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Cabling
Cable is used to interconnect computers and network components together. There are THREE main cable types used today [twisted pair, coax and fiber optic]. The choice of cable depends upon a number of factors, like

• cost
• distance
• number of computers involved
• speed
• requirements [called bandwidth] i.e., how fast data is to be transferred

Shielded twisted pair uses a special braided wire which surrounds all the other wires, which helps to reduce unwanted interference.

The features of twisted pair cable are,

• used in token ring (4 or 16MBps), 10BaseT (Ethernet 10MBps), 100BaseT (100Mbps)
• reasonably cheap
• reasonably easy to terminate [special crimp connector tools are necessary for reliable operation
• UTP often already installed in buildings
• UTP is prone to interference, which limits speed and distances
• low to medium capacity
• medium to high loss
• category 2 = up to 1Mbps (Telephone wiring)
• category 3 = up to 10Mbps (Ethernet and 10BaseT)
• category 5 = 100MBps (supports 10BaseT and 100BaseT)

Unshielded Twisted Pair cable used in Category 5 looks like

Category 5 cable uses 8 wires. The various jack connectors used in the wiring closet look like,

The patch cord which connects the workstation to the wall jack looks like,

Distance limitations exist when cabling. For category 5 cabling at 100Mbps, the limitations effectively limit a workstation to wall outlet of 3 meters, and wall outlet to wiring closet of 90 meters.

All workstations are wired back to a central wiring closet, where they are then patched accordingly. Within an organization, the IT department either performs this work or sub-contracts it to a third party.

In 10BaseT, each PC is wired back to a central hub using its own cable. There are limits imposed on the length of drop cable from the PC network card to the wall outlet, the length of the horizontal wiring, and from the wall outlet to the wiring closet.

Patch Cables
Patch cables come in two varieties, straight through or reversed. One application of patch cables is for patching between modular patch panels in system centers. These are the straight through variety. Another application is to connect workstation equipment to the wall jack, and these could be either straight through or reversed depending upon the manufacturer. Reversed cables are normally used for voice systems.

How to determine the type of patch cable
Align the ends of the cable side by side so that the contacts are facing you, then compare the colors from left to right.

If the colors are in the same order on both plugs, the cable is straight through. If the colors appear in the reverse order, the cable is reversed.