com industry during the last 10 years have been deciding factors that contributed to the sharp decline of voice communication costs. The traditional local or long-distance carrier is now in serious danger of extinction if it does not adapt quickly to the realities of the new network. ATM, LAN EMULATION (LANE), MULTIPROTOCOL OVER ASYNCHRONOUS TRANSFER MODE (MPOA), AND IP OVER ATM The emergence of ATM in the 1990s as the promising successor of frame relay for reasons that have been widely documented is another factor that had to be taken under consideration. 24,25,26 ATM was created as a versatile way for carriers and service providers to more flexibly allocate bandwidth and to provide different levels of QoS. The basic idea was to mesh together ATM switches on point-to-point ATM links or interfaces. These would usually be interfaces to the Synchronous Optical Network/Synchronous Digital Hierarchy [SONET/SDH] hierarchy. The transmission units of ATM are small fixed-length bit packets (53 bytes), which are called cells. ATM switches can indeed transmit traffic cells from one interface to another very fast (up to several gigabits per second), and traffic can be transmitted with a very small and predictable delay. This fundamental characteristic of ATM is the key enabling factor for the delivery of voice and data services with a certain QoS in terms of available bandwidth, delay, and jitter. ATM was expected to become the solution to the backbone congestion problem we described ear- lier. With projections of sharply increasing sales, vendors of ATM products hoped that the costs of ATM products and more specifically adapters would drop significantly, thereby opening up the huge markets of desktops. To facilitate acceptance of the technology, several standardization efforts were put forth by the ATM Forum, an industry consortium devoted to the promotion and advancement of ATM. These efforts led to the creation of protocols that allowed LAN Emulation (LANE) over ATM or the trans- mission of several network and transport 