Appendix B. ATM Overview

How can you control and manage differences in rates due to impairments for both asymmetric and symmetric DSL? How can you allocate bandwidth among different classes of service? Finally, how can ATM satisfy different applications' traffic requirements?

High-bandwidth constant-rate data is not needed for all applications. A technology that can integrate data types (voice, data, and video) with varying traffic quality contracts is required to mix traffic, including delay-sensitive voice and video service.

ATM represents the current best solution to accommodate these needs. The main advantages that ATM cell-based service provides over a frame-based service, such as Frame Relay, are different classes of service, less latency, bandwidth efficiency, and scalability.

This appendix provides sufficient and necessary ATM explanation if you have no knowledge of ATM or if you need a review. This ensures a good starting point for Chapter 1, “DSL Primer,” and should add to your appreciation of the different network architectures presented in Chapter 3, “TCP/IP Over ATM.”