All About Cables & Hubs

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 cables 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.

10BaseT Cabling

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 cable cannot 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.

Common Problems & Solutions
Here are some ways to avoid the most common cabling pitfalls that network installers face.

Avoid Interference
Network cabling can be run under floors, around office dividers, or over dropped ceilings. When planning your wiring layout, try to keep cables away from power outlets, florescent lighting fixtures, uninterruptable power supplies, and other sources of strong electromagnetic interference. Coiling up cables can also cause interference.
Thin Coax Cabling
When using thin coax cabling, you must always use a T-connector at each PC and termination at both ends of the network, even if you’re only connecting a couple of computers together.
10BaseT Cabling
When using 10BaseT cabling, you must use a hub–even if you’re only networking 2 PCs together. Many first time networkers forego a hub and simply plug a 10BaseT cable between two PCs’ network cards. Such an installation is guaranteed to either (1) not work, or (2) be unreliable.