Discrete-event simulation: When prototyping of large, complex systems is impossible, this technique, based on known behaviors of interacting elements, is useful

A group of scientists and engineers at AT&T Bell Laboratories, working on a communications network, was faced with a problem: develop a design that was resistant to damage and overload. Building a prototype would have taken years. The engineers took a dual approach to the problem that cut development time to a manageable level while still assuring the reliability of the design.