Webopedia on Google+Webopedia on TwitterWebopedia on FacebookTech Bytes Blog
Main » TERM » A »

ATM - Asynchronous Transfer Mode

Short for Asynchronous Transfer Mode, a network technology based on transferring data in cells or packets of a fixed size. The cell used with ATM is relatively small compared to units used with older technologies. The small, constant cell size allows ATM equipment to transmit video, audio, and computer data over the same network, and assure that no single type of data hogs the line.

Some people think that ATM holds the answer to the Internet bandwidth problem, but others are skeptical. ATM creates a fixed channel, or route, between two points whenever data transfer begins. This differs from TCP/IP, in which messages are divided into packets and each packet can take a different route from source to destination. This difference makes it easier to track and bill data usage across an ATM network, but it makes it less adaptable to sudden surges in network traffic.

When purchasing ATM service, you generally have a choice of four different types of service:

  • constant bit rate (CBR): specifies a fixed bit rate so that data is sent in a steady stream. This is analogous to a leased line.
  • variable bit rate (VBR): provides a specified throughput capacity but data is not sent evenly. This is a popular choice for voice and videoconferencing data.
  • available bit rate (ABR): provides a guaranteed minimum capacity but allows data to be burstedat higher capacities when the network is free.
  • unspecified bit rate (UBR): does not guarantee any throughput levels. This is used for applications, such as file transfer, that can tolerate delays.






  • TECH RESOURCES FROM OUR PARTNERS
    DID YOU KNOW?
    11 Tips to Boost Your Wi-Fi Signal

    It's not just your lawnmower and household tools that your neighbor won't return. Our top picks include everything from updating device firmware... Read More »

    Interesting Times: Transformation in the IT Channel

    Business transformation will remain the buzzword of the moment as channel firms continue to assess the direction of their companies in the age of... Read More »

    What is a Virtual Private network (VPN)?

    Companies and organizations will use a VPN to communicate confidentially over a public network and to send voice, video or data. Read More »

    QUICK REFERENCE
    29 Free Android Apps for Cash-Strapped Students

    From wacky alarm clocks to lecture hall tools and after class entertainment, these Android apps are a good fit for a student's life and budget. Read More »

    Network Fundamentals Study Guide

    A network is a group of two or more computer systems or devices, linked together to share resources, exchange files and electronic communications.... Read More »

    Computer Architecture Study Guide

    This Webopedia  study guide describes the different parts of a computer system and their relations. Read More »