2.1.e Implement and troubleshoot EtherChannel

2.1.e [iv] Etherchannel misconfiguration guard

EtherChannel is supposed to be point-to-point and the feature is adding a consistency check based on the source mac address of the BPDU received. If you keep receiving BPDUs from several source mac addresses, this feature will assume that you have a bundling problem and shut down the port.

You can enable EtherChannel guard to detect an EtherChannel misconfiguration if your switch is running PVST +, rapid PVST +, or MSTP. Actual command to turn this feature on is spanning-tree etherchannel guard misconfig.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 1706-1712).  . Kindle Edition.

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/12-2_55_se/configuration/guide/3750xscg/swstpopt.html#wp1113708
Understanding EtherChannel Guard

You can use EtherChannel guard to detect an EtherChannel misconfiguration between the switch and a connected device. A misconfiguration can occur if the switch interfaces are configured in an EtherChannel, but the interfaces on the other device are not. A misconfiguration can also occur if the channel parameters are not the same at both ends of the EtherChannel. For EtherChannel configuration guidelines, see the “EtherChannel Configuration Guidelines” section.

If the switch detects a misconfiguration on the other device, EtherChannel guard places the switch interfaces in the error-disabled state, and displays an error message.

You can enable this feature by using the spanning-tree etherchannel guard misconfig global configuration command.