define a generic voice and data wiring system that is multi-purpose and multi-vendor
	help minimise cost of administration
	simplify network maintenance and changes

A building wiring system covers a number of different elements

	horizontal wiring
	backbone wiring

Horizontal Wiring The horizontal wiring extends from the wall outlet to the system centre (telecommunications closet). It includes the:

	the wall outlet
	the horizontal cable
	cross-connects or patch cables in the telecommunications closet (TC)

Some general features of the horizontal wiring scheme are:

	uses star topology
	limit of 90 meters (295′) from TC to wall outlet
	limit of 3 meters (10′) to connect from wall outlet to PC
	patch cords and cross-connect leads are limited to 6 meters (20′)
	minimum of two outlets per user (phone+data)
	standardized media, Outlet A=4pair 100ohm UTP, Outlet B=same or 2 pair 150ohm STP

Backbone Wiring
The backbone wiring system interconnects telecommunication closets, equipment rooms and entrance facilities (ie, the outside world). Some general features are:

	star topology
	maximum of two hierarchical levels
	interconnections between any two TC must not go through more than 3 cross connects
	use of recognised media
	adherence to distance limitations

Cabling Types

Twisted Pair (STP and UTP)

	used in token ring (4 or 16MB/s), 10BaseT (Ethernet 10MB/s)
	cheap
	easy to terminate
	UTP often already installed in buldings
	UTP prone to interference
	low to medium capacity
	medium to high loss
	category 3 = 10MB/s, category 5 = 100MB/s

Unshielded Twisted Pair cable used in Category 5 looks like:
Category 5 cable uses 8 wires. The length of exposed wires is very critical, the standard limits this to less than 1/2″ an inch. The various jack connectors look like:
The patch cord which connects the workstation to the wall jack looks like:
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 jack, the length of the horizontal wiring, and from the jack to the wiring closet.
This is obviously a physical STAR configuration, in that each PC is wired back to a central point (the Hub).
Ethernet 10Base-T wiring specifies an 8 position jack, but uses only two pairs.
TWISTED PAIR ETHERNET HORIZONTAL WIRING (Solid 24Awg)

Each run < 80m from nearest hub
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 eitherstraight 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.

Coaxial Cable

	medium capacity
	Ethernet systems (10MB/s) and Arcnet
	slighter dearer than UTP
	more difficult to terminate
	not as subject to interference as UTP
	care when bending and installing is needed

Thin coaxial cable [RJ-58AU], as used in ethernet LAN’s, looks like
The connectors used in thin-net Ethernet LAN’s are T connectors (used to join cables together and attach to workstations) and terminators (one at each end ofthe cable). The T-connectors and terminators look like

Fibre Optic
The features of fibre-optic cable systems are

	expensive
	used for backbones or FDDI rings (100MB/s)
	high capacity
	immune to electro magnetic interference
	low loss
	difficult to join
	connectors are expensive
	long distance

Fibre optic is often used to overcome distance limitations. It can be used tojoin two hubs together, which normally could not be connected due to distancelimitations. In this instance, a UTP to Fibre convertor is necessary.
Fibre obtic cable.
In addition, fibre optic patch panels are used to interconnect fibre cables.

NETWORK SEGMENTS
A network segment

	is a length of cable
	devices can be attached to the cable
	it has its own unique address
	it has a limit on its length and the number of devices which can be attachedto it

Large networks are made by combining several individual network segments together, using appropriate devices like  routers and/or bridges.

When network segments are combined into a single large network, paths exist between the individual network segments. These paths are called routes, and devices like routers and bridges keep tables which define how to get toa particular path. When a packet arrives, the router/bridge will look at thedestination address of the packet, and determine which network segment thepacket is to be transmitted on in order to get to its destination.