Abstract: A method of protecting ATM connections in a telecommunications network including at least one protection domain which covers only a portion of a connection, each protection domain comprising a source node and a peer sink node. Each source node and its peer sink node can be interconnected by at least two alternative connection segments and can switch over from one connection segment to the other. Any node of the network can send an alarm message downstream over a current path and each node can store a connection fault status when it receives such an alarm message. Each sink node which receives the alarm message sends a switchover request message to its peer source node to request a switchover which is executed only if the peer source node has not itself stored an alarm message. The sink node switches over only if the peer source node has responded positively.

Abstract: An ATM switching matrix has input ports, output ports and a passive optical core consisting of optical couplers. Each output port includes at least p optical receivers which are tuned to the same fixed wavelength which is specific to the output port. Each receiver has an input respectively connected to a port of one of the p couplers, a buffer having p inputs respectively connected to the outputs of the p receivers and an output connected to an output of the matrix. The matrix includes distributed allocation arrangements which control switching arrangements of each input port to connect, to k separate couplers, k respective input ports which at the time concerned are receiving k cells addressed to the same output port, k being less than or equal to p, and this operation being repeated for each output port.

Abstract: In a method of transmitting asynchronous time-division multiplex transmission link control information the control information produced by the control process is transmitted in the form of control cells. At the transmitting end the control cells conform to a format enabling them to be identified as such, the empty cells to be transmitted on the link are identified and any control cell to be transmitted is substituted on the link for an empty cell which is not transmitted. At the receiving end the control cells are detected and extracted to be used in the control process and are replaced as necessary with empty cells.

Abstract: A device evaluates the throughput of virtual circuits conveying cells and using an asynchronous time-division multiplex transmission medium. It comprises a store in which each virtual circuit is assigned a context containing a set of data defining the conditions for evaluating the throughput of the virtual circuit and data obtained from previous such evaluations. A clock supplies a current time and a processor unit reads the context of the respective virtual circuit when each cell is received. This context contains a start time which was the current time observed and stored when a previous cell of the virtual circuit in question was received. The start time is subtracted from the current time and the time difference obtained in this way together with the number of cells observed between that for which the start time was recorded and the present cell provide a basis for evaluating the throughput.

Abstract: An optical connection system for connecting customer premises networks to a switching center of a telecommunication network providing interactive and non-interactive services includes a switching center comprising central office termination equipments, a connection network, a control unit, an optical distribution network and customer premises networks. Non-interactive services are connected to the control central office termination equipment so that non-interactive service signals are sent to all customer premises networks on standby at the control central office termination equipment wavelength. These customer premises networks can therefore use these services without having to set up a call individually and so without having to busy a central office termination equipment for each customer premises network.

Abstract: An automatically configurable optical connection system for connecting customer premises networks to a switching center of a telecommunication network includes an optical distribution network connecting all central office termination equipment optical senders to all customer premises network optical receivers and connecting all customer premises network optical senders to all central office termination equipment optical receivers. A control unit assigns a different wavelength to each customer premises network communicating at a given time, this wavelength representing an available central office termination equipment which is not the control central office termination equipment.

Abstract: An apparatus for evaluating data rates of virtual circuits occupying an asynchronous time-multiplexed transmission path includes a memory in which each virtual circuit is allocated space containing a context defining conditions for evaluating the data rate of the virtual circuit. This context contains a starting time which was the current time as recorded on receiving an earlier cell in the virtual circuit under consideration. Each time a cell is received, the context of the virtual circuit to which the cell belongs is read, and the starting time is subtracted from the new current time, with the time difference established in this way constituting the basis on which the data rate is evaluated, and with repressive countermeasures being initiated in the event of the data rate being excessive. The apparatus further includes device for cyclically scanning the contexts and for incrementing a scan cycle counter in each context during the cyclic scanning, the scan cycle counter having an initial position.