To determine which local ports are involved in the misconfiguration and in the err-disabled state, enter
the show interfaces status err-disabled privileged EXEC command. To check the EtherChannel
configuration on the remote device, enter the show etherchannel summary privileged EXEC command
on the remote device.
After you correct the configuration, enter the shutdown and the no shutdown interface configuration
commands on the associated port-channel interface.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
spanning-tree etherchannel guard misconfig
Enable the EtherChannel guard feature, and display an
error message when a loop caused by a channel
misconfiguration is detected.
This feature is enabled by default.
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.
