Abstract: A technique is disclosed for sending alarm information to a network management station from at least one of a plurality of network stations wherein an unusual event(s) has occurred. The network stations are located in a wide area network and are managed by the network management station using a control path. An occurrence of an unusual event is detected in the at least one of the plurality of network stations. Following this, alarm information is generated in the network station wherein the unusual event has occurred. The alarm information includes address information for specifying the network station. Subsequently, the alarm information is sent using an alarm path, which is dedicated to transmission of the alarm information, to the network management station.

Abstract: A multiplexing device in a network system has an address number which is assigned to the multiplexing device. Through a reception line, the multiplexing device receives a reception signal which has a signal frame and carries a command signal in a predetermined area of the signal frame. The command signal carries a command and an address code. The multiplexing device comprises a first detecting section responsive to the command signal for detecting whether or not the address code is coincident with the address number to produce the detection signal when the address code is coincident with the address number and a second detecting section for detecting whether or not a vacant area exists in the signal frame to produce a location signal representative of a location of the vacant area when the vacant area exists in the signal frame. A producing section produces a response signal in response to the command carried by the command signal.

Abstract: A cross-connect communications system has an identifier separator for separating from a multi-bit header of an ATM cell a first multi-bit identifier to identify a destination of the ATM cell. The separator also separates a single bit broadcast identifier in the header which has first and second bit states and data in an information region of the ATM cell and associated with header information other than the first identifier and the broadcast identifier. A first memory stores a second identifier for obtaining the number of communications nodes to be broadcast and a new destination to which the broadcast is to be made in a position based on the first identifier when the broadcast identifier is in the first state. The first memory also stores a third identifier in a position based on the first identifier when the broadcast identifier is in the second state. An output circuit produces a count value corresponding to the number of nodes stored in the first memory.

Abstract: A cell flow control unit for use in ATM transmission networks is provided with a cell buffer memory circuit for temporarily storing a plurality of ATM cells each of which has a predetermined number of bits and is transmitted at any time interval via either an input virtual path or an input virtual channel in the sequence of their transmission, a timing control circuit for generating first and second timing pulses to define, respectively a first period of a predetermined length and a second period equal in length to an integral multiple of this predetermined length; and a reading pulse control circuit for generating a first pulse sequence to be fed to the cell buffer memory circuit to read the ATM cells out of the cell buffer memory circuit and transferring them to an output virtual path and either an output virtual channel or a self-routing switch, and a second pulse sequences indicating how many times the ATM cells have been read out of the cell buffer memory circuit.

Abstract: A digital multiplex communication system for carrying out digital multiplex communication between a plurality of terminal stations, at least two including one initiating party and the other party to communicate with, via a branching unit. In this system, groups of bits in a communication frame are allocated in advance for use in communication between one party and the other. In order to diagnose the state of the transmission line to the other party including the branching unit, loopback setting signals for setting the other party in the loopback test mode and loopback test signals are inserted into specific bit positions of the preallocated groups of bits in performing communication.

Abstract: A line interface for high-speed line capable of detecting not only errors occurred on the line but also errors occurred in itself. A first multiplex cifcuit multiplexes a transmission frame synchronizing (sync) signal with data to be transmitted to the line and sends the multiplexed signal as a signal to be transmitted. A second multiplex circuit multiplexes the signal to be transmitted with a signal received from the line. A frame sync circuit synchronizes in phase to both of the received signal and signal to be transmitted multiplexed by the second multiplex circuit and, when not failed to synchronize, outputs a frame error signal. A demultiplex circuit separates data to be transmitted and received data from the output signal of the second multiplex circuit. A pattern comparator compares the data to be transmitted outputted by the demultiplex circuit and the data to be transmitted fed to the first multiplex circuit and, if they are not identical, produces a data non-coincidence signal.

Abstract: In a channel bank at one of TDM hierarchical levels, a TDM demultiplexer includes a plurality of high-speed interfaces connected respectively to high-speed digital transmission lines. Each interface receives detects a line fault and appends an alarm signal of a time-slot duration to time slots of digital signals. The outputs of the high-speed interfaces are multiplexed into a TDM frame sequence and the time slots of data signals in that TDM frame sequence are interchanged according to a prescribed rule. The slot-interchange frame sequence is demultiplexed into plurality of TDM signals greater in number than the number of the high-speed interfaces. Low-speed interfaces respectively receive the demultiplexed TDM signals to detect the time slot in which the alarm signal is contained and transmits a line fault signals to a respective one of low-speed transmission lines.

Abstract: A remote test circuit for testing the performance of a channel terminal which is applicable even to multi-point connections such as 1:N communication. The circuit sets up a return path only through a particular channel terminal whose address is designated, thereby rendering that channel terminal active.