Chapter List

Introduction

In this chapter, we cover concepts of virtual private networks (VPNs), how they operate, and the different types of VPNs in use today. Before we dive into the details, you may be thinking, What is a VPN, and why would I need to use one? There are several good reasons to implement VPN technology in your infrastructure, starting with security. A VPN is a means of creating secure communications over a public network infrastructure. VPNs use encryption and authentication to ensure information is kept private and confidential. This means you can share data and resources among several locations without the worry of data integrity being compromised. Alone, the ability to make use of a public network to transmit data is also an advantage of VPN technology. Without using the Internet as a transport mechanism, you would have to purchase point-to-point T1s or some other form of leased line to connect multiple locations, or use frame relay service. Leased lines are traditionally expensive to operate, especially if the two points being connected are across a large geographic region. Using VPNs instead reduces the operating cost for your company.

VPNs are also cost effective for traveling users. Without VPNs, a traveling salesperson working outside the office might have to dial in to a modem bank at the office and incur long distance charges for the call. A dialup VPN is much more cost effective, allowing the salesperson to...