Overview

Asynchronous Transfer Mode (ATM) is a high-speed switching network architecture that was created in the late 1980s/early 1990s to apply circuit switching concepts to data networks. ATM is also known as cell relay to distinguish it from frame relay (see Chapter 12). In many regards ATM is considered a "universal" network because it can combine the delivery of a wide range of services (data, voice, and video) over a single network, has a robust quality of service (QoS) facility, can provide seamless interconnectivity between local and wide area networks, and supports a wide range of data rates from 25 Mbps to 155 Mbps over copper, and from 100 Mbps to 622 Mbps (OC-12) and higher over fiber (multimode or single mode). A common implementation is 155 Mbps ATM over SONET (see Chapter 7). ATM has been briefly presented from various perspectives in nearly every chapter of this book. In this chapter we provide a more detailed examination of this technology.

1. What is ATM?

   Asynchronous Transfer Mode (ATM) is a sophisticated, multispeed network environment that provides a variety of complex network services for applications requiring various types of network solutions. It can be used to carry data, voice and video separately or simultaneously over the same network path, and is one of the most complex communications technologies available today for public or private network infrastructures. ATM can be used in LANs, MANs, and WANs, all at the same time if needed. Using terminology developed in previous chapters, ATM might also be considered...