Asynchronous Transfer Mode (ATM)

Asynchronous transfer mode, or ATM, is a connection-oriented transmission technology in which data is transferred in cells with a fixed length of 53 bytes. The uniform cell size allows voice, video and data traffic to share a single network while being assigned defined quality of service classes. Switching is based on virtual channels and paths that are established before transmission begins. ATM was mainly used in wide area networks, in the backbone networks of telecommunications providers and in DSL access networks. It has since been largely replaced by Ethernet, MPLS and IP-based technologies, which scale more flexibly and at lower cost. ATM components can still be found in legacy infrastructures and in specific industrial environments. As a foundational topic, ATM remains relevant in networking.