Users warned on inefficient switches

D-Link has introduced business-targeted desktop Ethernet switches that include its Green Ethernet technology, which detects inactive ports and short cables, and throttles its transmit power accordingly. The company claimed that in tests, this reduced a switch's power consumption by up to 46 percent.

"D-Link leads the market with Green Ethernet," claimed Chris Davies, the company's U.K. general manager. "With the energy and costs savings the technology can deliver, there's simply no excuse for organizations not to migrate to energy-optimizing network solutions."

The maximum power saving occurs when all the connected devices are switched off, as disconnected switch ports are powered down.

However, D-Link said that its new DGS-1016D 16-port and DGS-1024D 24-port unmanaged Gigabit switches can save power on active ports as well, because they dynamically detect the cable length and reduce their transmit power to suit.

In contrast, most other desktop switches assume that every cable is the maximum permissible length of 100m, and transmit at full power accordingly.

D-Link formerly offered Green Ethernet technology only in small switches aimed at the small- and home-office market. It said it is particularly relevant to Gigabit Ethernet switches, as they generate more heat than slower varieties. Reducing a switch's power consumption could also extend its lifespan, the company added.

It said that its Green Ethernet plans are separate from the IEEE's energy-efficient Ethernet (EEE) study group, but it will incorporate the IEEE-EEE specs when they become available.

EEE is researching ways to save energy such as reducing the speed on a link when traffic volumes are low. However, while this offers greater opportunity for power savings, it will require changes at both ends of the link, whereas the D-Link technology works with existing devices.