Chapter 27: Designing a Windows-Based Local Area Network

What Is a Network and Why Would You Need One?

A network provides a connection between computing resources, a way to share hardware and files, and a paperless way to communicate. A local area network (LAN) is a network limited to one building or group of buildings, in which the computers are usually connected by cables. A LAN can be as useful in a small office of two or three computers as it is in a large office.

Larger networks also exist. Wide area networks (WANs) connect computers that are geographically dispersed, and the Internet--the biggest network of them all--is a worldwide network of interconnected networks, including LANs and WANs.

Sharing Hardware

Without a network, each resource (hard disk, CD-ROM drive, printer, or other device) is connected to only one computer (printers may be an exception if you have a switch box). Examples of resources in your office may include a hard drive on which the company's main database is stored, the color printer everyone wants to use, and the tape drive on which nightly backups are made. Without a network, you can use a resource only from the computer to which the resource is attached. With a network, anyone using a computer attached to the network can print to the color printer or open the database, and the computer with the tape drive can access all the hard disks on various machines that need to be backed up. You might also want to share more specialized devices, such as CD-ROM writers and Zip drives.

The cheapest way to share resources is what some techie types call sneakernet--take a removable disk, copy the file you need to print or share, and jog over to the computer with the printer or the person who needs to use the file. But sneakernet isn't very efficient--in the long run you save time and hassle (which of those 12 floppies or Zip disks has the current version of that file?) with a network. If you have a small office, using a network and only one printer--to which everyone can print--is more cost effective.

Sharing Files

If you want to share files without the danger of creating multiple versions, you need a network, so every person who accesses the file uses the same copy. Some software (notably database software) enables multiple users to use one file at the same time. Other software warns you when a file is being used by someone else on the network and may even notify you when the file is available for your use.

When you work with files that are too large to fit on a floppy disk, moving them to other computers is cumbersome without a network.

Sharing an Internet Connection

If everyone on the network needs to access the Internet--to send and receive e-mail, browse the Web, or other Internet applications--it's silly for each computer to have its own modem, phone line, and Internet account. Instead, one computer on the LAN can have a fast Internet connection (perhaps a DSL or cable Internet) and serve as the gateway to the Internet. Or, you can use a specialized device called a router, which connects a LAN to the Internet over one or more phone lines.

Chapter 30 describes how to use Windows XP Internet Connection Sharing to connect a LAN to the Internet.