Port Status
Desirable
The port actively sends PAgP packets and is willing to form an EtherChannel. Ports in Desirable mode will initiate negotiations with other ports set to either Desirable or Auto modes.
On
This mode forces the port to be part of an EtherChannel without any PAgP negotiation. It’s essential to ensure that the ports on the other end of the EtherChannel are also set to “On” to avoid misconfiguration issues. This mode bypasses PAgP entirely.
Auto
Ports configured in “Auto” mode do not actively initiate EtherChannel negotiations but will respond to PAgP packets received from ports in Desirable mode. This mode is more passive and will only form an EtherChannel if the other side is actively seeking to form one.