Mohamed Koubaa

Work place: Laboratoire SYStèmes des COMmunications Département Technologies de l’Information et de la Communication École Nationale d’Ingénieurs de Tunis Université Tunis El Manar - BP 37, Le Belvédère - 1002 Tunis - Tunisia



Research Interests: Mathematical programming, Routing, Linear Programming, Heuristics, Computer Networking, Cloud Computing, Network Security


Mohamed Koubàa is an associate professor at École Nationale d'Ingénieurs de Tunis (ENIT) within the "Technologies de l'Information et des Communications" Department, Tunis, Tunisia. He is graduated from the École Supérieure des Communications (Sup'Com) Tunis, Tunisia, in 2001. He received a M. Sc. In electrical engineering and computer science (Hons) and a Ph. D. degree in Computer Science and Networks from the École Nationale Supérieure des Télécommunications (ENST) Paris, France in 2002 and 2005. He was the head of the "Technologies de l'Information et des Communications" Department from 2008 to 2011. He is in the program committee of various IEEE and IFIP conferences. His current research activities are focused on cloud computing and the design and dimensioning of optical transport networks.

Author Articles
Efficient Traffic Engineering Strategies for Optimizing Network Throughput in WDM All-Optical Networks

By Mohamed Koubaa Naama Amdouni Taoufik Aguili

DOI:, Pub. Date: 8 May 2015

In this paper we investigate traffic-engineering issues in Wavelength Division Multiplexing (WDM) all-optical networks. In such networks, the wavelength continuity constraint along with the wavelength clash constraint, lead to poor network performances when dealing with the lightpath provisioning problem. The impact of these constraints is especially severe when traffic demands are unpredictable and characterized by random arrivals and departures. In order to alleviate the impact of these constraints, we propose to employ intentional/active rerouting. Active lightpath rerouting is to intentionally reroute already established lightpaths, during their life period, so as to achieve a better blocking performance. We here assume that due to the large geographic area an optical WDM network can cover, upgrading such a network to support the huge demand for network bandwidth can be costly. Thereby, it is extremely important for network operators to apply traffic-engineering strategies to cost-effectively optimize network throughput. Two new routing and wavelength assignment (RWA) algorithms applying intentional rerouting are proposed. Both algorithms dynamically reroute some already established lightpaths from longer paths to vacant shorter ones so as to reduce the network resources consumption and hence improve the network throughput. The first algorithm, namely, Timer-Based Active Lightpath Rerouting (TB-ALR) initiates the rerouting procedure every time a timer expires. The second algorithm, namely, Sequential Routing with Active Lightpath Rerouting (SeqRwALR) initiates the rerouting procedure when a connection leaves and its lightpaths are released. To the best of our knowledge, our global approach has not already been investigated in the literature. Simulation results show that the proposed active rerouting algorithms yield much lower connection rejection ratios than rerouting algorithms previously presented in the literature while rerouting a small number of already established lightpaths. By rerouting a small number of existing lightpaths, we hope that the disruption period incurred due to rerouting is minimized.

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