ss than full-time at what- ever data rate the line was capable of. In situations where multiple terminals connected to the same central computer, or an enterprise operated several computers in separate locations, data communications networks evolved through various forms of simple aggregate and, later, statistical multiplexing tech- niques. Even when a terminal is connected to a computer or system hosting an application, traffic between the terminal and host is very asymmetric. Keystroke generation is rarely more than 75 bps, com- pared to information and screens generated by the host application 4 NETWORK TECHNOLOGY AND METHODOLOGY and sent back to the terminal that can require hundreds of kilobits per second, or even megabits per second. Statistical multiplexing techniques found their way into data communications equipment and networks. As more and more traffic was aggregated and trans- ported by data networks, the same techniques were used to gain efficiencies and utilization in those networks. Essentially, ATM was conceived and designed to cope with the bandwidth limitations in POTS and ISDN for the data communica- tions user, while at the same time improving use of lower layer transmission facilities providing leased or private line services. The basic characteristics of ATM are built around the virtual circuit con- cept, including virtual paths and virtual circuits. Because source and destination information is included in each cell, switching and routing of the traffic can be accomplished by network switching equipment examining each cell as it arrives in a network, and then determining where to route it on the outbound side. This basic capability allows configuration of a virtual path through the network between any two or more points connected to the network, and to set up connections between any two or more of those locations. Thus, a virtual circuit exists inside a virtual path. ATM also provides a capability for customer or user control of the network, enabling the user to configure switched virtual c