+Third, OFPT_PACKET_IN and NXT_PACKET_IN messages are sent only to
+OpenFlow controller connections that have the correct connection ID
+(see "struct nx_controller_id" and "struct nx_action_controller"):
+
+ - For packet-in messages generated by a NXAST_CONTROLLER action,
+ the controller ID specified in the action.
+
+ - For other packet-in messages, controller ID zero. (This is the
+ default ID when an OpenFlow controller does not configure one.)
+