Basically, one always gets into trouble trying to define these things too precisely because they aren't really clean concepts.
-Radia Perlman, 1996.
This chapter introduces some of the standard data networking terminology and concepts used throughout this book. Those readers already familiar with data networking technology could begin with Chapter 1, which is the real first chapter, with no loss of continuity.
Familiarity with the concepts presented in this chapter is important to understanding the issues of mobility and is assumed in the chapters that follow. Topics discussed in this overview include the communications channel, protocols, connection-oriented and connectionless protocols, the OSI reference model and it layers, protocol data units and networking entities.
This chapter is presented as a survey and is no substitute for the real thing-it is necessarily brief. Many fine texts, such as [STAL93], [PERL92] and [TANN95], are devoted to teaching data networking and cover this subject much more rigorously. Of course, true expertise comes only with study of actual standards documents.