Fujitsu Corporation

Fujitus Limited

Satoshi Kakuma

Shuji Yoshimura

Shiro Uriu

Masami Murayama

Yasuhiro Aso

Yoshihiro Uchida

Naoyuki Izawa

Kazuo Hajikano

Yuzo Okuyama

Noriko Samejima

Yoshihiro Watanabe

Tetsuo Tachibana

Takashi Hatano

Kenichi Okabe

Satoshi Kuroyanagi

Ryuichi Takechi

Takeshi Kawasaki

Hiroshi Tomonaga

Mikio Nakayama

Jyoei Kamoi

Naoki Aihara

Jin Abe

Toshio Shimoe

Naoki Fukuda

Tadahiro Takase

Atsuhisa Takahashi

Teruaki Hagihara

Yoshiharu Kato

Naotoshi Watanabe

Toshio Soumiya

Jun Itoh

Masafumi Katoh

Hiroshi Nishida

Eiji Ishioka

Shigeru Sekine

Hiroshi Miyake

Satoshi Esaka

Miyuki Kawataka

Fumio Hirase

Yoshiyuki Karakawa

Yasuhiro Nishikawa

Shinichi Araya

Nobuyuki Tsutsui

Atsuko Suzuki

Shouji Kohira

Hiromi Yamanaka

Yoshihisa Tsuruta

Atsushi Kagawa

Sumie Morita

Tadashi Hoshino

Megumi Shibata

William Lipp

Youzou Iketani

Yasusi Kobayasi

Yasusi Kobayashi

H Paul Holzworth

Yumiko Kato

Yasunori Tonooka

Katsuyuki Nakamura

Noaki Fukuda

Gary Deval

A switch station including an ATM switch; a memory storing control data for operations of the switch station; an intra-station device, accommodating a subscriber line, performing communication operation on subscriber ATM cell; a control processor generating control information in link access protocol (LAP) format; and an interface unit converting LAP control information into ATM cell to the intra-station device through the ATM switch, wherein the control information is communicated according to LAP, the intra-station device receives the control information and transmits a direct memory access request to obtain control data stored in the memory, the interface unit obtains and converts the data format of the control data into ATM cell to transmit to the intra-station device through the switch, and the intra-station device performs the communication operation on the subscriber ATM cell based on the control data received through the switch.

Intra-station control system for connectionless communications system

An adjustable connection admission control method and device for packet-based switches assigns equivalent bandwidths to variable speed connections. The equivalent bandwidths of the variable speed connections are increased or reduced by a scaling factor to achieve an assigned bandwidth. The method and device determine whether to accept or refuse new variable speed connections based on whether the sum of equivalent bandwidths for existing variable speed connections and new variable speed connections exceeds the bandwidth available to variable speed connections. The connection admission control method and device also determines whether to accept or refuse new constant speed and new unspecified connections. For constant speed connections, the sum of existing and new constant speed connections is obtained. If the sum of bandwidths for existing and new constant speed connections exceeds a maximum factor, the bandwidth available to constant speed connections is reduced by a constant speed traffic factor. At least a portion of the unspecified connections do not have a sustained cell rate. The sustained cell rate is determined by multiplying a peak cell rate by an SCR factor. Equivalent bandwidths are assigned to unspecified connections and are increased or reduced by the scaling factor to achieve an assigned bandwidth. New unspecified connections are accepted or refused based on whether the sum of bandwidths for existing and new unspecified connections exceeds a bandwidth available to unspecified connections. The scaling factor, traffic factor, maximum factor, constant speed traffic factor and SCR factor can be adjusted.

Adjustable connection admission control method and device for packet-based switch

The object of the present invention is accomodating local connectionless information (data that is immediately transferred without establishing a path to a receive side), such as LAN data in a local area network, by an asynchronous transfer mode (ATM) network using a connection-oriented communication system (which makes data transfers after verifying that a path to the receive side has been established), thereby performing efficient, fast routing of connectionless information. A connectionless communication system of the present invention is equipped with connectionless information cell assembly/deassembly means for bi-directional conversion between variable-length connectionless information and fixed-length connectionless cells, routing control means for analyzing a destination address of information in connectionless cells and controlling the routing of the connectionless cells; and an ATM network for connecting the connectionless information cell assembly/deassembly means and the routing control means by a permanent virtual channel serving as a fixed path and connecting the routing control means together by a virtual channel serving as a semi-fixed path, whereby connectionless information is segmented into connectionless cells and the connectionless information is exchanged within the ATM network in connectionless cell units.

Connectionless communication system

The quality and performance of the connectionless communications system are improved. When a BOM is received, the destination address DA of the L3-PDU stored in the payload of the BOM is retrieved, and the tag information is obtained from the DA (S,). The output message identifier MID is reserved (S,), and the tag information and output MID are assigned to the BOM (S,). Then, the tag information and output MID are written to the table. When a COM is received, the tag information and output MID are retrieved using the MID of the COM as a key, and the information is provided for the COM (S,and S,). When an EOM is received, the tag information and output MID are retrieved using the MID of the EOM as a key, and the information is provided for the EOM (S,and S,). Then, the output MID is released (S,).

Connectionless communications system, its test method, and intra-station control system

A supervision control system for an ATM cell switching system counts the number of cells transmitted from a subscriber in a predetermined duration unit, attaches a sign to the cells when the counted value exceeds a predetermined value, and discards the cells to which the sign is attached when a buffer does not have enough capacity during a cell multiplexation.

