Digital & Communication Technology
The hidden energy cost of communication
…and how to minimize it with Zenoh. By Angelo Corsaro, PhD CEO/CTO, ZettaScale Technology I
t is undeniable that there is growing scrutiny on the energy consumed by IT infrastructure. Clearly, there is increased attention to reducing the energy consumption of hardware as well as a trend toward provisioning energy from renewable sources. As a consequence, today, many of the cloud mega-vendors pride themselves with having a green data centre — which is indeed great. Thus, the natural question should be: is there anything else we can do?
Surprisingly, the general perception is that we have addressed the bulk of the energy problem, yet the reality is different. Before getting into the details, I want to give you an example that will make this extremely concrete. An example that you can relate to in your daily experience with your mobile phone. Think for a moment about the activity that drains the mobile phone’s battery the fastest. Yes, you got it, it is using the Internet, or more precisely, it is communication in general. This refl ects a general fact that engineers are familiar with: communication is more energy- hungry than computation.
Now that we’ve seen the rabbit hole, let’s follow the white rabbit a bit deeper. Suppose that you are using your mobile phone to control a connected device, such as a thermostat in your living room. In this case, it is almost certain that in order to interact with your device you are communicating with a cloud service sitting thousands of kilometers away from you, which in turn is communicating with your smart device. Imagine for a moment how many network elements you are traversing in this planetary journey…only to reach something that is sitting in front of you. Wouldn’t it be more efficient to interact directly with your device? Of course, it would, thus why don’t we do that? Finally, to give you a sense of the amount of energy we are talking about, let me share a commonly reported example.
34 December/January 2023
Despacito’s video – the fi rst YouTube video hitting the fi ve-billion-views mark – burned, in the process, as much energy as 40,000 US households consume in a calendar year. Based on what I’ve read on the analysis of this number, I’d argue that the communication cost is not even properly considered, thus the situation is even worse.
Breaking down the problem Now that you have a clear understanding of the problem, let’s try to break down its key elements. We have essentially three ways of reducing the energy consumed by communication: ● Make communication devices and networks more power effi cient.
● Exploit locality whenever possible. ● Reduce the amount of data that is sent across the network.
I won’t be expanding on the fi rst point, as this is the predominant approach taken today to reduce consumption, thus I’ll be focusing on the remaining two points.
Without getting into discussions of data Components in Electronics
parsimony, recently advocated by some initiatives such as the Shift Project, there is a lot we can do to reduce the amount of data sent across the network. Locality plays a big role – the key idea is to retain communication as local as possible and thus avoid burning energy with data crossing the Internet without any good reason. For instance, in the example of the connected home device, exploiting locality would mean being able to communicate directly with the device whenever possible — as opposed to systematically letting the data travel across the globe. In addition to locality, reducing the amount of unnecessary data sent across the network can also help a lot. There are two ways of reducing unnecessary data, one is to avoid sending data that nobody is interested in and the other is to reduce to the bare minimum the protocol overhead necessary to carry the user data.
The bad news is that most of the technology deployed today doesn’t make it easy for exploiting location and has
not necessarily been designed to minimize the amount of unnecessary data (from an information theory perspective) sent across the network.
As an example, many of the messaging protocols that are used today for connected devices, such as MQTT, make it extremely hard if not impossible to exploit communication locality due to the limitation of the communication topologies supported. In other terms, MQTT allows applications only to communicate via the mediation of a broker. This broker is usually deployed on a cloud, and here we go, we are missing any chance of exploiting locality.
Luckily, a new protocol designed to address the challenges posed by existing technologies, with energy being one of those, is experiencing enormous traction and adoption. This protocol is called Zenoh (Zero network over-head). Let’s discover what it can do for us.
Zenoh: The zero network over-head protocol
www.cieonline.co.uk
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