Category 6 Patch Cord PerformanceSterling Vaden, VP of Research & Engineering, Optical Cable Corporation

In a study performed by the CCCA, 499 patch cords were performance tested to the TIA Category 6 requirements. 379 were from “lesser known brands” and 120 were from “well known US manufacturers”

Of the 379 from “lesser known manufacturers”, 322 failed Near End Crosstalk (NEXT) requirements. Or 85%Of the 120 from “major manufacturers”, 0 failed NEXT requirements.

They also found poor quality plugs with non-uniform plating and dimensional problems.

What is the basis of these startling results?

In May 2001 the Telecommunications Industry Association (TIA) published TIA 568-B.2 Commercial Building Telecommunications Standard which included new procedures for qualifying the performance of modular cords, commonly referred to as patch cords. This included requirements for Cat 5e and below cabling products. The new patch cord requirements included a test method for qualifying NEXT loss and return loss (RL) The test procedures specified that the cords would be tested mated with “qualified” Cat5e connecting hardware, and the resulting performance was calculated as the sum of connecting hardware plus the cable. The calculations were fairly complex for the time, and the limits varied depending on the length of the cable. Field tester manufacturers responded to the new market opportunity by making available special “patch cord test” adapters for their hand-held testers which included the “qualified” connectors, and the corresponding limits programmed into the testers. The design of the Superior Modular Products patch cord test adapter was written into the TIA 568-B.2 standard including dimension drawings and performance data, as well as where to purchase.

NOTE - A test head that meets these requirements may be obtained from: Superior Modular Products, Swannanoa, NC 28778. Any alternate test head that meets the requirements of clause F.5 may also be used.

Figure 1 Sample test data of Cat5e patch cord test adapter

Here is some historical background. It was found during standards development that the performance of connecting hardware was very sensitive to the performance of the modular plug on the patch cords. Some plug designs were much better than others, and the operator termination skill was also a significant factor. Traditionally, the way to test the plug performance was to cut it from the end of the cord and do a complete set of measurements. This was extremely time consuming as well as having the unfortunate consequence of destroying the cord for further use. The plug performance had to be within a specified range, or the mated connecting hardware performance would fail. That meant that the plug performance

needed both low and high limits. This proved to be impossible to qualify using several proposed methods which included testing with special pin connectors or with standard modular jacks. Thus the method of mating to true Cat5e connectors was conceived. Figure 1 shows the mapping of plug performance vs mated performance for the patch cord test adapter. The plug performance is on the horizontal axis and goes from -30 to -40 dB. The mated performance is on the vertical axis and goes from -36 to -44 dB. On the graph you will see that the mated performance starts at -38 for the -32 plugs and gets higher (-40 to -44) for the mid range plugs and then decreases again for the high (-39) plugs. This enabled the plug centering to be achieved by requiring the mated performance of the patch cord test adapter to be better than -42 dB, and it would eliminate both the low plugs and the high plugs. By combining the limits of two mated connectors, the patch cord plugs could be qualified without having to cut the plugs off and they could be tested in production or in the field with hand-held testers.

It took a while for the new procedures to catch on. Many manufacturers were using “channel limits” rather than “patch cord test” limits to test their cords, if they were testing them at all!

In June 2002, TIA released ANSI/TIA/EIA-568-B.2-1-2002 which now included requirement for Category 6 cabling. New test procedures were a major enhancement over the previous standard and included much tighter test plug requirements for connecting hardware qualification, new test fixture requirements (again provided by Superior Modular Products) and new patch cord test adapter requirements.

Superior Modular Products became the sole supplier for the qualified test heads, as no other manufacturers were interested in the low-volume, highly test sensitive business. The qualification of the test heads for Category 6 was quite a challenge. Every connector had to be tested on a sophisticated network analyzer and the performance for NEXT and RL compared to strict limits which were well above normal requirements and which also included “centering” requirements. The centering requirements meant that the connectors had to be tested with sets of “low” and “high” plugs and the difference in NEXT with these low and high plugs had to be within a narrow range. Production connectors were tested to these requirements and approximately 20% would pass. This was after the connector designs were carefully adjusted and optimized for the best yields. Nevertheless, prices were adjusted to compensate for the labor and low yields and OCC is still the sole supplier for these patch cord test adapters.

As a side note, the test procedures for connecting hardware and patch cords were subsequently adopted into ISO/IEC 11801 and ISO/IEC 60603-7 International standards literally word-for-word from the TIA standards. This gave international endorsement of the TIA methods, the SMP fixtures and adapters, and harmony between the North American and International standards.

In February 2008, TIA published TIA/EIA-568-B.2-10, standard for Augmented Cat6 cabling (Cat6A). Again the critical test procedures, test fixtures, and requirements were updated and again SMP Data Communications was the sole supplier of these products.

All test fixture components referenced in this annex may be obtained from: SMP Data Communications, Inc, Swannanoa, NC 28778 www.smpdata.com.

The standard included 25 drawings and photos depicting SMP specific fixtures and hardware. The new Cat6A patch cord test adapter requirements were further complicated by different connecting hardware requirements between the ISO and TIA standards, with the ISO requirements being much more restrictive at high frequencies. SMP (now OCC) responded by designing the patch cord test adapters to comply with the stricter ISO/IEC requirements while using the TIA test methods and procedures. Extensive qualifications were performed jointly between Fluke Networks and OCC to verify that the new Cat6A patch cord test adapters conformed to all requirements and were suitable for their Fluke DTX-1800 Cat6A patch cord test adapters, which were released in 2010.

In August of 2009, TIA published ANSI/TIA-568-C.2-2009 Balanced Twisted-Pair Telecommunications Cabling and Components Standards which consolidated and updated all of the Cat5e, Cat6 and Cat6A requirements into a single document, with enhanced, updated and streamlined test methods. Now,

however, the explicit references to suppliers were removed at the request of TIA legal department and all of the figures now carry the notation:

1 Plugs of this type may be obtained from industry sources. Alternative equivalent components may also be used.2 Photos are for illustrative purposes only and do not constitute an endorsement by TIA.

Figure 2 Figure H.9 from TIA 568-B.2-10 (also fig. E.9 TIA 568-C.2)

This now gives us enough background to explain the results of the patch cord survey by CCCA. What we have found is that in order to successfully manufacture Cat6 and Cat6A patch cords that comply with the TIA and ISO/IEC requirements, 100% performance testing is required in production. Not only must the design of the plugs be optimal, and the performance of the cable be compliant, but the operators applying the plugs to the cable need the guidance of performance testing to help them to use the right assembly techniques. It would not surprise us that manufacturers may not understand these principles and in pursuit of the lowest costs, not apply them. Inevitably it results in poor patch cord performance which results in poor connector and channel performance. This will become increasingly important as the IEEE 10GBASE-T networking becomes more popular.

OCC 100% performance tests all Cat6 and Cat6A patch cords using our own industry standard patch cord test adapters and our own industry standard test fixtures.