Abstract: 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.

Abstract: An ATM path changing system and method for use in an ATM communication apparatus and ATM communication network are provided which can set an alternating route in the event of a failure occurring in a transmission line or VP. A header converter in a line controller includes a plurality of output path routing tables, a selector, a comparator, a register for failure RTG and a register for failure VPI and when the contents of the register for failure RTG or VPI coincides with a RTG or VPI of the output path routing tables, an output is selected in accordance with the contents of a selected emergency-route RTG or VPI register.

Abstract: A cell multiplexer includes a multiplexing unit for time-divisionally multiplexing ATM cell signals given from a plurality of input lines, a write controller for storing cell signals outputted from the multiplexing unit in a buffer memory successively correspondingly to the input lines, a read controller for reading the cell signals stored in the buffer memory from the buffer memory in the form of data blocks synchronized with an ATM cell structure, and a cell delineation controller for detecting delineation states of the data blocks read out from the buffer memory, notifying the read controller of delineation control information corresponding to a result of the detection and transmitting data blocks read out in synchronism with a predetermined cell structure to the output line selectively, wherein the read controller determines the read beginning addresses of data blocks to be read out nextly correspondingly to the input lines on the basis of the delineation control information notified by the cell delineati

Abstract: Policing method and policing circuit for parallelly conducting a plurality of policing which are dependent on policing items in the policing for defining the traffic of an asynchronous transfer mode network are provided. A plurality of traffic monitor circuits 11 parallelly and independently conduct the traffic monitoring of a plurality of items for the input cell for the communication service to be provided by the asynchronous transfer mode network. Each monitor circuit monitors only the violation of the traffic independently and outputs the result. A total determination circuit determines whether to tag, discard or pass the input cell in accordance with a determination rule prescribed for the communication service based on a CLP value contained in a header of the input cell and the monitor result parallelly obtained from the respective monitor circuits to conduct the policing.

Abstract: An optical frequency division multiplexing network includes first optical communication paths connected to terminals, respectively, a second optical communication path connected to the outside and a node composed of a selection unit for selecting signals having optical frequencies to be sent to the plurality of terminals, respectively, from signals transmitted through the second optical communication path in optical frequency division multiplexing, a conversion unit for converting the selected signals into signals having a single optical frequency and an output unit for producing the converted signals to the terminals through the first optical communication paths, respectively.

Abstract: A looped bus system includes several nodes connected by unidirectional buses having opposite directions of signal transmission. The head of bus function for each bus is located at a node different from the head of bus function for the other bus. The head of bus function for each bus is located at the same node as the termination of bus function for the other bus; As a result, the buses can be reconfigured and nodes can be added freely by the use of a bus portion that is unused in the looped bus under normal condition.

Abstract: 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.

Abstract: A digital signal multiplexing method and apparatus include statistically multiplexing packet signals which are transferred through first circuits having a first speed to a second circuit having a second speed, the second speed being higher than the first speed. The method includes the steps of dividing the signal transmitted to the second circuit into a plurality of circuit management units, distributing the packet signals to the plurality of circuit management units and transmitting on a packet unit basis, dividing the multiplexing packet signals which were statistically multiplexed to the second circuit into receiving circuit management units corresponding to the plurality of circuit management units, and generating the received packet signals included in the receiving circuit management units corresponding to the first circuits.

Abstract: A method of modifying a virtual path capacity in a communication network which transfers a first cell in an asynchronous transfer mode between node apparatuses. The first cell has a first virtual path identifier indicative of a virtual path which the first cell passes through. A bandwidth allocated to the virtual path is modified. Notification of the modification of the bandwidth is provided to a node apparatus included in the virtual path by passing a second cell through said virtual path. The second cell has information of the modification and a second virtual path identifier same as the first virtual path identifier. The second cell is received by the node apparatus and a third cell having information of confirmation of reception of the second cell is returned by the node apparatus.

Abstract: An ATM switching system which includes an input interface which is provided every incoming line and serves to convert header information of each input cell into internal routing information, a shared buffer memory and a cell writing control unit which forms normal cell list structures, which are prepared in correspondence to outgoing lines and in which a plurality of normal cells are chained together with their next addresses, and a broadcast cell list structure, in which a plurality of broadcast cells are chained together with their next addresses, in the shared buffer memory, and serves to add successively the input cells to ones of the list structures, which are selected in correspondence to respective internal routing information. The invention also includes a cell reading control unit which serves to fetch selectively the cell from the list structures formed in the shared buffer memory to distribute the cell thus fetched to the associated outgoing lines.

