Hitachi, Ltd.

Hitachi Communication Systems, Inc.

Yutaka Torii

Shinobu Gohara

Yoshito Sakurai

Noboru Endo

Kenichi Ohtsuki

Kenji Kawakita

Jiro Kashio

Makoto Mori

Yumiko Nishi

Norihumi Komatu

Seiichi Takaki

Isao Fukuta

In a packet communication method, a packet communication device, an input transmission frame of V (bytes/sec) consisting of a transmission overhead of V.sub.OH (bytes/sec) containing control information for transmission and a pay load of V.sub.p (bytes/sec) of c (=a+b) bytes, the outer cell consisting of an information field of a b-byte length containing transmission data and a header field of an a-byte length containing a first control information for transmitting the information field. The transmission overhead is removed from and a second control information is added to the input transmission frame. The input transmission frame with the second control information and without the transmission overhead is converted to a plurality of inner cell trains of f (=b+j) bytes length, the inner cell trains consisting of an information field of a b-byte containing the transmission data and a second header field of j (=a+d) bytes consisting of the first control information and the second control information (where f.times.g=h.times.V, h is an integer or a fraction of an integer). Packets switching are performed on each inner cell. A plurality of inner cells are converted to an output transmission frame of V (bytes/sec) having the same format as the input transmission frame for transmission.

Packet communication method, packet communication device and packet

A packet switching equipment housing therein a plurality of pairs of an input line and an output line is provided with a monitor circuit for monitoring a packet congestion state in the packet switching equipment for each output line. When a packet congestion is detected in association with either one of the output lines, a congestion indicator is added to a packet to be delivered to the output line so as to return the packet as a congestion notice packet to an equipment as the transmission source of the packet; furthermore, the input packet is relayed via the output line to the destination equipment.

Packet congestion control method and packet switching equipment

A telephone exchange system has a plurality of bit synchronization circuit each provided for an individual subscriber's line. A single clock generating circuit which generates a plurality of clocks is provided in common to the plurality of bit synchronization circuits. The bit synchronization circuit selects one clock of a phase suitable for regenerating an input data signal among the plurality of clocks applied thereto by the clock generating circuit, and regenerates and phases the input data signal by using the selected clock.

Bit synchronization circuit

In the ATM switching system, an ATM speech path is divided into a plurality of functional blocks. A routing function for distributing cells (packets) each of a fixed length to addresses outgoing lines and a logical multiplexing function are imparted to a switch, while other functions associated with a line typified by a phase synchronizing function and a flow control function are incorporated en bloc in ATM line terminating units and functions capable of being processed by hardware in common to the lines are assembled in a line common unit. The ATM line terminating unit physically terminates transmission lines and performs the processing relevant to header information of the cells each of a fixed length (ATM terminating processing) and includes a cell phase synchronizing circuit for matching the temporal positions of the cells among the lines and a flow control circuit for avoiding overload exceeding the load declared by subscriber terminal. The line common unit serves for processings of call control signals and the calls and includes a signal processing circuit and a control circuit. The switch performs cell multiplexing and switching and is constituted by a self-routing switch.

ATM switching system

Growing community of inventors

Yokohama, Japan

Yutaka Torii