When a processing method determination means is not able to determine a processing method for a communication flow of packets, flow identification information transmission means transmits information within the packets equivalent to a portion or all of first flow identification information for identifying the communication flow to a processing determination unit. Control action determination means determines a control action on the basis of information received from a communication flow processing unit and second flow identification information stored in control action storage means. Control instruction means instructs the communication flow processing unit to control the communication flow on the basis of the control action. Processing method registration means registers a processing method for the communication flow with process method storage means on the basis of control instructions from a control unit.
