Ethernet Cables Explained
Tags: beginners, networking, tutorial
Published: 2019-11-21 18:02:05

Ethernet cables are used within networking to connect computers to devices or other computers. Ethernet cables can be found plugged into routers, or into a client computer to supply network and internet access. They have a small plastic connector clip on each end called an RJ45. The RJ in RJ45 stands for Registered Jack and the 45 refers to the interface standard. Inside an ethernet cable are various copper wires that are used to transmit data and information between the two devices by using analog/digital signals. These cables are used to connect multiple devices and creating or connecting devices to both Local Area Networks (LAN) and Wide Area Networks (WAN). These devices can include but are not limited to, computers, routers, switches, computers, printers, and basically any device that can be network connected. 

## Categories

There are many different types of ethernet cables that all come with their own pros and cons. One of the main differences in the category of the cable. The categories of cables are number 1 through to 8 and vary in terms of speeds, ideal distance, and bandwidth. The higher the numbered category the fast speed and frequency of the cable. The speed is measured in megabits per second (Mbps) and determines the speed of data transfer, the bandwidth or frequency is measured in megahertz (MHz) and determines how much data can be sent simultaneously. However, just because the speed and bandwidth of CAT 8 cable are better than Cat 5 it doesn't necessarily mean it is the right cable to use. This is due to the maximum and recommended length for each category, each category has a recommended length or distance to run the cable. This means when deciding which category of cable to use, you need to consider what speed, bandwidth, and the length you reckon to pick the best cable for that situation.

## Straight Through vs Cross over?

Depending on what components are being connected together using an ethernet cable will determine if the cable has to be straight-through or crossover. There are two groups of devices when deciding between straight-through and crossover cable. Data Communication Equipment (DCE) refers to devices used to establish, maintain and terminate communications across a network such as routers, modems, switches, etc. Data Terminal Equipment (DTE) are devices that act as the source or destination of communications for a network, such as your personal computer, printer, etc. A straight-through cable is used when connecting devices that differ, such as connecting DCE to DTE or vice versa. A crossover cable is used when connecting devices that are the same, such as connecting DCE to DCE or DTE to DTE. Crossover cables are also referred to as patch cables. 

Inside ethernet cables, there are small wires that are held together within the plastic cover. Depending on how these cables are connected the RJ45 determines if the cable is a straight-through or a cross over cables, all the wires are identical within both cables but the way in which they are ordered is different. 

## Shielded vs Unshielded

The shielding of the ethernet cable also creates another difference to be considered. Shielded Twisted Pair (STP) has an outer shield around the wires made from a conductive material. It is called 'twisted pair' as the wires inside an ethernet cable are twisted around each other in pairs, meaning every pair of wires are twisted around each other. The conductive material that surrounds each pair of twisted wires needs to be grounded and can cancel the effect of Electromagnetic Interference (EMI) which reduces the amount of cross talk and interference in the communication. The other shielding type is Unshielded Twisted Pair (UTP) which has no shielding and therefore an increased risk of cross-talk and higher interference. It is important to note that the grounding of STP most be done properly otherwise the performance can actually be worse than that of UTP.

## Solid vs Stranded

Stranded cables are more flexible and are what most people use day to day. This are the cables you will use inside a home or office as they are a lot more flexible than Solid cables. Solid cables are used when the cable does not need to be flexible, such as long horizontal paths, as they have better corrosion protection and outdoor protection. The difference between these cables is the thickness and amount of copper wires inside. Each ethernet cable has 8 pairs of wires inside, each covered in a particular plastic coloured coating. A solid cable will use one cooper wire per wire where a standard cable uses multiple thinner copper wires per coloured wire. Stranded may give you added flexibility but they're also more susceptible to signal interruption and interference. This is why solid cables are generally used for long distances and stranded cables are used for short distances, e.g. from a router/switch to a computer.

## Cable Colouring

The last difference between ethernet cables is more obviously, the colour of the outer coating. You can get ethernet cabling in various different colours, such as; red, green, white, etc. These are generally used within businesses and networks to differentiate different subnetworks or different devices. For example, you could use red cables for one network, or only use green cables when connecting to printers. This can make the maintenance of the network easier. Most people are unaware of any formal standard for the colours and their usage but the Telecommunications Industry Association (TIA) has actually created a standard for when to use which colour. The TIA standard is not mandatory, as the ethernet cables inside are exactly the same and only difference in appearance and not function.

## Fiber

Inside typical ethernet cables, there are copper wires but you can get fiber cables that contain glass fibers instead. Instead of sending electric signals through copper they send light pulses through the glass fibers. This can result in faster speeds and less signal interruption. The reason fiber cables are not used everywhere is due to cost, they are a lot more expensive than the copper counterpart, and a lot of the copper cables are already laid and setup. Generally, copper cables are used in large areas, such as continental, and fiber is used for shorter distances such as running into your home. 

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