At&t Bell Laboratories

American Telephone and Telegraph Company and At&t Information Systems

Louis R Goke

Gary J Grimes

Bryan Scott Moffitt

James J Ferenc

A time slot converter for communicating multi-rate data on a single channel by using multiple time slots. By utilizing multiple replications of the time slot converter, any size time division switching unit such as time slot interchangers or time multiplexer switches may be assembled. The time slot converter has a plurality of switching elements and a switching element uses a time accounting arrangement that has the same overhead in assigning multiple time slots to a channel as in assigning one time slot to a channel. The switching element requires less buffer storage because each time slot has only one bit, and it is not necessary to store multiple frames. In addition, switching delay is reduced, since the delay due to buffering is always less than a frame period. Data order is maintained by using time slots for high capacity channels that are equally spaced in time and whose order is guaranteed. Also, the utlization of equally spaced time slots eliminates the need for output and input buffering to and from endpoint terminals.

Wide range mixed rate TDM bus using a multiple of time slot interchange

A modular, substantially infinitely-growable, multi-node switching system operates under distributed control to serve integrated circuit-switched and packet-switched traffic at the data rates appropriate for each type of traffic. The system comprises a plurality of interconnected identical switching units that form at least one communication switching node. A communication switching node is a modular building block of the system; a switching unit is a modular building block of a switching node, and hence also of the system. A plurality of communication endpoint nodes--illustratively PBXs--is connected to the one or more switching nodes for communicating with each other through the switching nodes. A plurality of communication links each connect a different one of the system's switching units to either (a) one of the communication endpoint nodes or (b) a unit of another switching node. All of the links have the same communication format. Each switching node includes a plurality of different ones of the identical switching units, and a communication medium that interconnects all of the units of the switching node to allow each unit of a node to broadcast all communications received from a connected link to all of the units of the node.

Building-block architecture of a multi-node circuit-and packet-switching

Apparatus for and a method of inserting circuit switch information and packetized data into different time slots of a time division multiplexed bus. A memory having a location individual to each time slot is written with information specifying whether the time slot individual to each location is to serve the circuit switch information or the packet data. The readout of each memory location during the occurrence of it's associated time slot controllably effects the application of either the circuit switch information or the packet data to the bus.

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Austin, TX, United States of America

Louis R Goke