Networking: the Category 6 question

Antony Savvas

Friday 05 May 2000 12:00

Companies wanting to take advantage of high-speed networking technologies face confusion over which cabling they require, Antony Savvas report

Category 6 cabling is simply not necessary to run high-speed Gigabit Ethernet, says BT, in its contribution to the ongoing broadband networking debate.

The UK's biggest cabling installer has recommended that businesses should install Category 5 enhanced (Category 5e) copper cabling for broadband services and steer clear of unproven Category 6 standards.

But whether companies need to upgrade from Category 5 to Category 5e for high-speed technologies such as Gigabit Ethernet, is still open to question, and network managers still need more information.

When Gigabit Ethernet appeared as an option for companies to deliver high-speeds to the desktop using traditional twisted-pair copper cabling, a debate started to rage as to whether the existing Category 5 cabling installed in most buildings could cope.

BT cabling product manager Kevin Sollis says, "During the last two years BT has installed Category 5e cabling that is guaranteed to support Gigabit Ethernet, but Category 6 is simply not necessary for Gigabit Ethernet.

"Even after more than a year, the standard for Category 6 is still very much unresolved. Test methods for connecting hardware are still under development, potentially leading to sub-Category 6 performance with hardware supplied by different manufacturers."

And Sollis claims companies considering combining both Category 5e and early versions of Category 6 will suffer lower performances than Category 5e. He says that any companies wanting higher speeds than Gigabit Ethernet should opt for fibre instead.

But Terry Fisher, network operations manager at installer Compusys, says, "Most users are aware of the benefits of a good structured cabling system, and use the wiring to support differing technologies such as Token Ring, Ethernet and Asynchronous Transfer Mode, with support for future network technologies. But will such a strategy always deliver? A new Category 5 system will enable 100Mbit Fast Ethernet hubs and switches to be connected, but will it perform when the next generation of networking arrives?"

Minimum requirement

Says Fisher, "Much has been said about Gigabit Ethernet transmissions over copper cabling, with Category 5 seen as the minimum requirement, but even a Category 5e system may not be able to cope with the bandwidth demanded by improved networking technology in five year's time.

"The new international standard for structured cabling is now Category 6, and, although the standards bodies are not due to ratify the technology until next year, the draft specifications have been available to manufacturers for over 18 months. Category 6 gives headroom far in excess of Category 5e, which is probably why, according to Alcatel, 500,000 have specified Category 6 already."

Compusys says any business intending to stay in its premises for over three years should try and use Category 6. It says the cost of choosing Category 6 is around 15-20% higher than Category 5. The labour installation costs are, of course, exactly the same.

Computacenter is even more forward thinking, although its straightforward solution is rather more expensive. Tony Cooper, network marketing manager at Computacenter, says, "The really long-term thinkers aren't looking at Category 5, 5e, 6 or 7 [yes, this is in the process of being ratified too], they're ramping up to fibre.

"However, for those of a more conservative disposition, our advice is fairly simple. Most people now accept that Category 5 running at 100mbps is close to its limits. Category 6 is not yet ratified, but all the major players are stating they will certify their Category 5e equipment to Category 6 as soon as the standard comes in. On that basis, Category 6 cabling has to be the favourite."

But Cooper stresses, "The major cost of cabling is actually nothing to do with the hard wiring. It is all about disruption. If you are going to undertake a new cabling project, especially in a green field site, our advice is to flood wire it."

Disruption

Cooper explains, "Think of how many points you need and treble it, disruption to the business is hugely expensive. Don't forget how frequently companies find that a lovely conference room is taken over a year or so later as the demand for offices makes conference rooms a luxury."

For network managers, particularly those forced to make do with what they've got, what it comes down to is the connection distances. But suppliers have seized on a potentially lucrative market created by companies' fears that their networks won't be future-proofed for faster technologies.

Suppliers, led by Lucent, have already formed the 10 Gigabit Ethernet Alliance, which could create even greater anxiety among network managers, but the IEEE standards body is not in the pocket of the suppliers.

The IEEE maintains that 90% of installed copper wire (Category 5) should be able to cope with Gigabit Ethernet as long as the connection distances are less than 100m. But this has not stopped some large companies installing enhanced copper wiring when upgrading existing networks or installing new ones.

NatWest has chosen to install a mixture of Category 5e and Category 6 and will use Lucent Gigaspeed untwisted pair throughout its banking network. NatWest has signed a three year contract with WG&R Communications, which will take responsibility for the technical decisions.

NatWest group purchasing manager Mark Marney says this method of networking has been chosen to ensure that the bank has enough bandwidth to take advantage of Gigabit Ethernet and future networking technologies. The fact that WG&R is responsible for the technical decisions and the implementation of the project ties in with the advice of the IEEE.

The IEEE advises companies not to rely solely on supplier advice, but to test their networks themselves or hire a third party to see if their networks can avoid signal interference or echo.

The BT advice on installing Category 5e is supported by BT rival BICC Brand-Rex, which says the multi-pair, bi-directional transmission technique used by Gigabit Ethernet, and new parameters such as Far End Cross Talk and Return Loss, requires Category 5e.

BICC maintains that ordinary "barely compliant" Category 5 systems with no "headroom" will find it difficult to cope, and that signals being sent down different sections of the twisted pair copper risk being delayed if enhanced Category 5 is not used. This advice has been taken up by Elf petrol stations across the UK.

Moving target

However, cable installer Pinacl Communications admits it is hard to tell users what to do. Pinacl design manager Neil Metcalfe says, "What BT says is generally true, Category 6 is a moving target, but some clients are installing Category 6, while others are choosing Category 5e, which is a good system that supports all the necessary protocols, including Gigabit.

"If a customer asks us which one to choose, it can be difficult, but often users have an idea already." Pinacl customers who have chosen Category 5e include BAA (Heathrow), Boots, Thomas Cook, and, most recently, the Lloyds Shipping building in London.

Metcalfe believes the hiatus around the Category 6 standards committee mainly involves disputes between newer entrants to the cabling market - who have alternative solutions to get around technical difficulties when using Category 6 - and established suppliers.

BT has already demonstrated its own demand for Category 5e by signing a £3.4m contract with Elf to install Category 5e and new telephone systems to link its 350 petrol stations. This will include ISDN and videoconferencing connectivity.

Elf has chosen to effectively future-proof its network, but companies on tighter budgets, or those who do not need anything as fancy as bandwidth-hungry videoconferencing, should perhaps take heed of the adage, "it's tougher to look than to leap".

What Copper to use