Seifert Rich - The all-new switch book the complete guide to LAN switching technology

The All-New Switch Book: The Complete Guide to LAN Switching Technology, Second Edition

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Wiley Publishing, Inc.

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Copyright 2008 by Rich Seifert and Jim Edwards

Published byWiley Publishing, Inc., Indianapolis, Indiana

Published simultaneously in Canada

ISBN: 978-0-470-28715-6

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To my granddaughter, Annaliese Grace. May she enjoy all of the happiness that life has to offer. I am looking forward to all of the things that she will be teaching me for the many years to come.

Jim Edwards

Credits

Executive Editor

Carol Long

Senior Development Editor

Tom Dinse

Production Editor

Rachel McConlogue

Copy Editor

Nancy Rapoport

Editorial Manager

Mary Beth Wakefield

Production Manager

Tim Tate

Vice President and Executive Group Publisher

Richard Swadley

Vice President and Executive Publisher

Joseph B. Wikert

Project Coordinator, Cover

Lynsey Stanford

Proofreader

PubServices

Indexer

Jack Lewis

Cover Image

Jupiter Images

Preface

The invasion of Local Area Networks (LANs) into the commercial, industrial, university, and even the home environment during the 1980s and 1990s was nothing short of phenomenal. No longer did organizations consider whether they need a network, but only what type of network should be employed and what devices should be used to build the network infrastructure.

Most early LANs were designed around the use of a shared communications channelfor example, a coaxial cable bus. During the late 1980s and early 1990s, two phenomena occurred that would fundamentally change the way that end user LANs were designed:

• LAN topology migrated from the use of a shared medium to standardized structured wiring systems, implemented primarily using unshielded twisted pair (UTP) cable and central wiring hubs.
• End user computing equipment and application requirements advanced to the point where the capacity of a shared LAN could actually limit overall system performance.

These two factors (together with commensurate advances in silicon technology) fostered the development and deployment of LAN switches. While traditional, shared-bandwidth wiring hubs are still in use today, they are generally considered acceptable only at the edge of the network or when application demands do not seriously tax LAN performance. Switches have become almost ubiquitous for backbone interconnections. As switch prices decreased, they became popular even for desktop use, as they can provide performance advantages and growth capability for only a very small premium over their non-switched counterparts.

Along with the power and performance advantages offered by switches comes an increase in features, options, and complexity. This book will guide both network users and product developers through the murky sea of issues surrounding the capabilities, use, and design of LAN switches and switched internetworks.

Who Should Read This Book

This book is aimed at the needs of:

• Network users: This includes network planners, designers, installers, and administrators; MIS management; value-added resellers (VARs); and operations staff in any organization that selects, installs, or uses LAN switches and related network products. This book will help these people to understand and become more comfortable with switching technology and to make informed decisions regarding the selection, purchase, and deployment of LAN switches. In many cases today, these people depend primarily on equipment suppliers as their main source of information. Such information is always suspect, as suppliers have a strong motivation to sell their particular technology regardless of whether it is appropriate or not.
• Network technologists: This includes engineers working for companies involved in the design and manufacture of computers, communications, and networking products; academics (both instructors and students); network product marketing and sales personnel; independent consultants; and anyone interested in understanding LAN switch operation beyond the level of detail typically available in product data sheets, trade journals, and general networking books.

The reader is assumed to be at least casually familiar with computer networks (in particular, Local Area Networks), network protocols, and common network application environments. No attempt is made to provide a complete, from-the-ground-up tutorial suitable for novices. Indeed, such a work would require an encyclopedia and would make it impossible to focus on the critical issues of LAN switching. Network technologists and users grounded in network fundamentals will learn everything they need to completely understand the workings of LAN switches. In the process, they will gain enormous insight into the reasons why things are done the way they are, rather than just getting a presentation of cold facts.