Is your network 10GigE ready? The cabling industry is ahead of the new IEEE standard with products available today.

Now that the IEEE has approved the latest LAN high-speed transport technology for running 10-Gigabit Ethernet (10GigE) over unshielded twisted-pair (UTP) cabling, the quickest adoption will probably be in the data center and server farm areas. This is because aggregate backbone speed requirements have already surpassed the current Gigabit Ethernet standard requirements. This is also due to the availability of copper-based solutions that will reduce expansion costs that are typically higher with fiber-based 10GigE systems.

The real hurdle for implementing this new copper 10GigE UTP technology is the cable, connector and patching products required by the new standard. An entirely new cabling system is mandatory in order to make 10GigE operate correctly. The existing Category 6 cable plants might be useable at distances less than 37 meters, but the current TIA 42.7 working groups are still defining the component requirements for both the new 100-meter Category 6A cabling standard, TIA 568-B.2-Ad10, and the 37-meter, existing Category 6 mitigation TSB-155.

Early in the IEEE process, the physical layer performance requirements were established for the entire cabling "channel" (i.e., the cable, connectors and patching that go between the new 10GigE switching equipment and the end device's network interface card, or NIC). Ultimately, this enabled industry working groups to come up with a firm channel model and propose a performance specification.

In the steady progression of Ethernet, the demand for more capacity per channel has been self-fulfilling. As the design moved away from coax-based systems to UTP, the transmission hardware has been on an almost exponential slope by factors of 10 times every four years or so.

The core electronics that make these Ethernet evolutions possible have become more complex and demanding as the speed has increased. The switches, routers and NICs into which they go are required to operate with tighter design specifications and must compensate for more heat. Not surprisingly, the increase in bandwidth has always come with an increase in the operating frequency of the chips that make it work. This increase in frequency has also made the design of the cabling systems more difficult.

The design of cables and connectors and how they interact with each other in installed systems has also changed exponentially with the increase in system frequency. As the frequency increases, the performance of copper-based transmission systems degrades and becomes more susceptible to noise. To offset this, manufacturers have developed physical and system designs to enable this tenfold increase in bandwidth.

As a result, there has been a corresponding doubling of the transmission frequency with each generation of Ethernet. Manufacturers have designed these systems in concert with IEEE, and have also added new digital signal processor technologies to increase signal strength and minimize noise so that systems can operate with minimal errors.

The higher application frequency requirements associated with 10GBase-T transmission have also increased the complexity of verifying the cabling system's performance in both the lab and real-world environments. The signal modulation used by 10GBase-T, known as PAM-16, has multiple levels, where bits of data are encoded onto the signal being transmitted.

With 16 discrete encoding levels, 10GBase-T copper systems need 500 MHz of useable bandwidth to operate properly over the maximum UTP cabling distance of 100 meters, the maximum distance requirement for Ethernet-based systems. While 500 MHz may be considered a relatively low frequency for broadband applications, it is twice the bandwidth of what Category 6 cabling can deliver.

The 500-MHz transmission frequency of 10GBase-T has introduced a new type of noise impairment on balanced UTP cabling systems called alien crosstalk, which is signal or noise coupling between adjacent cables. Alien crosstalk coupling occurs with respect to both the near end and far end of the installed cabling system.

Transmission performance on the cabling can be verified with testing conducted on a single Category 5e or Category 6 cable. Testing for alien crosstalk requires that multiple cables (known as disturber or exciter cables) be energized simultaneously in a cable bundle. This testing ensures that they do not affect the transmission of 10GBase-T signals on adjacent disturbed (i.e., victim) cables.

Problems such as alien crosstalk arise with most new technologies when each of the systems is taken to its design limits. Operational tolerances can overlap and result in system failures. The best way to avoid this is to over-design the systems, and to install cabling infrastructures that exceed the minimum design specifications whenever possible.

For the past six months, intensive independent testing has been performed on the major 10GigE cabling systems currently available on the market. Data has shown that there are some good-performing 10GigE systems being sold and installed today that will fully meet the required channel performance requirements. When the 10GigE switching hardware is fully available, buyers will already have many viable solutions available on the market to choose from.

Purchasing a 10GigE solution, however, can be somewhat of a daunting and challenging task if you are not equipped with all of the latest facts and statistics on all of the 10GigE solutions available on the market. How do you know how or why to choose one manufacturer's solution over another?

If a company says it meets 10GigE requirements in its collateral, should that be enough? In reality, the answer is no. Buyers should always do their due diligence on any 10GigE cabling solution prior to buying it. Dig beneath the brochure hype, and require full disclosure from the manufacturer or distributor. Buyers always have the right to request a copy of the manufacturer's spec sheets or test results that will verify that the 10GigE cabling products meet the testing parameters as specified in ISO, TIA or IEEE cabling standards.

There are also independent third-party companies that will provide these test results to you at no additional charge. At the end of the day, the manufacturer or distributor should prove that its 10GigE cabling solution meets the standard requirements and will efficiently run your applications today and well into the future.

Pete Lockhart is vice president, technologies, for Anixter, Glenview, Ill.

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