Saving Power and Money with Energy Efficient Ethernet (EEE)
In today’s increasingly competitive business landscape, companies look to every cost-saving advantage available. Manufacturers need to be more efficient than ever before. One place, however, that most companies overlook is the network infrastructure on the factory floor.
Hundreds of network devices, including switches, greedily consume power around the clock, seven days a week, 365 days of the year. Given enough time, these costs add up. It would be worth it if they were constantly doing productive work, but the fact of the matter is that there’s plenty of idle time where our equipment isn’t transmitting any data. It’s just sitting there, using electricity and raising our bills.
That’s why so many organizations are turning to Energy Efficient Ethernet (EEE), also known as Green Ethernet, to save money without sacrificing performance. EEE is defined by the official 802.3az standard, which was approved by the IEEE Standards Board in 2010.
So what is EEE? In short, it cuts wasted power in networks by “putting them to sleep” when they’re not in use. These “micro-naps” may be as short as a millisecond, but aggregated over time, they provide noticeable and tangible cost savings.
How Does EEE Work?
It all starts at the physical hardware layer — with devices like switches, routers, and “end devices” (such as PLCs, HMIs, and I/O). This equipment forms the backbone of our network. For information to flow across this network, we need to connect them to let them talk to each other, and Ethernet, with its openness and flexibility, is the dominant technology utilized.
Historically, Ethernet links constantly consumed power even when the link was idle. Even though our devices aren’t sending information across the network, these devices remain on high-alert standby, wasting power. In fact, LAN links generally average less than 10% utilization. And it doesn’t end there; we also see a multiplier effect as devices throughout the network continue in the same vein.
EEE manages our Ethernet links to minimize power consumption. To do so, it uses a signaling protocol called Low Power Idle (LPI). Essentially, ports exchange LPI indications to figure out whether or not there’s any traffic coming across the network. If not, then the link goes idle and enters low-power mode until the next packet arrives.
In order to get the most out of EEE, we need to optimize our transmissions so that our links send the most amount of data in the shortest amount of time. This lets us maximize low-power time and thereby lowers our electric bill. This brings us to packet coalescing.
Roger Allen explains in Power Electronics, “This involves the use of a first-in first-out (FIFO) memory queue in the Ethernet interface (in the host network interface controller or NIC card and switch or router line card). The FIFO collects, or coalesces, multiple packets before sending them on a link as a burst of back-to-back packets.”
It’s like making a grocery list. Instead of running out to the store whenever we use the last milk or bread, we’ll make a list and buy everything at once during a weekly trip. It just makes sense. Simply put, we’re applying that same logic to Ethernet.
Further demonstrating its benefits to work in several types of networks, EEE can accomplish all of this with only a miniscule impact to the determinism of the network.
Implementing EEE
As awareness of the benefit of energy efficiency increases, the number of devices supporting EEE continues to grow. This trend is continuing for both enterprise and industrial equipment. Generally, it is very simple to realize the benefits of EEE. You simply need to ensure you are using devices that comply with the IEEE 802.3az standard, and that the feature is enabled. Many unmanaged switches come with this feature enabled out of the box, while managed switches and other end devices may require a quick settings change.
Photo by Taylor Vick on Unsplash
The Takeaway: Your Network on EEE
Let’s not forget the most important question: Why do we want to use EEE?
According to Michael Bennet at the Lawrence Berkeley National Laboratory (LBNL) and chairman of the IEEE 802.3az Task Force, this standard can bring savings between 1.47 and 2.21 TWh/year to commercial data centers in the United States. That results in annual savings of $118 to $177 million.
To drive this point home, an industrial unmanaged switch has a typical current consumption of about 500 mA and a supply voltage of 24 V DC to 48 V DC. EEE can cut the energy consumption by 40%. If your application uses multiple switches, this will result in a significantly lower electric bill over time. And that’s not even factoring in the environmental impact of all that wasted electricity. As more companies commit to reducing their carbon footprint, EEE is a crucial tool for accomplishing this goal. As devices become faster and more resource-intensive, we need to conserve power when we can. With EEE, individual switches can cut energy usage by 40 to 80 percent. When we factor in the multiplier effect that this has on higher level devices, companies can realize even more savings.
Ultimately, Energy Efficient Ethernet (EEE) is an obvious choice because it cuts cost without sacrificing productivity. We don’t need to compromise. This makes capitalizing on the benefits of EEE even more attractive to companies that want to stay competitive in tomorrow’s technological world.
Originally published at https://www.linkedin.com.