Future perfect

"When a company is making an investment in a cabling infrastructure they want something that is going to support all the systems that they have in place today and they want to know that it will support all the emerging technologies, even the technologies that haven't been identified yet, as far into the future as they possibly can," explains James Potter of specialist installer Black Box Network Services (Northampton). And future technologies in the voice and data sector mean larger cable bandwidths.

There are several ways of fulfilling structured cabling requirements so certain facts must be determined before designing a system. A company must first define its business case states Potter: what are the business drivers, what is likely to be added in the future, how many staff are employed; this will define the operating parameters.

It must then be decided if the cabling system is to satisfy a single project or if it is part of a wider strategy, developed for national or international implementation. This is vital to the decision of which products to use – the manufacturer's distribution abilities may have a large impact on project times and, for international strategies especially, it is essential for there to be distributors and registered installers in the countries that the company is based.

It is then possible to examine the available cabling systems that can satisfy the requirements and are standards compliant. The manufacturers can be called on for help at this stage – most have technical experts that can help clients to fulfill their business case. "It always goes back to the business case and then its how does that fit into the products available," states Potter. "When a firm moves into a building they may have spent £4 million on the building and the cabling is only around £200 000 – it's not major. But two or three years down the road they will have to spend that again if they haven't married the business case with the standards compatibility."

"The final choice of cable may not be the highest performance available," explains Nick Andrews of Datwyler Cables & Systems. "You have to take an economic viewpoint as well. You can't pre-empt too much because there are so many routes that technology can go down in the future that by investing in a very high technology cable you might not be doing yourself any favours."

The standards issue
With no ratified standards for the higher categories, how can clients be sure the products selected will meet the final specifications?

Nick Andrews participated in a number of the bodies involved in preparing the standards. He explains that although Cat 7 is still an unpublished draft standard, the parameters, such as crosstalk and attenuation, are "pretty well defined" and the standard is due to be ratified in September 2002. The Cat 6 standard is due to be confirmed next year also.

Cat 7 is defined as a 600 MHz bandwidth cabling solution; Cat 6 is 250 MHz and Cat 5e is 100 MHz. The demand has been led by the Germans, explains Andrews: "They came up with a proposal for a 600 MHz standard. This is not the limit of what you can achieve with that type of cable, you can go beyond that, but the standard has been set at 600 MHz. That won't change."

Installation issues
With increased bandwidth cables, installation times and cost will "inevitably be a lot higher" advises Andrews. More preparation time will be needed; they are bigger cables hence will need more management and larger trunking.

  One advantage of Cat 7 cabling though is that it is a shielded product. This means that, unlike untwisted pair cables, the power and data cables can be laid side by side as there is no problem with noise interference. This gives greater flexibility for the implementation of the cabling structure.

"Cat 7 cable is a lot more forgiving in terms of the installation practices that are used compared to the Cat 6 cable, which is really pushing the performance envelope of that sort of cable technology so it's very susceptible to bending, torsional loads and tension loads," states Andrews.

There are some installation guidelines that need to be applied if somebody has not installed Cat 6 or Cat 7 cable before.

Although Cat 7 cabling is being installed, infrastructures have to be completed with Cat 6 shielded patch panels, outlets and floorboxes. This is because the Cat 7 connector technology has yet to be finalised. There are two proposals for connecting hardware: an Alcatel product and the Siemon Tera connector.

The first fits the RJ45 format and uses the same type of plug and socket arrangement that are used for Cat 5 and 6. There have been problems in ensuring its reliability to date and it is not yet ready for production. The Tera solution is available now but is not an RJ45 format so backwards compatibility issues can create problems – existing devices cannot be plugged into the new connection hardware without some sort of interface. This is the part of the standard that remains to be ratified.

  When testing these mixed Category systems, it is only possible to test to the lowest performance component ie the Cat 6 connections and patch panels. "You can only test to draft standard," confirms Andrews. "The warranty is effective to the draft standard, but we're confident that when the standard is fully ratified the solution will still be approved." To maintain a warranty, the same manufacturers patch leads and connectors should be used.

If anyone is yet to be convinced of the advantages of installing Cat 7 cable now as a future-proofing measure, Datwyler has done the sums. "We have done some work comparing installing Cat 5e now, installing Cat 5e and upgrading it to Cat 7 or just installing Cat 7 from day one. Installing Cat 7 will cost you about 20% more than installing Cat 5e, but if you put in Cat 5e now and upgrade within the next five years it will cost between three and four times times as much because you will pay for both installations and the removal of the first cabling system." The replacement of Cat 6 connections to make it a fully Cat 7 system will cost 10-15% above the cost of the initial installation, states Andrews.