In this paper we devise an highly-efficient load balancing algorithm, called LB-HTA, for the dynamic provisioning of connections with known duration in WDM networks. We introduce a time-dependent link-weight assignment that captures future congestion of links, leveraging the knowledge of connection durations. By means of an extensive set of simulative experiments, we compare our approach to other traditional, yet holding-time agnostic, dynamic routing algorithms. For a typical US nationwide network, LB-HTA obtains significant saving in blocking probability for practical scenarios. Moreover, we address two key-questions regarding holding-time-aware dynamic routing. Three main traffic models are considered here, namely i) dynamic traffic, ii) dynamic traffic with known durations and iii) scheduled traffic: how much the knowledge of connection durations improves the performance with respect of a holding- time-agnostic solution? Is the obtained solution close to the most effective solution provided by scheduled traffic? In order to exhaustively evaluate the performance of LB-HTA, we consider as benchmark the solution obtained under the well-known Scheduled Traffic model (TI-ST) and also under an approximated, but more effective, approach for traffic scheduling, called Time- Variant Scheduled Traffic (TV-ST). For both TI-ST and TV-ST, Integer Linear Program (ILP) formulations are proposed and results compared with dynamic routing algorithms.

Progress in network technologies and protocols is paving the road towards flexible optical transport networks, in which dynamic leasable circuits could be set up and released on a short-term basis according to customers requirements. Recently, new solutions for automated network management promise to allow customers to dinamically specify the terms of the Service Level Agreement (SLA) to be guaranteed by the service provider. Since this new information is made available, we propose to exploit the knowledge of connection holding time, among the other Service Level Specifications (SLS), to improve the routing efficiency. In this work, we consider that a typical electronic-layer (e.g., SDH or MPLS) demand requires only a fraction of the capacity of the single wavelength bandwidth and we investigate a new algorithm for traffic grooming of sub-wavelength connections in an optical mesh network. We rely on the knowledge of the holding time of connection requests to exploit lightpath capacity and hence to achieve significant reduction in blocking probability for the traffic grooming problem. Our new methodology is applied on a typical US nation-wide network and results are compared with those given by previous known approaches.