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.
