Controller role-status messages (OFPT_ROLE_STATUS
) are sent from a switch to a set of controllers when the role of a controller is changed as a result of the OFPT_ROLE_REQUEST
message. For example, suppose there are three controllers connected to a switch (say controller1
, controller2
, and controller3
) and controller1
sends an OFPT_ROLE_REQUEST
message to the switch. Then the switch sends OFPT_ROLE_STATUS
to controller2
and controller3
.
If the controller wants to receive a port-status event from the switch, then it should configure the switch accordingly. Refer to the Sending a switch configuration message to the switch recipe of Chapter 1, OpenFlow Channel Connection Establishment (Part 2), for the procedure to configure the switch to send a port status message.