The Cabling Connection

As Computer networks become more common and useful, the connections of the networks are also important. Data, or information is transmitted from one computer to another through the network medium. In networking parlance, the term “transmission media” refers to both the cable media and the wireless media. While wireless signals the future, cables and cabling are still the most common media used on most computer networks today.
The cable is quite popular for wide variety of communication systems: TV, Telephone, Computer Networks, etc.
Different cable types are used in modern computer networks. Size, cost, data transfer rates, minimum/maximum lengths, Attenuation (Reduction of transmission quality) and ease of installation vary for all of them. Lets take a brief look at cabling for today’s networks.

TWISTED-PAIR CABLE

Twisted Pair cable consists of two independently insulated wires twisted around one another. One wire carries the signal while the other wire is grounded and absorbs signal interference. Twisted-pair cable is used by older telephone networks and is the least expensive type of local-area network (LAN) cable, and most networks still contain some twisted-pair cabling at some point along the network.
The twisting of the wires helps to reduce cross talk and other types of outside interference.
The main types of twisted pair cabling are Unshielded Twisted-Pair (UTP) and Shielded Twisted-Pair cabling (STP).

Unshielded Twisted-Pair (UTP)
As the name states, "unshielded twisted pair,” (UTP) cabling is twisted pair cabling that contains no shielding. UTP has five categories for cable standards defined by the Electronic Industries Association and Telecommunications Industry Association (commonly known as EIA/TIA).

CAT5 is the 5th generation of twisted pair Ethernet cabling and the most popular of all twisted pair cables in use today. Though newer cable technologies like CAT6 and CAT7 are being developed, CAT5 cable remains the popular choice, because it is both affordable and fast enough for today's LANs.

Shielded Twisted-Pair cabling (STP)
Shielded Twisted-Pair cabling has traditionally been used in several network types, including AppleTalk and Token-Ring. STP cable usually contains, at its core, four more pairs of twisted copper wires. It is different from UTP in that the twisted pairs are in a shield with electrically grounded woven copper mesh separating them from the cable’s outer sheath. The essence of the shielding is to provide resistance to external Electromagnetic Interference (EMI) and to prevent crosstalk. STP is considered to be more secure than UTP, because of its shielding. It is however more expensive than UTP.

COAXIAL CABLE

Coaxial cable is another popular type of communication transmission cable. Coaxial cabling is the primary type of cabling used by the cable television industry and is also widely used for computer networks.
Coaxial was the first cable type used to connect computers together. Although more expensive than standard telephone wire, it is much less susceptible to interference and can carry much more data such as data, voice, and video conversations simultaneously. It consists of a copper conductive center wire that is thicker than the wires found in twisted-pair cable, thus enabling higher data transmission rate over longer distances. The center conductor is covered by a layer of plastic foam insulating material, which, in turn, surrounded by a second conductor, usually woven copper mesh. This outer conductor is not used to transfer data, but it provides an electrical ground, and shields the center conductor from internal and external interference.
The two types of coaxial cable are: Thinnet (10Base2) and Thicket (10Base5).
Although not used as much as UTP in newer network installations, coaxial cabling is still common in much of the already-installed computer network base. It can transmit data at 10Mbps, with distances of up to 185 meters (for Thinnet) and 500 meters (for Thicknet).

FIBER OPTIC CABLE

Fiber optic cabling uses thin glass fibers to transmit data. Fiber optic cabling consists of three concentric layers: The "core" is the central region of an optical fiber through which light is transmitted. The "cladding" is the material in the middle layer. It has a lower index of refraction than the core, which serves to confine the light to the core. An outer "protective layer", or "buffer", serves to protect the core and cladding from damage.
Fiber optic cables can carry more data than other cable media because they have a much greater bandwidth. Fiber optic cables are also less susceptible to interference. Fiber optic cables are much thinner and lighter than other cable media.
Furthermore, in fibre optic cabling, data can be transmitted digitally (the natural form for computer data) rather than by analogue means. Though fibre optics can be expensive to install, is difficult to split and is also more fragile than wire, it is becoming increasingly popular for computer networking and telephony. Fibre optics is in fact expected to take over the cabling arena for all manner of communications in the future.

I hope this article has given you a glimpse into the world of cabling. While wireless is the trend of the future, network cables and cabling will still be around for sometime to come.

By:

Tunde Ayolomo

Tunde Ayolomo is Technical Officer with Jidaw Systems Limited. He has extensive knowledge in Networking and Technical Support. Drop him a line at: tunde@jidaw.com