Asynchronous Transfer Mode (ATM) is a core network protocol that encodes data, voice, and video into small, fixed-sized cells of 53 bytes. By using uniform cells rather than variable-length packets, the network can process traffic in hardware with highly predictable latency and guaranteed quality of service. It was heavily used in carrier backbones before being largely superseded by IP and Ethernet technologies.
The legacy voice switch is still handing off traffic over an ATM circuit, so we need to maintain that virtual path.
The 53-byte cell size was a historic compromise between the US preference for 64 bytes for data efficiency and the European preference for 32 bytes to minimize voice latency.
Also heard as
- Asynchronous Transfer Mode
Related terms
AAL
A protocol layer that formats higher-level data into standard cells for asynchronous transfer mode networks.
AAL2
An ATM adaptation layer designed for variable-bitrate, timing-dependent traffic like compressed voice.
AAL5
An ATM adaptation layer optimized for transporting standard data traffic like IP packets.