Flow removed messages (OFPT_FLOW_REMOVED
) are sent from the switch to the controller when a flow entry is removed from the flow table. The switch sends this message only to the controller channel wherein the controller requested the switch to send it.
If the controller wants to receive flow removed events from a switch, then the controller 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 flow removed messages.
The message format that will be used by the switch to send a OFPT_FLOW_REMOVED
message is defined in the Sending a flow-removed message to the controller recipe in Chapter 2, Symmetric Messages and Asynchronous Messages (Part 1).
When the controller receives this message, based on its control logic, it should take the...