Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: The disclosed asynchronous transfer mode (ATM) switching network evenly scatters individual cells of an ATM data stream in the first half of the network and routes them to their intended destination in the second half of the network. The network is constructed from interchangeable switching modules each preferably containing only two stages of switching elements, with each switching element having a common memory, thus reducing the component count by one third compared to Clos' 3-stage non-blocking modules. Each individual module provides a switched path from any selected one of its module inputs to any selected one of its module outputs, with the common memory acting as a buffer until a path becomes available to the desired module output. Since the additional stages between the module's input stage and the module's output stage typically used to provide a non-blocking module are dispensed with, not only the component count, but also the transmission delay through the switching network may be reduced.

Abstract: Fixed numbers of packets are combined into frames within the switching facility, and all packets are divided into subpackets of equal length and distributed to subframes. Switching takes place on the basis of subframes using synchronous time-division multiplexing. The amount of storage space needed in the switching network is reduced in the ratio of frames:subframes. The buffers are those which are necessary for synchronous TDM switching anyhow.

Abstract: A digital switching network is disclosed in which paths can be preset from any inlet to any outlet either for circuit-switched connections or for packet-switched messages (packets), as required. At any point in time, the paths preset for the packet-switched messages form a network whose nodes lie in the switching facilities of the switching network. The switching facilities contain the functional units required to switch each data packet on the path preset for it. This makes it possible to dynamically divide a single switching network into a circuit-switching network and a packet-switching network as required.