ATM is the switching and multiplexing technique chosen by the ITU-T for the broadband access of the ISDN and specifically designed to support integration of data, voice and video applications. ATM delivers important advantanges over existing LAN and WAN technologies, including the promise of scalable bandwidths at unprecendented price and performance and Quality of Service guarantees - and so capable of handling new classes of trafflic like multimedia traffic efficiently. ATM neworks, are designed to provide four different service types. Here users declare their bandwith requirement at the connection setup time.
Examples are transmission of fixed-rate uncompressed video.
Here users specify their peak rate and a sustained rate. Example of VBR traffic include compressed packetized voice or video. Examples include a wide variety of applications wherein a connection is setup before data is transmitted. This service is for users who cannot control their rate of traffic and will want to use the bandwidth if available. Examples include datagram traffic.