Asynchronous Transfer Mode (ATM) Networks
Demand for fast and dependable access to Web-based applications and real-time delivery of multimedia transmissions via an integrated network infrastructure drives implementation of ATM (Asynchronous Transfer Mode) broadband solutions. ATM is a high-speed, high-performance multiplexing and switching technology that provides bandwidth on-demand for seamless transport of full-motion video, audio, data, animations, and still images in local and wider area environments.
A flexible and extendible telecommunications solution, ATM interlinks distributed networks and heterogeneous technologies into integrated configurations, thereby eliminating the need for multiple network overlays. ATM interworks with diverse narrowband and broadband wireline architectures, protocols, and technical solutions such as SONET/SDH (Synchronous Optical Network and Synchronous Digital Hierarchy), WDM (Wavelength Division Multiplexing), and DWDM (Dense WDM). ATM also interoperates with FDDI (Fiber Data Distributed Interface), Ethernet, Fast Ethernet, Frame Relay, ISDN, and IP (Internet Protocol) and wireline and wireless residential broadband access networks employing cable modem, DSL (Digital Subscriber Line), and VSAT (Very Small Aperture Terminal) solutions. In addition, ATM works in conjunction with second-generation GSM (Global System for Mobile Communications) and third-generation UMTS (Universal Mobile Telecommunications Systems) cellular communications technologies.
The ATM platform enables fast access to basic and sophisticated tele-education, telemedicine, electronic commerce (E-commerce), and electronic government (E-government) services. ATM networks are reliable, dependable, and scalable, and flexibly accommodate an array of topologies, applications, and services.
PURPOSE
ATM is a complex cell multiplexing and switching technology. This chapter provides a high-level introduction to ATM technical attributes, features, and functions. Representative ATM implementations that support a diverse and powerful mix of applications are examined. Wireless ATM (WATM) configurations are described, and the capabilities of next-generation ATM networks are explored. Research initiatives in the ATM arena are highlighted.
ATM DEVELOPMENT
The ATM platform enables multimedia transmission via fixed-sized 53-byte packets called cells in network environments ranging from desk area networks (DANs) to global implementations. The term “Asynchronous” refers to ATM support of intermittent bit rates and traffic patterns in accordance with actual demand. The phrase “Transfer Mode” denotes ATM multiplexing capabilities in transmitting and switching multiple types of network traffic.
Bell Labs initiated work on ATM research projects in the 1960s and subsequently developed cell relay technology and cell switching architecture for handling bursty transmissions. Originally, ATM was called Asynchronous Time-Division Multiplexing (ATDM) and regarded as a successor to TDM (Time-Division Multiplexing). As with TDM, ATDM supports transmission of delay-sensitive and delay-insensitive traffic. TDM and ATDM assign each fixed-sized cell or information packet to a fixed timeslot. By contrast, ATM supports dynamic allocation of timeslots to cells ondemand. In comparison to ATM, TDM and ATDM protocols are limited in optimizing utilization of available bandwidth for effectively handling volume-intensive multimedia applications.
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