Category 6: Change for changes sake?

Category 6 is being heard throughout the industry -- at Bicsi, the Telecommunications Industry Association (TIA), the International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) and in casual conversation. What does Category 6 represent; what does it mean for Category 5; and should cable system users be concerned about Category 6 when making decisions about cabling infrastructures?

Sep 1st, 1996

Pete Newman

Leviton Telecom

Category 6 is being heard throughout the industry -- at Bicsi, the Telecommunications Industry Association (TIA), the International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) and in casual conversation. What does Category 6 represent; what does it mean for Category 5; and should cable system users be concerned about Category 6 when making decisions about cabling infrastructures?

Various entities are suggesting 155-, 300- and 600-MHz bandwidth limits for Category 6. Category 5, however, can already support 155-Mbit/sec Asynchronous Transfer Mode (ATM), and a cabling system already exists, specified by the TIA/EIA-568A standard, which is characterized to 300 MHz. Category 5 cable can even support 622 Mbits/sec with specialized implementation. That kind of bandwidth should keep us going for a very long time.

The telecommunications industry has standardized on Category 5 as the highest level of performance for unshielded twisted-pair (UTP) cable, with fiber- optic cable as the "next step up" in terms of bandwidth. But now we are hearing about Category 6.

The idea of Category 6 UTP cable comes from a combination of a misperception of enhanced Category 5 products, hype from manufacturers of shielded and screened twisted-pair cabling, and interest from the European Community-- where mainly shielded cable is used in premises installations. In fact, the only written Category 6 proposal so far is a German draft submitted at the ISO/IEC meeting in Sydney, Australia, held last spring. The German draft proposes 100-ohm shielded cabling, with modular connectors, characterized to 600 MHz, with non-return-to-zero coding--primarily to support 622-Mbit/sec ATM-to-the-desk.

The proposal for Category 6 is not coming from the TIA standards groups. Nor is it driven by customer or application needs. Marketing forces-- rather than market forces--are driving the so-called need for higher performance cable. Shielded-cable vendors are driving Category 6 because they can make it, not because market needs exist.

Future-resistant systems

Many customers are looking for a future-proof cabling solution, and manufacturers are responding by raising the bar in terms of cabling speeds. With so much discussion about the Internet, intranets, multimedia and the elusive "killer" application, many will argue: Why shouldn`t Category 6 be developed?

A more important question might be: Why develop a new system when the existing ones meet all current and projected needs, with bandwidth to spare?

Category 5 supports most of today`s existing and foreseeable applications, generally at a lower cost than fiber. Equipment is widely available to support dedicated and switched 100-Mbit/sec service to the desk. Prices are falling, installers are trained, warranties abound, and--let`s face it--100 Mbits/ sec is a respectable data-transfer rate.

Should users want more bandwidth-- and they most likely will when video, voice and data multimedia applications come to the desktop--fiber-optic cabling is a proven alternative. If you really want to meet future needs, you should install singlemode fiber-optic cable to the desk. Category 6 exists now only as a suggestion; it is an undefined, unproven technology that will be years in the making. And it is expected to debut at a higher cost than fiber, so why not just install fiber?

One thing is certain: whichever medium a user chooses, it will change in time. It`s just a matter of when. There is no such thing as "future-proof." What an end-user buys is time between recablings. Instead, today`s systems should be called "future-resistant."

When choosing a system, what you need to ask is: How long does the user need the cabling to last, and at what cost? Then, decide which system meets those criteria.

Category 6 is affecting the telecommunications industry in several ways. For example, because the medium for Category 6 is likely to be 100-ohm shielded twisted-pair or screened twisted-pair cabling, Category 6 is adding to the shielded camp in an industry already divided between twisted-pair and fiber. End-users, too, are concerned about Category 6, and may feel cheated about their Category 5 investments--after all, they were told that Category 5 was the highest performance level for twisted-pair cable.

Contractors, specifiers and installers should develop a wait-and-see attitude until a standard is developed. Products are typically developed to meet a market need, but Category 6 is a product looking for a market. What`s the point in change for change`s sake? Category 5 is a great copper horizontal solution, and unbeatable when installed with a fiber backbone.

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