US 5,091,903 AGranted

Switching network and switching-network module for an ATM system

AssigneeAlcatel

InventorKarl Schrodi

Life of this patent

Estimating the term…

Loading patent…

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.

Switching network for information transmitted synchronously as sequences of cells, said network comprising a plurality of interchangeable switching modules each further comprising a multi-stage switching arrangement including at least two first stage switching elements and at least two last stage switching elements, wherein each switching element further comprises

two or more element inputs for receiving individual ones of said cells,
two or more element outputs for transmitting said individual cells,
means for transferring a cell received at any said element input of said each switching element to any said element output of said each switching element, and
a common memory for buffering a cell so received at said any element input until it is so transferred to said any element output,
each said element input of each first stage switching-element is connected to a respective module input of the element's associated switching module,
each said element output of each last stage switching element is connected to a respective module output of the element's associated switching module,
during the passage of each cell through successive stages of the switching network,
the element outputs to which said each cell is initially successively transferred as the cell traverses a first portion of the switching network are selected independently of a predetermined destination of said each cell, and
the element outputs to which the cell is finally successively transferred as the cell traverses a last portion of the switching network are selected in accordance with said predetermined destination,
at least one path is possible from any module input of said each switching module to any module output of said each switching-network module, and
if the number of said successive stages of said multi-stage switching arrangement were to be reduced for said each switching-network module, no path would be possible through said multi-stage switching arrangement from at least one module input of switching-network module to at least one module output of the same switching-network module.

8 more elements

Abstract

Claims6