Networking FOR DUMmIES.
Getting Started with Networking
Chapter
1
Networks Will Not Take Over the World, and Other Network Basics
In This Chapter
► Getting a handle on
networks
►
Considering why networking is valuable (and everywhere)
►
Telling the difference between servers and clients
►
Looking under the hood at the network
operating system
► Asking, “How’s
it work when a network
works if a network works for me?” (Say what?)
►
Assessing how networks
change computing life
►
Identifying (and offering
sympathy to) the network manager
► Comparing servers to clients: What have they got that you don’t?
deadly terminator robots, and sends them back through time to kill everyone unfortunate enough to have the name, Sarah Connor. In The Matrix movies, a vast and powerful computer network enslaves humans and keeps them
trapped in a real-world simulation. And in one of Matthew Broderick’s first movies, War Games, a computer whiz kid nearly starts World War III by connecting to a Defense Department network and playing a game called Global Thermonuclear War.
Fear not. These bad networks exist only in the dreams of science-fiction writers. Real-world networks are much calmer and more predictable. They don’t think for themselves, they can’t evolve into something you don’t want them to be, and they won’t hurt you — even if your name is Sarah Connor.
Now that you’re over your fear of networks, you’re ready to breeze through this chapter. It’s a gentle, even superficial, introduction to computer networks, with a slant toward the concepts that can help you use a computer that’s attached to a network. This chapter goes easy on the details; the really detailed and boring stuff comes later.
What Is a Network?
A network is nothing more than two or more computers connected by a cable (or in some cases, by a wireless connection) so that they can exchange information.
Of course, computers can exchange information in other ways besides networks. Most of us have used what computer nerds call the sneakernet. That’s where you copy a file to a diskette and then walk the disk over to someone else’s computer. (The term sneakernet is typical of computer nerds’ feeble attempts at humor, and why not? As a way to transfer information, the sneaker- net was pretty feeble.)
The whole problem with the sneakernet is that it’s slow — plus, it wears a trail on your carpet. One day, some penny-pinching computer geeks discovered that connecting computers together with cables was actually cheaper than replacing the carpet every six months. Thus the modern computer network was born.
You can create a computer network by hooking all the computers in your office together with cables and installing a special network interface card (an electronic circuit card that goes inside your computer — ouch!) in each computer so you have a place to plug in the cable. Then you set up your computer’s operating-system software to make the network work, and — voilà — you have a working network. That’s all there is to it.
If you don’t want to mess with cables, you can create a wireless network instead. In a wireless network, each computer is equipped with a special wire-less network adapter that has little rabbit-ear antennas. Thus, computers can communicate with each other without the need for cables.
Figure 1-1 shows a typical network with four computers. You can see that all four computers are connected with a network cable to a central network
device called a hub. You can also see that Ward’s computer has a fancy laser printer attached to it. Because of the network, June, Wally, and the Beaver can also use this laser printer. (Also, you can see that the Beaver has stuck yesterday’s bubble gum to the back of his computer. Although not recommended, theble gum shouldn’t adversely affect the network.)
Computer networking has its own strange vocabulary. Fortunately, you don’t have to know every esoteric networking term. Here are a few basic buzzwords to get you by:
v Networks are often
called LANs. LAN is an acronym that
stands for local- area network. It’s
the first TLA, or three-letter acronym, that you see in this book. You don’t really need to
remember it, or any of the many TLAs that follow.
In fact, the only three-letter acronym you need to remember is TLA.
v You may guess that a four-letter acronym is called an FLA. Wrong! A four- letter acronym is
called an ETLA, which stands for extended three-letter acronym. (After
all, it just wouldn’t be right if the acronym for four-letter acronym had only three letters.)
v Every computer
connected to the network is said to be on the network.
The technical term (which you can forget) for a computer that’s on the network
is a node.
v When a computer is turned on and can access the network, the computer is said to be online. When a computer can’t access the network, it’s offline. A computer can be offline for several reasons. The computer can be turned off, the user may have disabled the network connection, the computer may be broken, the cable that connects it to the network can be unplugged, or a wad of gum can be jammed into the disk drive.
v When a computer is turned on and working properly,
it’s said to be up. When a computer
is turned off, broken, or being serviced, it’s said to be down. Turning off a computer is sometimes called taking it down. Turn- ing it back on is
sometimes called bringing it up.
v Don’t confuse
local-area networks with the Internet. The Internet is a huge amalgamation of computer networks
strewn about the entire planet. Networking the computers in your
home or office so they can share information with one another and connecting
your computer to the worldwide Internet are two entirely separate things. If
you want to use your local-area network to connect your computers to the
Internet, you can consult Chapter 18 for instructions.
