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What Is Ethernet?

Today some 80% of all LANs use Ethernet.  That's because it is inexpensive, (mostly) easy to set up and run, and because it will allow you to run Internet Protocol over your LAN.  This makes it a natural for hooking up computers to the Internet. 

Ethernet is a "protocol," that is, an agreed upon way of doing things.  Ethernet protocol is a way to transmit data over short distances (of about a soccer field in length).  Ethernet is not a specific physical device.  Rather, it is a technique that can use many different kinds of cables, with electricity or light used to carry data.  Ethernet also allows other data transmission protocols to be used within it, for example TCP/IP (the protocol that runs the Internet), Novell or NetBUI.  So you will have many choices about how to physically set up an Ethernet, and what kind of networking software to use with it.

Newbie note: What is a Local Area Network (LAN)?  In ancient days, when people wanted to move information from one computer to another, they had to physically pick up carry objects such as punched cards, punched tapes, magnetic tape, etc. from one computer to another.  Nowadays you are more likely to use floppy disks, CD-ROMs, Jazz or Zip disks.  But using them is a hassle and slow.  If you hook up computers with a cable, however, they can share a hard disk and move information at high speeds -- much higher than you get with a phone modem to the Internet.  Because of this convenience, most businesses, even many small businesses, put their computers on a LAN.

How to Set Up an Ethernet LAN

Types of Ethernet Cabling

To set up a LAN, you need some sort of cable to connect your computers.  There are several ways to cable Ethernets.  The oldest technique is Thick Coaxial cable.  Forget it, almost no one uses it any more.  The next technique invented, Thin Ethernet (also called Thin Net) is still in wide use.  It has its own IEEE standards (10BASE-5 and 10BASE-2), adopted in 1984.  Thin Ethernet uses coaxial cables to string together computers like beads on a chain.  To work properly, each end of this connector must be terminated with a little metal device.  You don't need a hub for Thin Ethernet, all you need is network cards, cable, connectors and terminators.  If you connect only two computers, you don't even need terminators.

This technique is only good for small networks.  Also, if anything breaks a Thin Ethernet cable, the entire LAN shuts down.  Still, it remains popular with small businesses because it's the easiest way to build a LAN.

However, if you want the experience of running an Ethernet in your home that is more like many of the ones you will encounter in large businesses or Universities, you'll want to use 10BASE-T Ethernet (ten megabits/sec speed), or even 10BASET (100 megabit/sec).  It's easy to install and run. It requires, however, that you buy an Ethernet hub, making it somewhat more expensive than Thin Net.

The basic way 10BASE-T works is that you run a UTP cable (looks like an oversized version of the line to your home phone) from each computer to the hub, which manages traffic on your LAN.  In 1990, this technology was accepted as IEEE standard 802.3i/10BASE-T.

Then there are fiber optics cables for Ethernet. If you are reading this, you are probably enough of a beginner that you aren't ready to learn how to install fiber in your home.

Switched Ethernet, Full-Duplex, Fast, Gigabit, and Layer 3 Ethernet are other advanced ways to network.  They also have the drawback that they are expensive and difficult to implement on a home network.  This Guide will only cover Ethernet technologies that are easy to do at home: Thin Net and 10BASE-T.  Even so, what you learn here are techniques widely used in businesses and schools.  Get good at running a Thin Net or 10BASE-T network at home, and you will be prepared to run networks at most businesses and schools.

Types of Ethernet Devices

Just as there are many ways to cable an Ethernet, there are many different devices that make a computer able to communicate via Ethernet.  Some computers, for example those built by Sun, Silicon Graphics, and Apple's iMacs, have Ethernet built into them.  All you have to do is hook a cable to one of these, set up your network information using tools provided by the operating system of your computer, and your LAN is running.

However, if you are like most computer enthusiasts, you own at least one PC -- a personal computer based on an Intel 386, 486 or Pentium central processing unit (CPU).  This Guide covers how to network using Windows, which runs on PCs, which usually do not have have built-in Ethernet interfaces.  So if you plan to network two or more PCs, you get to learn how to install Ethernet network interface cards (NICs).  You poor thing.

Oops, sorry to frighten you.  Actually, installing a NIC can often be easy.  If it turns out it isn't easy, at least it will be a character-building experience.  So let's get on with building character!