FEATURE COPPPER CABLING
Surveying the Copper Structured Cabling Landscape What’s on the Wire? By Ken Hodge, Chief Engineer, Brand-Rex
As 10 Gigabit Ethernet switches finally hit the market, Ken Hodge takes a look at the current and future landscape for copper structured cabling.
Hype and excitement for 10 Gigabit/s over balanced twisted pair copper first appeared way back in 2005. However, the first active equipment supporting 10 Gigabit/s Ethernet over copper actually used short-reach twin-ax CX4 Infiniband technology cable assemblies with a max reach of 15 metres. This was basically because the interface electronics were less complex than a BASE-T solution which meant that products could be developed more quickly. The recent history of technology
substitution of 1GbE CX style solutions with RJ-45 based 1000BASE-T shows us that as soon as the RJ-45 based network interface cards and switches become available, conventional BASE-T structured cabling rapidly replaces the more expensive CX products. The new technology ‘best fits’ the environment. We are now poised to see the same happen with 10GBASE-T. Until recently, no mainstream
10GBASE-T switches had been available. However, a quick Google search shows that 10GBASE-T switches have appeared over the last couple of months from many of the main switch vendors. So, most of the rather expensive CX-4 short length interconnections can be expected to be rapidly superseded with what has for decades been the lowest cost solution for data transmission, BASE-T. Some network managers had the
foresight to install Category 6A / Class EA structured cabling systems as early as 2005/6. These early-adopters are now poised to reap the reward of their foresight, as they will now be able to easily upgrade their technology to 10GbE. Meanwhile, those who decided not to do so may find that they are looking at a prematurely obsolete cabling system and another infrastructure replacement in the next two or three years.
Cat5’s nine lives
Is this the end of Cat5e? Not yet. It’s absolutely rock solid for 100Mbps and if good quality standards conformant cable and components are used then it’s fully capable of supporting Gigabit – although it doesn’t have much in the
22 NETCOMMS europe Volume II, Issue 1 2011
way of headroom or safety margin at Gigabit speeds. Cat 6 continues to be the best option
for Gigabit, with eight times the safety margin compared to Cat5e. This makes it far more forgiving of less than perfect installation and more able to perform as it suffers the ravages of time. While Cat 5e will continue, most medium and large installations will now use Cat 6A, with those that don’t foresee the need for 10Gbps on the horizontal using Cat 6. One word of caution though: 10Gbps equipped PCs are probably just around the corner, so think carefully about what’s going to be expected of your cabling installation over the next 10 years before you under-provide! As for the data centre, Cat 6A should be recommended as the basic level installed.
Digital TV
I don’t refer to carrying HDTV over structured cabling, but the fact that both DAB digital radio and Digital TV are being broadcast country-wide from 400 kW transmitter sites. Their spectrum is in the 0-500 MHz frequency band that we use for 10GBASE-T Ethernet. Transmissions on unshielded twisted- pair (UTP) cabling can suffer from the interference generated by broadcast and other electromagnetic interference (EMI) radiating technologies. We tested first generation
10GBASE-T technologies on UTP cabling against the EMC Directive and found that issues, including transmissions, completely stopped when there were noise levels of 3V/m. Although we haven’t tested them yet, it is highly probable that even the third generation 10G chipsets are susceptible to EMI on UTP cabling. So my advice concerning the risk presented by radio interference is this - why take the risk? Shielded Cat 6A has a similar
installed cost to unshielded, yet provides high levels of electromagnetic compatibility or RF immunity by shielding the conductors from the radio frequency energy. It also offers a far better alien crosstalk performance. Therefore, on the basis of fitting the best possible solution for the budget, shielded Cat 6A/class EA is an obvious
engineering choice where electrical noise from radio interference is a possibility.
Infinity and beyond
There was a time when engineers thought that 100 Mbps was the limit for balanced copper pair cables. Technology subsequently improved and a few years later we had 1 Gbps and now 10Gbps. Of course, 40 and 100 Gbps short-
range Ethernet over multi-lane twinaxial copper with SX4 and SX10 connectors have arrived and are being used to top of rack connections. It is too early to say whether the next
10-times step to 100GBASE-T will be possible, but it is now looking probable that 40GBASE-T will be in the not too distant future. The deployment of each ‘next-
generation’ cabling actually leads the introduction of volume production of higher speed commercial equipment by three or even five years. Power over Ethernet (PoE) has been part of the standards for many years, and is now becoming a major application on the structured cabling system. This development was significantly
aided by the PoE+ standard released in 2009, which increased power capability from 13 watts to 30 watts per device, with non-standard offerings taking this up to 50 or 60 watts and above. We could see these higher powers incorporated into the standards in due course.
IIM
One interesting development with the arrival of 10GBASE-T switching is that IT managers are taking a much greater interest in cabling technology, and no longer leaving the choice of technology to the facilities department. This is having two noticeable effects. The first is a much greater
uptake of Cat 6A/Class EA, and the second is a greater deployment of intelligent infrastructure management (IIM). These effects are taking place as IT people realise that, with critical 10Gbps payloads and the possibility of massive disruption due to outages, the physical cabling layer can
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