IEEE approves first energy efficient Ethernet standard

The IEEE has approved the first standard for reducing the power consumption of Ethernet links. The standard may not have a large impact initially, but it could trigger further developments that will yield a significant reduction in global ICT power consumption and carbon emissions.

New EEE standard is an important step, but its initial impact won’t be dramatic

The Energy Efficient Ethernet (EEE) standard, or IEEE 802.3az, aims to reduce energy consumption at the silicon level by sending network interfaces into a low-power mode during periods of low link utilization. In other words, it makes Ethernet switches and devices less chatty during “quiet states” (i.e. when an active Ethernet connection is not transmitting user data) without interrupting the network link. One of EEE’s advantages is that no complex configuration is needed as EEE-enabled devices will save energy automatically.

The need for the EEE standard, which was ratified in September, has arisen from faster Ethernet speeds and greater network loads, which have resulted in higher electricity bills. EEE’s long-term importance is significant given that the amount of Ethernet traffic will continue to grow and speeds will continue to increase.

The greatest power-saving opportunities for EEE are for devices with low network utilization rates. The less a device utilizes an Ethernet connection, the more quiet states (and therefore the more power-saving opportunities) it has. EEE power savings will be limited in datacenters because there is generally less network traffic downtime in these environments than there is with client devices. However, in notebooks, desktops, and workstations, deploying EEE on the Ethernet port could reduce the device’s total energy consumption by 75% to 80% – a rate that could lead to cumulative annual savings of multiple terawatts.

Jeff Lapak, who is the industry lead for the EEE taskforce at the University of New Hampshire Interoperability Laboratory, estimated that if all Ethernet devices in the US that currently run over twisted-pair cable were EEE-enabled it would save approximately $300m per year. Obviously, the replacement of traditional Ethernet ports with EEE-enabled ports will happen gradually over the next decade, although by late 2012 all new Ethernet ports will likely be EEE-enabled. However, $300m per year is a drop in the ocean of total datacenter power costs, let alone total ICT power costs.

EEE’s greatest potential is to spur energy efficient software standards for client device CPU and memory functions

EEE is focused on 10GbE and backwards, and does not cover 40GbE and 100GbE, which makes sense given that these are aimed at datacenters where server architectures are designed to minimize idle time. EEE also works over a Power-over-Ethernet connection because EEE reduces power consumption at the physical layer of the Ethernet connection regardless of the power source.

Where EEE falls down is fiber-optic Ethernet. The standard does not cover multi- or single-mode fiber-optic connections. While fiber-optic represents a small portion of the overall Ethernet market, future energy conscious standards will need to address it as its usage is likely to grow, especially due to the increasing deployment of PON technologies.

Ovum believes that the greatest impact of EEE will likely be from its impact on potential new software standards. EEE only exploits the link utilization between Ethernet port and switch, but a device’s CPU and memory consume far more power than the Ethernet port. However, if the EEE-enabled Ethernet port can recognize when the link is idle, it could also alert software to shut down some CPU and memory activity beyond the reductions available from current idle-state technologies. In other words, EEE may lead to software triggers that turn off further computing resources at the system level, not just at the silicon level.

This is where Ovum sees EEE’s greatest potential – as an enabling technology for new energy efficient software standards.