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Scott Jernigan
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Few PCs remain islands unto themselves forever. To experience the full power of computers, you must connect them to other computers. Imagine you receive a new computer, but it’s not on a network, so you can’t send e-mail messages, download music, or interact over the Internet with your friends. How boring!
Connecting to a network, however, opens up you and your computer to a new set of troubleshooting issues. What if you can’t connect to the network? What if you can’t share that important document? What if you pick up a nasty virus?
This lesson eases you into the world of networking. You’ll learn how networks work and what components you’ll need to make one of your own. Next, you’ll discover the advantages and disadvantages of wireless networks. Finally, you’ll learn about the biggest network of them all: the Internet.
Move on to Chapter 2 to start at the beginning: How do networks work?
When you link computers, you create a network. This chapter covers all the pieces of a computer network, focusing on the hardware needed to make the physical connections.
Networks come in many sizes. Some people connect two computers in their house so they can share files and play games. Some companies have thousands of employees in dozens of countries and need to network their computers to get work done.
A local area network (LAN) covers a small area and contains a modest number of computers. You usually find LANs in a single building or a group of nearby buildings. Typical LANs include home and school networks.
A wide area network (WAN) covers a large area and can have a substantial number of computers. WANs often connect two or more LANs. All the LANs in all the schools in your district, for example, link to form a WAN.
Computers in a WAN usually connect through some type of public network. This might be a telephone system, leased lines, or satellites. The largest WAN is the Internet, a worldwide network that connects millions of computers and networks.
People use two types of computers in networks these days: servers and clients. Servers share things, such as files, folders, and printers. Clients enable you to access those shared things. Almost any personal computer can act as a server or a client or both! A lot of it has to do with how you set up the computer.
Client computers enable you to access the shared resources and services on server machines. Computers running Windows, Mac OS X, and the many varieties of Linux make up the vast majority of clients. Other clients include:
Server computers come in all shapes and sizes, but they serve (if you'll pardon the pun) a similar purpose. Servers manage network resources, like printers, e-mail—all the stuff that makes a network valuable. They also enable the central storage of files. In addition, they provide services for the users like having the printer server tell the printer to print, or having the e-mail server send your e-mail.
You can classify networks into client/server and peer-to-peer, depending on the role each computer plays in the network. In a client/server network, one computer system acts as a server, while the remaining computers access resources from the server as clients. Some home or small office networks, however, might not use a separate server. Instead, every computer on the network acts as a client and a server. These are peer-to-peer networks.
Knowing the size of a network and the purpose of each connected device can help you organize and use networks more efficiently. You can troubleshoot network issues a lot faster if you know that the client device can't access any shared music because the music server is broken.
Networks can greatly enhance your computing experience, but they can also harm your data in ways not possible for a non-networked computer. You need to understand how creating a network affects your computing life.
Networks offer many benefits:
Communication means emailing your friends, family, and coworkers while sipping café au lait from a bistro in Paris, even if they live and work back home in Kansas. Using Google Talk or another instant messaging program, your computer can alert you when your friends come online. That means you can send them a quick hello at any time of the day or night.
Being able to work (and play) with others over a network increases your productivity. You can send your next best-selling manuscript to your agent in Los Angeles from your hideaway in Tahiti. You can work on a project with five people in five different cities. You can smack your best friend in an online game when he's 3,000 miles away!
Sharing files, folders, printers, and scanners over a network can lead to lower costs. If you have 10 people in your class who need to print something, you could share a single printer among all 10 computers.
Finally, networking enables centralized control over certain aspects of the networked computers. You can designate one computer as a file server. (A file server stores and manages files that other computers on the network access). You could also designate a print server—a computer connected to one or more printers for other computers on the network to use. You can create a workgroup for all the users and require proper user names and passwords, thus enhancing security.
Why security? Let's look at the downside of network computing.
Creating a computer network can make you lose control over your computer, add cost, and cause security problems. Because of security concerns, a network user doesn't usually have complete control over computer settings and software. Costs for servers, cables, and network cards can also add up.
There's also a human cost. Someone needs to administer the network resources, maintain the network, and fix problems. You must also consider the hazard of network hardware or software failure.
Finally, opening up a folder full of your data onto a network of any size creates a gaping security hole. Only your vigilance and forethought can stop a hacker or thief from grabbing or deleting your files. Just being on the Internet can create huge problems too, with the many viruses and evildoers out there.
