Setting asynchronous configuration

Every OpenFlow channel conveys messages from the switch to various controllers present in the network. The controller manages its asynchronous configuration with the use of the OFPT_SET_ASYNC and OFPT_GET_ASYNC_REQUEST messages. The OFPT_SET_ASYNC message is used by the controller to determine whether it should receive any asynchronous message from the switch, while OFPT_GET_ASYNC_REQUEST is sent from the controller to the switch's reply message, OFPT_GET_ASYNC_REPLY, with the properties of the asynchronous configuration properties being sent to the controller in order to determine what is enabled.