IPSec VPN Design

Chapter 1. Introduction to VPNs

Virtual private networks, commonly referred to as VPNs, are not an entirely new concept in networking. As the name suggests, a VPN can be defined as a private network service delivered over a public network infrastructure. A telephone call between two parties is the simplest example of a virtual private connection over a public telephone network. Two important characteristics of a VPN are that it is virtual and private.

There are many types of VPNs, such as Frame Relay and ATM, and entire books can and have been written about each of these VPN technologies. The focus of this book is on a VPN technology known as IPSec.

Motivations for Deploying a VPN

This chapter introduces some of the VPN technologies and helps ...