Networks go green and save you money

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 began 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' 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 10 kW for server racks, says Rakesh Kumar, analyst at Gartner Inc. The average cabinet today consumes about 4 kW, 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.

More efficient technology

Technology improvements that favor energy efficiency are gradually evolving in several areas. "As new generations of products hit the market, more of these kinds of features will be implemented," says Cosgro. Some examples:

  • More modular application-specific integrated circuit (ASIC) designs that allow switches to turn off components not in use, from LED panel lights to tables in memory.
  • General advances in silicon technology will minimize current leakage and gradually boost energy efficiency with each new generation of chips. Eventually, says Cosgro, "we should be able to get networking equipment that uses 100 watts today down to 10 watts."
  • The development of more efficient software that consumes fewer CPU cycles -- and less energy.
  • Equipment designs that run at higher operating temperatures to reduce cooling costs.
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