Hitachi, Ltd.

Nippon Telegraph and Telephone Corporation

Toshiya Oouchi

Akihiko Takase

Naoaki Yamanaka

Noboru Endo

Ryoji Takeyari

Junichirou Yanagi

Shiro Tanabe

Yusuke Mishina

Mitsuhiro Takano

Youichi Sato

Nobuhiko Ido

Shigeo Shinada

Keiko Kuroda

In an input cell policing method in a network of an asynchronous transfer mode, according to information contained in a header field of each input cell, a group to which the cell belongs is identified. For each group, there are set a plurality of time frames having a predetermined length and mutually different phases to count the number of input cells in each time frame period. For each time frame, the count value of input cells is compared with a predetermined threshold value. An input cell for which the count value exceeds the threshold value in either one of the time frames is assumed to be an excess cell. The excess cell is discarded or a violation mark is added thereto.

ATM cell policing method and apparatus

Distributed LANs are connected to a wide area network through terminal adapters, which are interconnected by virtual circuits to form a logical bus network. Each terminal adapter copies cells received through the virtual circuit that is allocated for multicasting, and transfers the copied cells to the adjacent terminal adapters via preset virtual circuits. The terminal adapters assemble a part or all of the transmitted message from the received cells and, according to the contents of the assembled message, transfer the copies of the cells to the adjacent terminal adapters through predetermined virtual circuits.

Multicast communications method

In a packet communication network in which a plurality of subscriber's lines are connected with a packet switching unit via a multiplexer and each of terminal units declares the packet rate on call request, a packet rate monitoring circuit is provided between the packet switching unit and the multiplexer. The packet rate monitoring circuit includes a circuit for monitoring the cell arrival rate, a circuit for detecting a packet cell violating the declared value which is transmitted from the terminal, a circuit for adding a mark representative of the violation cell to the violation packet which is detected by the detecting circuit, and a circuit for automatically modifying the declared parameter. The modifying circuit applies the declare parameter which was automatically modified in accordance with utilization condition (the number of multiplexings and the line utilization) of the multiplexer disposed between the subscriber's terminals and the rate monitoring circuit so that the detecting circuit detects the violation packets based upon the modified declared parameter.

Method of and system for monitoring packet rate in packet network

There is provided a packet-rate control method for a packet network, in which a declaration of parameters indicating the rate of fixed-length packets is so made to a call control system by a subscriber terminal device prior to communication as to be associated with a logical channel number. The rate of packets inputted to the network is so measured as to be associated with a logical channel number. While the degree of violation is low, packets transmitted in violation of user-declaring parameters are provided with a violation mark and taken in the network. If the degree of violation is high, the packets transmitted in violation of user-declaring parameters are discarded on the input side of the network. When there appears a possibility of congestion in the network, the marked packets are discarded. As a result, it is possible to prevent violation packets and marked packets from affecting the quality of service using normal packets.

Method of and system for controlling packet-rate in communication network

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Kokubunji, Japan

Toshiya Oouchi