Creating a Home Network : Creating a Wired LAN, Creating a Wireless LAN

1. What Is a LAN?

A local area network (sometimes referred to as a LAN, a workgroup, a private network, or just a network) is a small group of computers within a single building or household that can communicate with one another and share resources. A resource is anything useful to the computer. For example:

• All computers in the LAN can use a single printer.

• All computers in the LAN can connect to the Internet through a single modem and Internet account.

• All computers in the LAN can access shared files and folders on any other computer in the LAN.

In addition, you can move and copy files and folders among computers using exactly the same techniques you use to move and copy files among folders on a single computer. However, it's not entirely necessary to move or copy a document that you want to work on, because if a document is in a shared folder, you can open and edit it from any computer in the network. This is good, because you only have one copy of the document, and you don't have to worry about having multiple, slightly different copies of the same document all over the place to confuse matters.

2. Planning a LAN

3. Creating a Wired LAN

If you have two or more computers to connect, and they're all in the same room and close to one another, you can use a traditional Ethernet hub and Ethernet cables to connect the computers with cables. You'll need exactly one NIC and one traditional Ethernet cable for each computer in the LAN. Figure 51-1 shows an example of four computers connected in a traditional LAN. Notice how each computer connects to the hub only — no cables run directly from one computer to another computer.

By the way, even though the printer in Figure 51-1 is connected to the same computer as the modem, that's just an example. The printer can be connected to any computer. In fact, you could have several printers connected to several computers. All computers will be able to use all printers, no matter which computer that printer is (or those printers are) connected to. In addition, a printer with a network interface need not be connected to a computer at all, but rather can be connected directly to the network.

3.1. Traditional Ethernet Speeds

When it comes time to purchase network interface cards, cables, and a hub, you'll need to decide on the speed you want. As with everything else in the computer industry, network speed costs money. However, in the case of networks, the cost differences are minor, whereas the speed differences are huge. The three possible speeds for Ethernet LANs are listed in Table 1.

If it's difficult to relate the numbers to actual transfer rates, consider a dial-up modem, which tops out at 50 Kbps. That's 50,000 bits per second. A 100Base-T network moves 100,000,000 bits per second. That's 2,000 times faster or, in other words, you only have to wait 1/2,000 as long for the same file to transfer across a 100Base-T connection. So, a file that takes 33 minutes (2,000 seconds) to transfer over a dial-up modem takes 1 second to transfer over a 100Base-T network.

Figure 1. Example of four computers connected in a traditional Ethernet LAN.

3.2. The slowest component rules

When purchasing hardware, it's important to understand that the slowest component always rules. For example, if you get Gigabit Ethernet cards, but connect them to a 100Base-T hub, the LAN will run at 100Mbps. The faster Gigabit NICs can't force the slower hub to move any faster.

It makes sense if you envision the electrons going through the wire as cars on a freeway. Let's say lots of cars are zooming down a 10-lane freeway, but there's some road construction where the freeway narrows to one lane. Cars are going to pile up behind that point, because the one-lane portion is slowing things down. Where the one lane reopens back to 10 lanes, cars will still be trickling out of the bottleneck — the single lane — one at a time. The 10 lanes at the other side of the bottleneck can't "suck the cars through" the bottleneck any faster than one car at a time.

Likewise, if your computers are connected together with a Gigabit LAN, but all share a single broadband connection to the Internet, your Internet connection is still 512 Kbps. Your fast LAN can't force the data from your ISP to get to your computer any faster than 512 Kbps. Furthermore, if two people are using the 512-Kbps broadband connection at the same time, they have to share the available bandwidth, meaning that each user gets only 256 Kbps. But, if only one person is online, she gets the full 512 Kbps because she's not sharing any bandwidth when nobody else is online.

NOTE

If you have only two computers to connect, and each has an Ethernet card, you don't really need a hub. Instead you can connect the two computers directly using an Ethernet crossover cable.

4. Creating a Wireless LAN

Wireless networking reigns supreme when it comes to convenience and ease of use. As the name implies, with wireless networks you don't have to run any cables. Plus, no computer is tied down to any one cable. For example, you can use your notebook computer in any room in the house, or even out on the patio, and still have Internet access without being tied to a cable.

To set up a wireless LAN, you need a wireless NIC for each computer. To set up an ad-hoc wireless network, that's all you need. The computers can communicate with each other, so long as they're within range of one another. If you want Internet connectivity for all of the computers in a wireless LAN, you'll need some kind of access point that acts as a central location for all the computers and also provides an Internet connection. Typically, that device would be a Wireless Broadband Router, as illustrated in Figure 2.

4.1. Wireless Broadband Router

The big advantage of wireless networking is, of course, the lack of cables. This is especially handy on a notebook computer, because the computer isn't tethered to one location by a cable. Granted, you can't stray too far from the wireless access point (100 to 150 feet or so), but that will probably be sufficient in most cases.

Also, many universities and other locations offer public Internet access from any computer that has an 802.11b, 802.11g, or 802.11n wireless network interface. So, if you create your home wireless network using either of those standards, you'll also be able to use public Wi-Fi Internet access where it's available.

Figure 2. Example of four computers connected in a wireless LAN.

Wireless networks are built around four different standards. 802.11n is the newest, although as of this writing it is still in draft and not technically a standard. Table 2 summarizes the main differences between the four standards. The Public Access column refers to Internet Wi-Fi hotspots such as those found at some airports, hotels, and other places.

In most cases, when setting up your network you're really setting up two networks. The first network involves the computer-to-computer communication. This includes the wireless setup or a wired setup . The second network is the Internet. Connecting to the Internet involves some form of an ISP. Today, two of the most popular methods are either a standard dial-up modem connection or a broadband connection. If you're sharing an Internet connection, one device in your network will have physical access to the Internet and the other computers will share the connection. The one device that actually sees the Internet can either be a computer or you can purchase an inexpensive device that connects to the Internet called a Broadband Router.

4.2. Other useful wireless goodies

If you already have a wired network with Internet connectivity, and just want to add some wireless computers to that network, you don't need a Wireless Broadband Router. Instead, you need a Wireless Access Point (WAP). First you'll need to configure the hub, as per the manufacturer's instructions, by connecting it directly to one of the computers in your wired network. Then you can disconnect the WAP from the computer and connect it directly to the hub for your wireless network. The wireless computer can use the same shared Internet connection that the wired network uses.

Getting a wireless network to cover a whole house can be a challenge, especially if you have two or more floors. If you want to extend Wi-Fi to the entire house, you may need to use one or more wireless range expanders to extend the reach of the network. Putting one near the staircase is a good idea when you need to reach upstairs or downstairs. You can also use multiple access points to achieve the same results.

A Wi-Fi finder can also be helpful. It's a device that's small enough to fit on a keychain and it measures the strength of a wireless network signal at wherever you're standing. It can help you determine where the edge of a signal is, which is a good place to put a range expander to get more coverage.