Supervision control system

A congestion control system appropriately controls congestion of cells independently of the configuration of source and destination terminal units in, for example, an ATM switching unit, and shortens the time taken from the generation of congestion to the start of control. A buffer for switching the cells in a switch device adds to the cells transmitted through the switch device an EFCI for use in notifying the destination terminal unit of the congestion state of the cells. An output line device detects together with a VPI/VCI the EFCI added to the cell to be output from the switch device to the destination terminal unit. The output line device transmits to the switch device the VPI/VCI corresponding to the detected EFCI and an RM cell in which backward congestion indication is set.

Congestion control system for controlling congestion in switching cells

Four SR modules are provided in the second stage of a 3-stage MSSR switch. To guarantee the MSSR switch the capacity of 20 Gbps, SR modules are provided in each of the first and third stages of the switch. When the capacity of the MSSR switch is extended from 20 Gbps to 40 Gbps, SR modules are added to both of the first and third stages and connected to the four SR modules in the second stage. To further extend the capacity of the MSSR switch to 60 or 80 Gbps, the SR modules are sequentially added to the first and third stages, and the newly provided SR modules are connected to the four SR modules in the second stage.

Multistage connection switch and extension method

For both a bandwidth-guaranteed connection call and a non-bandwidth-guaranteed connection call together, with respect to the bandwidth-guaranteed connection call, a schedular allocates the number of time slots which correspond to a required bandwidth to the bandwidth-guaranteed connection call from among the N time slots that constitute one period and so controls as to transmit an ATM cell at an allocated time slot. The non-bandwidth-guaranteed call transmitting unit transmits an ATM cell of a non-bandwidth-guaranteed connection call at a time slot which is not allocated to any bandwidth-guaranteed connection call. A congestion/normal state monitoring unit sets in advance a queue length which is regarded as the occurrence of a long-term congestion in a queuing buffer and compares the actual queue length with the preset queue length so as to detect the occurrence of a long-term congestion.

ATM exchange for monitoring congestion and allocating and transmitting

A first optical transmission device 1 is connected to a second optical transmission device 2, and the second optical transmission device 2 is connected to a third optical transmission device 3, via a plurality of optical transmission lines. Transfer data and a clock signal synchronous with the transfer data are transferred in parallel from the first optical transmission device 1 to the second optical transmission device 2 through the plurality of optical transmission lines. Transfer data and a clock signal synchronous with the transfer data are transferred in parallel from the second optical transmission device 2 to the third optical transmission device 3 through the plurality of optical transmission lines. The second optical transmission device 2 stops outputting data to the third optical transmission device 3 when the clock signal transferred from the first optical transmission device 1 cannot be detected.

Parallel optical transmission system and optical transmission apparatus

A communication system for use with a network for transmitting fixed-length cells from a transmitting terminal via a virtual connection in the network to a receiving terminal. The communication system includes a converting device, connected to the transmitting terminal or the receiving terminal, for performing a bi-directional conversion between a variable-length packet and the fixed-length cells, the transmitting terminal or the receiving terminal outputting the variable-length packet, a buffer capacity monitoring device in the receiving terminal for monitoring a capacity of a buffer in the receiving terminal receiving the fixed-length cells and for outputting an alarm signal at the time of detecting a congestion state of the capacity of the buffer, a congestion state alerting device in the receiving terminal responsive to the alarm signal from the buffer capacity monitoring device for outputting an alert signal to the transmitting terminal, and a traffic transmission control device in the transmitting terminal responsive to the alert signal from the congestion state alerting device in the receiving terminal for controlling a transmission of the fixed-length cells to the receiving terminal.

A congestion-monitor control apparatus monitors a congestion condition of each output highway in an asynchronous transfer mode switching system transferring cells to output highways by using a cell-storage buffer. The apparatus includes a monitor circuit monitoring the number of cells stored in the cell-storage buffer for each output highway at a plurality of timings during a given monitor time interval. The apparatus further includes a first determination circuit comparing the number of times when the number of cells from the monitor circuit is equal to or more than a first threshold value during the given monitor time interval with a second threshold value and determining whether the congestion has occurred in a corresponding output highway based on a comparison result.

Congestion-monitor control apparatus and switching system

In a data access device for writing into or read from a data conversion table on the basis of a clock signal extracted from a cell being transferred over a line, a clock signal generator of the invention generates a second clock signal which differs from the first clock signal extracted from an incoming cell. A write/read control unit writes data into or reads data for maintenance from the data conversion table on the basis of either the first clock signal or the second clock signal when the line is normal. In the event of the occurrence of a failure in the line, on the other hand, the write/read control circuit permits the data conversion table to be written into or read from for maintenance on the basis of the second clock signal.

Virtual channel converter and VCC table access method

A communication system for transmitting a fixed-length cell converted from a variable-length information including data and a destination of the data. The system includes a cell assembly/disassembly device for performing bi-directional conversion between the variable-length information and the fixed-length cell, a routing control device for receiving the fixed-length cell converted from the variable-length information by the cell assembly/disassembly device, for analyzing the destination of the data and for controlling a routing of the fixed-length cell based on the analyzed destination, and having an error detecting device for detecting an error of the variable-length information in the fixed-length cell, and a network for connecting the cell assembly/disassembly device and the routing control device by a fixed capacity path and for connecting the routing control device to another routing control device by the fixed capacity path or a variable capacity path.

Growing community of inventors

Kawasaki, Japan

Satoshi Kakuma