Weighing the downside versus the upside in networking tips the balance in favor of networking. But you have to implement and maintain security. The life you save might be your computer's!
For any network, you need connectivity between PCs and a way to communicate. Computers connect to a network in one of two ways:
A typical network client has a network adapter or network interface card (NIC). Each connects to a cable that plugs into a central network box, called a hub or a switch. (I'll explain the difference between hubs and switches in a moment.)
To make this into a nicely configured network, add another network client. Throw in a server. Don't add water, but turn on network sharing. Voilà! You have a network. Each machine attaches to a network cable that connects to the hub or switch. Any machine attached to a network—client, server, printer, or whatnot—is called a node.
It takes hardware and software to make network communication work well. Let's say Johan's computer requests an MP3 file from Michael's computer. Michael's operating system and other software take that MP3 file and break it into small, individually numbered units called packets. The NIC takes the packets and wraps them up into network frames. Then the NIC sends out the frames along the cable to the central network hub or switch.
How can you tell what sort of cable to use for a network? How do you determine the type of hub or switch required? Networking means communicating; the computers need to speak the same language and follow the same technology.
The Ethernet standard defines everything about modern network hardware. Ethernet cables have standard connectors, for example, such as the RJ-45 connector. Ethernet defines electrical signaling as well. That way, the sending NIC breaks data into little pieces, and the receiving NIC knows how to put them together.
What if two machines don't have the same kind of networking technology? Then they can't network. This used to be a common problem. I don't want to bore you with a list of all the old networking technologies. Just know that Ethernet reigns over all the rest.
Hubs and switches sit at the center of networking, receiving and sending packets of data. Each functions differently when receiving an Ethernet frame.
A hub repeats the frame down every network cable connected, searching for the recipient machine. (Johan's laptop is an example of a recipient machine.)
A switch, in contrast, learns the network address of every machine connected to it. Then it sends them to the appropriate connection only.
Switches now dominate the marketplace, although you'll still see lots of hubs in service.
You've learned a lot about networks and networking components this chapter, but we still need to discuss wireless networks. When you're ready, continue on to Chapter 3.
Wireless networks use radio waves to communicate, eliminating the need for cables. These days, most wireless networks use the IEEE 802.11 wireless Ethernet standard (Wi-Fi).
Today we'll cover the components and technologies that power wireless networks. We'll also discuss configuring a wireless network.
Most mobile or portable devices use integrated wireless components. You can also add wireless capability with internal or external add-on components.
A wireless access point (WAP) centrally connects wireless network nodes in the same way that a network hub or switch connects wired PCs. Many WAPs also act as high-speed switches and Internet routers. (I'll cover these in the next chapter.)
Wireless network adapters use Plug and Play technology. The term Plug and Play means "ready to use." So any modern version of Windows immediately recognizes one of these adapters when you install it into a PCI or PCIe slot or a USB port. Windows will prompt you to load any needed hardware drivers.
Note
Expansion cards (such as network interface cards) use PCI or PCIe slots on your motherboard to connect to your computer. The PCI/PCIe installation procedure is beyond the scope of this lesson, but know that to add wireless connectivity to your PC, you may need to open it up and install a new component. In a later lesson, I'll discuss adding new components to your computer.
Windows XP, Vista, and 7 include built-in tools to configure additional settings such as adding a network name.
This utility enables you to determine your link state and signal strength. It also enables you to configure your wireless networking mode and set security encryption options.
Wireless networks have two important limitations: speed and range.
Wireless speed mostly depends on the standard used by the networked wireless devices. Wireless throughput speeds range from a measly 2 Mbps to a snappy 100-plus Mbps. (Mbps stands for "megabits per second," which is slightly more than a million bits per second. It's how people measure the speed of network connections.)
Another factor affecting speed is the distance between wireless nodes, or between wireless nodes and centralized WAPs. Wireless devices dynamically negotiate the top speed at which they can communicate without dropping too many data packets. The maximum throughput speed can be achieved only at extremely close range (less than about 25 feet). At the outer reaches of a device's effective range, speed may decrease to around 1 Mbps before it drops out altogether.
Finally, interference from other wireless devices operating in the same frequency range (such as cordless phones and baby monitors) can affect throughput speed. So can interference from solid objects. Dead spots occur when something blocks the radio signal between wireless network nodes. Large electrical appliances (and some smaller ones, such as microwaves) do this very effectively. Other culprits include fuse boxes, metal plumbing, and air conditioning units.
Wireless networking range is hard to define. You'll see most descriptions listed with qualifiers, such as "around 150 feet" or "about 300 feet."
