Introduction

OVERVIEW

The volume in your hands is the fourth edition of the worldwide, best-selling introduction to Cisco networking. Since its introduction, this book has sold over 60 thousand copies, has been translated into numerous languages, and is distributed all over the world. This level of interest confirms what you already know-Cisco is, and continues to be, a huge player in the communications industry, and people want to better understand how this behemoth works.

Although two years have passed since writing the third edition, the book has remained quite popular, and we felt that another refresh was in order. As with the third edition, we took the book apart and reexamined each chapter. Although we were hard-pressed to find material we thought was no longer pertinent, we certainly found new subjects that just had to be discussed. For instance, Cisco has really kicked up its Voice over IP (VoIP) offerings with its recent Cisco Unified Communications solution. With a whole new technology and line of products, it's something that needed coverage. In the third edition, we expanded coverage of Cisco business solutions, including VoIP, storage area networks (SANs), and content distribution networks (CDNs). Since this content continues to evolve, we continued to expand the content in all three chapters. Also, since wireless networking has taken such a leap, that section has also been bolstered. Because security has become ever more important, we also beefed up the security section. Of course, all chapters were updated to cover the latest hardware and software offerings from Cisco.

So what's the reason for all of this work and revision? We continue to think that there is an enormous need by networking professionals for a clear, concise introduction to Cisco and its technology. What is truly needed is a simple understanding of networking and Cisco's role in networking to make sense of many IT issues.