Flow monitoring is a mechanism provided by OpenFlow specification to send an asynchronous event to the controller whenever there is any change in the flow entry. The Flow monitoring mechanism will be very useful in multi-controller deployment, wherein any change in the flow entry by one controller can be intimated to the other controllers in the system.
When the controller wants to configure a flow monitor, it sends an OFPMP_FLOW_MONITOR
multipart message (ofp_multipart_request
) to switch.
When the switch receives the OFPMP_FLOW_MONITOR
message with the command field set as OFPFMC_ADD
, the switch should check whether there is any monitor entry already configured in the system with the same monitor_id
. If there is an entry already present, then the switch should respond with an error message.
After which, the switch should examine the flags field and perform the action as follows:
OFPFMF_INITIAL
: This is set, then the switch should...