Common Network Cable types
Cables are commonly used
to carry communication signals within LAN. There are three common types of
cable media that can be used to connect devices to a network and they are
coaxial cable, twisted-pair cable, and fiber-optic cable.
Coaxial
cable
Coaxial cable looks
similar to the cable used to carry TV signal. A solid-core copper wire runs
down the middle of the cable. Around that solid-core copper wire 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.
There are two types of coaxial
cabling: thinnet and thicknet. Thinnet is a flexible coaxial cable about ¼ inch
thick. Thinnet is used for short-distance. Thinnet connects directly to a
workstation’s network adapter card using a British Naval Connector (BNC). The
maximum length of thinnet is 185 meters. Thicknet coaxial is thicker cable than
thinnet. Thicknet cable is about ½ inch thick and can support data transfer
over longer distances than thinnet. Thicknet has a maximum cable length of 500
meters and usually is used as a backbone to connect several smaller
thinnet-based networks.
The bandwidth for coaxial
cable is 10 mbps (mega bits per second).
Twisted
Pair Cable
Twisted-pair cable is the
most common type of cabling you can see in todays LAN networks. A pair of wires
forms a circuit that can transmit data. The pairs are twisted to provide
protection against crosstalk, the noise generated by adjacent pairs. When a
wire is carrying a current, the current creates a magnetic field around the
wire. This field can interfere with signals on nearby wires. To eliminate this,
pairs of wires carry signals in opposite directions, so that the two magnetic
fields also occur in opposite directions and cancel each other out. This
process is known as cancellation. Two Types of Twisted Pairs are Shielded
Twisted Pair (STP) and Unshielded Twisted Pair (UTP).
Unshielded twisted-pair
(UTP) cable is the most common networking media. Unshielded twisted-pair (UTP)
consists of four pairs of thin, copper wires covered in color-coded plastic
insulation that are twisted together. The wire pairs are then covered with a
plastic outer jacket. The connector used on a UTP cable is called a Registered
Jack 45 (RJ-45) connector. UTP cables are of small diameter and it doesn’t need
grounding. Since there is no shielding for UTP cabling, it relies only on
the cancellation to avoid noise.
UTP cabling has different
categories. Each category of UTP cabling was designed for a specific type of
communication or transfer rate. The most popular categories in use today is 5,
5e and 6, which can reach transfer rates of over 1000 Mbps (1 Gbps).
Optical
Fiber Cable
Optical Fiber 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 cable: Single Mode Fibre (SMF) and Multi Mode Fibre (MMF).
1. Single Mode Fibre
(SMF) uses a single ray of light to carry transmission over long distances.
2. Multi Mode Fibre (MMF)
uses multiple rays of light simultaneously with each ray of light running at a
different reflection angle to carry the transmission over short distances