Networks Can Be Green Too

More-efficient network equipment designs could soon help reduce data center power and cooling costs.

Servers get most of the glory when it comes to energy management, but networking gear is about to catch up.

Over the past year, network equipment vendors have begun to emphasize energy-efficiency features, something that was never a top priority before, says Dale Cosgro, a product manager in Hewlett-Packard Co.'s ProCurve network products organization.

Networking infrastructure isn't in the same class as servers or storage in terms of overall power consumption -- there are far more servers than switches -- but networking can account for up to 15% of the total power budget.

And unlike servers, which have sophisticated power management controls, networking equipment must always be on and ready to accept traffic.

Also, networking power use at the rack level is significant. A Cisco Catalyst 6500 series switch consumes as much as 2kW to 3kW per 42U-high rack. Cisco Systems Inc.'s largest enterprise-class switches, the Nexus 7000 series, can consume as much as 13kW per rack, according to Rob Aldrich, an architect in Cisco's advanced services group. A 13kW cabinet generates more heat than many server racks -- enough that it requires careful attention to cooling.

By way of comparison, most data centers top out at between 8kW and 10kW for server racks, says Rakesh Kumar, an analyst at Gartner Inc. The average cabinet consumes about 4kW, says Peter Gross, vice president and general manager of HP Critical Facilities Services.

Vendors have already adopted some energy-related features, such as high-efficiency power supplies and variable-speed cooling fans. But with switches, there's a limit to what can be done in the area of power management today. Most idle switches still consume 40% to 60% of maximum operating power. Anything less than 40% compromises performance, says Aldrich. "Unless users want to accept latency, you have to have the power," he adds.

But huge improvements are coming, says Cosgro.

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