TABLE OF CONTENTS Location is a quantity which is so fundamental that it forms part of the gestalt of every human being. Everyone has an instinctive sense of what is meant by location, and yet if you were to ask for a definition of the term you might be surprised by the varied responses it would elicit. Ask somebody "Where are you now?" and you will get responses ranging from "I'm at home," "I'm in the car," "I'm at 27 Homebay Drive, Watsonia," or going to the extreme of subjectivity: "I'm in a state of confusion." In very rare circumstances, somebody may actually reply "I'm 32 degrees south latitude and 150 degrees east longitude ." All of the preceding are potentially correct and are expected responses, depending completely on the context within which the questions were asked. But in discussing location in this book, at least some refinement of the term is needed.
As a starting point, location in this book refers to "geographical location." That is, it is concerned with a spatial location associated with a physical point or region relative to the surface of the earth. It does not refer to other types of location such as a logical network location. For example, an IP device will certainly have a physical spatial location, but the IP address does not represent that location. The IP address represents a logical network location; it identifies the network and host-ID associated with the device and tells internetworking elements how to route...
