Energy-efficient design of flexible-grid networks is investigated. We focus on the design of the logical layer, usually disregarded when dealing with flexible-grid networks. More precisely, we evaluate the impact of introducing an energy-aware electronic traffic grooming in flexible-grid networks design. We propose two greedy heuristics for the network design, one exploiting traffic grooming, and we compare their energy efficiency. Results have been retrieved for several randomly generated networks of different size, with different connectivity, average physical link length and traffic scenarios. Significant energy savings can be achieved for low traffic loads and large network size when performing traffic grooming.

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This paper presents the concept of virtual DBA, a method we propose to virtualize upstream capacity scheduling in PONs, which provides multiple independent virtual network operators with the ability to precisely schedule their upstream traffic allocation. After a brief introduction on the evolution of access network sharing, we present our virtual DBA architecture, detailing its main components. We then provide a summary of the work done in this area both from theoretical and practical implementation perspectives. In this paper, we propose a novel stateless algorithm for merging multiple independent virtual bandwidth maps based on priority classes and analyze its performance in terms of efficiency of capacity allocation and latency. Through our results we discuss the existence of a trade-off between traffic load and grant size distribution vs. efficiency and latency. We find that, differently from residential single-tenant application, when PONs are used for low latency and multi-tenant applications, the system has better overall performance if grants are allocated in small size. In addition, our analysis shows that for high priority, strict latency services, our proposed merging algorithm presents delay performance that is independent of the traffic distribution considered.

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Abstract-We consider the power-efficient design of an Internet protocol (IP)-over-wavelength division multiplexing (WDM) network, tackling the problem of installing optical and IP layer equipment to satisfy traffic requirements. We take into account routing constraints and consider a comprehensive set of realistic scenarios defined by network topology, traffic matrix, and power consumption values of network devices in both layers. Furthermore, besides defining and solving an optimal integer linear programming model, we propose an efficient heuristic to solve the problem up to medium-sized networks. The proposed heuristic requires at most 30% of additional power with respect to the optimal solution, but with a significantly reduced complexity. We show that the largest power consumption is due to line cards and routers rather than WDM equipment. Furthermore, we find that multipath routing reduces the network power consumption with respect to single-path routing, but not significantly. Finally, we show that a two-step design procedure, in which power is separately minimized in each layer (i.e., IP and WDM layers), can find results with a total power consumption comparable to the one achieved by a more complex joint multilayer design procedure.