Defining the Mode of the Shared Port
The shared port on one end of the common link must be configured to be the controller. This is the end responsible for blocking ports when the common link fails, thereby preventing the superloop.
The shared port on the other end of the common link must be configured to be the partner. This end does not participate in any form of blocking. It is responsible for only sending and receiving health-check messages.
To configure the mode of the shared port, use the following command:
configure eaps shared-port ports mode controller | partner