The two most popular types of network cabling are twisted-pair (also known as 10BaseT) and thin coax (also known as 10Base2). 10BaseT cabling looks like ordinary telephone wire, except that it has 8 wires inside instead of 4. Thin coax looks like the copper coaxial cabling that's often used to connect a VCR to a TV set.

When 10BaseT cabling is used, a strand of cabling is inserted between each computer and a hub. If you have 5 computers, you'll need 5 cables. Each cablecannot exceed 325 feet in length. Because the cables from all of the PCs converge at a common point, a 10BaseT network forms a star configuration, or geometric design, when viewed from above. In the figure below, three computers are connected together with 10BaseT cabling and a hub.

A 10BaseT hub is basically a box with a row of 10BaseT jacks. Most hubs have 5, 8, 12, or 16 jacks, but some may have more. Most hubs also have an uplink port, which is a special 10BaseT or thin coax port that allows the hub to be connected to either (1) other hubs, or (2) a thin coax backbone (see below for information on backbones). By uplinking multiple hubs together, you can add additional computers to your network whenever you need to.

10BaseT cabling is available in different grades or categories. Some grades, or "cats", are required for Fast Ethernet networks, while others are perfectly acceptable for standard 10Mbps networks--and less expensive, too. About 85% of the networks in the U.S. use standard unshielded twisted-pair (UTP) Category 5 10BaseT cabling because it offers a performance advantage over lower grades. If you are using a 10Mbps network, category 3 is fine. If you plan on building a Fast Ethernet network at some time in the future, it's best to install Category 5 cabling.

	 		
			10BaseT 
			Category     What It's Used For
			-------------------------------------------------------
 			5	     Fast Ethernet (and everything below)
			4	     Networks other than Ethernet
			3	     10Mbps 10BaseT 
			2	     Alarms, telephone voice lines
			1	     Unknown (not rated for anything specific)
			

If possible, decide whether you'll be using standard Ethernet or Fast Ethernet technology before you begin building your network. If you're not sure which technology you'll eventually use, choose to install Category 5 cabling. Remember, Fast Ethernet network adapters and hubs are not directly compatible with each other. It is possible to have both 10Mbps and 100Mbps segments on the same network, provided you have a switching hub between them that allows them to communicate.

The geometric design that is formed when thin coax cabling is used is called a linear or backbone configuration. The reason for this is that thin coax is always arranged in a straight line of PCs, hubs, or other devices. Thin coax networks always require termination, which is the act of "plugging up" both ends of the network. Instead of inserting an incoming thin coax cable directly into a PC, a T-connector is inserted instead, splitting the network adapter's input port into two separate ports. One port receives an incoming network cable; the other receives an outgoing network cable. If the PC is at the end of the network chain, a terminator plug is inserted into the empty hole of the T-connector.

Thin coax is only used with 10Mbps Ethernet networks. Fast Ethernet networks, which are 10 times faster than standard Ethernet, use category 5 10BaseT cabling.

The figure below shows three PCs connected together in a backbone configuration. Note that the backbone has termination at both ends, and each "T" connector plugs directly into a PC, where it allows for an incoming and outgoing connection. The maximum length for any thin coax segment is 607 feet.

Finally, thin coax backbones and 10BaseT cabling & hubs can be connected together to allow for a wide variety of expansion options. In the more complex example below, a thin coax backbone connects two 10BaseT hubs together, along with a computer in-between. Each hub, in turn, branches off to still more computers with 10BaseT cabling. Note that the ends of the thin coax backbone are properly terminated.

There are two things to consider when deciding on the type of cable to use for your network.

1. How many PCs do you want to link together?
2. How long (in feet) is your network going to be?

The answers to these two questions will determine the cabling that's best for you, and whether or not you'll need a hub.

Use thin coax cabling if you...
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