Networking Cables


From Wikipedia, the free encyclopedia

Networking cables are networking hardware used to connect one network device to other network devices or to connect two or more computers to share printers, scanners etc. Different types of network cables, such as coaxial cable, optical fiber cable, and twisted pair cables, are used depending on the network’s physical layer, topology, and size. The devices can be separated by a few meters (e.g. via Ethernet) or nearly unlimited distances (e.g. via the interconnections of the Internet).

There are several technologies used for network connections. Patch cables are used for short distances in offices and wiring closets. Electrical connections using twisted pair or coaxial cable are used within a building. Optical fiber cable is used for long distances or for applications requiring high bandwidth or electrical isolation. Many installations use structured cabling practices to improve reliability and maintainability. In some home and industrial applications power lines are used as network cabling.

Contents
1 Twisted pair
2 Fiber optic
3 Coaxial
4 Patch
5 Power lines

Twisted Pair


Twisted pair cabling is a form of wiring in which pairs of wires (the forward and return conductors of a single circuit) are twisted together for the purposes of canceling out electromagnetic interference (EMI) from other wire pairs and from external sources. This type of cable is used for home and corporate Ethernet networks. Twisted pair cabling is used in short patch cables and in the longer runs in structured cabling.

An Ethernet crossover cable is a type of twisted pair Ethernet cable used to connect computing devices together directly that would normally be connected via a network switch, Ethernet hub or router, such as directly connecting two personal computers via their network adapters. Most current Ethernet devices support Auto MDI-X, so it doesn’t matter whether you use crossover or straight cables.

Fiber Optic


An optical fiber cable consists of a center glass core surrounded by several layers of protective material. The outer insulating jacket is made of Teflon or PVC to prevent interference. Optical fiber deployment is more expensive than copper but offers higher bandwidth and can cover longer distances.

There are two major types of optical fiber cables: short-range multi-mode fiber and long-range single-mode fiber.

Coaxial


Coaxial cables confine the electromagnetic wave inside the cable, between the center conductor and the shield. The transmission of energy in the line occurs totally through the dielectric inside the cable between the conductors. Coaxial lines can therefore be bent and twisted (subject to limits) without negative effects, and they can be strapped to conductive supports without inducing unwanted currents in them.

The most common use for coaxial cables is for television and other signals with a bandwidth of several hundred megahertz to gigahertz. Although in most homes coaxial cables have been installed for transmission of TV signals, new technologies (such as the ITU-T G.hn standard) open the possibility of using home coaxial cable for high-speed home networking applications (Ethernet over coax).

In the 20th century they carried long distance telephone connections.

Patch


A patch cable is an electrical or optical cable used to connect one electronic or optical device to another or to building infrastructure for signal routing. Devices of different types (e.g. a switch connected to a computer, or a switch connected to a router) are connected with patch cords. Patch cords are usually produced in many different colors so as to be easily distinguishable, and most are relatively short, no longer than a few meters. In contrast to on-premises wiring, patch cables are more flexible but may also be less durable.

Power Lines


Although power wires are not designed for networking applications, new technologies like Power line communication allows these wires to also be used to interconnect home computers, peripherals or other networked consumer products. On December 2008, the ITU-T adopted Recommendation G.hn/G.9960 as the first worldwide standard for high-speed powerline communications. G.hn also specifies communications over phonelines and coaxial wiring.

Ethernet Cable Identification and Use


Category 5, Cat. 5e, Cat. 6, Cat. 6a, Cat. 7, and Cat. 7a Cable Comparison

So you’ve got a bundle of ethernet cables and you’re not really sure if you should use them in your network, this short guide should help you identify and correctly use any of the common ethernet cables you are likely to run across.

Identify the Cable

ethernet03

ethernet04

ethernet05

Category 6 Ethernet Cable Category 5 Ethernet Cable Category 5e Ethernet Cable
As you see above almost all ethernet cabling has the category of cabling printed on the side (hover over an image for the caption). The category shows what bandwidth the cable is rated to carry. If you encounter anything other than the categories listed in the table below, you probably should not use them in your network.

Below you can see that the various categories of cable can be relatively reliably identified by the end connector and the diameter of the cable, however, this is not a be all end all. In general a higher category of cable is thicker because it uses thicker wire for better transmission quality. If you are at all unsure, always check the printing on the side of the cable.

ethernet02

From top to bottom: Cat. 6, Cat. 5e, Cat. 5, and a standard telephone cable for comparison.

Common Ethernet Categories, Speed, and Usage

Common Ethernet Categories

Notes:

MbE stands for Megabit Ethernet, 100MbE means that the cable can carry 100 Megabits per second of Ethernet trafic.
GbE stands for Gigabit Ethernet, 10GbE is equivalent to 10000MbE.
* Speeds marked with a star are possible over a short run (less than 10 meters) on that category, however for longer runs up to 100m it is reconmended to use a higher quality cable.

General Tips For Using Ethernet Cables

  • Do run cables over distances up to 100 meters with their rated speed.
  • Do mix different cable types as long as the minimum cable category supports the maximum speed of your network. As noted in the table above, all the cables are backward combatible with prior ethernet standards.
  • Do make your own cable if you need lots of varying lengths. More information can be found here.
  • Do buy cables that have no-catch connectors, as seen in the two left-most images of Cat. 6 cable below (hover over the image for the caption). A no-catch connector won’t snag on carpets, clothing, and other cables when you are installing it. The right-most image indicates a traditional connector.

.ethernet06ethernet07ethernet01

  • Category 6 Ethernet Cable with no-snag connector Category 6 Ethernet Cable with no-snag connector Category 5e cable with traditional snagging connector
  • Don’t order anything less than Cat. 5e cable.
  • Don’t use cable in your network if it is rated less than the maximum speed of the network.
  • In most cases don’t buy cable from retail stores. BestBuy sells 25′ of Cat. 6 cable for $30, you can buy the same from online stores for ~$10 shipped.
  • Don’t buy overpriced “super-high-quality” cable. This $500(!) cable comes to mind. If a cable is rated as Cat. 5e then it will perform at that rating.
  • Don’t crimp or staple cable, this can easily cause breaks in the cable which are sometimes hard to track down.
  • Ethernet cables are not directional in any way, you cannot install one backwards.
  • Lighter colored cables are usually a better choice for two reasons: They are easier to see in the dark, and it’s easier to read the cable catogory stamped on the side.
  • Use a patch cable when connecting a computer to a router or hub, use a cross over cable when connecting two computers directly together. If you are unsure, buy a patch cable, if the cable is not labled as “patch” or “cross over” it is a patch cable.

Kevin Castor July 10th 2008 kcas88@gmail.com
Last Updated May 21st 2011

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