Fueled by the growing resource crisis and potential economic incentives, significant research attention has recently been devoted to improving the power efficiency of IP over Wavelength-Division-Multiplexing (WDM) networks. Previous works on power savings in IP over WDM networks have required explicit knowledge of the traffic between each network node pair and the resource assignment of each fiber link. However, it is difficult to accurately estimate this information in live networks due to the inherent features of IP traffic, e.g., bursts, unpredictability and variability. Furthermore, the number of ports consumed in Optical Cross-Connects (OXCs) trends to grow due to the use of traffic grooming and optical bypasses for power savings. Therefore, it is necessary to achieve joint power efficiency and port savings in live IP over WDM networks where the traffic between each network node pair and resource assignment of each fiber link are not known in advance. Since the problem of grooming, routing and wavelength/waveband assignment is NP-hard, a new heuristic approach, the Robust and Integrated Grooming (RIG) algorithm, is proposed in this paper. RIG uses a novel metric, a power ratio defined by the power consumed over the power saved, to evaluate the power efficiency. By determining the Traffic Distribution Vector (TDV) with the lowest power ratio using the Minimizing Power Ratio First (MPRF) method, the previously unknown information can be acquired. By performing traffic matrix transformations, we construct a green optical virtual topology to groom connection demands into established lightpaths using Hybrid Grooming Schemes (HGSs) for power efficiency and waveband switching for port savings. The simulation results demonstrate that RIG can, on average, achieve power efficiency and port savings of 15% and 32%, respectively, compared to state-of-the-art robust grooming methods. To the best of our knowledge, this paper is the first work addressing robust and integrated grooming for power- and port-cost-efficient design in IP over WDM networks.
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