Copper Tops 10 Gigabits

Two emerging standards promise to bring 10 Gigabit Ethernet speeds to copper cabling

When the first 10 gigabit Ethernet standard was released nearly two years ago, 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 first products could appear later this year—but there is a catch.

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. But the specification is still in an IEEE study group and remains in the early stages of development. Vendors say it might take another two years to develop and ratify the final specification. 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 exists in many sites today.

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.

If the final twisted-pair standard does require Cat 6, Tim Link, CIO at Ohio State University-Newark Campus, will be ready. The school has already begun installing Cat 6 cable to run 10 Gigabit Ethernet within some building locations across its 300-acre campus. The current campus backbone uses the established 10 Gigabit Ethernet standard: It runs over single-mode fiber and uses six Extreme Networks Inc. Black Diamond 10 Gigabit Ethernet switches.

But the university has also installed Cat 6 cable in a new conference building and will add it to a planned student center and library with an eye toward supporting 10 Gigabit Ethernet over copper. The new cabling system, from CommScope Properties LLC in Hickory, N.C., will support 10 Gigabit Ethernet to the desktop as a means of future-proofing the school for high-bandwidth needs such as distance learning and desktop video applications.

Link says he can "certainly see using copper in the backbone, because it is certainly cheaper." He notes that running fiber-optic cable costs twice as much as twisted-pair. But nobody is going to pull out fiber to put in copper, he adds, so it will be used only in new buildings or for expansions.

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

Some vendors are also unsure whether they will provide products supporting both copper standards, because they are uncertain how much interest customers will have. But Cisco Systems Inc. is already working with suppliers to get parts to support the CX4 standard. 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, although none has made formal product announcements.

Mark Hurley, senior product manager at Enterasys in Andover, Mass., says his company expects to release a CX4 product sometime in the third quarter. "There's very high interest in copper," he says, 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.

See more Emerging Technology articles.


Ethernet Evolutions: AT A GLANCE

10Gbit Ethernet (802.3ae)10GBase-CX4 (802.3ak)10GBase-T
Date of ratification2002 (products shipping now)20042006
CablingSingle-mode or multimode fiberFour-pair twin-axial cablingStar-wired Cat 6, Cat 7 or possibly Cat 5 twisted-pair cable
Range300 meters (over multi-mode fiber), 40 km (over single-mode fiber)15 meters100 meters (Cat 7) or 55 meters (Cat 6)
CostAbout $4,000 to $8,000 per portPredicted to cost half the price of comparable 802.3ae equipmentExpected to come in at one-half to one-third the cost of optical Ethernet
Best useNetwork backbone interconnectsHigh-bandwidth inter-connects between switches and servers in data centersData center inter-connects, backbones and subnetworks that aggregate traffic

Copyright © 2004 IDG Communications, Inc.

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