Traffic and Power-Aware Protection Scheme in Elastic Optical Networks (Invited Paper) Jorge L´ opez ∗‡ , Yabin Ye ∗ , V´ ıctor L´ opez † , Felipe Jimenez † , Ra´ ul Duque † , Peter M. Krummrich ‡ , Francesco Musumeci § , Massimo Tornatore § , Achille Pattavina § ∗ Huawei Technologies Duesseldorf, Riesstr. 25, 80992 Munich, Germany † Telef´ onica I+D, c/ Don Ram´ on de la Cruz 84, 28006 Madrid, Spain ‡ TU Dortmund, High Frequency Institute, Friedrich-Wohler-Weg 4, 44227 Dortmund, Germany § CNIT, Italy and Dept. of Electronics and Information, Politecnico di Milano, via Ponzio 34/5, 20131, Milan, Italy E-mail: ∗ jorge.vizcaino; yeyabin@huawei.com; † vlopez; felipej; e.pt1@tid.es; ‡ peter.krummrich@tu-dortmund.de; § fmusumeci; tornator; pattavina@elet.polimi.it Abstract—Currently, the need for “greener” telecommuni- cation networks is stimulating research efforts to find new solutions to cope with power consumption and sustainability issues. Exploiting the potential of optical Wavelength Division Multiplexed (WDM) networks for this purpose has been identified as an attractive approach. However, the traditional WDM fixed- grid, where 50 GHz-spaced optical carriers are used with Single Line Rates (SLR), may result in lower efficiency from both the spectral occupation and power consumption perspectives. Higher flexibility can be provided by adopting Mixed Line Rates (MLR) and, especially, the so-called Elastic Optical Network (EON) paradigm, which is enabled by the Orthogonal Frequency Division Multiplexing combined with Coherent Detection (CO- OFDM). In this scenario a finer channel spacing is considered so the spectrum can be best fitted to actual traffic needs. Another critical issue is the network robustness to failures, accomplished by reserving additional resources as a backup for protection. Traditional approaches allocate dedicated (1+1) resources for protection and the peak-rate capacity is reserved in both working and protection paths for every traffic demand. Thus, the power consumed in resilient network is substantially increased compared to the unprotected case. In this paper, we evaluate the impact of the hourly network traffic variation to reduce the power consumed by backup resources, by adapting their rate to the current required bandwidth. We apply this paradigm to the SLR, MLR and EON scenarios and find that, especially in the EON case and for high traffic load conditions, substantial energy savings (up to 27%) can be obtained by exploiting the information on hourly traffic variation. Index Terms—Elastic Optical Network; Protection; Traffic fluctuation; Energy efficiency. I. I NTRODUCTION The deep penetration of Information and Communication Technology (ICT) services, such as Video on Demand (VoD), high-definition Internet Protocol (IP) TV and teleconferenc- ing, in everyday life is leading telecommunication networks operators to substantially increase network capacity and look for new solutions to efficiently exploit resources and to cope with this traffic growth. It is envisioned [1] that the Internet traffic increase will be around 40% in the coming years, corresponding to a growth factor of 1000 in approximately 20 years. Correspondingly, an increase in the power consumption of the Internet will be experienced so that power requirements will represent one of the major constraints when performing network design and operation. Therefore, new power efficient solutions need to be investigated in order to jointly reduce the impact of network Operational Expenditures (OpEx), mainly affected by the power requirements, and Capital Expenditures (CapEx), i.e., network devices. In this scenario, optical technology exploiting the Wave- length Division Multiplexing (WDM) technique is commonly recognized as an efficient solution to reduce power consump- tion within the network. However, in the conventional optical transport based on a fixed frequency grid the typical optical carriers spacing is 50 GHz, as standardized by International Telecommunication Union (ITU) [2], and operates with a single line rate (SLR). This dictates a rigid spectrum allocation scheme for the provisioning of new traffic demands and may lead to inefficient use of spectral resources, since low capacity demands need to be served by an entire WDM channel. Several alternatives have been proposed to address this issue. One example is the adoption of mixed line rate (MLR) in WDM networks, where using transponders operating at different line rates (e.g., 10, 40 and 100 Gbit/s) provides higher flexibility to manage heterogeneous traffic demands. This solution has also been demonstrated to be efficient from the power consumption perspective [3]. Furthermore, additional flexibility can be obtained by adopting finer channel spacing and introducing elastic bandwidth provisioning by allocating a variable number of lower bit-rate subcarriers, according to the actual demands requirement. The optical Orthogonal Frequency Division Multiplexing (OFDM) technique, com- bined with coherent detection (CO-OFDM) and the possibility of exploiting multiple modulation formats for the different subcarriers are two powerful technologies which make the Elastic Optical Network (EON) a promising solution for future networks from both the cost and power consumption point of view, so that it is currently being studied by ITU committees 978-1-4673-1391-9/12/$31.00 c  2012 IEEE