Twisted pair
Twisted pair cabling, which is inexpensive and easy to use, is one of the most popular types of cabling used today. It gets its name from the fact that it contains four pairs of wires twisted around each other inside the cable’s outer jacket. The jacket is the term used for the outer covering of the cabling that is shown in Figure-1 and Figure-2 . In addition, twisted pair cabling comes in two different flavors: —
The two types of twisted pair cabling are fairly similar; the only difference is that STP cabling has an extra layer of insulation. The extra layer helps prevent interference from outside devices or cabling — interference that can distort the data traveling along the cable length.
Unshielded Twisted Pair cabling comes in a number of different flavors, called grades or categories. Figure-3 lists the categories of UTP cabling, as well as their purpose and speed.
Because twisted pair cabling does not have the layers of shielding found in other forms of cabling, the data is pretty much unreadable — or the integrity of the data is questionable — after 100 meters. For this reason, twisted pair cabling has a maximum length of 100 meters.
Twisted pair cabling uses a special type of connector to connect the cable to the system or network devices. This connector is similar to the one used to connect a telephone to a telephone jack. Network devices that use twisted pair cabling use the RJ-45 connector, while telephones use the RJ-11 connector. Figure-4 shows an example of an RJ-45 and RJ-11 connector.
Coaxial
Coaxial (coax) cabling is the type of cable you use for cable television. A copper wire in the center of the cable is responsible for transmitting information. Furthermore, the copper wire is protected by two levels of insulation and an exterior plastic covering, as shown in Figure-5.
Like UTP, coaxial cabling used for networking comes in different flavors ==>>'Two' to be exact. The first type of coax cable, called Thinnet, is only .25 inches thick, while the second type of coax, Thicknet, is .50 inches thick. Figure-6 shows the difference between thinnet and thicknet.
Notice in Figure-6 that the coaxial cable type is specified by what is known as a Radio Grade (RG). There are a number of grade standards for coaxial cable, and each standard has a specific purpose and connector type that will work with that type of cabling. For example, RG-58-grade cabling, also known as thinnet, uses BNC connectors (discussed in more detail in the next section), while an RG-8 grade cable uses an AUI connector.
Television cable uses RG-6 grade cable.
Connecting with thinnet
When using thinnet to connect to a workstation, you need to use a British Naval Connector (BNC), which comes in a few forms. You will most likely encounter the plain old BNC and the BNC-T.
The BNC connector connects thinnet cable to a networking device, such as a network card, using the barrel connector on the back of the network card, as shown in Figure-8.
The BNC-T is shaped like the letter “T” and is used to continue the cable length and “T” off to connect a system to the network, as shown in Figure-9.
Notice in Figure-9 that the BNC-T connects to a “metal barrel” type port on the back of the network card. If you don’t need to continue the cable length, and this is your last workstation, you are required to “terminate” the end with a terminator on the T connector, as shown in Figure-10.
Connecting with thicknet
A system or device connected to a thicknet network uses an Adapter Unit Interface (AUI) port (shown in Figure 11), which connects the system to the thicknet cabling by using a transceiver known as a vampire tap.
The vampire tap gets its name by having small “teeth” that clamp to the cable and cut into the cable’s core, allowing the electrical signal to travel from the system to main network cable and beyond.
Fiber Optic
Fiber optic cabling is one of the fastest types of network media available today. Fiber optic cabling is made up of a glass fiber core (optical fiber) surrounded by a layer of glass cladding insulation that is then covered with an outer covering, also known as a jacket. There are two fiber channels in fiber optic cable one for sending information and the other for receiving information. Figure-12 illustrates a fiber optic cable.
Fiber optic cabling can carry a signal greater distances than twisted pair and coaxial cabling. Fiber optic cabling can reach distances of 2 km or more. Fiber optic cabling can transmit information at speeds of 1 Gigabit per second (Gbps) and above. Because fiber carries data in pulses of light instead of electronic signals, it is impossible for the data to be corrupted by outside electronic interference.
There are two different implementations of fiber optic cabling — Single-Mode Fiber (SMF) and Multimode Fiber (MMF) — as explained in the following list:
✦ Single-mode fiber (SMF): SMF uses only one ray of light, known as a mode, to carry the transmission over great distances.
✦ Multimode fiber (MMF): MMF takes advantage of multiple rays of light, or modes, simultaneously. Each ray of light runs at a different reflection angle and is used to transmit data over short distances.
Fiber optic cabling uses a number of different types of connectors.
✦ Straight Tip (ST): The straight-tip connector is derived from the BNC-style connector but uses a fiber optic cable instead of the copper cabling that was used with BNC. Figure-13 shows an SC and ST connector.
✦ Subscriber Connector (SC): The subscriber connector is rectangular and is somewhat similar to an RJ-45 connector. Figure-13 shows an SC and ST connector.
✦ Fiber Local Connector (LC) and Mechanical Transfer-Registered Jack (MT-RJ):
These are newer fiber optic connector types that resemble the registered jack and fiber SC shape. The MT-RJ is a small connector that is similar in appearance to an RJ-45 connector. The LC is similar in appearance to the fiber SC connectors and is the preferred connector for transmissions exceeding 1 Gbps because of its small form factor.
Enjoy this article for now. More will be coming in the next few days.
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