Efficient heuristics for energy-aware routing in networks with bundled links

Current networks are typically over-provisioned to ensure low delays, redundancy and reliability. These Quality of Service (QoS) guarantees are typically achieved using high end, high power network equipments. Their use, however, has led to concerns regarding green house gas emissions, which garnered a lot of attention recently and have resulted in a number of global initiatives aim at reducing the carbon footprint of Internet Service Providers (ISPs). These initiatives have motivated ISPs and researchers to design novel network algorithms and hardware that scale the usage or active time of a network according to traffic load. To this end, this paper considers the problem of shutting down a subset of bundled links during off-peak periods in order to minimize energy expenditure. Unfortunately, identifying the cables that minimize this objective is an NP-complete problem. Henceforth, we propose several practical heuristics based on Dijkstra’s algorithm and Yen’s k-shortest paths algorithm. We evaluated our heuristics on the Abilene network – with both real and synthetic traffic matrices and several larger random topologies with various loads. Our results show that the proposed heuristics to be effective and efficient. Moreover, our approaches could potentially reduce the energy usage of cables used in the Abilene network by up to 56.7%, assuming the traffic demands recorded on September 5, 2004

Energy management in communication networks: a journey through modelling and optimization glasses

The widespread proliferation of Internet and wireless applications has produced a significant increase of ICT energy footprint. As a response, in the last five years, significant efforts have been undertaken to include energy-awareness into network management. Several green networking frameworks have been proposed by carefully managing the network routing and the power state of network devices. Even though approaches proposed differ based on network technologies and sleep modes of nodes and interfaces, they all aim at tailoring the active network resources to the varying traffic needs in order to minimize energy consumption. From a modeling point of view, this has several commonalities with classical network design and routing problems, even if with different objectives and in a dynamic context. With most researchers focused on addressing the complex and crucial technological aspects of green networking schemes, there has been so far little attention on understanding the modeling similarities and differences of proposed solutions. This paper fills the gap surveying the literature with optimization modeling glasses, following a tutorial approach that guides through the different components of the models with a unified symbolism. A detailed classification of the previous work based on the modeling issues included is also proposed

Power-Aware Routing and Network Design with Bundled Links: Solutions and Analysis

The paper deeply analyzes a novel network-wide power management problem, called Power-Aware Routing and Network Design with Bundled Links (PARND-BL), which is able to take into account both the relationship between the power consumption and the traffic throughput of the nodes and to power off both the chassis and even the single Physical Interface Card (PIC) composing each link. The solutions of the PARND-BL model have been analyzed by taking into account different aspects associated with the actual applicability in real network scenarios: (i) the time for obtaining the solution, (ii) the deployed network topology and the resulting topology provided by the solution, (iii) the power behavior of the network elements, (iv) the traffic load, (v) the QoS requirement, and (vi) the number of paths to route each traffic demand. Among the most interesting and novel results, our analysis shows that the strategy of minimizing the number of powered-on network elements through the traffic consolidation does not always produce power savings, and the solution of this kind of problems, in some cases, can lead to spliting a single traffic demand into a high number of paths

On the effects of energy-aware traffic engineering on routing reliability

Current network infrastructures are over-provisioned to increase their resilience against resource failures, e.g., bundled links and nodes, as well as congestion during peak hours. However such strategies waste resources as well as exhibit poor energy efficiency at off-peak periods. To this end, several energy aware routing algorithms have been proposed to maximally switch off redundant network resource at low traffic load to minimize energy usage. These routing solutions, however, do not consider network reliability as critical back-off links/nodes maybe switched off. Henceforth, we aim to quantify the effects of five recently proposed green routing approaches, namely FGH, GreenTE, MSPF, SSPF, and TLDP, on the following two reliability measures: (i) 2-terminal reliability (ii) path reliability. Experiments using three topologies with real and synthetic traffic demands show that switching off redundant links significantly affects the 2-terminal reliability. Routing traffic through multiple paths has lesser reliability impact while reducing energy, especially when the paths are link disjoint. Interestingly, TDLP and MSPF have better path reliabilities than using shortest path routing

Distributed algorithms for green IP networks2012 Proceedings IEEE INFOCOM Workshops

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 constraint

A green intelligent routing algorithm supporting flexible QoS for many-to-many multicast

