Upgrading and Repairing Networks (5th Edition)

SOME OF THE MAIN TOPICS IN THIS CHAPTER ARE

The Point-to Point Protocol and the Serial Line Internet Protocol

The Serial Line Internet Protocol ( SLIP )

The Point-to-Point Protocol ( PPP )

An Example: Configuring a Windows XP Professional Client

When Dial-Up Isn't Fast Enough

If you operate a large corporate network, you might be tempted to skip this chapter. After all, you probably have one or more routers/firewalls and other devices connecting your corporate network to the Internet using a large dedicated data pipe, such as ATM (Asynchronous Transfer Mode) or Frame-Relay switch. However, if you have workers on the move, or employees who work from home, about the only way they can connect to your network is by using a dial-up modem or a broadband Internet connection. The former is more likely the case because broadband connections, which are discussed in following chapters, although quite popular, do not have nearly the user base of traditional dial-ups. So why are dial-up connections still important in a corporate setting? Keep in mind the following:

• As with any new technology, you should always have a backup procedure. What happens if the broadband connection fails? The broadband connection should not be a single point of failure in your network. A backup dial-up solution, while slower than broadband, might just satisfy your business need for the day or two that it takes to fix your higher bandwidth connection.

• What can you do if a mobile employee is staying overnight at a hotel that provides only dial-up access?

• Do you have personnel who work from home? Do they require the bandwidth provided by high-speed connections? If only a few keystrokes are needed to operate your applications, or if downloading a document or data file for processing is needed, then can you justify the cost of broadband against a single, inexpensive dial-up telephone line?

• For noncorporate users, there will come a time when you indeed need a broadband connection. You don't want to spend hours downloading a few files from the Internet. However, at this point in time, a simple dial-up connection may satisfy your needs.

Just as you can use Virtual Private Networks (VPNs), which are discussed in Chapter 50, "Virtual Private Networks (VPNs) and Tunneling," to create a secure path through the Internet, you can create VPNs using dial-up techniques and establish a server to handle incoming connections. Until the telcos and cable providers have finished wiring the world for broadband connections, you may have no choice other than dial-up access.

For those reasons, you should read this chapter to understand just how dial-up protocols (such as PPP) work.