TIA Approves Category 6

After almost five years in the making, Category 6 is—believe it or not—now an official standard, having been approved and published. While Category 6 may not have set the record for the longest time required to approve a standard, it may have set the record for the longest time in which the industry supplied prestandard product.

The Telecommunications Industry Association and its international counterpart, the International Organization for Standardization (ISO), began working on Category 6 in August 1997 and almost immediately, manufacturers started shipping product to this draft standard.

Fortunately, no longer do we have to ask the question, “Which draft is the most current?” Draft 11 with minor modifications was approved June 5, 2002. The official name for the standard is TIA/EIA-568-B.2-1 Addendum 1: Transmission Performance Specifications for 4-pair 100 W Category 6 Cabling.

The standard meets originally established objectives, which were to specify not only the system (channel and permanent link) but all system components to include cable, connecting hardware, patch cords and field testers. Additionally, specifications were needed to ensure interoperability between manufacturers, a time-consuming task in the standard’s development, especially for connecting hardware. The committee also worked out procedures and fixtures to ensure consistent measurements between laboratories. Several laboratories with numerous manufacturers’ products performed significant round-robin testing to ensure interoperability and consistency. The above is easily understood by simply examining the 71-page document, of which 29 pages deal with system and component specifications and the remaining 42 pages with test methodology and fixtures—all new to the industry. Opinions will vary regarding how well this effort truly results in interoperability, but most will agree the TIA committee members efforts goes a long way in that direction. Given the complex nature of going from laboratory conditions to production to actual field installations, time and experience is necessary to obtain true interoperability.

Fortunately for installers and end-users, manufacturers are required to test all components; however, these requirements will ensure all reputable manufacturers will test in the same way to the same requirements. By now everyone knows Category 6 doubles Category 5e bandwidth—200 MHz useable and performance values out to 250 MHz—and offers significant performance improvements even within the 100 MHz range. But what are some of the lesser-known facts within this standard?

You can mix and match Category 6 components with Category 5e, 5 and 3 components. But the resulting system performance may meet the lowest category component’s capability, and it’s hard to understanding why anyone would do this.

Patch-cord performance, at least for near-end crosstalk (NEXT) loss and return loss, has been established. However, do not believe this means that installers can now make their own Category 6 patch cords in the field. The test methodology is very complicated and the text fixturing very elaborate. The test heads on the fixture must actually be centered between the high and low NEXT performance values established. However, TIA did significantly better this time than it had previously with Category 5. The committee took three years to specify the patch cord after releasing the standard.

Specifications have been established for bundled and hybrid Category 6 cables, requiring a 1.2 dB power sum NEXT loss improvement for bundled and hybrid Category 6 cables over four-pair Category 6 cable. This applies to pairs internal and external to the jacket. Most important, Category 6 cable cannot be simply bundled together; it must meet the performance requirements after bundling. Additionally, the bundled or hybrid cable must meet or exceed all other parameters, especially return loss––no small feat given the interaction between the pairs.

Category 6 improves all but two performance parameters over Category 5e–– propagation delay and delay skew, which were simply extended from 100 MHz out to 250 MHz. The parameters were not improved or made more demanding because doing so would not result in any better application performance or reliability.

A new parameter has been added for cable and connecting hardware component performance—longitudinal conversion loss, a measurement of cable or connecting hardware balance. Proper balance minimizes the coupling of undesired signals and is related to the cabling’s emission and immunity characteristics.

Another significant fact is that for Level III (Category 6) field testers there are baseline, permanent-link and channel performance specifications. These three performance specifications recognize the impact of and include the performance of the permanent link and channel adapters in the applicable specification.

Now that Category 6 has been approved, the remaining question is, “How much impact will this have on the industry’s adoption of the standard? Will the industry shift from Cat 5e to Cat 6 or will it move fiber?” EC

BEAM is director of systems marketing at AMP NETCONNECT Systems. He can be reached at tebeam@tycoelectronics.com or 336.727.5784.

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