In today's evolving networking arena, the difficult task in writing a book is to pre­ sent the information in a timely manner. Although I have tried to present the theory and practice of the technology to date, still there may be some facts that are overlooked. This is due to the time it takes from writing the manuscript to its pub­ lication. However, I do firmly believe the contents of this book are enormous and careful readers will be able to apply them to their everyday work. My primary objective is to share with the readership my learning and experience and facilitate a thorough understanding of the most commonly used internetworking technology that emphasizes practice rather than theory. Therefore, the text can be considered as tutorial in nature. Following recent trends, data and telecom technologies have been integrated into one complex infrastructure of unified transport means, fueled by the merger mania of dataltelecom giants. Such a unified information transport mechanism has identified the reliable transfer of information as an important factor for internet­ working. As a result, a major part of the industry has embraced IP (Internet proto­ col) as the primary transport means for information interchange. With the new ad­ vent and complexity of integrated networking, practitioners and users are more overwhelmed than ever before. Hence, in this book, I have foIlowed the industry trend in LAN (local area network) technologies and ended with a practical guide to a unified solution.