Asynchronous Transfer Mode

ATM is a highbandwidth, lowdelay switching and multiplexing technology. It is a datalink layer protocol. This means that it is a protocolindependent transport mechanism. ATM allows very highspeed data transfer rates at up to 155 Mbps. Data is transmitted in the form of 53byte units called cells. Each cell consists of a 5byte header and a 48byte payload. The term “asynchronous” in this context refers to the fact that cells from any one particular source need not be periodically spaced within the overall cell stream. That is, users are not assigned a set position in a recurring frame as is common in circuit switching. ATM can transport audio/video/data over the same connection at the same time and provide QoS (Quality of Service) for this transport.