Overview

Asynchronous Transfer Mode (ATM) emerged in the late 1980s as a new switching technology based on the earlier development of Broadband Integrated Services Digital Network (B-ISDN). Unlike many competing frame-based technologies, ATM is a cell-relay technology. ATM builds on some of the benefits of fast packet switching and provides basic multiplexing and circuit switching. Multimedia applications require high bandwidth and real-time transfer of information with minimal delay variation, and ATM has the required characteristics (guaranteed delay, bounded jitter rate) to support these applications, together with true bandwidth scalability. Cell relay combines the high throughput and bandwidth optimization of Frame Relay with the predictability characteristics of time division multiplexing, making it suitable for bursty legacy data traffic and isochronous voice and video traffic. ATM is based on work done by the International Telecommunications Union, the Telecommunications Standardization Sector (ITU-T), and the American National Standards Institute (ANSI) to apply Very Large-Scale Integration (VLSI) technology to the transfer of data within public networks. The ATM Forum is the body responsible for defining enabling technologies that guarantee interoperability between public and private networks. This forum has over 300 members comprising users, carriers, service providers, and network equipment manufacturers.