Current Projects

• A comparison study on IP QoS Reliability and IP Quality of Protection (QoP) between DiffServ and DiffProtect in IP/WDM networks.
• Impact of Switch and Grooming Costs in the Design of Hybrid Optoelectronic IP/MPLS-based WDM Networks
• Design of agile multidimensional photonic networks for the Next Generation Internet
• Reliability and Survivability of MPLS networks
• Performance and synthesis of burst-switching networks
• Performance of voice over IP over DOCSIS networks
• Simulation of user perceived Quality of Service in an EDGE network
• Efficient bandwidth management in WDM/TDM hybrid networks
• Survivability in MPLS/WDM Networks
• Design Optimization of a Next Generation Petabit-per-second Network
• Performance study of multilayers networks protected by p-cycles

A comparison study on IP QoS Reliability and IP Quality of Protection (QoP) between DiffServ and DiffProtect in IP/WDM networks.

Person in charge :     Christian AWAD DiffServ, a relatively low cost protection scheme, is being used to guarantee a certain QoS to prioritized traffic such as VoIP. In this project, we investigate the extent of the robustness of Differentiated Service in the event of system failures. We specifically compare the IP QoP obtained with pure DiffServ with the one obtained with the so-called Differentiated Optical Protection. Therefore our main objective is to propose a network model where the ratio Protection/Cost is maximized by offering optimal protection to our high priority traffic (VoIP) while minimizing the cost of the protection at the physical layer which is known to be highly expensive. Publications : B. Sansò, A. Girard, C. Awad, A Comparison Between Differentiated Optical Protection and Differentiated Services Protection, Extended Abstract, INFORMS Telecommunications Conference, Boca Raton, Florida, March 9, 2004. C. Awad, B. Sansò, A. Girard, DiffServ vs DiffProtect : A Comparison Study On IP QoS-Reliability, Presentation, INFORMS Telecommunications Conference, Boca Raton, Florida, March 9, 2004. Data

Impact of Switch and Grooming Costs in the Design of Hybrid Optoelectronic IP/MPLS-based WDM Networks

Person in charge :     François Cartier In this project, we consider the design of hybrid opto-electronic networks base on IP/MPLS/WDM. We assess the capacity of the network by evluating an optimal trade-off between the cost of the electronic switches, the cost of grooming connections and the cost of optics. We have carried out a study to evaluate the impact of the different features and we have developed a heuristic based on Tabu Search and genetic algorithm to solve the problem. Publications : A. Medded , A. Girard, B. Sansò, F. Cartier, The Impact of Switch Cost on the Design of Hybrid Opto-electronic Networks. Les Cahiers du GERAD, G-2004-08, 21 p., January 2004. Other publications in preparation.

Design of agile multidimensional photonic networks for the Next Generation Internet

Person in charge :     Jules Richards Dégila Director :     Brunilde Sansò, Ph.D. Due to its tremendous potentialities, the optical networking is well admitted as a good candidate for the next generation high capacitated communication networks, such as the Internet. The attraction of the optical technologies grew with the development of the wavelength division multiplexing and also with the agile photonic switching technology that allows circumventing the limitations of the electronics. On the other hand, the heterogeneity of networks such as the Internet, their versatility and also their increasing need in networking optical resources raises multiple optimization challenges. The problems raised are usually difficult to solve and concern the setting up and the engineering of the network equipments. In this work, we address the proposal of an optimized topology for a desired high capacitated optical network proposal, the YottaWeb, which is based on recent advances in opto-electronic fast switching and on dynamic capacity allocation by a photonic optical agile core. The agile core provides fully meshed connectivity between electronic controlled edge nodes. The YottaWeb that is proposed with a multidimensional regular lattice topology, is designed to reach a total capacity of the order of the yottabit-per-second (1yotta =). The objective of this work is to propose effective optimization methods to optimize the YottaWeb structure. For that purpose, it is question, in a first step, to survey, compare and discuss proposals in the literature of performance measures and topologies for high capacitated optical networks. Secondly, we address the highly combinatorial problem of minimizing the number of hops between the edge nodes, while taking into account the traffic. We use both combinatorial and mathematical programming tools. Thirdly, we deal with the update and the expansion of the proposed lattice regular structure. Finally, one seeks for other topological more versatile optimized and well-suited structures for the YottaWeb. Publications : Dégila, J., SANSÒ, B., Design Optimization of a Next Generation Yottabit-per second Network. Les Cahiers du GERAD, G-2003-10, 13 pages, February 2003. (To appear in the Proceedings of IEEE ICC'04) Dégila, J., SANSÒ, B., Topological Design Optimization of a Yottabit-per-second Lattice Network. Les Cahiers du GERAD, G-2003-11, 30 pages, February 2003. (To appear in IEEE-JSAC, special issues on "Optical Communications Networking") Dégila, J., SANSÒ, B., A Survey of Topologies and Performance Measures for High Capacitated Networks. Les Cahiers du GERAD, G-2003-80, 25 pages, November 2003. (Submitted for Publication in IEEE Communications Surveys and Tutorial Magazine)

