Alcatel N.v.

Alcatel Sel Aktiengesellschaft

Bodo Pfeiffer

Karl Schrodi

Bozo Cesar

Gert Eilenberger

Stefan Wahl

Klaus-Dieter Menk

Thomas Banniza

Jean-Michel Delmas

A method of operating a switching network, a switching network, and an exchange with such a switching network are described. The switching network consists of several switching modules and an interconnect network between these switching modules. The interconnect network includes a switch unit and interconnects the switching modules in accordance with a logic interconnection structure. The switch unit is simple and can be implemented by all-optical means. By means of the switch unit the logic interconnection structure can be reconfigured. This makes it possible to reconfigure the switching network in the event of a failure of a switching module or according to the load characteristic (video, voice, computer-computer communication). Further, a uniform switch unit can be used to meet different requirements ('flexible hardware').

Method of operating a switching network, as well as switching network

A buffer or other communications resource in, e.g., an ATM switch element receives random data which is then used by different data sinks. After the data has been outputted to the data sinks, the communications resource (e.g., the memory locations of the buffer) are released, i.e., labeled as free again. However, a resource which is not marked as free as a result of an error (whether erroneously the data is not retrieved or whether the release procedure is erroneous) remains blocked. To avoid permanent blockage of those memory locations whose contents have been in the buffer so long that they definitely (or at least very likely) should have been called for, information on the time of entry is stored together with the data. All memory locations are checked at regular intervals for the age of their contents. Upon attainment of a predetermined age, the location is labeled as free.

Method of and circuit arrangement for freeing communications resources,

Prior Art/Technical Problem: During the establishment of a call through a switching network 20, the path is selected on the basis of the instantaneous loading of the switching network and maintained during the call. The problem of eliminating local blocking by rearranging existing connections has not been satisfactorily solved because of errors occurring during the rearranging process. Basic Idea: Provide in an ATM exchange operating with virtual connections the same devices which assure the correct order of the cells in the 'connectionless' mode. Solution: Each output of the switching network is followed by an output unit 30 which ensures that the cells are output in the correct order. Advantage(s): Virtual connections can be adapted to the instantaneous loading of the switching network error-free at any time. The assurance of the correct order can be implemented so as to largely compensate for delay jitter.

ATM exchange which resequencies the cells using their sequence numbers

A switching element with a plurality of operating modes, in particular for switching asynchronous time-division multiplexed packets, comprises inputs, outputs, a selective retransmission device for retransmitting a packet received on one input to one or more outputs on the basis of routing data associated with the packet, and a retransmission control device determining the mode of operation of the retransmission device. The retransmission control device comprises a direct routing device adapted to receive from the label of a packet received on one input a destination indication and to decode it into an output identifier corresponding to one output at least in order to retransmit the packet to an output designated by the identifier. It additionally comprises a translated routing device adapted to receive from the label of a packet received on one input a reference number and to translate it using a translation memory into one or more output identifiers each corresponding to at least one output for retransmitting the packet to one output for each output identifier designated by the identifier. It additionally comprises a routing mode selector device adapted to receive from the label of a packet received on one input routing mode data and adapted to command selectively according to the data the use of a selected routing device which may be one of the above-mentioned routing devices. The routing mode selector device commands alternately the use of at least one predetermined non-selective routing mode according to the routing mode data contained in the label of a received packet.

Switching element with multiple operating modes and switching network

In practice, switching is a continuously changing mixture of point-to-point connections, point-to-multipoint connections with low fanout, and point-to-multipoint connections with high fanout. The switching elements of a switch optimized for point-to-point connections are additionally enabled to copy a few input signals for an arbitrary number of outputs, so that a very large number of copies is attainable for few input signals. This switch is supplemented by a copy switch which serves exclusively to make limited numbers of copies for a large number of input signals, which are then switched in the (group) switch as point-to-point connections. Point-to-point connections are operated as connectionless connections, but outside the switch act as virtual connections. Point-to-multipoint connections are operated as virtual connections (connection-oriented) by means of connection tables.

ATM exchange with copying capability

To be able to load an ATM switching network as efficiently as possible, the successive cells of one and the same connection are routed to the output by as many different paths as possible; however, mutual overtaking of successive cells must be avoided or corrected. Each cell is held at the output until it is certain that no older cell can be buffered in the switching network. Before the cell is passed on, a check is made to determine whether the cells received from the switching network later include an older cell which must be passed on before that cell. At the input end, consecutive numbers ('Sequence Numbers') are allocated to the cells. A buffer (1) at the output end is operated, at least in part (1 . . . d), in the manner of a shift register, thereby introducing a predetermined delay. Prior to the output of a cell, at least the shift-register-like portion of the buffer is examined as to whether a cell written in later is to be put out earlier: if so, the two cells are interchanged.

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Schwieberdingen, Germany

Bodo Pfeiffer