Flow monitoring is a mechanism provided by OpenFlow specification to send an asynchronous event to a controller whenever there is any change in the flow entry. The flow monitoring mechanism will be very useful in multicontroller deployment, wherein any change in the flow entry by one controller can be made known to other controllers in the system.
When the controller wants to configure a flow monitor, they should send the OFPMP_FLOW_MONITOR
multipart message (ofp_multipart_request
) to the switch.
In order to configure the flow monitor entry in the switch, the controller should send a multipart request message with the type
field set as OFPMP_FLOW_MONITOR
. The message format that should be used by the controller to form the multipart request message is defined in the Introduction section in Chapter 5, Handling Multipart Statistics Messages (Part 2).
The body
field should be filled with the following structure by the controller...