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Top1. Introduction
Information and Communication Technology (ICT) and telecommunication networks have been historically and fairly considered as the enabling factors for monitoring third-party energy wastes and in achieving high levels of efficiency (EU Commission, 2008). For instance, the ICT and network technologies are even more applied for building smarter and more energy-efficient environments (e.g., buildings, homes), in energy distribution (i.e., smart grids), and in many other industrial fields. But today, state-of-the-art ICT and network technologies themselves are not ready to effectively support all these third-party applications, since they are not enough energy efficient (Roth, 2006), and even the same evolution of the Internet might be eventually constrained by energy-related aspects (Baliga, 2007). The International Telecommunication Union (ITU) estimated the ICT carbon footprint (excluding the broadcasting sector) to be between 2% and 2.5% of total global greenhouse gas emissions (ITU, 2009). The main components within the ICT industry include the energy requirements of PCs and monitors that contribute with 40% and data centres with 23% of the total emissions. These figures become not so surprisingly, if we consider that, except for mobile and handled devices, energy-efficiency has almost never been a design constraint/objective.
Triggered by the increase in energy price, the continuous growth of customer population and networked device density (e.g., PCs at homes or offices, servers into datacenters), the spreading of broadband access, and the expanding number of services (in datacenters) being offered by telecom operators and Internet Service Providers (ISPs), the energy efficiency issue has become a high-priority objective also for wired networks and service infrastructures.
For these reasons, the control of energy consumption on telecommunication networks and networked devices is nowadays a research topic of enormous interest in academic and industrial communities. Much likely as in other fields, there are two main motivations that drive the quest for energy-efficiency (Bolla, 2011):
- 1.
The environmental one, which is related to the reduction of wastes, in order to impact on CO2 emission;
- 2.
The economic one, which stems from the reduction of costs sustained by the operators to keep the network up and running at the desired service level and their need to counterbalance ever-increasing cost of energy.
Many efforts have been undertaken by the research community in order to deeply understand the source of such inefficiencies, to develop new technologies and eco-friendly solution, and to reduce ICT and network energy absorptions (see section II). Next-generation network nodes, ICT equipment, and protocols will certainly include new advanced energy-aware capabilities, allowing to drastically increase their energy-efficiency and making their energy absorptions proportional to the real workload.
However, in systems so complex, multi-layered and distributed like the ICT ones, these research efforts may benefit of the presence on the field of auxiliary tools able to monitor and to suitably and synthetically evaluate current deployed infrastructures in terms of operating behaviours, instantaneous performance and energy consumption. Notwithstanding these auxiliary tools may eventually increase the overall energy consumption, as suggested by the Jevsons’ paradox (Alcott, 2005), they can provide very useful data that may help researchers, engineers and system administrators in evolving, designing and developing new green technologies, as well as suitably dimensioning and consolidating future ICT infrastructures and services.