Words: Gabriel Verdejo Álvarez (/rdlab); Ivana Golub (PSNC); Maria Isabel Gandìa (CSUC); Sebastian Neuner (Belwü); Silvia Fiore and Tony Barber (GÉANT); and Simon Leinen (SWITCH).
Energy efficiency is a hot topic these days and rightfully so, due to both environmental reasons and increasing electricity prices. This is why it was the main topic of the 17th meeting of the Special Interest Group on Network Operation Centres (SIG-NOC) which took place in November 2022 in Paris hosted by the French NREN, RENATER.
Even though awareness of a strong dependency on external energy sources was known and considered before, recent global events caused high increases of energy costs that, together with a growing eco- and green-consciousness, motivated network operators to explore deeper their current modus operandi as well as existing solutions and opportunities to reduce carbon footprints.
The change is visible in several areas, and equipment vendors are providing Management Information Bases (MIBs) with power consumption data which enables network operators to monitor it on a regular basis. Using this opportunity, network operators are taking further steps by analysing existing usage and measuring energy usage per port. They are also considering alternative solutions, such as optimisation of system topology and configuration, lowering network over-provisioning for power savings, interaction with energy network, and also considering lower consumption equipment during a network equipment procurement process.
For these reasons, many NRENs in Europe and beyond are actively working on using renewable energy sources in two domains – electricity and waste heat, and being able to offer generated energy to other organisations.
Unexpected consequences
Another presenter was Simon Leinen, Network Engineer at SWITCH. He shared that halfway through 2022, Swiss authorities pointed out the risk of a nationwide shortage of electrical power for the coming winter(s). Countermeasures included planned four-hour regional outages. Rightfully, many in the local community were concerned how the SWITCHlan backbone could survive such outages! SWITCH’s equipment is mostly hosted at universities, and for decades they have been relying on the power provided to them. After running a survey, a few “soft spots” were identified, where unlucky combinations of regional outages could “partition” the backbone—a situation to avoid. Some of those were addressed by individual member institutions improving backup power; for others, SWITCH procured, tested, and deployed their own battery-based backup solutions.
According to Simon “This all was a significant amount of (unplanned) work that sometimes pushed us out of our comfort zone. On the other hand, our community appreciated the effort and was eager to help.”
Intelligence design to reduce power
“As a general rule of thumb, you always need more: space, power, battery run-time, cooling,” says Sebastian. “With more efficient gear and a more efficient design, you can do more using the same resources.”
His team decided to run their own lab tests with some brand new 32x 100GE router line-cards that just had arrived. They found that the actual traffic passing through the line-cards could theoretically be up to 23% of the power consumption. This is at maximum packets per second, so in practice the traffic would only make up a single digit percentage of the power. A whopping 70% of energy goes to the line-card itself, without traffic or configured services running, even with the interfaces disabled.
Disabling links between routers during times with low traffic volumes could save between 7% and 10% at the cost of losing redundancy and maybe sending traffic on longer paths. Having a network design where additional capacity is collected on a common line-card that can be powered down while traffic levels are low could save a lot of energy. Switching line-cards on and off is currently very slow and inconvenient, but there are situations like power outages, where this sort of load shedding could be helpful.
As the attendees of the SIG-NOC meeting could see, increasing costs and the green consciousness have pushed several organisations in the research and education community to investigate and work on energy-related initiatives from different angles. On the one hand, the risk of nationwide power outages and restrictions makes it mandatory to have all the right backup mechanisms in place. On the other hand, optimising energy consumption for the computing and networking areas is becoming more relevant every day. The strategy of the organisations needs to be aligned with reduction of the carbon footprint, as investments may be needed to achieve the final goals and the architecture, the services and the physical devices are involved. From using renewable power sources or re-using the heat generated by the equipment to switching down connections while they are not in use, all the options are open and can help.
Research and education organisations can follow the path to energy efficiency from the ideas and the discussions held during the meeting. For instance: having a set of recommendations for tenders and procurements of network equipment and services to invest in energy-efficient systems, collaborating with other organisations to re-use heat generated by the datacentres, performing measurable actions that have a real impact in power consumption. And, of course, being ready for unplanned network outages!
If you want to learn more about the topic, you can visit the meeting wiki page and download all the presentations.
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