For the many installers who want to expand into networking, the “security” aspect is actually the least of your challenges. If you’ve been installing cameras for years, you know perfectly well what’s needed at the sharp end.
The confusion, and sometimes fear, comes from having to become acquainted with the heart of the system, an area traditionally reserved for the IT person. But the ‘black art’ of structured cabling is not so daunting – welcome news to those seeking the basic understanding necessary to progress into this sector.
Structured cabling allows businesses to build an infrastructure for their data and telecommunication needs to last well into the new century. The ulti-mate goal is to run anything, anywhere, at any time.
As today’s networks become more complex – as more users share peripherals, as more video and network solutions are developed and as the need for faster access to information increases – a good foundation for these networks become increasingly important. The first step toward the adaptability, flexibility and longevity required of today’s networks begins with structured cabling – the foundation of any information system. So let’s get down to it…
How it evolved
In the early 1980s, when computers were first linked together in order to exchange information, many different cabling designs were used. Some companies built their systems to run over coaxial cables. Others thought that twinaxial or other cables would work best. With these cables, certain parameters had to be followed in order to make the system work. Certain connectors had to be used, maximum cable distances had to be established and particular topologies were necessary.
By defining every aspect of their system, manufacturers “locked” customers into a proprietary system. One manufacturer’s system would not work with another, or run over any other type of cabling. If a customer decided to change systems, not only would new electronics and software need to be purchased, but new cabling would need to be installed as well.
In those days, troubleshooting proprietary systems was very difficult and time consuming compared to today’s structured systems. A problem at one workstation could bring the entire proprietary system down, leaving no indication to the network manager where the problem may have occurred. In the case of daisy-chain topology, troubleshooting consisted of starting at one machine and physically tracing the cables to each of the other machines on the network. Eventually, the cause of the problem, such as a broken connection, was found. Once repairs were completed, the system would be back on line. The troubleshooting process could last hours – or days – leaving users sitting idle.
Moves, adds or changes were also difficult with a proprietary system. Each time a new machine was added to the network, new cable had to be installed and inserted into the ring or attached to the bus. Furthermore, the whole system might have had to come down to add the new user.
The desire for one system that could run any application or system without the accompanying hassles and headaches of past systems was magnified exponentially.
Enter structured cabling …
Three attributes (generic cabling, flood wiring and patch panels) are the essential characteristics of a structured wiring system.
Generic cabling
A structured cabling system consists of outlets, which provide the user with an RJ45 presentation, usually supplied as either one or two RJ45 connectors mounted in a standard single gang face plate or floor box.
Each user outlet is cabled back to a patch panel using an individual cable containing four twisted pairs, this cabling is known as the ‘horizontal cabling’. In most cases, the main medium for the transporting of data will be a Category 5e specification type cable; the cable can be unshielded, known as UTP or shielded, known as STP.
The maximum length of cable between the patch panel and any outlet must be 90 metres to comply with EIA/TIA and ISO requirements. The standards allow a further 10 metres for connecting leads and patch leads to final network based active equipment, making a total drive distance of 100 metres.
In a true structured cabling system, the horizontal cabling and user outlets are the same for all services, so that any outlet can be configured for voice, ethernet, RS232, video or other service. As user requirements change, simply changing the patching configuration in the equipment room can change the service provided on the outlets.
If necessary, an adaptor is used in the outlet to convert it to the service being provided (for example, a video balun will provide the standard composite video outputs required for CCTV).
Flood Wiring
One of the key selling points of a structured cabling system is its ability to overcome the problems associated with “churn rate”. The churn rate is the average frequency that each person in an office moves location in a year. In many large organisations this can be as high as 70%. By flood wiring, outlets are installed on a grid layout to a specified density, rather than to individual user positions. This allows for more flexibility, without having to re-cable, when changes are made to the layout of the building in the future.
Patch Panels
In the equipment room, the individual 4 pair cables from the user outlets are terminated on to the IDC (Insulation Displacement Connection) on to the rear of a patch panel, and provide an RJ45 presentation on the front in configurations of 16, 24 or 48 connector formats for further patching to active equipment.
The final stage is the mounting of the patch panels in standard 19inch racks, either wall mounted or free standing.
In large organisations where the main server room could be located beyond the 90m, the need for a fibre optic “Back bone” system becomes crucial as the final link.
Putting it to work…
As we’ve said, structured cabling allows businesses to build an infrastructure for their data and telecommunication needs to last well into the new century. A properly planned and installed system will allow companies to spend their time, attention and scarce capital resources in other areas.
In the next instalment we’ll be looking at structured cabling networks for the home. If the Americans class it as the fourth utility, why can’t we? … Plus a glossary of terms used.