How can you increase the range of your wireless network? You can install multiple WAPs to permit "roaming" between one WAP's coverage area and another's. Or you can install a higher-gain antenna on some models that increases a single WAP's range.
To help you understand wireless network technology, here's a brief look at the standards used.
The IEEE 802.11 wireless Ethernet standard defines how devices can communicate using spread-spectrum radio waves. A spread spectrum broadcasts data in small, discrete chunks over different frequencies within a certain range.
The 802.11-based wireless technologies broadcast and receive on one of two radio bands: 2.4 GHz and 5.8 GHz. (GHz stands for gigahertz and means "a billion cycles per second.") Even though the ISM band is 5.8 GHz, we just say "5 GHz" for some reason.
Currently, Wi-Fi is by far the most widely adopted type of wireless networking. Thousands of private businesses and homes have wireless networks. Many public places, such as coffee shops and libraries, do too.
You don't need to know everything about each standard, but here are some important facts:
Newer wireless devices can communicate with older ones. The exception to this is 802.11a (a much less popular standard), which requires that all the equipment directly support it.
People often think of the Internet as some monolithic, centralized thing. However, it's actually made up of many small networks linked together in a giant "supernetwork." This chapter introduces you to the basics of the Internet. First, I'll discuss how the Internet works, including the individual pieces that come together to make world's largest network. Then you'll learn about the many ways you can connect to the Internet, including dial-up and broadband connections.
The Internet's designers wanted to make certain that nothing could stop the flow of communication, not even a nuclear attack. So they specified a highly decentralized network, with multiple connections between computers. The heart of the Internet—called the backbone—consists of many university, corporate, and government networks. These connect to each other through thick bundles of glass filaments called fiber-optic cables.
Routers provide the connection points between networks. They also determine the route a data packet takes.
Routers range from the high-end machines that direct huge amounts of Internet traffic to the little box attached to your cable modem at home. Home routers (or broadband routers) often offer multiple functions. Most have built-in switches and wireless access points (and are often called "wireless routers").
Routers know the destination of packets of data because routers use TCP/IP, the common tongue of the Internet. They read the network ID of each data packet and send it by the shortest route they know about to its destination.
The multiple connections between the backbone networks offer great resilience for the Internet in times of crisis. If one route goes down, the routers update their maps of the Internet and re-route traffic. This doesn't do much for you unless you can connect to a backbone network.
An Internet service provider (ISP) leases connections to the Internet from a backbone network. It's your gateway to the Internet.
Establishing a link between your computer and the ISP requires three things:
Your computer and other network devices use the TCP/IP protocol to communicate over the Internet. To do this, however, it must be installed on your PC. Fortunately, Windows installs this protocol by default.
So how can you connect to an ISP?
You can connect least expensively using dial-up networking. It consists of a modem, a working telephone line, and an ISP.
The modem enables the computer to communicate through phone lines. The phone line provides the link between the modem and the computers at the ISP. The ISP computers connect to the Big Kahuna of all networks, the Internet.
For this process to work, you must have a properly installed modem with the correct drivers loaded. You need properly set up software, such as Dial-up Networking (DUN) in Windows. Your ISP gives you the configuration information, such as a telephone number, user name, and password. Of course, the ISP computers need to be set up properly to receive your modem's call. If the ISP computers don't recognize your name and password, you can call all day long and not get a connection.
Dial-up connections provide the least expensive way to get on the Internet. Prices in the typical metropolitan area in the United States, for example, range from free to about $20 per month. The technology has been around for a decade or more, and it works smoothly and easily. So, what's the catch?
Dial-up connections provide the slowest connection. And this bottleneck continues to worsen as more Web sites incorporate multimedia content, such as movies and Flash animations.
Dial-up speeds max out at 56 Kbps (kilobits per second). More commonly, especially outside the big cities in the United States, you'll get closer to 40 Kbps consistently. It'd take around 47 seconds at the fastest dial-up speed and a whopping 90 seconds at 28.8 Kbps to open www.microsoft.com, and that's a fairly plain site.
A dedicated, or broadband, connection gives your computer or network access to the Internet through a single high-speed connection. It's always on, so you don't have to wait for the connection to go through. It's also much faster.
Two technologies dominate the broadband connection field: cable and DSL. Both require the same sorts of equipment:
Cable connections use regular cable TV cables to provide upload speeds of up to 1.5 Mbps and download speeds from 2 to 24 Mbps. Remember that Microsoft home page? It's an almost instantaneous download on cable!
