This chapter is from the book
This chapter is from the book
This chapter is from the book
Network Hardware
Hardware for computer networking was once very expensive, but today networking hardware costs as little as $5 to $40 per computer. When you consider that a network can let you share a single printer between two or more computers, or share a single high-speed Internet connection, a network can pay for itself the first day you set it up.
This section gives you a quick run-through of the various types of network hardware you can use to tie your computers together.
Wireless Versus Wired
A network lets your computers “talk” to each other. They can do this through wires or through radio signals, using one of the following types of networks:
- Ethernet uses a physical cable to connect the computers. Ethernet networking runs at either 10 million bits per second (Mbps), 100Mbps, or 1000Mbps (1Gbps). 100Mbps is the most common speed at present. (10Gbps Ethernet is coming, but it’s not something the average home user needs to worry about yet.)
Wireless or Wi-Fi networking sends data through radio signals over the air. Wireless networking doesn’t require you to string cables between your computers, but it’s less reliable (that is, it may stop working for a few seconds every once in a while, disrupting a long download or file transfer), and the signal sometimes has problems passing through walls and floors. Wireless networking comes in several flavors named after standards published by the International Association of Electrical and Electronics Engineers (IEEE). The wireless network types for home and small offices are named 802.11b, which runs at up to 11Mbps, 802.11g, which runs at up to 54Mbps, and 802.11n, which can run at up to 200Mbps or more and has better signal strength. “Up to” is the key phrase there. In real-world use, you’ll get at most half of the rated maximum speed, and if signal quality is low, much less. Still, wireless speeds are fine for surfing the Internet, and if you have 802.11n, even big file transfers should perform well.
Most current equipment is 802.11g. At the time this was written, the 802.11n standard was not yet finalized, although several manufacturers are presently selling “pre-n,” that is, uncertified products that are not guaranteed to work well with products from other manufacturers. (They will presumably be upgradable via software when the final specification is made, but until the standard is finalized in late 2008, buy this stuff at your own risk.)
In addition to Ethernet and wireless, there are two lesser-used wired network types that don’t require you to run new cables because they use your existing household wiring:
- Powerline networking sends data via radio signals sent through your electrical wiring, using adapters that plug into wall outlets. Powerline networking runs at 10Mbps, which is a bit slow by today’s standards—it can take hours to back up a large hard disk over a 10Mbps connection. But it would be fine for sharing an Internet connection.
- Phoneline sends data via radio signals sent through your telephone wiring, using adapters that plug into telephone jacks. (All the jacks must be connected to the same telephone extension.) Phoneline networking also runs at relatively slow 10Mbps.
You can set up a network using any of these hardware types, and you can even mix and match the types if you want, using access points or devices called bridges to connect the different network types together. Wired Ethernet connections are the least expensive, the fastest, the easiest to set up, and the most reliable, but it can be annoying to have to run the cables around. So for example, you might use Ethernet connections to hook up several computers in close proximity, and then use a wireless access point or a powerline/Ethernet bridge to extend the network to a computer in another room.
Network Interface Adapters
Whatever type of network(s) you decide to use, you’ll need a network interface adapter for each computer. Adapters come in several forms: internal (PCI) cards for desktop computers, PCMCIA cards for laptops, and USB adapters for either desktops or laptops. I’ll briefly discuss each adapter type here:
- Ethernet—Typical internal adapters are PCI cards. These can cost as little as $5 each. USB and PCMCIA adapters are available for laptops at a slightly higher cost. Better yet, many desktops and most laptops have Ethernet built in already, so in most cases no add-on adapter is needed. Ethernet adapters are labeled “10/100Mbps” or “10/100/1000Mbps,” meaning that they can run at any of the listed speeds, depending on the capability of the hub into which they’re plugged.
- Wireless—There are some internal PCI adapters for desktops. Most are USB, for either desktops or laptops, or PCMCIA for laptops. Some manufacturers make PCI cards for desktops into which you plug a PCMCIA wireless network adapter. Many laptops have wireless built in, so no add-on adapter is needed. If you need to buy an adapter for a desktop, I recommend the USB variety because you can easily move these around to get the best signal reception.
- Powerline—Typically packaged as a box that plugs into a wall outlet and connects to your computer through a USB cable. Some adapters have Ethernet connectors instead, which you would connect to an Ethernet adapter in your computer, or to a hub.
- Phoneline—Typically internal (PCI) cards or external USB devices.
Cabling
If you are making a wired Ethernet network, you have to run a cable from each computer to the nearest hub (hubs are discussed in the next section). Ethernet cable is also called Unshielded Twisted Pair (UTP) cable because it looks like ordinary telephone cable, with four pairs of wire twisted together inside the cable’s jacket. However, it’s specially manufactured for computer use, and the electrical properties of the wire are very strictly controlled. UTP cable for networking use is rated according to the highest data speed that it’s designed to carry, as listed in Table 6.1.
Table 6.1. Ethernet Cable Ratings
|
Ethernet Speed |
Minimum Cable Rating |
|
10MBps (10BASE-T) |
CAT-3 |
|
100MBps (100BASE-T) |
CAT-5 |
|
1000MBps (1000BASE-T) |
CAT-5, but CAT-6 or CAT-5e is recommended |
Even if you have only older, slower 10Mbps equipment, I recommend that you use at least CAT-5 cabling for all Ethernet networks.