Abstract: An optical frequency division multiplexing network includes first optical communication paths connected to terminals, respectively, a second optical communication path connected to the outside and a node composed of a selection unit for selecting signals having optical frequencies to be sent to the plurality of terminals, respectively, from signals transmitted through the second optical communication path in optical frequency division multiplexing, a conversion unit for converting the selected signals into signals having a single optical frequency and an output unit for producing the converted signals to the terminals through the first optical communication paths, respectively.

Abstract: A hit-less protection switching method and apparatus therefor for ATM transmission lines for selecting first cells from normal received signals and writing the same into a normal cell buffer, selecting second cells from emergency received signals and writing the same into an emergency cell buffer, reading the first cells from the normal cell buffer after a first delay time, reading the second cells from the emergency cell buffer after a second delay time, comparing the contents of the first cell with the contents of the second cell and changing the difference between the first delay time and the second delay time, when a state of discrepancy between the contents of the first cell and the contents of the second cell is continuously detected for a predetermined time, to dissolve the state of discrepancy, and selecting one of the cells read from the normal cell buffer and the emergency cell buffer with a delay as communications information.

Abstract: In a communication apparatus using an asynchronous transfer mode, there is provided a system switching method, and apparatus, without loss of signal for performing cell multiplexing or cell switching in a duplex system including a primary system and a standby system. In system switching, control information for switching between the primary system and the standby system is prepared. When a cell is inputted to the communication apparatus, the prepared control information is appended in a header portion of the cell. The cell with control information appended thereto is transmitted to the duplex system including the primary system and the standby system. On the basis of the control information, cell transfer of each system is controlled.

Abstract: A traffic shaping method and circuit of a packet switching system in which input packets having a fixed length and multiplexed on a plurality of inputs are multiplexed to be delivered on any output of a plurality of outputs, connects the input packet to a list structure using an address chain formed for each output, forms the list structure even for each line identifier provided in the packet, and assigns the identifier for each time slot of the output to take out the packet from the list structure, to thereby prevent the packet having the same identifier from being multiplexed and delivering to the output continuously.

Abstract: A method of modifying a virtual path capacity in a communication network which transfers a first cell in an asynchronous transfer mode between node apparatuses. The first cell has a first virtual path identifier indicative of a virtual path which the first cell passes through. A bandwidth allocated to the virtual path is modified. Notification of the modification of the bandwidth is provided to a node apparatus included in the virtual path by passing a second cell through said virtual path. The second cell has information of the modification and a second virtual path identifier same as the first virtual path identifier. The second cell is received by the node apparatus and a third cell having information of confirmation of reception of the second cell is returned by the node apparatus.

Abstract: A method and system are provided for concentrating calls for a packet switching system in a hierarchical communication network. A plurality of terminals communicate with an associated plurality of packet concentrators that, in turn, communicate with switching equipment. The system and method comprise initiating a call at a call terminal to be communicated to the packet concentrator and identifying the call terminal by associating a line number communicating the terminal with the concentrator with a first logical channel number for communication from the packet concentrator to the switching equipment.

Abstract: In a cell delineation circuit, an input signal is converted into parallel signals, and a plurality of parallel signals (i.e. series of parallel signals) which are shifted one bit by one bit from each other are formed from those parallel signals. CRC (Cyclic Redundancy Check) calculations are executed in parallel for the plurality of parallel signals. A series in which a pattern to be calculated satisfies a CRC rule is determined from results of the CRC calculations, and this series is generated, thereby establishing a cell delineation.

Abstract: An optical receiving method utilizing polarization diversity is disclosed in which first and second reference lightwaves having different frequencies and having polarization planes substantially perpendicular to each other, are combined with a signal lightwave to form a combined lightwave. The combined lightwave is subjected to heterodyne detection to obtain a detection signal and the detection signal is separated into first and second intermediate-frequency signals having different carrier frequencies. The first and second intermediate-frequency signals are converted into first and second baseband signals, respectively, and the first and second baseband signals are added to obtain an output signal.

Abstract: A communication network system includes a communication line, a plurality of communication stations each having a node coupled to the communication line and a network controller coupled to the stations for controlling routing for communication messages between nodes. In one embodiment, the messages are sent from plural terminals connected with each node along with communication performance prerequisites. The communication performance prerequisites for a communication message are discriminated in the node which receives the message. Traffic in various routes between the nodes is continually measured in the communication stations and the measuring results are stored in a database storage unit.

Abstract: The invention provides a communication method and system for use in a network for digital data exchange/transfer through a circuit switched network. According to the method and system, a call is given the attribute of an intermittent transfer mode, and a device for identifying attributes is provided on network controls in connection paths so that the network control establishes a path only in response to a data transfer request from identified call and releases the path when the call is held on standby for data transfer.