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Part I
Getting Your House In Order

Hour
1  “The Telephone Analogy”: Becoming Familiar with Basic Networking Concepts
2  “You Can’t Have Too Much Documentation, Money, or Love!”

Hour 1
The Telephone Analogy: Becoming Familiar with Basic Networking Concepts

Trying to understand the pieces and parts that make up a computer network can be pretty daunting, even to folks who are fairly computer literate in other areas. If you’re already familiar with network terms and concepts, you can skip this hour and move on to bigger and better things; if you’re not, here’s a good way to get comfortable with the basics of network technology.

Getting a handle on something foreign to you by using terms and concepts you already know is a good way to learn it faster. Learning the lingo helps a lot, but even getting good at the jargon does you no good if you don’t have something familiar with which to compare the new terms.

The following term comparisons are analogies. They are not identical; be careful not to assume they are.

Therefore, it might help you to consider that computer networks are very much like the public telephone network. Although many differences exist under the hood, there are enough similarities on the surface to allow you to start to get a good concept of how a network really works. In theory, network calls act very much like telephone calls. See Figure 1.1 for a rough comparison of a data network to the telephone system. Also, here’s a quick reference list:

Network Buzzword Telephone Equivalent
NIC (network interface card) The telephone in your house.
Network media (cabling) The phone wire.
Address The telephone number (167.195.162.5 is no more intimidating than 1-212-888-5555).
Router or gateway The telephone company’s central office equipment that connects different “area codes.”
Switch or bridge The local phone box that connects private lines and “party lines” (hubs).
Hub or concentrator The party line shared by folks in a common area.
Protocol The language. You can communicate with someone only if you both understand the language being used. Any language can be used for any kind of conversation, but some languages are more suited to certain situations (Italian is best for opera, French for love poems, and so on).
Packet or frame A sentence of a conversation (not the entire conversation, but one idea from it).
Socket The extension. Suppose you want to speak to Ms. Jones, who works at Company XYZ. Typically, you’ll call Company XYZ’s main phone number and ask for Ms. Jones’s extension.
Program or service The entity on the other end of the line that can provide information, or a service that you get during a conversation. Once you get Ms. Jones on the line by asking for her extension, you can then ask her how much a particular gadget costs, or you can ask her to send a technician out to install your gadget. Not all services can handle more than one protocol—just as not all people speak more than one language.
Directory services (WINS, DNS) The “electronic” phone book. Instead of having to remember that Ms. Jones’s number is 1-212-888-5555, you can simply perform an automatic lookup-and-dial on “Ms. Jones.”


Figure 1.1  A rough comparison of a data network versus the telephone system.

Network Interface Cards

As mentioned earlier, your telephone is very much like the network interface card (NIC) in your computer. Both of them help an individual entity (you, in the case of your telephone, and your computer, in the case of the NIC) talk to others. Also, both the telephone and the network card are oblivious to who is being communicated with and what kind of business is being transacted.

Your telephone is a physical piece of hardware that enables you to connect through telephone company equipment to talk to folks next door or halfway around the world. This is also true of your NIC. It can talk to other NICs on the same line as well as NICs on different lines by using switching equipment that’s connected to the line.


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