Last week’s blog post covered the uses for Category 6A cable, including emerging applications and recommendations for adoption by industry standards bodies. This week, we take a look at the factors that go into the choice of a Category 6A cable. While all Category 6A products must meet the same base set of specifications, they are surprisingly different in their physical properties, and how well they deliver at the extremes of performance. Those extremes are important, because the extremes of today are the expectations of tomorrow.
Here are the key considerations to weigh when choosing a Category 6A cable.
Category 6A operates at frequencies up to 500 MHz -- twice that of Category 6. Controlling noise and crosstalk at higher frequencies has required Category 6A cables up to 50% larger than their category 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 Category 6A options remain significantly larger and heavier, the newest category 6A cables are only about 15 percent larger than Category 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 Category 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.
In a conventionally designed cable, the spline and jacket surrounding each copper pair create an insulated compartment that is prone to high heating when delivering power-over-Ethernet. Newer thermal-barrier designs distribute heat around the circumference of the cable, eliminating hotspots and some are capable of delivering up to 100W PoE while keeping thermal rise within acceptable limits.
Some small-diameter Category 6A cables may not support the full 100 m distance per-channel, especially when delivering PoE, and need to be de-rated to less than full length. A cable that can handle the full 100 meters not only provides an extra margin of performance, but supports a wider range of data center configurations, including top-of-rack, end-of-row and middle-of-row configurations.
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.
Belden’s Category 6A 10GX System overcomes the traditional drawbacks and compromises associated with Category 6A installation and use. The system has been specifically designed to support the mission-critical needs of data centers, server farms, storage area networks, and campus backbones or network access nodes. Belden’s copper team has been working hard to ensure that our 10GX Solution is ready to meet emerging application demands.
Throughout his career Stephane has worked in the telecommunications industry; in R&D, product management, training and marketing. Since 2014, Stephane as Director Technology and Applications is focusing on technology roadmap and ideation, networking applications and trends, and standards engagement.