Why Bother?
Frankly, computer networks are a bit of a pain to set up. So why bother? Because the benefits of having a network make the pain of setting one up bear- able. You don’t have to be a PhD to understand the benefits of networking. In fact, you learned everything you need to know in kindergarten: Networks are all about sharing. Specifically, networks are about sharing three things: files, resources, and programs.
v Sharing files: Networks enable you to share information with other com- puters on the
network. Depending on how you set up your network, you can share files with
your network friends in several different ways. You can send a file from your
computer directly to a friend’s computer by attaching the file to an e-mail message and then mailing it. Or, you can let your friend access your computer
over the network so that your friend
can retrieve the file directly from your hard drive. Yet another method is to
copy the file to a disk on another computer, and then tell your friend where
you put the file so that he or she can retrieve it later. One way or the other, the data travels
to your friend’s computer over the network cable, and not on a
floppy disk as it would in a sneakernet.
v Sharing resources: You can set up certain computer resources — such as a hard drive or a printer — so all the computers on the network can access them. For example, the laser printer attached to Ward’s computer in Figure 1-1 is a shared resource, which means that anyone on the net- work can use it. Without the network, June, Wally, and the Beaver would have to buy their own laser printers.
Hard drives can be shared resources, too. In fact,
you must set up a hard drive as a shared resource in order to share files with other users.
Suppose Wally wants to share a file with the Beaver, and a shared hard drive
has been set up on June’s computer. All Wally has to do is copy his
file to the shared hard drive in June’s computer
and tell the Beaver
where he put it. Then, when the Beaver gets around to it, he can copy the
file from June’s
computer to his own. (Unless,
of course, Eddie Haskell deletes the file first.)
You can share other resources, too, such as an Internet connection. In fact, sharing an Internet connection is one of the main reasons many net- works are set up.
v Sharing programs: Rather than keeping separate copies of programs on
each person’s computer, sometimes putting programs on a drive that everyone
shares is best. For example, if you have ten computer users who all use a particular program, you can purchase and install ten copies
of the program — one for each computer. Or you can purchase a ten- user license for the program and then
install just one copy of the pro- gram on a shared drive. Each of the ten users
can then access the program from the shared hard drive.
In most cases, however, running a shared copy of a program over the network is unacceptably slow. A more common way of using a network to share programs is to copy the program’s installation disks or CDs to a shared network drive. Then you can use that copy to install a separate copy of the program onto each user’s local hard drive. For example, Microsoft Office enables you to do this, if you purchase a license from Microsoft for each computer on which you install Office.
The advantage of installing Office from a shared network drive is that you don’t have to lug around the installation disks or CDs to each user’s computer. And the system administrator can customize the network installation so that the software is installed the same way on each user’s computer. (However, these benefits are significant only for larger net- works. If your network has fewer than about ten computers, you’re prob- ably better off installing the program separately on each computer directly from the installation disks or CDs.)
Remember that purchasing a single-user copy of a
program and then putting it on a shared network drive — so that everyone on the
network can access it — is illegal. If you have five people who use the
program, you need to either purchase five copies of the program or purchase a network license that specifically allows
five or more users.
Another benefit of networking is that networks enable computer users to com- municate with one another over the network. The most obvious way networks allow computer users to communicate is by passing messages back and forth, using e-mail or instant-messaging programs. But networks also offer other ways to communicate: For example, you can hold online meetings over the network. Network users who have inexpensive video cameras (webcams) attached to their computers can have video conferences. You can even play a friendly game of Hearts over a network — during your lunch break, of course.
Servers and Clients
The network computer that contains the hard drives, printers, and other resources that are shared with other network computers is called a server. This term comes up repeatedly, so you have to remember it. Write it on the back of your left hand.
Any computer that’s not a server is called a client. You have to remember this term, too. Write it on the back of your right hand.
Only two kinds of computers are on a network: servers and clients. Look at your left hand and then look at your right hand. Don’t wash your hands until you have these terms memorized.
The distinction between servers and clients in a network has parallels in sociology — in effect, a sort of class distinction between the “haves” and “have-nots” of computer resources:
v Usually, the most powerful
and expensive computers
in a network are the servers.
There’s a good technical reason: Every user on the network
shares the server’s resources.
v The cheaper and less powerful computers in a network are the clients. Clients are the computers used by individual users for everyday work. Because clients’ resources don’t have to be shared, they don’t have to be as fancy.
v Most networks have more clients than servers. For example, a network with ten clients can probably get by with one server.
v In many networks, a clean line of demarcation exists between servers and clients. In other words, a computer functions as either a server or a client, and not both. For the sake of an efficient network, a server can’t become a client, nor can a client become a server.
v Other (usually smaller) networks can be more even-handed, allowing any computer in the network to be a server and allowing any computer to be both server and client at the same time.
