Gigabit Ethernet to go copper

Users wanting speed without a high cost may get their wish next year, when the copper version of Gigabit Ethernet is standardized by the IEEE.

Industry watchers predict prices of copper-based Gigabit Ethernet cards will sink as low as $250, much less than the fiber-optic versions, which start at around $750. Copper-based switch ports are expected to cost at least 25% less than their fiber counterparts.

Vendors expect to have copper prototypes by year-end, with products shipping as early as the first quarter of next year. At the same time, users can expect to see 100/1000M bit/sec cards, adjustable in the same way 10/100M bit/sec cards are today, says Stephen Haddock, chief technical officer at Gigabit Ethernet switch maker Extreme Networks.

The standard will become final by March "with a good tailwind," says Colin Mick, editor of the IEEE copper Gigabit Ethernet document and principal of The Mick Group. The IEEE working group on the topic, 802.3ab, met earlier this month to go through comments on the latest draft, and Mick says there are no major glitches at this point. The working group hopes to close its ballot by November.

But Mick cautions that the standard goes into uncharted territory. Unlike Fast Ethernet and fiber Gigabit Ethernet, the physical interface for copper Gigabit Ethernet is untested in the real world. Fast Ethernet's physical interface was based on FDDI, and Gigabit Ethernet was based on Fibre Channel.

The physical layer for copper Gigabit Ethernet draws on 100Base-T2, a standard for Fast Ethernet over two pairs of wires in a Category 3 cable. Under 100Base-T2, the other two pairs in the cable could be used for a phone line, but the standard overcame the problem of any cross-talk interference that phone conversations might generate. Still, the standard never resulted in commercial products because it came out so late, Mick says.

The copper version of Gigabit Ethernet uses all four pairs of wires in a Category 5 cable, so the technology needs to get past the same cross-talk hurdles. Mick says the working group has solved that problem, but only in simulations.

A factor that may drive up the cost of copper-based Gigabit Ethernet is the speed needed on the receiving processor of a network interface card or switch, Mick points out. To keep up with the gigabit rate, the processor has only eight nanoseconds to retrieve a full byte from the cable, meaning the processor would have to be as fast as a 486 chip, he says.

Still, Mick says he expects the first copper Gigabit Ethernet adapters to be priced "considerably under $500."

Copper-based Gigabit Ethernet is likely to be confined to server connections. In network backbones, price is less of an issue than other factors, such as reliability. Plus, fiber doesn't have the copper standard's distance limitation of 100 meters.

"I'm sure in a year or two we'll end up with some copper and a lot of fiber Gigabit Ethernet," says Steve Toy, assistant network systems engineer at SAS Institute, which has fiber Gigabit Ethernet. In the backbone, the SAS Institute needs fiber optics to travel up to a mile between switches.

But backbones may benefit as well, as copper Gigabit Ethernet starts to put price pressure on fiber-optic components, says Justin Smith, senior analyst at International Data Corp.: "There's plenty of room to get fiber transceiver costs down."

The result, Smith says, is that users at smaller companies, with less advanced nets will be able to afford Gigabit Ethernet.