Packet data flow control method and device

A packet data flow control device for performing point-to-multipoint communication or point-to-point communication in a network comprising one or a plurality of packet exchanges accommodating respectively a plurality of communication terminals, comprising:

• switch means for switching packets received from an upstream link to a downstream link;
• buffering means provided at each output port of the switch means, for temporarily storing the packets that are switched to the downstream link;
• calculation means when congestion occurs for calculating a free capacity of the buffering means;
• transmission rate control means for controlling transmission rate of packets to be sent to the downstream link in accordance with a first load data that is notified from the downstream link;
• and
• notification means for generating a second load data based on the first load data and the free capacity of the buffering means calculated by the calculation means, and notifying the upstream link of the second load data.

A packet data flow control system in a packet exchanging network in which a plurality of terminals are connected to a network comprising one or a plurality of packet exchanges wherein simultaneous transmission of data packets is performed by setting up a point-to-multipoint connection in which an arbitrary one of the terminals is a transmission source terminal and a plurality of other terminals are respective destination terminals,

• the transmission source terminal comprising means for sending a congestion notification packet for exchanging load data with a downstream side relating to a direction of communication of the data packets,
• the destination terminals each comprising:
• first loading condition detecting means for detecting a loading condition of their own terminal;
• and
• means for overwriting, returning and sending the detection result of the first loading condition detecting means in the congestion notification packet received from an upstream side relating to the communication direction of the data packets,
• a first packet exchange that is located at a branch point of the point-to-multipoint connection, comprising:
• means for sending to the downstream side the congestion notification packet relating to the direction of communication of the data packets;
• load data determining means that receives the congestion notification packet that is returned from the downstream side and determines load data in accordance with the congestion notification packet;
• and
• means for overwriting the congestion notification packet by a result of the determination by the load data determining means and returning to the transmission source terminal when the congestion notification packet is received from the upstream side, and
• a second packet exchange that is located on the point-to-multipoint connection and which is not at a branch point, comprising:
• a second loading condition detecting means for detecting a loading condition of their own device;
• and
• means for receiving the congestion notification packet that is returned from the downstream side and for overwriting the congestion notification packet in accordance with a detection result of the second loading condition detecting means and sending it to the upstream side.