Fujitsu Corporation

Nippon Telegraph and Telephone Corporation

Michio Kusayanagi

Toshio Soumiya

Tomohiro Ishihara

Naotoshi Watanabe

Takeshi Kawasaki

Koji Nakamichi

Masato Okuda

Jun Tanaka

Yuji Kato

Toshiyuki Sudo

Naoaki Yamanaka

Shunji Abe

Kenichi Kawarai

Masafumi Katoh

Jyoei Kamoi

Toshio Shimoe

Hiroshi Takeo

Akio Morimoto

Hichiro Hayami

Haruo Mukai

Takao Ogura

Akihiko Takase

Tetsuya Nishi

Takafumi Chujo

Shigeo Amemiya

Yoichi Sato

Kazuo Iguchi

Masaki Hirota

Toshikazu Inoue

Youichi Sato

Koji Tatsumi

Shigeo Shinada

Nobuo Iguchi

Hisako Koyanagi

Kazuhisa Shimazaki

Satoshi Namura

Norihisa Uchimoto

Kazuhiko Hohara

Mituhiro Takano

Tetuhiro Okabe

Kiyoshi Saitou

Koichiro Yamada

Shinya Nakagaki

Kazuya Kumazaki

Mineharu Hattori

Tetsuji Ichikawa

A first communication device receives an ATM cell bound for a second ATM device from a first ATM device via an ATM interface, and then the first communication device sends a data frame including the ATM cell to the second ATM device via wide area Ethernet. In addition, the first communication device sends a synchronization frame to the second ATM device via the wide area Ethernet continuously at a predetermined time interval in accordance with a clock frequency of the first ATM device. A second communication device receives the synchronization frame and measures a clock frequency of the first ATM device in accordance with a time interval of receiving the synchronization frame so as to reproduce a clock having the same frequency as the measured clock frequency. After that, the second communication device sends the clock to the second ATM device via an ATM interface.

System for supporting communications among ATM devices, device for supporting data transmission, method for sending data, and computer program product

A converter for connecting its ATM network with other ATM networks through a LAN, which is provided with an address translation table storing external VPIs, internal VPIs uniquely assigned to the LAN, and opposing MAC addresses for opposing converters in correspondence and a processing unit for performing control for transmitting, to the LAN, frames changed from the external VPI/VCIs of headers of cells from its ATM network to the internal VPI/VCIs by referring to the address translation table and having opposing MAC addresses corresponding to the internal VPI/VCIs attached, removing the opposing MAC addresses of frames received from the LAN by referring to the address translation table, and transmitting cells changed from internal VPI/VCIs to external VPI/VCIs to its ATM network.

Converter and communication control method

To make an efficient network operation possible in which a user-side device connected by a permanent virtual connection path is selectively connected to one among multiple specified connection destinations, and multiple layerlinks are multiplexed to one path, a layerlink handler is connected to the user-side device by a permanent virtual connection path PVC via the ATM switch the layerlink handler has a path specifying units and is connected to multiple specified connection destinations by permanent virtual connection paths or switched virtual connection path via ATM switch that specifies one path of the connection request destinations from layerlink information emitted from the user-side device at the time of the layerlink connection request, and sets to the path of that specified connection destination a layerlink of the permanent virtual connection path PVC of the user-side device. Labels are assigned to layerlinks, and layerlinks may be multiplexed.

Layer 2 link handler and path connection method thereof

A packet switch interfacing between a WAN and a LAN accommodating a terminal includes an address table storing a relation between an address of the terminal and an input port receiving a packet transmitted from the terminal, and an address learning unit for storing in the address table the relation between the source address of the received packet and the input port receiving the received packet. Further the packet switch includes a SW unit for effecting control to transmit the received packet according to whether or not stored in the address table, and then transmit the received packet to the WAN when a packet having a source address identical with the destination address of the received packet has not been received from the LAN.

Packet switch for interfacing between LAN and WAN

A data transmission apparatus is provided for transmitting data received from a user terminal device through a plurality of networks to a destination, the user terminal device executing communication using an Internet protocol. The data transmission apparatus includes a routing table storing information relating a destination address of the data and addresses of the plurality of networks; an information table storing static and dynamic information about the plurality of networks; and a selection unit selecting one or the plurality of networks, through which the data transmission apparatus transmits the data to the destination, based on the static and dynamic information. The data transmission apparatus enables data transmission through the appropriate network by selecting the appropriate network based on the static and dynamic information about the plurality of networks.

Data transmission apparatus selecting efficient network or service class

The present invention includes a detection unit for detecting an active virtual channel of arriving ATM cells, and a management memory unit for managing management information about the detected active virtual channel on a virtual-channel-to-virtual-channel basis, wherein a frame-by-frame process is performed on cells whose virtual channel identifier matches that of an active virtual channel managed by the management memory unit. In this manner, virtual-channel-by-virtual-channel processing is achieved in ATM leased line services that are provided on a virtual-path-by-virtual-path basis, thereby dispensing with needs to register a virtual channel into management memory in advance and allowing a large number of virtual channels to be accommodated.

Dynamic virtual channel management apparatus

In an ATM switching system, an ABR service is implemented with a specific ABR control capability. A subscriber line processing device includes calculating a turnaround delay time of a cell, based on a period during which the cell doubles back at a terminal. A switch or a demultiplexer capable of detecting congestion. A rate calculator calculates a transmission rate corresponding to an output channel, and writes the calculated rate to the cell. A rate changer changes the transmission rate according to congestion. The rate changer counts the number of communicating connections. Then the number of communicating connections which should exist in a certain predetermined period is estimated based on the counted number of communicating connections. A coefficient is determined based on the estimated number of communicating connections and an actual number of communicating connections, and a next estimated value is estimated using the coefficient.

