What is Ethernet Cable?

What is Ethernet Cable ?

An Ethernet cable is a common type of network cable used with wired networks. Ethernet cables connect devices such as PCs, routers, and switches within a local area network. These physical cables are limited by length and durability. If a network cable is too long or of poor quality, it won't carry a good network signal. These limits are one reason there are different types of Ethernet cables that are optimized to perform certain tasks in specific situations.All Ethernet cables serve the same essential purpose: Connecting devices to networks, like the internet. The problem is, they're not all the same. Ethernet designations, like many things in modern networking standards, can be challenging to interpret and understand. 

What does 'Cat' mean?

When shopping for cables, you may notice they're nearly always classified as "Cat-5","Cat6e," or something similar. "Cat"simply stands for "Category." The number that follows indicates the specification version supported by the cable.

A general rule of thumb is that higher numbers represent faster speeds and higher frequencies, measured in megahertz (MHz). As is the case with most technologies, newer cables typically support higher bandwidths, and therefore increased download speeds and faster connections.

Keep in mind that longer Ethernet cables have slower transmission speeds. Cables bought for personal use rarely exceed 100 meters anyway and are unlikely to experience bottlenecked speeds.

Below, you can see the capabilities of each cable type.

Category	Shielding	Max Transmission Speed (at 100 meters)	Max Bandwidth
Cat 3	Unshielded	10 Mbps	16 MHz
Cat 5	Unshielded	10/100 Mbps	100 MHz
Cat 5e	Unshielded	1,000 Mbps / 1 Gbps	100 MHz
Cat 6	Shielded or Unshielded	1,000 Mbps / 1 Gbps	250 MHz
Cat 6a	Shielded	10,000 Mbps / 10 Gbps	500 MHz
Cat 7	Shielded	10,000 Mbps / 10 Gbps	600 MHz
Cat 7a	Shielded	10,000 Mbps/10 Gbps	1,000Mhz

Cat 3 and Cat 5

Both Cat 3 and Cat 5 Ethernet cables are, at this point, obsolete. You’ll still find Cat 5 cables in use, but you should avoid them altogether. They’re slow and discontinued.

Cat 5e

The “e” in Cat 5e stands for “enhanced.” There are no physical differences between Cat 5 and Cat 5e cables. However, manufacturers build Cat 5e cables under more stringent testing standards to eliminate unwanted signal transfers between communication channels (crosstalk). Cat 5e is currently the most commonly used cable, mainly due to its low production cost and support for speeds faster than Cat 5 cables.

Cat 6

Cat 6 cables support higher bandwidths than Cat 5 and Cat 5e cables. They’re more tightly wound too and often outfitted with foil or braided shielding. This shielding protects the twisted pairs of wires inside the Ethernet cable, which helps prevent crosstalk and noise interference. Cat 6 cables technically support speeds up to 10 Gbps, but only do so for up to 55 meters. That speed comes with a price, however, as Cat 6 cables are more expensive than Cat 5 and Cat 5e variants.

Cat 6a

The “a” in Cat 6a stands for “augmented.” Cables based on this standard are a step up from Cat 6 versions by supporting twice the maximum bandwidth. They’re also capable of maintaining higher transmission speeds over longer cable lengths. Cat 6a cables are always shielded, and their sheathing — which is thick enough to completely eliminate crosstalk  — makes for a much denser, less flexible cable than Cat 6.

Cat 7

Cat 7 cables support higher bandwidths and significantly faster transmission speeds than Cat 6 cables by utilizing the newest widely available Ethernet technology. They’re proportionally more expensive than other Ethernet cables, though their performance translates to a premium price tag. Cat 7 cables reach up to 100 Gbps at a range of 15 meters, making them an excellent choice for connecting modems or routers directly to your devices. Cat 7 cables are always shielded and use a modified GigaGate45 connector, which is backward compatible with regular Ethernet ports.

