This book is for people who feel pain when their Internet connection is down. It mostly takes the view that BGP is simply a means to an end: reliable Internet connectivity.  For the common scenarios using BGP in this way, BGP example configurations are provided so that you can get BGP going without getting bogged down in details of interest to those building huge BGP networks.
But reliable Internet connectivity doesn't happen automatically as soon as you configure your routers for BGP. This book takes the view that reliable Internet connectivity is the result of a system composed of many components designed and configured to work together toward your reliability goals. The components involved range from desktops and servers to hubs, switches, routers, communications lines, and ISPs. In this book, you'll find the information you'll need to build and maintain a reliable system made from all these components.
Many companies begin using the Internet by establishing a single, statically-routed connection with an Internet Service Provider (ISP). This is adequate till a second Internet connection is required. The second connection may:
Provide a backup in case the first connection fails,
Connect a second site directly to the Internet to keep Internet traffic off the corporate WAN,
Provide some degree of load sharing when both connections are up, or
All of the above.
Adding a second (or nth) Internet connection to your network is fundamentally different from adding your first. It's different because your network now has to choose which Internet connection to use for outbound traffic. It's different because the Internet now has to choose which connection should receive your inbound traffic.
You'll want the "optimal" choices to be made when both connections are working. And of course, you'll want any connections that're down to be avoided. These choices must be made quickly and without human intervention.
Early chapters will describe BGP and detail its role in providing reliable, high-performance Internet connections. They will also stress that BGP is a complex beastie. Although there are no alternatives that provide all the advantages of BGP, transition plans will be discussed that might allow BGP deployment to be delayed.
This book will show how to use modest equipment to achieve reliable Internet connections for one or more sites using one or more ISPs. Examples will be given for two connections to the same ISP from two sites and for two connections to different ISPs from a single site. These examples will contain not just the required router configurations, but also the steps required to allow a smooth transition from static routing.
The most important decisions you'll have to make define the architecture of your network. You'll have to decide how to assign addresses and how many routers and Internet connections to buy. Will one ISP be adequate or will you need more than one? Chapter 6 will identify these questions and help you make the best choices for your network.
BGP is nothing if it's not about choices. Taken together, the choices you make in configuring BGP will comprise your BGP policy. The range of possible choices is as broad as the spectrum of companies needing reliable, high-performance Internet connections. Chapter 7 provides guidance in choosing the right policy for your company.
Once BGP is operating, reliability should be tested by simulating network failures and other techniques. A chapter will discuss this critical step that is all too often left out.
Things can go wrong with BGP (when all connections are working well and when they're not). One or more chapters will be devoted to troubleshooting BGP connectivity problems.
Indeed, BGP has other uses and much of the material here is at least good background for those uses and often directly applicable. The part of the book on Big BGP addresses many uses that go well beyond reliable Internet connectivity.
Copyright © 1999-2000 by Robert A. Van Valzah