Johannesburg, 30 Jul 2009
Upcoming 802 standards will energise the development of energy-efficient Ethernet in the next year or two, according to global enterprise networking solutions provider 3Com.
David Law, Consultant Engineer at 3Com, who also serves as the chair of the Ethernet working group (IEEE 802.3) for the IEEE Standards Association, says: “Ethernet connections often lie idle much of the time. Despite this, the average network device uses approximately the same amount of energy during downtime as during peak usage.
“We want to change that with the IEEE P802.3az energy-efficient Ethernet project. This energy-efficient Ethernet project is planning to save power in two ways: first, by switching the link to a low power idle state when it has nothing to do, and second, by reporting that fact to the network devices linked to it.”
As an example, it has been estimated that a 1000BASE-T NIC can achieve a 90% power consumption saving between active and sleep mode, and yet further power savings can be achieved by placing other parts of the system in sleep mode at the same time. The ultimate energy saving will therefore be dependant on how much of the system can be placed in sleep mode as well as the ratio of the time the system is inactive verses active.
Law says: “The IEEE P802.3az Energy-efficient Ethernet project is a key component to green technology. It has adopted an approach called 'low power idle'. Since energy is power consumed over time, the most energy-efficient approach is to transfer the Ethernet data packets at the highest possible date rate, ie, in the least amount of time.
“The next step is to consume the minimum amount of power during the idle time between packets - this is termed low power idle. I believe, however, that another key feature of low power idle is the provision of a sleep and a wake signal to indicate when a link is entering and exiting the low power idle state.”
This enables the devices connected to the link to also enter a low power, or sleep, state when the link is in low power idle state, using the wake signal to exit in time to process the packets. “This feature,” says Law, “can enable significant energy savings over and above the savings that are achieved simply by making the Ethernet physical layer more energy-efficient.”
David Law will chair the next IEEE 802 Standards Education Workshop from 30 November to 4 December 2009, in Honolulu, Hawaii.
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