A control execution apparatus is provided with a communication unit that makes an inquiry concerning a packet processing method with respect to a predetermined control instruction apparatus, and a packet processing unit that processes packets based on an instruction from the control instruction apparatus. The control instruction apparatus is provided with a communication history management unit that manages communication history between nodes via the control execution apparatus, a node state determination unit that determines, making reference to the communication history of the communication history management unit, whether or not a node that is a transmission source or a transmission destination of the packet for which an inquiry concerning a processing method was received, is on a side that provides a service to another node, and a control instruction unit that prohibits, when at least the node is on the side that provides a service to another node, new communication from the node in question to the other node.