xxxiv Preface information). They have the newest, most up-to-date information and are worthy of your sup- port. Additionally, safety is the responsibility of system designers and operators. I include some general safety principles in this book; these are based on the way I do things and not necessar- ily on any industry standard. It is your responsibility to ensure safety in any system with which you deal! Finally, pieces of gear depicted in pictures or mentioned in the book are simply representative products which appear to me to be in widespread use. No endorsement of any sort is intended. North American Perspective I live and work in New York City. While I try to keep up with what is happening in other mar- kets throughout the country and the world, it's nearly impossible for me to be thorough on an international basis. I apologize in advance for any North American (or New York) bias (per- ceived or real) in this book! Opinion and Fact This book is a mixture of opinion and fact. The nature of this field is that there are generally dozens or hundreds of ways to accomplish any goal. If I relate to you the number of bits in an IP address, that's a fact and pretty much beyond dispute (assuming I didn't make a mistake, of