Ch1 - 1.01 - Network Cabling Flashcards
Coaxial Cable
Coaxial, or coax, cable looks like the cable used to bring the cable TV signal to a television. One strand (a solid-core copper wire) runs down the middle of the cable. Around that strand is a layer of insulation, and covering that insulation is braided wire and metal foil, which shields against electromagnetic interference. A final layer of insulation covers the braided wire. Because of the layers of insulation, coaxial cable is more resistant to
outside interference than other cablings, such as unshielded twisted-pair (UTP) cable
The two types of coax cabling are thinnet and thicknet
Twisted-Pair Cable
Coaxial cable is not as popular today as it was years ago. Today, twisted-pair cabling dominates the popularity contest. Twisted-pair cabling gets its name
from having four pairs of wires that are twisted to help reduce crosstalk or interference from outside electrical devices. Crosstalk is interference from adjacent wires. Figure 1-8 shows a twisted-pair cable. Just as there are two forms of coaxial cable, there are two forms of twisted-pair cabling—unshielded twisted-pair (UTP) and shielded twisted-pair (STP).
When working on a network that uses UTP cabling, you will come across different types of cable for different purposes. For example, sometimes you will use a straight-through cable or a crossover cable (At some point, you may need to connect two computer systems directly together without the use of a switch from network card to network card. Or you may find you need to connect one switch to another switch.).
Fiber-Optic Cable
The third type of cabling to discuss is fiber-optic cabling. Fiber-optic cabling is unlike coax and twisted-pair because both of those types of cabling use a copper wire to carry the electrical signal. Fiber-optic cables use optical fibers that carry digital data signals in the form of modulated pulses of light. An optical fiber consists of an extremely thin cylinder of glass, called the core, surrounded by a concentric layer of glass, known as the cladding. There are two fibers per cable—one to transmit and one to receive. The core also can be an optical-quality clear plastic, and the cladding can be made up of gel that reflects signals back into the fiber to reduce signal loss.
There are two types of fiber-optic cables:
Single-mode fiber (SMF) Uses a single ray of light, known as a mode, to carry the transmission over long distances
Multimode fiber (MMF) Uses multiple rays of light (modes) simultaneously, with each ray of light running at a different reflection angle to carry the transmission over short distances
Remember for the exam that fiber-optic is a more secure cable type to use because it does not carry an electrical signal, but instead carries data as pulses of light.
