Chapter 1. Introduction: Broadband Access and Virtual Private Networks

In this chapter, you learn about the following topics:

Broadband Networks and Operators
Service Models: Who Buys What
IP Virtual Private Networks for Broadband
A Simplified Framework for Broadband VPN

After a slow start, the massive deployment of broadband is finally starting to have an aura of inevitability around it. Some statistics demonstrate how quickly this is happening. According to the DSL Forum (http://www.dslforum.org), there were 63.8 million digital subscriber line (DSL) subscribers worldwide in March 2004, 8 million of which had been added in the previous 6 months! That is a rate of over 44,000 new customers per day for DSL alone. Add in other broadband technologies, and the rate of adoption becomes truly impressive.

The broadband phenomenon is also well spread out across the world. The top five countries in terms of percentage of phone lines converted to DSL (again, DSL Forum data for 2004) are South Korea, Taiwan, Belgium, Hong Kong, and Japan. The most growth occurred in Peru and Malaysia. China, Japan, and the U.S. each had more than ten million DSL subscribers and six countries in Europe have achieved over 10 percent market penetration. DSL Forum points out that this is "half-way to mass market status."

In the broadband service market, providers using different technologies compete with one another and must often fight over the same group of potential customers and try to tempt them away from the dark ages of dial-up networking to their own particular solution. Traditional service providers use existing networks and push DSL to anyone who will have it; cable operators add data services to their video service; finally, alternate providers try to use new technology, such as Ethernet, to provide lower-cost, higher-speed services and, in doing so, hope to take a chunk of business away from everyone else.

The tool of choice in this tussle for subscribers is services. Services are how providers make their money and are also what people actually buy. Services range from the very simple, such as Internet access, through the very sophisticated, such as network-based personal video recorders. Probably the most innovative services in the market today come from the Ethernet crowd, who offer cleverly bundled content and network-based applications, such as online video recorders. But the DSL and cable operators are hot on their heels, each strenuously pushing a service typically provided by the competition. Television-over-DSL trials are underway in several European and Asian cities already and cable operators tout voice over IP (VoIP) in North America, to cite just a few examples.

A Virtual Private Network (VPN) is one particular service that has a well-establishedand growingmarket and has its own set of competing technologies. When designing a VPN for broadband access, several differences stand out compared to more standard VPNs:

The number of subscribers is unlike anything seen elsewhere in IP networks.
The devices attached to the VPN are usually very unsophisticatedand the customer premises does not necessarily have a router.
Layers of government regulation might determine who can do what in a broadband network.

Later in the chapter, I propose a basic framework to compare different VPN solutions. Much more formal frameworks exist elsewhere, notably in Internet Engineering Task Force (IETF) drafts, but I wanted to provide something that focuses on broadband and is simple to understand. The goal behind the comparison is not so much to proclaim a "winning technology" as to offer some thoughts about what a network architect might consider when looking at different ways to solve a particular problem.

Finally, this chapter includes definitions of different types of VPNs.

But first, what is broadband? Who buys it and who sells it?