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Circuit Switching: Unique Architecture and Applications

IP.com Disclosure Number: IPCOM000131403D
Original Publication Date: 1979-Jun-01
Included in the Prior Art Database: 2005-Nov-10
Document File: 16 page(s) / 56K

Publishing Venue

Software Patent Institute

Related People

Amos E. Joel, Jr.: AUTHOR [+3]

Abstract

[Figure containing following caption omitted: Circuit switching systems predate computers. Partly for that reason, computer engineers may learn something from a look at their architecture.] Switching techniques have been essential to the development of modern computers and computer networks. These techniques include the use of logic, memory, signaling, and connectives, all of which were highly developed before the advent of modern computers. Connectives are the major functional elements that distinguish circuit switching from the forms of switching that are used where messages can be delayed. Although there are many ways to define or identify a circuit switch, it is difficult to couple the definition only to the concept of delay, since all telecommunications inherently involve some delay, no matter how small. Therefore, circuit switching is also defined as a form of switching capable of serving simultaneous two-way conversational communications of the desired bandwidth in real time. Figure l(a) shows the three major functions of a circuit switch. These include the so-called ";switching network,"; on which terminate, for purpose of interconnection, the circuits from outside the switch; the signal-processing function, for receiving and transmitting signals from outside the switch that indicate the connections desired of this or other switches in a broader network of switches; and the informationprocessing function, for interpreting and controlling the other two functions. In circuit switching, the term ";network"; is used in two different senses. One is that of the network of switches (in the broader sense) tied together with relatively long-distance transmission facilities; a public telephone network is a network of switches, where there is a circuit switch or ";office"; at each node. The other sense is that of a network of switching devices employing metallic contacts or semiconductor logic gates. In this article, I refer to the principal switching network required for a circuit switch as the ";switching center network,"; or SON.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

This record contains textual material that is copyright ©; 1979 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Contact the IEEE Computer Society http://www.computer.org/ (714-821-8380) for copies of the complete work that was the source of this textual material and for all use beyond that as a record from the SPI Database.

Circuit Switching: Unique Architecture and Applications

Amos E. Joel, Jr.

Bell Telephone Laboratories

(Image Omitted: Circuit switching systems predate computers. Partly for that reason, computer engineers may learn something from a look at their architecture.)

Switching techniques have been essential to the development of modern computers and computer networks. These techniques include the use of logic, memory, signaling, and connectives, all of which were highly developed before the advent of modern computers. Connectives are the major functional elements that distinguish circuit switching from the forms of switching that are used where messages can be delayed. Although there are many ways to define or identify a circuit switch, it is difficult to couple the definition only to the concept of delay, since all telecommunications inherently involve some delay, no matter how small. Therefore, circuit switching is also defined as a form of switching capable of serving simultaneous two-way conversational communications of the desired bandwidth in real time.

Figure l(a) shows the three major functions of a circuit switch. These include the so-called "switching network," on which terminate, for purpose of interconnection, the circuits from outside the switch; the signal-processing function, for receiving and transmitting signals from outside the switch that indicate the connections desired of this or other switches in a broader network of switches; and the informationprocessing function, for interpreting and controlling the other two functions.

In circuit switching, the term "network" is used in two different senses. One is that of the network of switches (in the broader sense) tied together with relatively long-distance transmission facilities; a public telephone network is a network of switches, where there is a circuit switch or "office" at each node. The other sense is that of a network of switching devices employing metallic contacts or semiconductor logic gates. In this article, I refer to the principal switching network required for a circuit switch as the "switching center network," or SON.

Actually, any switching network is an assemblage of connectives. AND gates with common inputs and capable of being enabled exclusively (one at a time) are basic connective elements. For example, the circuit switching system's functions are connected together through connectives or "access networks" -- NCAN, SAN, and CAN in Figure l(b). These might be used for access between the inputs and outputs and the signal-processing f...