Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header information) fixed-sized cells. ATM provides data link layer services that run over Layer 1 links. This differs from other technologies based on packet-switched networks (such as the Internet Protocol or Ethernet), in which variable sized packets (known as frames when referencing Layer 2) are used. ATM is a connection-oriented technology, in which a logical connection is established between the two endpoints before the actual data exchange begins.
The standards for ATM were first developed in the mid 1980s. The goal was to design a single networking strategy that could transport real-time video and audio as well as image files, text and email. Two groups, the International Telecommunications Union [ITU 2004] and the ATM Forum [ATM 2004] were involved in the creation of the standards. ATM has been used primarily with telephone and IP networks.
Contents[hide]
- 1 ATM Addressing
- 2 Successes and failures of ATM technology
- 3 Recent developments
- 4 ATM concepts
- 4.1 Why cells?
- 4.2 Cells in practice
- 4.3 Why virtual circuits?
- 4.4 Using cells and virtual circuits for traffic engineering
- 4.5 Types of virtual circuits and paths
- 4.6 Virtual circuit routing
- 4.7 Call admission and connection establishment
- 5 Structure of an ATM cell
- 6 References
- 7 Further reading
- 8 External links
taken from http://en.wikipedia.org/wiki/Asynchronous_Transfer_Mode
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