The tremendous energy consumption attributed to the Information and Communication Technology (ICT) field has become a persistent concern during the last few years, attracting significant academic and industrial efforts. Networks have begun to be improved towards being “green”. Considering Quality of Service (QoS) and power consumption for green Internet, a Green Intelligent flexible QoS many-to-many Multicast routing algorithm (GIQM) is presented in this paper. In the proposed algorithm, a Rendezvous Point Confirming Stage (RPCS) is first carried out to obtain a rendezvous point and the candidate Many-to-many Multicast Sharing Tree (M2ST); then an Optimal Solution Identifying Stage (OSIS) is performed to generate a modified M2ST rooted at the rendezvous point, and an optimal M2ST is obtained by comparing the original M2ST and the modified M2ST. The network topology of Cernet2, GéANT and Internet2 were considered for the simulation of GIQM. The results from a series of experiments demonstrate the good performance and outstanding power-saving potential of the proposed GIQM with QoS satisfied

Enabling Green Networking with a Power Down Approach

The most straightforward way to reduce network power consumption is to turn off idle links and nodes (switches/routers), which we call the power down approach. In a wired network, especially in a backbone network, many links are actually “bundles” of multiple physical cables and line cards that can be shut down independently. In this paper, we study the following routing problem for green networking in wired networks: Given a set of end-to-end communication sessions, determine how to route data traffic through the network such that total power consumption is minimized by turning off unused cables in bundled links and nodes, subject to the constraint that the traffic demand of each session is satisfied. We present an integer linear programming to provide optimal solutions. We also present two fast and effective heuristic algorithms to solve the problem in polynomial time. It has been shown by simulation results based on the Abilene network and the NSF network that the proposed heuristic algorithms consistently provide close-tooptimal solutions

The Internet of the Future: Quality of Service and Energy Efficiency

Una delle sfide più importanti del ventunesimo secolo nel campo delle reti di telecomunicazioni è la minimizzazione del consumo di energia fornendo congiuntamente una Qualità del Servizio (QoS). Pertanto, di recente la comunità di ricerca ha iniziato a studiare una serie di iniziative miranti a migliorare la QoS e l’efficienza energetica nell’Internet del futuro. In questo scenario, le Service Overlay Network (SON) sono emerse come un modo proficuo per affrontare questi problemi senza modificare l’infrastruttura sottostante. Invece, il Network Power Management (NPM) cerca i metodi che sono in grado di ottenere risparmi energetici sfruttando opportunamentele caratteristiche energetiche dei dispositivi di rete. In questa tesi, viene analizzato il problema della progettazione topologica di una SON dal punto di vista delle prestazioni. Poichè la soluzione analitica del problema è computazionalmente troppo complessa, si confrontano le prestazioni di un insieme limitato di topologie note. Sulla base di euristiche, tre nuove topologie overlay vengono proposte. Attraverso numerose simulazioni, le prestazioni delle topologie overlay candidate vengono valutate in diversi scenari di rete, tenendo conto del carico e del traffico accettato tra i nodi overlay. Inoltre, questa tesi si concentra sul NPM descrivendo quattro problemi di progettazione di rete per ridurre il consumo energetico delle reti attuali e future. I problemi sono risolti per mezzo di risolutori MILP e MINLP, che ottengono delle soluzioni ottimali o approssimate. Dal momento che in scenari di reti di grandi dimensioni questi approcci sono computazionalmente troppo complessi, sono proposte varie euristiche per i diversi metodi di NPM. L’efficacia degli approcci proposti e dell’euristiche viene esplorata in diversi scenari di rete reali, valutando l’impatto di diversi parametri di rete. I risultati mostrano che le topologie SON sono un’ottima scelta perchè mantengono le stesse prestazioni riducendo l’overhead associato. Inoltre, questa tesi mette in luce l’importanza di una buona caratterizzazione del comportamento energetico dei dispositivi di rete. Notevoli risparmi energetici possono essere raggiunti sfruttando le caratteristiche di potenza dei dispositivi. Le euristiche proposte sono in grado di ridurre il tempo di calcolo e di ottenere risparmi energetici comparabili

On the performance of online and offline green path establishment techniques

© 2015, Ruiz-Rivera et al. To date, significant effort has gone into designing green traffic engineering (TE) techniques that consolidate traffic onto the minimal number of links/switches/routers during off-peak periods. However, little works exist that aim to green Multi-Protocol Label Switching (MPLS) capable networks. Critically, no work has studied the performance of green label switched paths (LSPs) establishment methods in terms of energy savings and acceptance rates. Henceforth, we add to the current state-of-the-art by studying green online and offline (LSP) establishment methods. Online methods rely only on past and current LSP requests while offline ones act as a theoretical benchmark whereby they also have available to them future LSP requests. We introduce a novel metric that takes into account both energy savings and acceptance rates. We also identify a new simpler heuristic that minimizes energy use by routing source–destination demands over paths that contain established links and require the fewest number of new links. Our evaluation of two offline and four online LSP establishment methods over the Abilene and AT&T topologies with random LSP setup requests show that energy savings beyond 20 % are achievable with LSP acceptance rates above 90 %