Reliability and Survivability of MPLS Networks

Person in charge :     Florent Mobiot MPLS (Multiprotocol Label Switching) defines mechanisms based on label swapping (similar to VP/VC switching in ATM) which simplify and speed up IP packets forwarding. This new technology enhances the Internet by offering a better framework for the guarantee of QoS, virtual private networks (VPNs) and particularly traffic engineering. Since survivability is expensive but such a critical issue for most broadband applications, we are interested in integrated models for protection and fast restoration of MPLS-based networks. Publications : Mobiot, F., Sansò, B., Girard, A., A Method for the Integrated Design of Reliable GMPLS Networks, january 2003, 20 pages. This work won the best paper award of the Design of Reliable Communication Networks (DRCN) conference, Banff, Alberta, 2003.

Performance and synthesis of burst-switching networks

Person in charge :     Eloim Gutierrez In order to assess the performance of forthcoming burst switching schemes we have put in place a simulator and are proposing a new type of scheme to be able to make reservations with very little processing time. Publications : Not yet available.

Performance of voice over IP over DOCSIS networks

Person in charge :     Hatim Lachkar We are studying the transport of voice over IP over DOCSIS-based cable networks. We try to implement a simulation model based on the OPNET Modeler tool, in order to model a DOCSIS cable network carrying multiple voice flows, and then evaluate the quality of service (QoS) from the user's point of view. We wish also to study different scheduling/resource allocation algorithms in order to achieve optimum management of the network resources, while guaranteeing the particular requirements of voice flows. The performance of these algorithms will then be assessed using the OPNET Modeler tool. Publications : Internal working papers not available.

Simulation of user perceived Quality of Service in an EDGE network

Person in charge :     Weihua Chen EDGE (Enhanced Data Rate for GSM Evolution) is developed to enable the transmission of large amounts of data at a high speed. EDGE is a cost effective solution for 3G services, due to its compatibility of 2G and its possibilities to realize the high speed and the spectral efficiency by the use of the 8-PSK modulation in addition to the existiing GMSK and of an effective mechanism of link quality control(LQC). When deploying an EDGE network, an important problem is to be able to evaluate the QoS seen by the user. Our objective is to find a simulation model to evaluate the user perceived QoS in an EDGE network. Publications : Internal working papers not available.

Efficient bandwidth management in WDM/TDM hybrid networks

Person in charge :     Hua Jian We work with the WDM-TDM hybrid optical network, in which the fiber spectrum is firstly wavelength divided and then each wavelength is further time slotted. The fundamental problem in this type of network is to assign certain amount of time slots to each connection while satisfying its quality of service (QoS). Various approaches are studied to implement the bandwidth update while respecting the QoS. Publications : Internal working papers not available.

Survivability in MPLS/WDM Networks

Person in charge :     Oumar Mandione Gueye Survivability in MPLS/WDM Networks depends on the coordination of the protection and restoration mechanisms of this multilayer architecture. All of them offer a maximum delay of restoration, and the services such as teleconferencing, file transfer, e-commerce, email, and so on require a different level of protection. The main questions are how to protect any services? What mechanism protect which services?. In this project, we propose a new strategy for LSP (Label Switched Path) restoration. Publications : Internal working papers not available.

Design Optimization of a Next Generation Petabit-per-second Network

Person in charge :     Anne REINERT This project aims to optimally build an optical network with high capacity called the PetaWeb. The PetaWeb is a recently proposed architecture based upon optical core nodes that provide fully meshed connectivity between electronic edge nodes. It uses WDM fibers (Wavelength Division Multiplexed) and Optical Cross-Connectors (OXCs). We tackle the problem of finding the optimal location and dimension of the core nodes. It is a problem of topological design with the specific restrictions of the PetaWeb. The context of this project is an industrial one with Nortel Networks. We have proposed a mathematical formulation of the problem which has been validated with CPLEX tests. We are currently building an heuristic in order to decrease the resolution time and optimize scalable networks. