Aruna Prem Bianzino

Energy-aware routing: A reality check

In this work, we analyze the design of green routing algorithms and evaluate the achievable energy savings that such mechanisms could allow in several realistic network scenarios. We formulate the problem as a minimum energy routing optimization, which we numerically solve considering a core-network scenario, which can be seen as a worst-case for energy saving performance (as nodes cannot be switched off). To gather full-relief results, we analyze the energy savings in various conditions (i.e., network topology and traffic matrix) and under different technology assumptions (i.e., the energy profile of the network devices). These results give us insight into the potential benefits of different “green” technologies and their interactions. In particular, we show that depending on the topology and traffic matrices, the optimal energy savings can be modest, partly limiting the interest for green routing approaches for some scenarios. At the same time, we also show that the common belief that there is a trade off between green network optimization and performance does not necessarily hold: in the considered environment, green routing has no effect on the main network performances such as maximum link utilization.

GRiDA: A green distributed algorithm for backbone networks

In this work, we face the problem of reducing the power consumption of Internet backbone networks. We propose a novel algorithm, called GRiDA, to selectively switch off links in an Internet Service Provider IP-based network to reduce the system energy consumption. Differently from approaches that have been proposed in the literature, our solution is completely distributed among the nodes. It leverages link state protocol like OSPF to limit the amount of shared information, and to reduce the algorithm complexity. Moreover, GRiDA does not require the knowledge of the actual traffic matrix, an unrealistic assumption common to all other proposals. Results, obtained on realistic case studies, show that GRiDA achieves performance comparable to several existing centralized algorithms.

GRiDA: GReen Distributed Algorithm for energy-efficient IP backbone networks

In this work, we face the problem of reducing the power consumption of Internet backbone networks. We propose a novel algorithm, called GRiDA, to selectively switch off links in an Internet Service Provider IP-based network to reduce the system energy consumption. Differently from approaches that have been proposed in the literature, our solution is completely distributed and thus not requiring any centralized oracle. It leverages link-state protocol like OSPF to share a limited amount of information, and to reduce the problem complexity. Another key feature of GRiDA is that it does not require the knowledge of the actual and past/future traffic matrices, being able to run in real-time, where this information would not be available. Results, obtained on realistic case studies, show that GRiDA achieves performance comparable to several existing centralized algorithms, guaranteeing energy savings up to 50%.

Distributed algorithms for green IP networks

We propose a novel distributed approach to exploit sleep mode capabilities of links in an Internet Service Provider network. Differently from other works, neither a central controller, nor the knowledge of the current traffic matrix is assumed, favoring a major step towards making sleep mode enabled networks practical in the current Internet architecture. Our algorithms are able to automatically adapt the state of network links to the actual traffic in the network. Moreover, the required input parameters are intuitive and easy to set. Extensive simulations that consider a real network and traffic demand prove that our algorithms are able to follow the daily variation of traffic, reducing energy consumption up to 70% during off peak time, with little overheads and while guaranteeing Quality of Service constraints.

Apples-to-apples: a framework analysis for energy-efficiency in networks

Research on energy-efficiency of communication networks has already gained the attention of a broad research community. Specifically, we consider efforts towards improving environmental sustainability by making networks energyaware. An important step in this direction is establishing a comprehensive methodology for measuring and reporting the energy consumption of the network. In this work, we compare and contrast various energy-related metrics used in the recent literature, by means of a taxonomy definition, as well as through relevant case studies. We believe this to be a first necessary step towards the definition of a common framework for the performance evaluation of energy-aware networks.

Greening the Internet: Measuring Web Power Consumption

This evaluation of end-user PCs browsing the Web - and loading Flash plug-ins - measures power consumption by considering the hardware platform, operating system, browser, and website. It also reveals the unnecessary power expenditures of tabbed browsing.

Enabling sleep mode in backbone IP-networks: A criticality-driven tradeoff

The energy consumption of network devices, and, as a consequence, of communication networks, is generally independent from their level of utilization, which results in a waste of energy when the network is lightly loaded. Ideally the consumption of a network should be proportional to the amount of traffic it conveys. The most straightforward way to enforce such a proportionality between the network energy consumption and its utilization level, is to dynamically adapt the status of network devices to the load, forcing a subset of them to enter a sleep state during the low activity periods. We present in this paper an algorithm to dynamically put links into a sleep state, based on a cooperative-game approach, named “L-Game”. Our approach decides which links can be switched off based on a measure of the criticality of each link expressed as its Shapley value. This measure combines topological aspects and traffic conditions. Simulation results on real network scenarios show that our solution achieves a better trade off between energy saving and Traffic Engineering than other legacy approaches.

Testbed implementation of control plane extensions for inter-carrier GMPLS LSP provisioning

This paper presents a testbed implementation of an inter-carrier GMPLS (Generalized Multi Protocol Label Switching) service architecture recently proposed. This architecture couples the Path Computation Element (PCE)-based control plane with a service plane managing discovery, composition and activation functions of inter-carrier service elements. The testbed implements the required PCE Communication Protocol (PCEP) and Resource Reservation Protocol with Traffic Engineering (RSVP-TE) extensions, together with service request filtering operations performed with a policy based architecture1.

Energy-aware weight assignment framework for circuit oriented GMPLS networks

A branch of green networking research is consolidating. It aims at routing traffic with the goal of reducing the network energy consumption. It is usually referred to as Energy-Aware Routing. Previous works in this branch only focused on pure IP networks, e.g., assuming an Open Shortest Path First (OSPF) control plane, and best effort packet forwarding on the data plane. In this work, we consider instead Generalized Multi-Protocol Label Switching (GMPLS) backbone networks, where optical technologies allow to design “circuit switching” network management policies with strict bandwidth reservation policies. We define a simple and generic framework which generates a family of routing algorithms, based on an energy-aware weight assignment. In particular, routing weights are functions of both the energy consumption and the actual load of network devices. Using such weights, a simple minimum-cost routing allows finding the current least expensive circuit, minimising the additional energy cost. Results obtained on realistic case studies show that our weight assignment policy favours a consistent reduction of the network power consumption, without significantly affecting the network performance. Furthermore, the framework allows to trade energy efficiently and network performance, a desirable property at which ISPs are looking for. Simple and robust parameter settings allow reaching a win-win situation, with excellent performance in terms of both energy efficiency and network resource utilization.