Gail Leach Carvelli
When Anixter Inc. (Skokie, IL), a value-added provider of integrated communications systems and services, first introduced its Levels Program in the late 1980s, it did so because no uniform standard of measurement existed to compare one brand of cable to another. The distributor`s initiative, in turn, laid the groundwork for standards organizations, such as the Electronic Industries Association and Telecommunications Industry Association (eia/tia--Arlington, VA), to devise category designations for unshielded twisted-pair (utp) copper cable, based on the Anixter program.
To stay ahead of today`s advancing applications, Anixter is launching Levels `97, which is the most recent update of its cable-performance specification program. The updated program defines the performance characteristics of utp cabling beyond 100 megahertz. The company says this program is necessary for advanced applications, such as intranet technology, three-dimensional imaging, multimedia programs, video-to-the-desk, computer-aided design, and broadband video. The new program builds on the tia/eia-568a commercial building telecommunications cabling standard.
According to Gary Conrad, Anixter senior vice president for structured cabling systems, this type of program is needed because it often takes many years to ratify a standard, making portions of tia/eia-568a obsolete. "Therefore, implementing advanced applications could cause cable that adheres to today`s standards to fail in the future," he explains. "I don`t think many of us in the network-infrastructure industry, including Anixter, could have predicted that applications requiring increased bandwidth would be developed so quickly that a lot of standard Category 5 cable would become electrically insufficient."
The Levels `97 program divides cable into three performance levels:
- Level 5--Cable specified in this category must meet the more stringent requirements for Category 5 cables as spelled out in the international standard iso 11801, which allows cables meeting its requirements to be used globally. It must meet stringent 4-pair near-end crosstalk requirements, or power sum, to 80 MHz.
- Level 6--This level includes cable performance to what some in the industry have called high-end Category 5, or Category 5+ cables. It requires a 10-decibel attenuation-to-crosstalk ratio (acr) at 155 MHz, as well as power-sum requirements to 100 MHz.
- Level 7--This level encompasses a new generation of recently launched products that meet at least twice the Category 5 bandwidth requirement. These cables achieve 10-dB acr at 200 MHz and are power-sum tested to a higher near-end crosstalk value than Level 6. They should support multiple applications at different frequencies under one jacket, and will support Gigabit Ethernet at 100 meters.
To be considered for a specific Anixter level, cable must pass specification tests at the independent, certified Anixter Structured Cabling Laboratory in Mount Prospect, IL. All cables must also meet a stringent 4-pair crosstalk measurement using power-sum testing.
Frank Coletto, vice president of marketing for structured cabling systems, says that Anixter developed Levels `97 because distinguishing one Category 5 cable from another is almost impossible. "And," he says, "Category 5 cable construction and electrical performance vary widely among manufacturers. In fact, more than 100 different electrical designs of plenum cables exist, all of which have varying electrical-performance characteristics, yet are still Category 5-compliant."
He adds, "Today there aren`t any standards for cable over 100 MHz, even though there are gigabit network proposals requiring 250-megabit-per- second transmission over each of the four utp pairs."
Colleto says that Anixter`s goal is to clear up confusion in the industry and fill in the holes in existing standards. "Even more important," he says, "is to protect Anixter customers from making the wrong purchasing decisions by providing them with the information they need to select the best, most cost-effective product for current and future applications. Anixter worked with the top 40 cabling and systems manufacturers to create an unbiased system of specifying cable."
Cabling products certified to Levels `97 must fully meet the electrical requirements for the level, be marked with a sticker indicating level of performance met, come from a manufacturer registered to iso 9000, be manufactured with only virgin materials, and not include factory splices in insulated conductors.
For more information about the program, visit the Web site at www. anixter.com or call (847) 677-2600.