The role of Cat6a (augmented) cabling is to support 10Gig Ethernet; that is its only advantage over Cat5e and Cat6, but a ten-fold improvement in bandwidth is pretty impressive. The other side of the scales has a couple of disadvantages; you need to decide which way the scales tip for any particular application. The simplest thing to consider is the price as a Cat6a installation will, on average, cost you about 50% more than Cat5e. However, the main issue is that the size of the pathways and containment you’ll require. That includes risers, voids, cable trays, cable baskets, floor ducting and perimeter trunking. Straight runs of Cat6a need roughly twice the capacity of Cat5e but the minimum bend radius of installed Cat6a is upwards of 30mm.
If it’s for a new building or your premises are undergoing a major refit, it is easy enough to specify larger pathways and containment for your cabling systems. On the other hand, if you’re hoping to use existing containment and pathways, you may have to think again because the cost and disruption may make Cat6a unjustifiable.
You need to ask yourself whether, for the life of the cabling, you will ever need it to support 10Gig Ethernet. If it’s a backbone link, in a data centre or likely to be in use for over ten years, the answer is more likely to be yes. Bear in mind that 10Gig active hardware is currently expensive and it will be a few years before it’s affordable for the desktop.
Make sure the cabling system you are buying complies with the full standard not the draft standard, particularly the permanent links (the installed cable runs). You can save money by using Cat5e cords if you’re not yet implementing 10Gig Ethernet but some manufacturers only give a “channel link” warranty that, by definition, includes the cords.
Most Cat6a cabling systems are shielded and it is imperative that the buildings earth system is of a very high standard and that the cabling system is earth bonded by competent electricians. Good earthing ensures that high frequency noise is removed from the system via the shielding and helps prevent alien crosstalk between adjacent cables. If your earth system is not of a high standard, you may need to invest in some improvements.
Where does Cat6a leave Cat6? In my opinion, it makes it redundant because, although Cat6 has two and a half times the frequency range of Cat5e, no network standards have been adopted that run on Cat6 but not on Cat5e.