Dramatic growth in data center throughput has led to the increasing usage and demand for 10 gigabit Ethernet. Category 6A cable also referred to as Cat 6A cable, allows for transmission of up to 10Gbps and is becoming the cable of choice for many structured cabling networks. At present, shielded and unshielded cables are two main different types of Cat 6A cable. Which one should you choose? Some considerations you should know when choosing a Cat 6A cable will be provided in this article.
What Is Cat 6A Cable?
Cat 6A cable is designed to support next-generation applications, including the transfer of large amounts of data at high speeds. In fact, Cat 6A fully supports 10GBASE-T up to 100 meters in channel length which ensures that it can support the fastest Ethernet applications. Cat 6A extends electrical specifications to 500 MHz from 250 MHz for Cat 6 cable. It is also backwards compatible with Cat 6 and Cat 5e. A new electrical parameter measure of Alien Crosstalk (ANEXT) was introduced to ensure that the Cat 6A cabling system can properly run 10 Gigabit transmission, which was initially not a concern for Cat 5e and Cat 6 whose frequency was up to 100MHz and 250MHz respectively. However, due to operating at a higher frequency of 500MHz for Cat 6A it is important to consider the alien crosstalk effect.
Using Cat 6A UTP or Cat 6A F/UTP?
There has been much debate about Cat 6A unshielded twisted pair (UTP) vs. Cat 6A shielded cable pair (F/UTP) and which is the better option for supporting 10G networks. As shown in the picture below, Cat 6A F/UTP has a cable shield while Cat 6A UTP doesn’t have it. Therefore, since the metallic barrier of Cat 6A F/UTP offers superior protection from unwanted external noise than most other cables, Cat 6A F/UTP cable generally performs better than Cat 6A UTP cable counterparts.
The following picture shows the difference in alien crosstalk performance between a leading Cat 6A UTP and the F/UTP from the same manufacturer. We can see that Cat 6A F/UTP does an excellent job of eliminating ANEXT, providing an improvement in ANEXT performance over Cat 6A UTP. Since a wider margin to the limit line is desirable, the Cat 6A F/UTP clearly has more margin or headroom than the UTP cable does. In addition, the shield surrounding the pairs in the Cat 6A F/UTP cable helps prevents electromagnetic and radiofrequency interference (EMI/RFI) from coupling onto twisted pairs. This can help to eliminate the effects of noise from sources like machinery, generators, or medical imaging equipment, making Cat 6A F/UTP systems an ideal choice for 10G industrial environments.
What Else You Should Consider When Choosing Cat 6A Cable?
Besides knowing to choose from Cat 6A UTP and F/UTP, some other parameters of Cat 6A cables also affect its performance. We know all Cat 6A cables must meet the same base set of specifications, but they are surprisingly different in their physical properties. Here are four key considerations to weigh when choosing a Cat 6A cable.
Cable size and weight
Cat 6A cable operates at frequencies up to 500 MHz—twice that of Cat 6. Controlling noise and crosstalk at higher frequencies has required Cat 6A cables up to 50% larger than their Cat 6 predecessors. Larger size means fewer cables can fit into a cable tray or conduit, which is a huge concern in retrofit installations. While many available Cat 6A options remain significantly larger and heavier, the newest Cat 6A cables are only about 15 percent larger than Cat 6.
With larger cable diameters also comes a larger bend radius, which is important when routing cables in tight spaces such as inside wall cavities. The bend radius also has an impact on the ability to route cables for maximum airflow within racks. The smaller the bend radius, the easier the cable is to route and install.
Most Cat 6A cables are larger because they have more and thicker materials. More twists in the copper pairs, larger splines separating the pairs, and thicker outer jackets. All of these add up to cables that take longer to prepare and terminate. Thinner and more round cables take less time to install.
There is a perception that shielded cable provides better noise immunity, but the effectiveness of the shield depends on the quality and reliability of the shield termination, balance of the twisted pairs, and quality of the local and remote ground connections. The impedance of the ground connection can increase at higher frequencies and differences in ground potential can couple noise into the conductors. Cable designs that effectively surround the conductors with a Faraday cage can provide an electromagnetic barrier without the potential drawbacks of grounding.
Before deciding on the best Cat 6A cable, all factors need to be weighed up so that the installed system lasts well in to the future and is able to handle 10GBASE-T applications. The cable infrastructure is the most complicated and costly to replace if upgrading is necessary. Basically, if you are installing a cable infrastructure, install the most advanced solution possible. Besides, with the added benefits that a shielded solution offers, you should strongly consider that option. For a data center, computer room and backbone cabling where transmission speed and bandwidth is demanding, Cat 6A is now a popular option against fiber since it is cheaper and mechanically more robust than fiber. Just prepare choosing the right Cat 6A cable for your 10G networks!