VPNs Illustrated: Tunnels, VPNs, and IPsec

Preface

Introduction

There is a revolution going on in enterprise networking. Until very recently, enterprises that needed to link computers in geographically dispersed locations had to build their own wide area networks (WANs). Usually this meant renting expensive and, by today’s Internet standard, relatively slow frame relay circuits. A typical 56 Kb/s circuit could cost several hundred, or even over a thousand, dollars a month.

Today, the typical home computer user enjoys a broadband Internet connection having a 5 Mb/s download speed for a cost of about $40 per month. Commercial variants of this service, offering higher speeds and other amenities, are available for between $100 and $200 per month. Obviously, this significant increase ...