Twisted-pair cabling standards forge ahead
After the most recent Telecommunications Industry Association (TIA—Arlington, VA) TR-42 Engineering Committee meeting, we posed the following questions to Masood Shariff
As Category 6 gets closer to becoming reality, is there a future for Category 7 cabling?
After the most recent Telecommunications Industry Association (TIA—Arlington, VA) TR-42 Engineering Committee meeting, we posed the following questions to Masood Shariff. He chairs TIA's TR-42.7 Engineering Subcommittee on Copper Cabling Systems, which has primary responsibility for the TIA/EIA-568B.2 and TIA/EIA-568B.4 standards.
CI&M: What technical issues must the TIA clarify or resolve before a Category 6 standard can be ratified?
Shariff: TIA PN-3727 Draft 6 of the Category 6 standard is posted for review and comment. There has been considerable progress in resolving key issues, including interoperability, backward-compatibility, harmonization with ISO/IEC (International Organization for Standardization/International Electrotechnical Commission—Geneva), link and channel models, and measurement procedures. This draft still has portions of the document marked "TBD," which stands for "to be determined." These TBD areas are awaiting more test data for resolution. Areas so marked include insertion-loss deviation (ILD), return-loss models, and balance for links and components, to name a few. We expect these to be cleared up in the next couple of meetings and intend to ballot the document by year-end.
CI&M: When is the industry likely to see a completed Category 6 standard?
Shariff: The plan for the Category 6 standard has been delayed because of several other documents that the TIA TR-42.7 Engineering Subcommittee has been dealing with as higher-priority items. Those other documents include telecommunications systems bulletin TSB-95, TIA/EIA-568A-5, and the new revision of the 568 standard, TIA/EIA-568B.2. With these items either already completed or finishing soon, the focus and attention will shift 100% to the Category 6 effort. It is very likely that the Category 6 standard will be published in the second quarter of 2001.
CI&M: The Category 6 standard will require system testing to 250 MHz and specify positive attenuation-to-crosstalk ratio to 200 MHz. That is a robust transmission pipeline. For what current or future applications or protocols will Category 6 be an ideal infrastructure?
Shariff: The challenge to generate interest in the applications side is to have a stable Category 6 channel specification and plenty of installed base over which the applications can run. We can now say the Category 6 channel specifications have been stable for more than two years, and the installed base of Category 6 cabling is growing rapidly, with products available from a large number of vendors.
Applications committees have taken notice, and Gigabit standards are in progress both in TIA TR-41.5 and in the ATM Forum. During the week of May 15, the TIA TR-41.5 Engineering Subcommittee and its parent, the TR-41 Engineering Committee, both approved the PN-4657 document. The document is now out for ballot. The 1.2-Gbit ATM document is also close to ballot and should be sent out before year-end. These standards will enable lower cost and lower-power Gigabit transmission, making these applications much more affordable.
Both of these application protocols are designed for Category 6 cabling and will not work over Category 5 or Category 5E cabling. The Gartner Group (Stamford, CT) research firm has predicted 90% of the cabling to be sold in 2003 will be Category 6, so the message for applications developers is to move to better cabling that can support higher data rates more robustly and efficiently.
CI&M: Does the TIA frequently correspond with the Institute of Electrical and Electronics Engineers (IEEE—New York City)? Are the two organizations currently in contact regarding any forthcoming standards?
Shariff: The TIA and IEEE have had a good long-standing relationship that goes back to the days of Category 3, when the IEEE first developed its now-famous 10Base-T application. The 10Base-T standard was published well before the TIA/EIA-568 standard, but still refers to the then-unpublished TIA document for details on compliant Category 3 cabling to support 10Base-T. Since the late 1980s, the cooperation and interest in each other continues through Category 5, Category 5E, and even Category 6. Geoff Thompson, chair of IEEE 802.3, and Jim Carlo, chair of IEEE 802, were both at the most recent TIA meetings in Vienna, VA. Geoff makes it a point to attend every other set of TIA TR-42 meetings. It is important to realize that it was a request from the IEEE that extended the requirements of Category 6 from 200 to 250 MHz.
CI&M: Every so often, Category 7 gets mentioned. Is the TIA currently pursuing a Category 7 standard?
Shariff: Right now, there are no proposals or plans from anybody in the industry to work on a Category 7 standard in the TIA. Consequently, this is not an active project or even a study project at this point.
CI&M: Might that change as the ISO firms up its specifications for a Category 7/Class F standard?
Shariff: TIA members who attend both ISO and TIA meetings are probably keeping tabs. But since the market for Category 7 in North America is not clear and the applications that will use Category 7 are not happening, Category 7 is not yet a viable option for North America.
Masood Shariff is systems applications director at Avaya Communication (formerly Bell Labs of Lucent Technologies—Basking Ridge, NJ).
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Installers of premises and campuswide communications systems face constantly evolving standards, products, and technology. Keeping pace with these changes requires access to current information from informed peers who are knowledgeable in fiber and copper technology relative to premises communications. Cabling Installation & Maintenance provides peer-to-peer perspective in its interpretation of standards and technology, its presentation of installation techniques, and in the selection and use of products in premises communications.