Dedicated Servers and Peers
In some networks, a server computer is a server computer and nothing else. It’s dedicated to the sole task of providing shared resources, such as hard drives and printers, to be accessed by the network client computers. Such a server is referred to as a dedicated server because it can perform no other task besides network services.
Other networks take an alternative approach, enabling any computer on the network to function as both a client and a server. Thus, any computer can share its printers and hard drives with other computers on the network. And while a computer is working as a server, you can still use that same computer for other functions such as word processing. This type of network is called
a peer-to-peer network, because
all the computers are thought of as peers,
or equals.
v Peer-to-peer
networking features are built into Windows. Thus, if your computer runs
Windows, you don’t have to buy any additional software to turn your computer
into a server. All you have to do is enable the Windows server features.
v The network server features that are built into desktop versions of Windows (such as Windows XP) aren’t very efficient because these ver- sions of Windows were not designed primarily to be network servers. If you’re going to dedicate a computer to the task of being a full-time server, you should use a special network operating system instead of the stan- dard Windows operating system. A network operating system, also known as a NOS, is specially designed to handle networking functions efficiently. The two most commonly used network operating systems are the server version of Windows — which, depending on the version you use, is known as Windows Server 2003, Windows 2000 Server, or Windows NT Server — and Novell NetWare. I describe these alternatives briefly in the next sec- tion, “The NOS Choice.”
v Many networks are both
peer-to-peer and dedicated-server
networks at the same time. These networks have one or more server computers
that run a NOS such as Windows Server 2003, as well as client computers that use the server features of Windows to
share their resources with the
network.
v Besides being dedicated, it’s helpful if your servers are also sincere.
The NOS Choice
Most dedicated network servers do not run a desktop version of Windows (such as Windows XP, ME, or 98). Instead, they usually run a network operat- ing system (NOS) designed to efficiently carry out the tasks that coordinate access to shared network resources among the network client computers.
Although you have several network operating systems to choose from, the two most popular are NetWare and Windows 2000 Server. Here’s a bird’s-eye view of what’s out there:
v One
of the most popular network operating systems is NetWare, from a company called
Novell. NetWare is very advanced but also very compli- cated. So complicated,
in fact, that it has an intensive certification pro- gram that rivals the bar
exam. The lucky ones that pass the test are awarded the coveted title Certified Novell Engineer, or CNE, and a lifetime supply of pocket protectors. Fortunately, a CNE is really
required only for large
networks to which dozens (even hundreds) of computers are attached. Building a NetWare network with just a
few computers isn’t too difficult.
v Microsoft makes a special server version of its popular Windows operat- ing system. The latest and greatest version
is called Windows
Server 2003. Its predecessor,
Windows 2000 Server, is still widely used. In addi- tion, many networks
still use an even older
version called Windows
NT Server. (Throughout this book, I’ll use the term Windows Server
to refer to the various
server versions of Windows.)
Not wanting to be left out, Microsoft
has its own certification program for Windows server specialists. If you pass
the full battery of certifica- tion tests, you get to wear an MCSE badge, which
lets the whole world know that you are a Microsoft
Certified Systems Engineer.
v Other network-operating-system choices include Unix and Linux. Apple also makes its own network server operating system called Mac OS X Server, designed specially for Macintosh computers.
You get a closer look at these NOS options in Chapter 8.
Makes a Network Tick?
To use a network, you don’t really have to know much about how it works. Still, you may feel a little bit better about using the network if you realize that it doesn’t work by voodoo. A network may seem like magic, but it isn’t. The following is a list of the inner workings of a typical network:
v Network interface
cards: Inside any computer attached to a network
is a special electronic circuit card called a network interface card. The TLA for network interface card is NIC.
Using your network late into the evening is not the same as watching NIC at night. If the network is set up to use that time to update software and back up data, the NIC has to be robust enough to handle all-day-all- night use.
Although it’s also possible to use an external network interface that con- nects to the computer via the computer’s USB port, most networked com- puters use a built-in network interface card.
v Network cable: The network cable is what physically connects the com- puters together. It plugs into the network interface card at the back of your computer.
The most common type of network cable looks something like telephone cable. However, appearances can be deceiving. Most phone systems are wired using a lower grade of cable that won’t work for networks. For a computer network, each pair of wires in the cable must be twisted in a certain way. That’s why this type of cable is called a twisted-pair cable. (Standard phone cable doesn’t do the twist.)
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