Introduction

Virtual private networks (VPNs) in their many and varied guises are becoming more and more prevalent throughout the world. For the service provider and enterprise, they provide a means of enabling new services and applications over a wide-area network (WAN), while providing considerable concomitant cost savings.

VPNs are complex, so when things go wrong, they can be difficult to troubleshoot. What are your options? One option is to contact Cisco TAC. Alternatively, you can buy this book, roll up your sleeves, and get to work. Armed with as much information as I could cram into 800-odd pages, you'll be well on your way to solving your problem. And if your organization is considering deploying or optimizing a VPN and wants to avoid all the issues described in this book and more, please see my company website (www.mjlnet.com) or contact me directly (mark@mjlnet.com), and my very knowledgeable colleagues or I will soon be on site helping to ensure that the process goes smoothly (our services are chargeable, of course!). Furthermore, if your organization would like to improve staff productivity and expertise through advanced training, again please see the website.

A number of RFCs and Internet Drafts are referenced in this book. You should be able to locate many of these at the IETF Web site (www.ietf.org). Internet Drafts do, however, expire, so an alternative way of locating them is to use an archive such as www.watersprings.org.