Ethernet cables can’t be cut and spliced in the normal way. If you need to connect cables from end to end, you must use CAT-5 certified plugs and jacks.
You can purchase premade CAT-5 cables (called patch cables) in varying lengths from computer stores or online. You can also purchase bulk cable, connectors, and a connector crimping tool and make your own, although that’s beyond the scope of this book.
Be aware that the maximum length for Ethernet cabling is 100m (330 feet). If you have computers farther apart than this, you have to place the hub somewhere between them, or use multiple hubs in sequence, so that no single cable is more than 100m long. For a really long run, you may have to use fiber optic cable or wireless networking.
If your only goal is to connect two computers together with Ethernet, you can connect the two computers directly to each other, using a special cable called a crossover cable, which routes the send and receive data wires so that the cable can connect one Ethernet adapter directly to another. In most cases, however, you use regular Ethernet patch cables to connect each computer to a central hub or switch, as discussed in the next section.
Hubs and Switches
If you use a wired Ethernet network and have more than two computers or other devices, you need one or more switches or hubs. These devices route the signals between the computers. Hubs and switches serve the same purpose, so for the rest of this chapter, I’ll just use the term hub. (See the sidebar “Switch? Hub? What’s the Difference?” for an explanation of the two terms.)
A simple wired network was shown in Figure 6.1. If you have two or more groups of computers, separated by some distance, you can simplify your cabling job by using more than one hub, with just a single cable running between them, as shown in Figure 6.3.
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Figure 6.3 A more complex Ethernet network with more than one hub.
Hubs can generally adapt themselves to the various Ethernet speeds supported by the computers that you attach to them. Thus, they’re marketed as “10/100Mbps” or “10/100/1000 Mbps.” Most network adapters are rated 10/100, so these run at the higher 100Mbps speed when connected to a 10/100 hub. Higher-end desktops, some laptops, and most Macs usually have 10/100/1000Mbps adapters. If you have two or more computers with these high-speed (Gigabit) adapters, get a 10/100/1000 hub; otherwise, 10/100 is fine.
If you are going to be using wireless networking in addition to Ethernet, and/or you’ll be sharing a DSL or cable Internet connection, you may not need to purchase a hub at all because most wireless access points and DSL/cable sharing routers have a hub built in. Check for this before you spend the money on a standalone Ethernet hub.
Wireless Access Points
Wireless networks function in one of two ways:
- In an ad hoc network, the computers that participate in the network communicate directly to each other through their antennas.
- In an infrastructure network, a device called an access point serves as a sort of referee. Each networked computer transfers data to the access point, which then relays it to the other computers. Access points also provide a means of connecting the wireless network to a wired Ethernet network so that wired-in computers can communicate with the wireless ones. Additionally, an access point makes it easy to connect a high-speed Internet connection to the network, where it can be shared by all the computers.
I don’t discuss creating ad hoc networks in this chapter, but I do want to mention that Vista’s Windows Meeting Space collaboration tool can automatically set up a temporary ad hoc wireless network to let a group of computers share files and applications during a meeting.
For the purpose of this book, I recommend that if you want to set up a wireless network for your home or office, you should set up an infrastructure network, by purchasing an 802.11g or 802.11n (or pre-n) access point that has both a wired Ethernet switch and Internet connection-sharing router capability built in.
Gateways and Routers
A router is a device that transmits data between two or more separate networks. Routers serve much the same function as post offices, which examine the mail they collect, deliver what they can, and forward the rest on to other post offices for them to deliver. A router doesn’t get involved when data is being sent from one computer to another on the same network. But when data is intended for a computer on some other connected network, it’s the router’s job to forward the data from one network to another, to still others if need be, until it reaches its destination.
In corporate environments, routers are used to connect the local networks in separate offices or workgroups. In the home and small office, a router can connect your personal network to the Internet, which after all is nothing more than a bunch of networks just like yours, all connected together. (Tens of millions qualifies as a bunch, yes?) Routers that are specially designed to perform this Internet connection service are often called Internet gateways, or connection-sharing routers. Although routers intended for corporate use can cost thousands of dollars, home/small office connection-sharing routers can cost as little as $10, up to about $100 for models that include an 801.11n wireless network access point in the same unit. Connection-sharing routers have one 10Mbps or 10/100Mbps Ethernet socket that is used to connect to your DSL or cable modem. This is called the WAN port. (WAN stands for Wide Area Network.) Most sharing routers also include a 10/100 Ethernet switch (hub) for up to four wired Ethernet connections. These are labeled LAN ports. You can tack on additional switches or hubs if you need to connect more computers to the Internet.
If you’re setting up new DSL or cable Internet service, you may not even need to purchase a separate connection-sharing router. Your ISP may be able to give you a DSL or cable modem that has a sharing router built in.
The next section discusses wireless networking. If you’re going to set up a standard, wired Ethernet network, you can skip ahead to “Configuring a Workgroup Network.”