Network Cables

Network cable is the medium to connect one or more devices over a network. Network cables comes in a few type of forms. Below are the most popular network cables today:

1) Coaxial Cable

It an electrical cable with an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield.

Coaxial cable is used as a transmission line for radio frequency signals, in applications such as connecting radio transmitters and receivers with their antennas, computer network (Internet) connections, and distributing cable television signals.

In the networking environment, they were once popular when connecting in a Token Ring network topology which has already obsolete.

2) Twisted Pair Cable

This is a type of wiring in which two conductors (the forward and return conductors of a single circuit) are twisted together for the purposes of canceling out electromagnetic interference (EMI) from external sources; for instance, electromagnetic radiation from unshielded twisted pair (UTP) cables, and crosstalk between neighboring pairs.

Twisted Pair has 2 different model which is UTP (Unshielded Twisted Pair) and STP (Shielded Twisted Pair). The difference between these two is that STP comes with a metal shield inside the wire jacket to prevent electromagnetic interference.

Twisted Pair also has two types of setting which is Straight Cable and Cross Cable. Straight cable normally being used to connect between pc-switch-pc topology. Meanwhile the Cross Cable is used only in direct connection between pc-pc. Although they are using the same cable, but their wiring codes are a bit difference. Below is an example of the cabling inside a normal Straight Cable and also Cross Cable:

Straight Cable

Cross Cable

The twisted pair comes with different type of categories. Below is the table showing each cable category’s specification:

Category Maximum data rate Usual application
CAT 1 (de facto name, never a standard) Up to 1 Mbps (1 MHz) analog voice (POTS)
Basic Rate Interface in ISDN
Doorbell wiring
CAT 2 (de facto name, never a standard) 4 Mbps Mainly used in the IBM cabling system for Token Ring networks
CAT 3 16 Mbps Voice (analog most popular implementation)
10BASE-T Ethernet.
CAT 4 20 Mbps Used in 16 Mbps Token Ring.
Otherwise not used much.

Was only a standard briefly and never widely installed.

CAT 5 100 MHz 100 Mbps TPDDI
155 Mbps ATM.
No longer supported; replaced by 5E.
10/100BASE-T
4/16MBps Token Ring
Analog Voice
CAT 5E 100 MHz 100 Mbps TPDDI
155 Mbps ATM
Gigabit Ethernet.
Offers better near-end crosstalk than CAT 5
CAT 6 Up to 250 MHz Minimum cabling for data centers in TIA-942.
Quickly replacing category 5e.
CAT 6E Up to 500 MHz
(field-tested to 500 MHz)
Support for 10 Gigabit Ethernet (10GBASE-T.) May be either shielded (STP, ScTP, S/FTP) or unshielded (UTP). This standard published in Feb. 2008.
Minimum for Data Centers in ISO data center standard.
CAT 7
(ISO Class F)
600 MHz
1.2 GHz in pairs with Siemon connector
Full-motion video
Teleradiology
Government and manufacturing environments
Fully Shielded (S/FTP) system using non-RJ45 connectors but backwards compatible with hybrid cords.
Until February 2008, the only standard (published in 2002) to support 10GBASE-T for a full 100m.

Among all these categories, CAT5E is currently the widely used among normal networking interface and topology. But soon after, CAT6E usage is rapidly increasing as there has been more hardware that goes Gigabit-enabled. But in the data center environment, most of the network connection among their switches and routers are using Fiber Optic cables.

3) Fiber Optic Cable

An optical fiber cable is a cable containing one or more optical fibers. The optical fiber elements are typically individually coated with plastic layers and contained in a protective tube suitable for the environment where the cable will be deployed.

In practical fibers, the cladding is usually coated with a tough resin buffer layer, which may be further surrounded by a jacket layer, usually plastic. These layers add strength to the fiber but do not contribute to its optical wave guide properties. Rigid fiber assemblies sometimes put light-absorbing (“dark”) glass between the fibers, to prevent light that leaks out of one fiber from entering another. This reduces cross-talk between the fibers, or reduces flare in fiber bundle imaging applications.

As been mentioned earlier, the fiber optics cable are getting popular in the data center usage. Some are quite critical to serve as the network backbone of the data center’s communication to the Internet Service Providers. Fiber Optics are way faster than a normal twister pair cables. It transmit packet much faster and travel even further before the need to use Repeaters. Most importantly, it doesn’t being affected by electromagnetic interference and very hard to tap.

Currently most underwater cables are using fiber optics.

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