Project Description

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Today, energy efficiency can be considered as one of the biggest technological and financial challenges for developing a better and more sustainable world. This challenge arises from the need of reducing the operating, manufacturing and energy related expenses of enterprises, industries as well as residential buildings, while keeping an eye on targets for the reduction of greenhouse gas emissions. Such "green" trend is speeding up innovation in a wide range of technological fields and services, since it offers the building blocks of innovative efficiency policies for a sustainable but economically viable energy supply, one that would also encourage new industry and employment and generate broad support in society.
In this respect, Information and Communication Technology (ICT) plays a crucial role, since it is widely regarded as an enabler of energy efficiency across the economy. This includes fostering the change in citizens' behavior, as well as improving efficiency in the use of natural resources while reducing pollution and dangerous waste. ICT's nature is so pervasive throughout all kinds of economic and social activities, that a widespread opinion encourages its increasing use for achieving energy savings from the other industries.
Against this background, recent and official studies estimate that ICT industry accounts for approximately 2% of global CO2 emissions, overcoming even the carbon footprint of aviation. In detail, focusing on telecommunication networks, they are estimated to produce about 0.6% of the global CO2 emissions. Today, fixed and mobile network infrastructures have enormous and heavily increasing requirements in terms of electrical energy. For instance, the overall energy consumption of Telecom Italia in 2006 has reached more than 2 TWh (about 1% of the total Italian energy demand, and the second national consumer after the Italian railways), increasing by 7.95% with respect to 2005, and by 12.08% to 2004 [38]. In this respect, Tucker et al. [39] stated that today's networks rely very strongly on electronics, despite the great progresses of optics in transmission and switching, and outlined how energy consumption of the network equipment is a key factor of growing importance. In this sense, they suggested that the ultimate capacity of the Internet might eventually be constrained by energy density limitations and associated heat dissipation considerations, rather than by the bandwidth of the physical components [40]. In addition, starting from an expected deployment of the Telecom Italia network by 2015-2020, Bolla et al. [1] outlined how the power consumption of end-user network devices (e.g., home-gateways, VoIP phones, etc.) will represent a figure of more than twice the energy requirements of Telco equipment.
The origin of these trends can be certainly found in current Internet infrastructures, technologies and protocols, which are designed to be extremely over-dimensioned and available 24/7. Links and devices at access and core levels are provisioned for busy or rush hour load, which typically exceeds their average utilization by a wide margin. While this margin is seldom reached, nevertheless the overall power consumption in today's networks is determined by it and remains more or less constant even in the presence of fluctuating traffic loads.
Advanced features for power management are already available in the largest part of hardware technologies, today used for building network devices. Silicon of network interfaces and of device internal chips already has the possibility of entering standby modes, or of scaling its working speed and, consequently, of lowering their energy requirements.
However, the activation of this power management schemes is generally hindered by the network protocols and architectures themselves, since they are specifically designed to be always available at the maximum speeds. Even PCs are often left powered up 24/7, to maintain their network services and applications correctly working. Indeed, elements in standby (e.g., links, nodes or hosts) do literally “fall off” the network, since they are not able to exchange protocol signaling messages to maintain their “network presence”. Moreover, sleeping or wakeup events generally trigger network nodes to exchange signaling traffic, and to re-converge towards new network logical topologies and/or configurations, causing transitory network instabilities and signaling traffic storms.
Starting from these considerations, GreenNet aims at re-thinking and re-designing different aspects of the current Internet technologies and network protocols to smartly support hardware power management. The pursued approach will exploit two basic features already and largely present in today's networks and devices: the network resource virtualization and the modular architecture of nodes. These features give us the opportunity of using the same base concepts already applied in other fields (e.g., data-centers): decoupling physical elements (e.g., a line-card), which may be put in standby or scaled down their capacities to perform only base operations, from their (virtual) functionalities and resources, so that the latter can be migrated towards other active physical elements of the same device, or of other neighboring devices. In this way, the emptied physical elements may be put in standby mode, while their logical services may continue to work elsewhere.
The GreenNet project aims at investigating a coordinated set of architectural solutions, protocol enhancements, control and optimization strategies, and related software developments in order to support such kind of primitives at both core and access networks. From a more general point of view and in extreme synthesis, the development of such approach will allow:

  • Core network nodes aggregating routing and switching functionalities into a subset of their physical resources (e.g., line-cards), and put their emptied modules in standby mode.
  • End-host terminals (PCs, Customer Premises Equipment) migrating the “network presence” of their applications and/or services to network devices, and entering standby while maintaining network services up.

Obviously, the project goal is not so ambitious to pretend that it can provide a complete characterization of such a complex and multi-faceted task. However, the
approach it takes tries to focus on the integration of three main activities that contribute to the whole picture:

  1. Enabling Green Primitives in Next-Generation Network Devices
  2. Exploiting Virtualization Schemes in Network Protocols and Services
  3. Network-wide green optimizations

The activity 1) will provide the initial inputs by integrating power scaling and standby capabilities into network device hardware platforms. Specific efforts will be devoted to the study and the extension of “open” modular device architectures, able to flexibly distributing network operations to different “internal” sub-elements.
Starting from these energy-aware devices, the activity 2) will focus on network-specific virtualization schemes for decoupling network services and applications from physical elements, and make them able to migrate among active hardware. Specific research activities will be devoted to the virtualization of services and protocols at both home and core network levels. Then, the activity 3) is devoted to explore novel network-wide criteria to design and to control next-generation networks, composed by energy-aware nodes with the introduced capabilities.
The ideas carried out in the GreenNet project will not be limited to the development of analytical and simulative models, but they will be included in a green "proof-of-concept" prototype device (realized on Linux-based SW routers), in order to demonstrate their feasibility and main impact.

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