Why ATM?

Asynchronous Transfer Mode (ATM) is a cell-based switching and multiplexing technology designed to be a general-purpose, connection-oriented transfer mode.
It handles connection-oriented traffic directly, or through an adaptation layer.

ATM operates by means of Virtual Connections and Virtual Paths through a given medium or set of media. These connections may have constant bit rates (CBR) or variable bit rates (VBR). The connections can also be permanent or controlled by a switch.

ATM is considered asynchronous because the transmitted cells need not be periodic.

However, the greatest potential for ATM is the ability to standardize one network architecture by defining the multiplexing methods.