by Dinesh Thakur Category: Network Technologies

Asynchronous Transfer Mode (ATM) Also called cell relay, a high-speed switched network technology developed by the telecommunications industry to implement the next, BROADBAND generation of ISDN. ATM was designed for use in WANS such as the public telephone system and corporate data networks, though it has also been applied to create super-fast LANS. It can carry all kinds of traffic - voice, video and data – simultaneously at speeds up to 155 megabits per second.

ATM is a CONNECTION-ORIENTED scheme, in which switches create a VIRTUAL CIRCUIT between the sender and receiver of a call that persists for the duration of the call. It is a PACKET SWITCHING system, which breaks down messages into very small, fixed length packets called CELLS generally 53 bytes in length (48 bytes of data plus a 5-byte header). The advantage conferred by such small cells is that they can be switched entirely in hardware, using custom chips, which makes ATM switches very fast (and potentially very cheap).

The ASYNCHRONOUS part of the name refers to the fact that although ATM transmits a continuous stream of cells, some cells may be left empty if no data is ready for them so that precise timings are not relevant. This is ATM's greatest strength, as it enables flexible management of the QUALITY OF SERVICE so; an operator can offer different guaranteed service levels (at different prices) to different customers even over the same line. This ability will enable companies to rent VIRTUAL PRIVATE NETWORKS based on ATM that behave like private leased lines but in reality share lines with other users.

   ATM frame structure

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.

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