A Packet/Circuit Switch

Abstract

We propose a switch, suitable for an integrated local communications network, that will support packet switching and circuit switching, with a wide range of bit rates. Key components are two serial memories; a multiplicity of access units, each capable of writing and reading uniformly formatted, addressed information; and a programmed controller. Circuit switching is achieved when the controller repeatedly allocates memory slots, following call setup. Data communications can proceed concurrently without setup, competing for unused slots. We give an example of a lO,OOO-telephone-line switch carrying a similar load of other traffic. The switch would delay voice by less than 5 ms and could be interfaced to the existing telephone system. We indicate a method of fault detection and isolation that will limit the impact of a failure on a serial memory to an arbitrarily small group of connected lines. We define an index for measuring failure impact and use it to derive mostfavorable fault-isolating partitions.