What is a Cat 6a Cable?

Is it possible to run 10GBaseT over Cat5e or Cat6?

Cat5e definitely no. Cat6 stands a chance for shorter lengths, but nothing is guaranteed. Although it was initially proposed that Cat6 systems could run 10GbaseT up to 55 meters (subject to appropriate mitigation activity such as separating cables), more recent studies have suggested that this limit may more realistically be 37 metres. The problem is that correct operation at any length may depend on factors which will change with moves and changes etc.

Why Install Cat6a?

At the time of writing (2009), 10GBaseT interfaces are very new, expensive and power-hungry. Most users are still choosing either Cat5e or Cat6 systems, on the basis that these systems are perfectly capable of running an Ethernet cable installation up to 1000BaseT, which should prove more than adequate for the foreseeable future.

The argument for installing Cat6a now is one of future proofing. It is estimated that 10GBaseT NIC cards for laptop computers will become the norm in around 2012. Thereafter, only installations with Cat6a cabling will be sure of being able to exploit this new bandwidth. Therefore, the logic goes, if the planned lifetime of a new cabling system us five or more years, Cat6a should be considered as an option. If the planned lifetime is ten or more years, Cat6a definitely appears to be the favoured solution, even for relatively low performance users.

Areas where Cat6a is already proving popular include Data Centres and Building Backbones, where users will wish to exploit the 10GBaseT interfaces as soon as it becomes more cost effective than the 10G fibre equivalent. Again, this is likely to be by around 2012 or even earlier.

Cat6a Products

Over the past few years, most major cabling manufacturers have launched new Cat6a cabling systems. Theses come in various shapes and sizes (literally) with different manufactures making claims as to how effectively their system will meet the new standards. One thing to watch is that unlike Cat6, where effectively Cat6 = ClassE, Cat6a is not exactly equivalent to Class EA. Class EA is actually a tighter specification, so it is possible that a system which meets the Cat6a standard will not meet Class EA

One of the biggest Cat6a debates is the one regarding shielding. Traditionally in the UK, Cat5e and Cat6 systems have been installed as unshielded systems (UTP), on the basis that UTP works and shielded cabling is more expensive to buy and install and harder to maintain. However, one of the biggest technical problems when designing a Cat6a system is of meeting the strict alien crosstalk requirements necessary for a cable operating at 500MHz. Therefore many manufacturers and some consultants recommend a shielded Cat6a solution as the best way of meeting the requirements.

Another consideration when selecting a 10G cable system is its physical construction. For most purposes Cat5/Cat5e and Cat6 systems are physically the same. However, whilst reducing the alien cross talk on UTP systems, manufacturers have designed a range of interesting cable and patch panel designs. Cables can be quite bulky compared with Cat6, some also coming with various twists and non-round shapes. Patch leads are also typically less flexible. Ironically, shielded Cat6a cables tend to be smaller than their UTP counterparts.