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Tue 4 May 2004 04:00 AM

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Getting a grip

Cabling is all too often dismissed when talking about enterprise networks. True, it is far from glamorous, but it is essential to the creation of any successful infrastructure. As such, the industry is one that is consistently evolving as developments in fibre and copper technologies continue.

|~|nmecables_m.jpg|~|“I would say that 90% of all the backbones are built on fibre in this region,” says Tarek Helmy of Nexans Cabling Solutions.|~|Cables may be one of the most vital components of a network infrastructure, but they are seldom given the time of day unless new premises are being taken up or a holistic network upgrade carried out. Whereas networking kit such as switches, routers and servers — components of the active network — are upgraded every few years, the cabling infrastructure is generally trusted to run faithfully for years on end once installed.

The upshot of this is that cabling infrastructure purchasing decisions are made much more cautiously. They tend to be better informed and more prudent, and not subject to fads or competitive behaviour in the same way as applications can be. Installing a new cabling system is a major undertaking in terms of time and money and is also very disruptive, making design and initial consultation so important.

But with the dramatic increase in local area network (LAN) speeds over the past few years and the corresponding increase in the number of nodes and user workstations, so the underlying cabling infrastructure has advanced and is starting to be viewed more in terms of a long-term investment than a necessary spend. Advancements in fibre optic technology and copper cabling have also served to heighten end user awareness on cabling capabilities. The use of optical fibre cable has especially caught on among enterprises in the Middle East, where it is used in almost all the structured cabling backbones.

“I hardly ever come across a copper backbone. I would say that 90% of all the backbones are built on fibre in this region. This is our highest selling market for fibre optic cables compared with other regions, including Europe,” says Tarek Helmy, regional director of Nexans Cabling Solutions, Gulf & Middle East.

The general trend is to deploy multi-mode fibre within the building due to the cost of active equipment. Single-mode fibre is deployed outside of buildings, as well as being the cabling infrastructure of telecoms operators.

“Fibre optic cable is being deployed in the backbone to avoid the bottlenecks created when using copper cables in the backbone,” says Bassem Salhab, business development manager, Belden Wire & Cable, Gulf Region.

“In a shorter backbone the multimode is fine and suits more applications. Single-mode is more expensive especially if you need laser to drive it. Multi-mode on either a 50 or a 62 point fibre cable is still the most popular, but single mode has major benefits and could become the preferred solution for fibre networks,” adds Allan Bullen, managing director of Lynx Data Cabling.

Furthermore, there are also potential risks and noise problems associated with copper, which is another reason multimode fibre is deployed for shorter distances, plus it has the benefit of being able to go between earth zones. Fibre all the way to the desk is catching on to a degree, but less rapidly because of its expense. It is thought to account for about 5% of current installations.

“With copper you could have someone potentially tap into it. It is not that easy to do but it is a concern for some organisations,” comments Bullen.

A very recent development in this area is optic plastic fibre (OPF), the significantly cheaper alternative that has yet to be fully developed, and hence will not be deployed in the Middle East for some time.

“Markets in GCC countries are leaders in taking up the latest technology, and of course it would be due in this instance to the price factor as well. People will definitely go for it once it has matured, but the market here is very sensitive when it comes to under-developed technologies. They want to make sure first that it is working,” says Helmy.

So while fibre is mostly used on the backbone in the Middle East it is copper on the horizontal network. Thus it is a share of both fibre and copper that is growing rapidly. Salhab believes Cat5e is still the predominant cable on horizontal networks in the region, but that it is going through a transition period into Cat6. “We are witnessing increased demand for Cat6, as well as fibre,” he says.

“In the Middle East the percentage of CAT6 is growing rapidly because of an increase in local knowledge and the level of awareness has become better,” adds Christian Schillab, Fluke Networks’ product manager media test products, EMEA. A number of developments are driving the need for better cabling, such as the move to converged networks and IP, new enterprise applications such as bandwidth intensive media apps and peer-to-peer networking which requires strong backbones. A big factor fuelling demand at the moment is the move from fast Ethernet to GbE.

“GbE runs at a much higher frequency with all pairs transmitting and receiving at the same time, therefore one can not afford to have delays and bit errors due to cabling. All the cables must be reliable to withstand the load and offer headroom,” says Salhab.

The main drivers for CAT6, according to Mike Holmes, marketing and communications manager at Nexans Cabling Systems, are future proofing and reliability. People are also looking into a version of GbE over Cat6 instead of Cat5e because of the lower cost active equipment that it enables. Although, with pricing of GbE coming down, this argument is probably less relevant now.

“The main drivers have a lot to do with reliability, of what you want to do with your system. We have tested GbE active equipment over Cat6 [versus 5e] and it made it much more resilient and well within tolerance. However, where the active equipment was just in spec it did not have the resiliency. Cat5e was designed for 100Mbits/s then they decided to do GbE and tried to run it across Cat5e installed space. It became clear that with GbE new parameters were needed to ensure it works properly,” adds Holmes.

The explanation provided by HCS-HES Cabling Systems is that, compared to CAT5, CAT6 increases the data rate of all applications by reducing the Bit-Error-Rate (BER) and increasing overall signal-to-noise ratio (SNR). It also doubles the bandwidth from 100 MHz to 200 MHz and prepares the system for new applications such as EIA/TIA-854 and 10GbE over copper. It is further said to reduce the cost per port by 20% when running GbE using the TIA/EIA-854 protocol.

