Back أسلوب النقل اللاتزامني Arabic ATM Azerbaijani ATM BS Asynchronous Transfer Mode Catalan Asynchronous Transfer Mode Czech Asynchronous Transfer Mode German Modo de transferencia asíncrona Spanish Asynchronous Transfer Mode Basque حالت انتقال ناهمگام Persian Asynchronous Transfer Mode Finnish

Asynchronous Transfer Mode

IBM Turboways ATM 155 PCI network interface card

Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by the American National Standards Institute and International Telecommunication Union Telecommunication Standardization Sector (ITU-T, formerly CCITT) for digital transmission of multiple types of traffic. ATM was developed to meet the needs of the Broadband Integrated Services Digital Network as defined in the late 1980s,[1] and designed to integrate telecommunication networks. It can handle both traditional high-throughput data traffic and real-time, low-latency content such as telephony (voice) and video.[2][3] ATM provides functionality that uses features of circuit switching and packet switching networks by using asynchronous time-division multiplexing.[4][5] ATM was seen in the 1990s as a competitor to Ethernet and networks carrying IP traffic as, unlike Ethernet, it was faster and designed with quality-of-service in mind, but it fell out of favor once Ethernet reached speeds of 1 gigabits per second.[6]

In the Open Systems Interconnection (OSI) reference model data link layer (layer 2), the basic transfer units are called frames. In ATM these frames are of a fixed length (53 octets) called cells. This differs from approaches such as Internet Protocol (IP) (OSI layer 3) or Ethernet (also layer 2) that use variable-sized packets or frames. ATM uses a connection-oriented model in which a virtual circuit must be established between two endpoints before the data exchange begins.[5] These virtual circuits may be either permanent (dedicated connections that are usually preconfigured by the service provider), or switched (set up on a per-call basis using signaling and disconnected when the call is terminated).

The ATM network reference model approximately maps to the three lowest layers of the OSI model: physical layer, data link layer, and network layer.[7] ATM is a core protocol used in the synchronous optical networking and synchronous digital hierarchy (SONET/SDH) backbone of the public switched telephone network and in the Integrated Services Digital Network (ISDN) but has largely been superseded in favor of next-generation networks based on IP technology. Wireless and mobile ATM never established a significant foothold.

  1. ^ Cite error: The named reference bisdn was invoked but never defined (see the help page).
  2. ^ Telcordia Technologies, Telcordia Notes on the Network, Publication SR-2275 (October 2000)
  3. ^ ATM Forum, The User Network Interface (UNI), v. 3.1, ISBN 0-13-393828-X, Prentice Hall PTR, 1995, page 2.
  4. ^ "Recommendation I.150, B-ISDN Asynchronous Transfer Mode functional characteristics". ITU.
  5. ^ a b McDysan (1999), p. 287.
  6. ^ An Introduction to ATM Networks. John Wiley & Sons. 28 November 2001. ISBN 978-0-471-49827-8.
  7. ^ McDysan, David E. and Spohn, Darrel L., ATM : Theory and Application, ISBN 0-07-060362-6, McGraw-Hill series on computer communications, 1995, page 563.

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