LAN developer Solarflare has developed a chipset for 10Gig Ethernet over copper which is more compact than its previous generation and needs half as much power. It claimed this will enable a dual-port card for a server to operate well within the 25W limit of a single PCI Express slot.

It means that 10Gig Ethernet over CAT6 twisted-pair copper cabling - the 10GBase-T spec - is now the cheapest answer for data centers needing more speed, for example to support converged data and storage networks, argued Solarflare CTO George Zimmerman.

"We have priced the chips so our server adapter customers can bring cards to market at around $400 to $500," he said. "For switch customers, I think it will be around $600 to $700 a port, so a 10G switch-to-server link will be $1000 or so.

"That's around a quarter to a third the cost of the cheapest optical link, 10GBase-SR. Optical is still longer range, of course, and some service providers have standardized on fiber, but most data centers are cabled. 10GBase-T will be cheaper both in capital terms and operational."

The new chips are a PHY (physical interface) and a controller for 10GBase-T. Zimmerman said that the PHY includes a power-saving feature called SmartEnergy, which allows a network card to have a range of power modes all the way from wake-on-LAN to full power, where it consumes around 6W.

"SmartEnergy will make Energy Efficient Ethernet easier to do, but it also makes it the first 10G chip to be aligned with the PCI power spec," he said.

The lower power will also benefit switch makers, Solarflare said. With a typical budget for PHYs of 150-200W per switch, it puts a 32-port 1U switch within reach and 48-ports on the horizon - subject of course to suitable switching silicon becoming available.

"Getting the power down was really important," Zimmerman continued. "About half the decrease comes from the shift to 65nm - we had been using a mix of 90nm and 130nm. The other half comes from better design and getting rid of the interconnect - the PHY is now one chip instead of two."

It mirrors the reductions made in the Gigabit copper (1000Base-T) generation, he added: "The first PHYs were 8W, that dropped to 5.5W, and we went to market with under 5W."

He said that the new controller chip has built-in virtual NIC support, including Microsoft's TCP Chimney acceleration. It can support up to 4096 VMs per card, either using VMware's NetQueue, or a bypass scheme for Xen, which keeps a "slow path" running through the hypervisor so VMs can still be moved from one physical server to another.