2473-2400 (c) 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TGCN.2018.2862922, IEEE Transactions on Green Communications and Networking 1 Earthquake Tolerant Energy Aware Algorithms: A new approach to the design of WDM Backbone Networks Georgia A. Beletsioti, George I. Papadimitriou, Senior Member, IEEE, Petros Nicopolitidis, Senior Member, IEEE, and Amalia N. Miliou Abstract—The increasing energy cost of networking facilities, in conjunction with environmental instability and climate change, have led to many research efforts targeting the reduction of the energy consumption in telecommunication networks. Wavelength Division Multiplexing (WDM) optical networks is the key solution for the continuously growing bandwidth demands of backbone networks. However, the rise of traffic has led to the augmentation of energy consumption in such networks. Moreover, backbone networks in countries with high seismicity suffer from unexpected link failures caused by earthquakes, which in turn, cause a huge amount of bandwidth loss and service disruptions. In this work, a new power aware algorithm is introduced, which uses actual seismic information in order to maintain tolerant connectivity of the backbone network after a large scale earthquake occurs, while supporting energy efficiency. The objective of this paper is the design of a power and earthquake aware WDM backbone network, by establishing the minimum number of backup links in the virtual topology in order to maintain tolerant connectivity. The proposed scheme is evaluated via extensive simulation results by using actual seismic information provided by the Geodynamic Institute of the National Observatory of Athens, and it is verified that both goals of earthquake tolerance and energy efficiency are achieved. Index Terms—Earthquakes, tolerant connectivity, real seismic data, energy efficiency. I. I NTRODUCTION T O date, the primary restriction to the improvement of telecommunication systems basically depended on two factors, namely the cost of the network equipment, due to the numerous connected devices and transmission, due to the huge amount of data that has to be transferred. Moreover, the enormous spread and development of the Internet has brought about a critical increase in the energy consumption of the network equipment. Especially, the rise in Internet activity, due to the high-bandwidth demanding applications such as voice over IP, video on demand, high-definition video, gaming and also the continuous raise in the number of Internet users, has driven to both the increment of the amount of required equip- ment and the augmentation of energy consumption of such network devices. Subsequently, CapEx and OpEx of modern telecommunication networks render the market penetration of such deployment laborious. Energy savings have become particularly pressing over the previous years, due to the problems resulting from its unconsidered use at a global level. Global interest in climate change, its causes and implications have led the society and technology, in particular, to environmentally friendly solu- tions. As the energy problem intensifies, energy saving is an inevitable concern for modern man. Hence, a shift towards green technologies and eco friendly solutions have been made. Information and Communication Technologies sector itself accounts for about 2% of global carbon emissions, while Telecoms contributed around one quarter of this total [1]. These emissions are expected to double over the next decade unless initiatives are taken to reduce the carbon footprint [2]. Telecommunication networks and broadband access have been shown to consume a huge amount of energy for the trans- mission of digital data. Generally speaking, the telecommu- nications sector accounts for around 4% of global electricity consumption [3]. On the other hand, earthquakes can damage considerable parts of telecommunication networks. For instance, in March 2011, a huge earthquake occurred in Northeastern Japan and its associated tsunami (The 2011 off the Pacific coast of Tohoku Earthquake), destroyed many network facilities. Nip- pon Telegraph and Telephone Communications reported that “submarine cables connecting Japan with the United States and other parts of Asia have been partially damaged, facilities were damaged and commercial power supply was disrupted at ex- change offices, among other things, impacting approximately 1.5 million circuits for fixed-line services, approximately 6,700 mobile base station equipment, approximately 15,000 circuits for corporate data communication services and others” [4]. In 2008, a massive earthquake, Sichuan, measuring 8.0 on the Richter scale damaged around 30000 km of fiber optic cables and 4000 telecom offices [5]. The present work adheres to the natural hazards which affect optical backbone networks, techniques for the survivability improvement as well as energy efficiency issues. Particular emphasis is given to earthquakes, phenomenon that occur with an increasing frequency in several countries around the world [6], [7]. In this study, real seismic catalogs, retrieved from the Geodynamic Institute of the National Observatory of Athens, were used in order to evaluate the performance of the proposed algorithm after an earthquake occurrence on the Greek optical backbone network. These catalogs are used as input to the proposed algorithm, in order to achieve the design of a power and earthquake aware WDM backbone network, by establishing the minimum number of backup links needed in the virtual topology in order to maintain tolerant connectivity, as well as energy efficiency. Extensive simulation