EtherChannel Guard is a way of finding out if one end of the EtherChannel is not configured properly. This could be that there are some parameters not matching up such as duplex and speed. Or it could be that one side is a trunk and the other isn't.

When there is a misconfiguration found, the switch will place the interfaces in error-disabled state and an error will be displayed.

Configuration

To enable EtherChannel Guard, issue the global command:

SW1(config)#spanning-tree etherchannel guard misconfig

Verification

SW1#show spanning-tree summary
Switch is in pvst mode
Root bridge for: none
Extended system ID is enabled
Portfast Default is disabled
PortFast BPDU Guard Default is disabled
Portfast BPDU Filter Default is disabled
Loopguard Default is disabled
EtherChannel misconfig guard is enabled
UplinkFast is disabled
BackboneFast is disabled
Configured Pathcost method used is short

Name Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
Total 0 0 0 0 0

To view any disabled interfaces issue the show command:

show interfaces status err-disabled