Chapter16.Driving from Home onto the Globally Interconnected (Internet) Roadway

Chapter 16. Driving from Home onto the Globally Interconnected (Internet) Roadway

What You Will Learn

After reading this chapter, you should be able to

• Explain why connecting to the Internet provides a path for IP packets to be sent almost anywhere

• Describe how a modem can transmit data over an analog phone line

• Describe how telco creates DSL by using part of your local phone line

• Explain the basic concepts of sending data over your television cable

If you have a bunch of detailed road maps, you could probably find dozens of ways to drive to wherever you go on vacation. Some ways are faster or longer, use good roads, or use bad roads. But at least most places in the contiguous 48 states of the United States have a road nearby, which connects to the other roads. You can drive anywhere in the country, with lots of different options.

Similarly, there's already a large IP network that crisscrosses the globethe Internet. The Internet is a combination of a ton of different individual IP internetworks, connected to each other, so that each device has at least one, if not many, routes over which it can send packets to other hosts. Just like you can take the road near your house and drive almost anywhere in the country in your car, an IP packet can get into the Internet and be routed to almost any IP host on the planet.

In this chapter, you'll read a little about why the Internet is useful for getting IP packets to and from an enterprise network. Then, you'll see the basics of three technologies that you can use to access the Internet from homenamely, modems, DSL, and cable modems. And like in Chapters 14, "Leasing a (Network) Roadway Between Two Points," and 15, "Leasing a (Network) Roadway Between Lots of Places," this chapter focuses on the OSI Layer 1 and 2 standards and protocols, with reminders of how routers can then forward packets to the right destinations.