On the Efficiency of Dynamic Routing of Connections with Known Duration

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.