Networking

Copper tops 10 Gigabits

When the first 10 gigabit Ethernet standard was released, sky-high prices of more than $50,000 per port kept many IT organizations on the sidelines. Though prices have dropped since then, the technology remains expensive, in part because it runs only on fiber-optic cabling.

Two emerging standards could change that. Each will bring 10 Gigabit Ethernet speeds to copper cabling, enabling a new generation of switches and networking equipment that promise a less expensive entry point for 10 Gigabit networking.

The more evolved of the two standards, the 10GBase-CX4 specification, created by the Institute of Electrical and Electronics Engineers Inc.'s 802.3ak Task Force, enables Ethernet to run over CX4, or four twin-axial copper cable pairs. Although switch vendors say equipment supporting this scheme of 10 Gigabit Ethernet on copper will cost perhaps half that of a fiber infrastructure, the range is limited to 15 meters. Nonetheless, that's enough to connect switches or servers inside a data center—the standard's intended purpose.

The other proposed IEEE standard, called 10GBase-T, will enable 10 Gigabit Ethernet speeds on twisted-pair cabling over a range of up to 100 meters. And even when products appear, the standard may face an uncertain future. One reason: the worry that 10GBase-T will end up running only on Category 6e (Cat 6) twisted-pair cable, rather than the Category 5e (Cat 5) cabling that existed in many sites.

Several networking vendors that plan to offer networking products this year that support CX4 claim that the technology represents significant cost savings for customers planning data center connections with fiber. Final IEEE ratification of the CX4 standard is expected this month. In contrast, 10GBase-T is unlikely to be ratified until 2006, according to Bradley Booth, chairman of the IEEE's 10GBase-T Study Group.

As for the 10GBase-CX4, the best fit may be for short distances between switches inside a data center, possibly within a single chassis or to another chassis nearby, vendors say. But Jay Adelson, chief technology officer at Equinix Inc. in Foster City, Calif., isn't sure that the standard will be all that useful even within the data center. He says the collocation facilities his company runs for hosting Web sites are so large that the 15-meter distance limitation won't be enough for many purposes. Like many organizations, Equinix is already using fiber for high-speed backbones—and fiber can support 10 Gigabit Ethernet over cabling runs of up to 300 meters.

“Our facilities are large, and it would be harder to do copper. I'm not a copper fan, because of the distance limits. Optical fiber is already easy to terminate,” Adelson says.

Equinix uses San Jose-based Foundry Networks Inc.'s 10 Gigabit Ethernet switching gear. Adelson says he's sure Foundry will offer 10 Gigabit products that support the new copper standards, but given the extra cost, he wonders whether users will buy it.

Vendors Cautious

The cost for copper-switch modules should be half that of $4,000 fiber-optic modules used in Cisco's Catalyst 6500 series switches, says Bruce Tolley, senior manager for emerging technologies at Cisco.

Dan Dove, the chairman of the IEEE task force behind the 10GBase-CX4 twin-axial copper cable standard, says overall costs for copper in the data center should be 5% to 20% of the cost for fiber. He's hoping that CX4 can deliver 10 times the bandwidth of Gigabit Ethernet for two to three times the cost. “That was our guiding principle,” Dove says.

As for the nascent twisted-pair standard, Tolley says Cisco will support it, but he adds that the company “can't do anything until people deliver the parts to us.” He predicts that early installations of 10GBase-T will be expensive until volume sales bring down prices.

Tolley says that most installations of 10 Gigabit Ethernet have been at high-end data centers, service providers and universities, “where they have been quite comfortable with fiber.” But, he adds, “there has been demand for a lower-cost solution.”

Several other vendors, including Extreme, Foundry, Nortel Networks Ltd. and Enterasys Networks Inc., say they expect customers to begin to ask for copper connections.

Mark Hurley, senior product manager at Enterasys in Andover, Mass, says, while agreeing with Cisco that connection modules for CX4 could sell for half that of fiber units.

But analysts aren't enthusiastic about either standard catching on. “The demand for either copper standard is relatively small,” says Mark Fabbi, an analyst at Gartner Inc. in Stamford, Conn.

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