Shielded or Unshielded, Which to Choose for Cat 6a Cabling?
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Shielded or Unshielded, Which to Choose for Cat 6a Cabling?

Posted on by FS.COM

With high bandwidth applications on the rise and network systems venturing into new areas such as factory environments, the need for Cat 6a cable has also increased. Accommodating network speeds that are 10 times that of the Gigabit Ethernet, 10 Gigabit Ethernet over Cat 6a infrastructure offers the throughput that many users now demand. For Cat 6a cables, will you go with the shielded one or the unshielded one? What are the pros and cons of each? This article will identify the strengths and weaknesses of each one so that the appropriate decision can be made.

shielded cable and unshielded cable

Basic of Cat 6a Cable

Category 6a (Cat 6a) cable is the latest iteration of Gigabit Ethernet cabling. The “a” stands for “augmented”. In accordance to the TIA/EIA 568-C.2 standard, Cat 6a cable is tested from 1 to 500 MHz. This wide range of frequency is required to handle the frequencies at with 10GBASE-T operates. Because of the higher frequencies utilized by 10GBASE-T, alien crosstalk performance parameters are incorporated into the TIA/EIA standard for Cat 6a cable and connectivity. Alien crosstalk occurs when signal from a cable jumper to an adjacent cable. Cat 6a is the first cable category standard to include alien crosstalk performance parameters.

Ways of Mitigating Alien Crosstalk

Alien crosstalk can be overcome by creating space (air) between the cores of adjacent cables. It is usually accomplished by means of adding internal space under the jacket. In the case of UTP (unshielded twisted pairs) cable, the design helps to create space between adjacent cable cores, or some type of physical barrier is used to block alien crosstalk. Most UTP cables use a combination of unique non-metallic fillers that play a role in separating the conductors within the cable and impact alien crosstalk with adjacent cables. On the other hand, shielded cables incorporate a metallic tape barrier to mitigate alien crosstalk.

Strengths and Weaknesses of Unshielded Cables

The ANSI/TIA-568-C.2 standard states that category cable must be smaller than 0.354 inches in outside diameter, regardless of whether the cable is shielded or unshielded. Because of the use of space and fillers as a barrier against alien crosstalk, UTP cables tend to be larger in diameter than shielded cables. Actually, many UTP cable designs fall close to the maximum diameter permitted. Larger conduit and hanging devices must be used to support UTP cables due to their larger outside diameters. This can add cost to a project as well as necessitate more pathway space for the cables. With an established cable design, the UTP cables are simple to terminate since they do not possess shields and the prerequisite drain wire. This translates to quicker termination times and thus reduced cost. UTP cable and unshielded connective hardware (jacks and patch panels) also tends to cost less than their shielded counterparts.

Types of Shielded Cables

Two types of shielded Cat 6a cable designs can be chosen. One is a shielded cable with foil around each of the four individual pairs. This cable, known as U/FTP (overall unshielded, but foil over twisted pairs), offers excellent shielding performance. However, it is more challenging to terminate than other constructions since each pair is individually wrapped in foil.

U/FTP cable

The other is F/UTP (foil shield over unshielded twisted pairs) cable, which requires more technologically advanced manufacturing process to build. But it is significantly easier to terminate and has a smaller outside diameter than the U/FTP cable. F/UTP cable utilizes a single foil shield wrapped around the cable core and includes a drain wire, and it takes less time to terminate than U/FTP.

F/UTP cable

Strengths and Weaknesses of Shielded Cables

The smaller diameter of shielded cables (usually below 0.3 inches) allows for smaller conduit and pathways than most Cat 6a UTP cables, which will result in cost savings. Although the shielded cable and shielded connectivity do tend to cost more, in addition to overcoming alien crosstalk, the shielding also provides the added benefit of increased immunity from outside electronic interference. With more and more devices becoming networked, data cabling is finding itself in physical locations that tend to be detrimental to its performance. The presence of interference near the cables can corrupt data transmissions on category cables and severely hinder their performance. When data is critical to the daily operation of a business, a shielded solution seems to be the best option. Shielded cables with metallic barriers provide exceptional protection form this noise. In all, shielded Cat 6a cables perform better than the Cat 6a UTP counterparts simply because the metallic barrier offers superior protection from unwanted external noise than most other means.

Summary

It depends on a number of factors to choose shielded or unshielded cabling solution, such as ease of installation, cost, etc. All factors need to be weighed up so that the installed system lasts well into the future. Basically, if you are installing a cable infrastructure, install the most advanced solution possible. Always carefully evaluate your current and future throughput needs before selecting the appropriate network infrastructure.

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