Feedback control method and device in ATM switching system

A burst synchronizing circuit synchronizes a received data signal in a burst fashion and sampling phases with which the received data signal is sampled. A first part samples a data pattern with different sampling phases. A second part selects the received data signal sampled with an optimal sampling phase based on sampling phases with which the data pattern is detected.

Burst synchronizing circuit

In a first UPC, a PCR is set as a monitor rate for each connection. If a transfer rate of a cell exceeds the PCR set for the connection, the cell is discarded. In a second UPC, an ACR is set as a monitor rate for each connection. If the transfer rate of the cell exceeds the ACR set for the connection, a lower priority is assigned to that cell. Additionally, with a configuration where one UPC monitors a varying rate, a parameter change process is controlled by obtaining a time between a passage time of a detected B-RM cell and an arrival of a user cell and comparing the obtained time with maximum and minimum delay standard values. A parameter table including some parameters is provided. A header of an arrived cell in a forward direction is extracted, and it is determined whether or not the arrived cell is a violation cell using the leaky bucket algorithm, etc. If the arrived cell is a violation cell, it is discarded. An RM cell in a backward direction is received and extracted, and the parameter table is updated by calculating the minimum cell interval, etc. based on data included in a payload of the RM cell.

Packet flow monitor and control system

Specific ABR control capability for implementing an ABR service in an ATM switching system. A subscriber line processing device has a capability for calculating a turnaround delay time of a cell, based on a period during which the cell loops back at a terminal and returns. A switch or demultiplexer has a capability for detecting congestion. A rate calculator calculates a transmission rate corresponding to an output channel, and writes the calculated rate to the cell. A rate changer suitably changes the transmission rate according to the degree of occurrence of congestion. Additionally, the rate changer counts the number of communicating connections. At this time, the number of communicating connections which should exist in a certain predetermined period is estimated based on the counted number of communicating connections, which is counted in a period shorter than the predetermined period according to a predetermined method. Additionally, a coefficient is determined based on the number of communicating connections so estimated and an actual number of communicating connections, and a next estimated value is estimated to be a more suitable value using the coefficient.

An ATM connection is a virtual communication path specified by VPI/VCI. A plurality of ATM connections that are directed to the same output line is defined as an ATM connection group. A connection UPC (Usage Parameter Control) facility is provided for each of the ATM connections and a connection group UPC facility is provided for the ATM connection group. The connection UPC facilities and the connection group UPC facility are operated in either the monitor mode or the control mode. In the monitor mode, when the rate of flow of packets into a network exceeds a threshold, a control unit is informed of it, but cells are allowed to enter the network as they are. In the control mode, when the rate of flow of cells into the network exceeds the threshold, cells the flow rate of which exceeds the threshold are discarded.

A buffer control system is a system for implementing both a priority control process and a shaping process of cells with a hardware configuration of a small size in a network routing fixed-length packets which are respectively composed of transfer data and control information added to the transfer data, and to which priority information is assigned, according to the control information. If a cell written to an empty area of a cell buffer is a prioritized cell, and its expected output time is a time slot, an address where the cell is stored in the cell buffer is arranged in a time slot in a prioritized cell entry memory. When it reaches the time to read the cell stored in the time slot, the address stored in the time slot is written to an output list chain, and the cell is read from that address. The empty area of the buffer is managed using a free list chain.

Buffer control system

A UPC circuit fault diagnosis system for diagnosing a failure in a UPC circuit controls cell traffic volume on the basis of prescribed information about cell traffic. Failure diagnosis of a UPC circuit is provided by a usage parameter determination of at least one kind of cell, using more than one system and comparing determination results. The diagnosis system has an operating UPC circuit for controlling a total of m kinds of cells, and a standby UPC circuit for controlling a total of n kinds of cells. The system also has a total of q bridge memories for keeping a chronological record of the prescribed information of arriving cells. A fault diagnosis of the bridge memories is provided by comparing the contents of the bridge memories, using more than one system.

Trouble diagnosis system of UPC circuit

A usage parameter control circuit for effecting a policing control in an ATM transmission network, comprising a time interval measuring unit for measuring a time interval between a current arrival time of a cell to be judged, and an arrival time of a cell which arrived a reference threshold number of cells before the currently arriving cell arrives; and a judging unit for judging whether or not the measured time interval is shorter than a reference threshold time interval, whereby a longer accessing time is allowed and the circuit construction has a flexible expandability.

Usage parameter control circuit for effecting policing control in an ATM

A call admission control system in an asynchronous transfer mode exchange includes a unit for describing attribute parameters of a cell from the subscriber terminal; a unit for calculating, based on the attribute parameters, the average and the dispersion of the traffic speeds of the call; a unit for managing data of the average and the dispersion on each output route and data relating to each subscriber; and a unit for calculating the total average and the total dispersion of the data speeds on the selection output route; and a unit for calculating prediction values of cell abandon rate and end-to-end delay based on the average and the dispersion on the selected output route calculated by the total average and dispersion calculating unit, and for comparing the prediction values with the required service quality of cell discard rate and end-to end delay, for determining whether or not the requesting call may be connected.

Traffic control system for asynchronous transfer mode exchange

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Kawasaki, Japan

Michio Kusayanagi