CONGESTION CONTROLLER AND CONGESTION CONTROL METHOD

PROBLEM TO BE SOLVED: To provide a congestion controller and a congestion control method capable of producing an effect stably and efficiently, and always minimizing the number of flows where a communication rate drops sharply.SOLUTION: The congestion controller 1 comprises window size addition means 7 for adding the current window size, as information, to the head packet of a packet group for the window size, window size information detection means 3 for detecting the information of the window size added to the head packet, flow selection means 4 for selecting a flow containing the largest window size from the window size information detected by the window size information detection means 3, packet discard means 6 for discarding other packet than the head packet of the flow selected by the flow selection means 4, and a control unit (control means) 5 which controls each means. The congestion controller 1 is connected with an edge node 9 by a network 8 through an interface 2.