Glossary

Structured Cabling

In the dim distant past, well only just over a decade, a network consisted of a single cable shared by everybody using the network. As you can imagine things didn’t scale too well. If there were just a small number of people using the network then great, but as more and more people used the network things started to slow down.

Not only was available speed a problem, errors on the network were also shared liberally around too. A single fault with one of the network devices could easily kill the whole network.

Structured cabling is an attempt to solve both the bandwidth problem and the reliability issues of older shared networks.

Structured cabling is based around the idea of having at least one cable to each network device.

By separating each network device from each other increases the speed of traffic but also helps to reduce the chances of errors affecting other devices on the network.

Because each network device has its own cabling, a switch is required to pass network traffic to each device.

Patch Panel

One of the driving forces of modern networks is the convergence of many different network cabling standards onto a single cabling infrastructure.

The main reasons for the convergence is the increased flexibility afforded by having all of your outlets able to support any function, be it telephone, networking or video. In addition, because all outlets in a converged network can be used for any purpose, often fewer outlets need to be installed.

In the past, telephones, network and video applications all used different cabling. Each type also necessitated a separate outlet.

A patch panel is an essential tool to promote the flexibility afforded by converged network cabling.

A patch panel makes it easy to change the configuration of the cabling without having to change the network itself.

Switch

Switches send traffic to each device that is destined only for that device. By intelligently routing traffic the switch is able to increase the effective bandwidth of the network as a whole.

As an electrician it is unlikely that you’ll be expected to install the network switches.

Router

The chances are that if you have broadband connection you also have a router. A router directs network traffic between different networks.

In the most common domestic setting of a router connected to an ADSL connection, the router sends traffic from the network in your home down the ADSL line to the network at your ISP and from there to the Internet at large.

The Internet is comprised of many millions of networks, ranging from the very, very large to the very small.

Routers don’t necessarily have to connect to the Internet. Many companies run private networks over leased lines connecting their various offices and plants.

Though, even private networks are tending to converge onto the Internet as a way to reduce costs. Leased lines are prohibitively expensive over long distances so virtual circuits are becoming increasingly common that route inter office traffic over secure virtual connections using the Internet.

As an electrician it is very unlikely that you’ll be expected to install routers.

PBX

In an office context, every desk typically has a telephone. It would be prohibitively expensive to provide each desk with its own external phone line.

That’s where PBX (Private Branch Exchange) or PABX becomes useful, each internal telephone is connected to the PBX. The PBX is then connected to the external telephone lines. When you dial a number from your desk the PBX then obtains one of its external lines for you to use.

In all probability, there are substantially fewer external lines than there are internal telephones. So, theoretically, if everybody dialed their phones simultaneously then a large percentage of dialers would not be successfully connected.

Whilst traditionally telephone cabling has been simple copper wiring, today it is more likely to be using UTP (Unshielded Twisted Pair) cabling like CAT5e or CAT6. Even in quite small offices everything runs over a single cable infrastructure. A patch panel is used to connect a given outlet either to the PBX or to the network switch as necessary. The network configuration can be changed very quickly to accommodate new requirements and to bring an unused outlet into use.

A recent development of telephony has been the emergence of voice over IP (VOIP.) IP (Internet Protocol) defines the rules and message formats used by the Internet.

VOIP encodes the telephone conversation as regular network traffic just like email and web traffic, which can then be sent over any compatible network allowing users to communicate world wide, and very cheaply.

Video / CCTV

Older video installations have traditionally used coax copper cabling. Today, it is more likely that video will use structured cabling systems. This brings the kind of flexibility and reduced costs to video as have been brought to bear on networks and telephone infrastructures.

Many CCTV installation have gone one step further towards IPTV. Video can be sent over the network using IP just as regular email and web traffic.

By converging on the network, even greater flexibility can be attained because the camera and TV can be on completely different networks separated by great distances.

One of the big problems with current networks is that the distances regular network cabling can operate are quite limited.