The cable speeds I've listed refer to the United States. Other countries, like Japan and South Korea, have prioritized Internet speed. They get more than 100 Mbps from the same type of cable.
Cable connections use a cable modem that connects to a NIC in your PC through an Ethernet cable. The cable TV companies take advantage of the fact that their TV signals occupy only a fraction of the capacity of the cables running into your home.
Digital Subscriber Line (DSL) uses your telephone line as its pipeline. Standard copper telephone lines can handle a much greater range of frequencies, or bandwidth, than what they need to transmit your voice during phone calls. DSL uses this extra bandwidth capacity to send data over the wires without disturbing their ability to carry voice conversations.
DSL creates always-on Internet connections at blindingly fast speeds. Upload speeds commonly reach about 512 Kbps, while download speeds come in around 1 to 6 Mbps.
DSL requires very little setup from a user standpoint.
Within moments, you're surfing at blazing speeds. You don't need a second telephone line. You don't need to wear a special propeller hat or anything.
Unfortunately, DSL requires your house to be a short distance from the neighborhood switch—something like 18,000 feet. This pretty much stops everybody but city dwellers from accessing DSL service.
Now you know a lot about networks! When you feel ready to wrap things up, jump over to Chapter 5 for a summary.
In this lesson, you learned that local area networks connect computers so they can share resources, such as files and printers. Wide area networks connect multiple LANs into an even larger network.
Computers connect using wires or radio waves. Wired networks use Ethernet cables and hubs or switches to create a network. Wireless networks require a wireless access point for nodes (devices on the network) to connect to. When setting up a wireless network, you need to keep in mind the range of the devices you use. Also, watch out for anything that might cause interference.
Networks need two types of devices: servers and clients. Servers provide files and other resources to the clients, who receive it. A PC works as client and server, since it sends and receives network resources.
Connecting your PC to a network enables you to communicate more easily and increase productivity, but it can also lead to security threats and increased maintenance costs.
You can connect to the Internet using one of three options. Dial-up uses your telephone connection and is the oldest, slowest, and cheapest method. DSL also uses your telephone line and has higher speeds and costs. Cable runs even faster than DSL, but it has similar costs.
After you’ve mastered the material in this lesson, you’ll be ready for Lesson 7. You’ll learn how to troubleshoot uncooperative network and Internet connections.
Cisco Systems (owners of the Linksys brand) is a major producer of networking hardware and software, ranging from wireless routers for home use to super-powerful machines that help run the Internet. Their site contains information about the components you need to set up a network.
CNET’s a popular site for tech news and reviews. It has a wireless network buying guide to help you figure out which components are right for you. You can browse different categories, such as Home Office Network and Online Gaming. Most of the products listed also include reviews.
A: Each has advantages and disadvantages. Wired networks can be a pain to set up, since there are so many cables to connect (and possibly holes to drill, if you don’t want messy piles of cabling). But it doesn’t suffer the same range and interference issues as wireless networks. Also, you don’t have to worry about connecting your device to the network and remembering passwords; just plug in the cable and go.
Wireless networks, on the other hand, let you go anywhere with your device (within range). Try surfing the Web on your couch with a laptop just once, and you’ll never go back. You can also find free Wi-Fi in a lot of public locations. Unfortunately, wireless networks suffer from security vulnerabilities and some speed limitations.
A: Three factors affect your choice.
First, cable and DSL generally cost a lot more than dial-up. Cable costs around $50 U.S., but it offers the highest download speeds. DSL sits in a nice sweet spot between cable and dial-up in both cost and speed.
Second, you can get cable in every metropolitan area (in the United States, at least) but not in many rural settings. DSL coverage remains limited, even within cities. You can get dial-up almost anywhere.
Third, cable and DSL offer extra inducements. If you have a TV tuner card in your PC, you can use the same cable connection (with a splitter) to watch TV on your PC. With DSL, you can use your existing phone lines and not worry about installing cable or any other equipment.
Two or more computers can use DSL and cable modem Internet connections if those computers are part of a LAN.
Assess your personal home networking situation. Are your computers networked? If not, how easy would it be for you to network them? Would you use a wired or wireless network? Depending on the network type, what components do you need? Use the Internet to find exactly which components you'd use.
If you already have a network, make a list of all the network devices you use. Map out their connections. Is there room for improvement? Is it time to upgrade any hardware? Record this information for reference later.
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