Cat 8

Cat 8 is an emerging technology; thus you won’t find related products saturating the market just yet. This standard promises a maximum frequency of 2,000MHz and speeds of up to 40Gbps at 30 meters (~100 feet). That high frequency requires shielding, meaning you’ll never find unshielded Cat 8 cables. Even more, Cat 8 supports two connectors. Thus it only allows for three connected cables with a combined length of 30 meters. Older specifications, like Cat 6a, enable four connectors for a total of five cables with a combined length of 100 meters. Cat 8’s distance limitation ensures the 40Gbps speeds and related power requirements. Cat 8 cables are expensive, however, costing $16 for a three-foot cord, for example.

Ethernet glossary

The differences between the various types of Ethernet cables are rather simple, but some of the terminology can be confusing. To help out, we put together a quick rundown on what the different terms mean, and what you should expect when buying cables with those designations.

Cat: Short for “category.”

TP (Twisted Pairs): Refers to how the wires inside twist together. Twisted Pairs are an industry standard, and are only inferior to fiber-optic cabling in terms of maximum length and speed drop-off.

UTP (Unshielded Twisted Pairs): These cables won’t have foil or braided shielding. That means they’re more flexible and cheaper to produce, but you’ll sacrifice signal quality and increase vulnerability for crosstalk.

STP or SSTP (Shielded Twisted Pairs): Braided shielding protects these cables. They’re usually made of copper or another conductive polymer. Shielding reduces noise and improves connection quality.

FTP or SFTP (Foiled Twisted Pairs): Foil shielding protects these cables. This helps reduce noise and improves connection quality.

Physical Differences

So how does a physical cable eliminate interference and allow for faster speeds? It does it through wire twisting and isolation. Cable twisting was invented by Alexander Graham Bell in 1881 for use on telephone wires that were run along side power lines. He discovered that by twisting the cable every 3-4 utility poles, it reduced the interference and increased the range. Twisted pair became the basis for all Ethernet cables to eliminate interference between internal wires (XT), and external wires (AXT).

There are two main physical differences between Cat-5 and Cat-6 cables, the number of twists per cm in the wire, and sheath thickness.

Cable twisting length is not standardized, but typically there are 1.5-2 twists per cm in Cat-5(e) and 2+ twists per cm in Cat-6. Within a single cable, each colored pair will also have different twist lengths based on prime numbers so that no two twists ever align. The amount of twists per pair is usually unique for each cable manufacturer. As you can see in the above picture, no two pairs have the same amount of twists per inch.

Many Cat-6 cables also include a nylon spline which helps eliminate crosstalk. Although the spline is not required in Cat-5 cable, some manufactures include it anyway. In Cat-6 cable, the spline is not required either as long as the cable tests according to the standard. In the picture above, the Cat-5e cable is the only one with a spline.

While the nylon spline helps reduce crosstalk in the wire, the thicker sheath protects against Near End Crosstalk (NEXT) and Alien Crosstalk (AXT) which both occur more often as the frequency (Mhz) increases. In this picture the Cat-5e cable has the thinnest sheath, but it also was the only one with the nylon spline.

Shielded (STP) vs. Unshielded (UTP)

Because all Ethernet cables are twisted, manufactures use shielding to further protect the cable from interference. Unshielded twisted pair can easily be used for cables between your computer and the wall, but you will want to use shielded cable for areas with high interference and running cables outdoors or inside walls.

There are different ways to shield an Ethernet cable, but typically it involves putting a shield around each pair of wire in the cable. This protects the pairs from crosstalk internally. Manufactures can further protect cables from alien crosstalk but screening UTP or STP cables. Technically the picture above shows a Screened STP cable (S/STP).

Solid vs. Stranded

Solid and stranded Ethernet cables refer to the actual copper conductor in the pairs. Solid cable uses a single piece of copper for the electrical conductor while stranded uses a series of copper cables twisted together. There are many different applications for each type of conductor, but there are two main applications for each type you should know about.

Stranded cable is more flexible and should be used at your desk or anywhere you may be moving the cable around often.

Solid cable is not as flexible but it is also more durable which makes it ideal for permanent installations as well as outdoor and in walls.

Justin Garrison December 13, 2016

Source：https://www.howtogeek.com/70494/what-kind-of-ethernet-cat-5e6a-cable-should-i-use/