While Cat5e does support GbE (1000BASE-T), it does require that receivers are fitted with processors that extract the original quarter signal using digital signalling processing (DSP). This ensures that a reasonable BER can be obtained, as GbE over Cat5e has a very low SNR at each receiving point, because the original signal competes with PS-NEXT (Power-Sum Near-End Crosstalk) PS-FEXT and Return–Loss (RL) or echo.

Over CAT5e, the GbE protocol has a four pair full duplex configuration where each pair carries 250Mbits/s. Using PAM-5 coding to transmit 1000 Mbits/s in both directions results in an effective frequency of 83MHz.

If we take a simpler 1000BASE-TX configuration, the RL is eliminated resulting in simpler and cheaper NICs. But this is achieved using only two twisted pairs in each direction, which then have to carry 500mbps each. Using PAM-5 coding, this requires an effective frequency of 167MHz. CAT5e, however, does not support frequencies over 100MHz, which is why a new category was invented to handle the higher frequency, namely CAT6. CAT6 networks provide larger ACR and EL-FEXT, the ultimate performance values which have the strongest effect on reducing BER, thereby increasing network throughput and data-rates.

However, some market commentators have predicted the end for copper at Cat 6, because beyond Cat6 unshielded twisted pairs (UTPs) are not able to support transmission of data on the higher bandwidth unless it is shielded from the outside environment. Helmy though believes that copper still has a long life in the market, and is not going to end at Cat6.

“But this is not the picture in the American market. What’s really behind this is the screening solution, or the shielding of the cable. The US market is dominated by UTP. When it comes to shielding, Europe is the place where most organisations are deploying it. In the Middle East, there is a mix of both the US and European way. Organisations here don’t take long to be convinced of the benefits of a shielded solution. Particular cases like hospitals for example need to use it to protect against interference. The shielding factor is the major difference between Europe and the US,” he explains.

“What they said was that copper was dead at 80Mhz then 1Gig happened and they said that was the end — now its 10Gig only on high performance copper. It just keeps on satisfying needs,” agrees Schillab. “Investing in high-end 10GbE over copper is the real application for CAT7 cabling. 10GibE over copper was initially only used in data centres as low cost alternative to fibre. Now banks want to do it as well to every work station cable, called 10GBAS-T,” he adds.

In the US, IEEE has not standardised on Cat7 because they have come to the end of the life for copper on Cat6. Cat7 is being standardised by only ISO and IEA/TIA. As Cat7 is more than double the bandwidth of Cat6, with 250 MHz on Cat 6 and 615-625 MHz on Cat7, it is being touted as the solution for high-end users with specific needs.

“Cat7 gives you bandwidth for future applications and security of investment. But I would rather say that Cat7 will remain a niche market for some type of customers, such as banks who have requirement for high end applications and bandwidth. SAN for banks or buildings you need a high transmission between the servers and the media, sending a lot of info between locations. Insurance companies as well are investors in Cat7. Hospitals use it for sending large amounts of info,” says Helmy.

There is no doubt today that there are no applications for Cat7 per se, but it would appear to be the most secured cabling for supporting 10 GbE up to the 100m channel. “Cat7 is not yet standardised and we don’t know the exact requirements, but the IEEE committee working on 10GbE development and standardisation are well aware of Cat7 in the market and that it is ratified. They will definitely consider this option when they are talking about the design of the active equipment that will provide it,” explains Helmy.

It is very clear here the relationship between the active and the passive, because the higher the bandwidth on the passive network, the lower the cost of the active equipment to develop. So Cat7 will be more important when the 10GbE-based Tx is standardised.

For the customer who doesn’t want to go for Cat7, the other option is a migration from copper to fibre of the complete network. If the network is already loaded on the Cat6 applications side, the next step is either Cat7 or fibre. “I would say that if applications come to market above Cat6 requirements, they would have to migrate from Cat6 to the fibre multimode. It could be the only option for those who don’t standardise on Cat7 or see it as a solution that is available,” says Helmy.

“In terms of the development, it was very different to move between Cat5e to Cat6 as you can use UTP, and we didn’t have to put foils around it or earth all these things. With Cat7 we have to use a screened system,” adds HolmesWith normal screened Cat6 cable you only need to have foil on the outside. With Cat7 each pair has five foils on it or four screens, all individually screened which means it’s more expensive to use.

“Connectors also have to be screened, so it is a big job to go to Cat7. There is a big cost differential which Cat7’s very high data rates only can justify, that is why Cat5e is being replaced mainly by Cat6 installations and Cat7 is for specialist areas, where the extra cost of it is out weighed by the benefit,” explains Bullen.

Instead of putting in 3-4 connectors into a work station and plugging the PC into one and the phone into another, it is possible to split the cable and put in multiple signals down the same cable, for example, fast Ethernet, phone and video down the same one. Whilst it is possible to do this with Cat6, it works better with Cat7 because of the individually separated channels with separate foil around them.

The one issue repeated by many in the industry is that when installing a new cabling system, it’s important to get the design right from the start. Otherwise it means going back to the start again, having to install backbone cables or cable to the desk in two years time, for example. “Whereas any decent cabling company in any country could install the cabling system, with the design it is different, if they have not got the expertise then it’s wise to call in outside expertise to assist with the design and offer guidelines on the implementation,” says Bullen. “It would be good advice to anyone installing a sizeable infrastructure to use a BICSI qualified person to do the design.”

With most construction companies these days putting in pathways for the cable before hand, whereas it used to be more of an afterthought, end users really only need to consider how long they’re going to be in the building for to help decide what cabling to install. In some areas within the Middle East, that itself would not seem an easy task.||**||

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