Networks go green and save you money

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These types of applications represent "a huge opportunity for savings," says Cosgro.

Better specs and standards

Emerging standards could soon help save energy during periods when networks sit unused and will help IT compare the relative efficiency of competing products.

Energy Efficient Ethernet

The emerging IEEE P802.3az Energy Efficient Ethernet (EEE) draft standard may offer the biggest bang for the buck by cutting power consumption for network equipment when utilization is low. Today Ethernet devices continuously transmit power between devices, even when network traffic is at a standstill. Equipment supporting the EEE standard will send a pulse periodically but stay quiet the rest of the time, cutting power use by more than 90% during idle periods.

In a large network, that's "a whole lot of energy" that could be saved, Cosgro says.

The standard will allow "downshifting" in other modes of operation as well. In a 10Gbit switch, for example, individual ports that are supporting only a 1Gbit load will be able to drop power down from 10Gbit/sec. to what's required to support a 1Gbit/sec. configuration, saving energy until activity picks up again.

Products built to support the EEE standard should start appearing by 2011, says Aldrich.

Virtual NICs

Another emerging technology, the PCI-SIG's Multi-Root I/O Virtualization, provides servers within a rack with access to a shared pool of network interface cards. This happens via a high-speed PCI Express bus -- essentially extending the PCIe bus outside of the server. "Instead of a NIC in every server, you'll have access to a bank of NICs in a rack, and you can assign portions of the bandwidth of one of those NICs to a server," probably using tools provided by the server vendor, says Burton Group's Reeves.

Energy savings will come from increased utilization of the network -- achieved by splitting up the bandwidth in each "virtual NIC" -- and the need for fewer NICs and switch ports, he says. He expects to see standards-compliant products perhaps as early as 2012.

Energy efficiency ratings

Finally, standardized measurements of energy efficiency have started to appear on some networking equipment. Juniper Networks, for example, includes an Energy Consumption Rating (ECR) on the data sheets for some of its products. ECR is a draft specification, created by the ECR Initiative consortium. Lawrence Livermore Labs, Ixia and Juniper developed the specification, which measures performance per energy unit for networking and telecommunications equipment.

green networks

Both Cisco and Juniper are backing the Alliance for Telecommunications Industry Solutions' Telecommunications Energy Efficiency Rating (TEER) specification, which ATIS introduced last year.

However, neither specification has been universally accepted. Juniper supports ECR but doesn't include the rating on all of its products' data sheets. Cosgro says HP hasn't included either of the energy-efficiency standards in its data sheets because users don't understand the metrics. "What they care about is the number of watts used by the solution," he says.

Another strike against the specifications, Cosgro says, is that they lack a detailed, open rating methodology. That means vendors can choose rating firms with methodologies that best suit their needs.

That kind of truly open specification isn't likely to appear until later this year, when the EPA's Energy Star rating for large networking equipment should be released. (The EPA developed an Energy Star Small Network Equipment specification last December, but most enterprise networking equipment will be covered by the upcoming Large Network Equipment specification.)

According to an EPA spokesperson, the agency plans to announce a draft specification for data centers in June 2010, and in late 2010 for data center networking equipment. The new specification, which will cover components such as power supplies and internal chips, Energy Efficient Ethernet and overall power consumption for a device, will be "the key energy efficiency standard" going forward, Cosgro says.

The easiest way for network administrators to increase energy efficiency today is to buy new equipment, but that's likely to be a gradual process because administrators must weigh the age of equipment against potential efficiency gains. While a 15% cut in energy costs adds up when spread across thousands of servers, on a few racks of switches the total savings are much smaller.

Even for a single rack, the cost per kilowatt usually won't support an upgrade. "Most people will not save enough energy in the short run to justify replacing their equipment," warns Burton Group's Reeves. "Stay on your regular life cycle."

Robert L. Mitchell writes technology-focused features for Computerworld. Follow Rob on Twitter at, send e-mail to or subscribe to his RSS feed.

Copyright © 2010 IDG Communications, Inc.

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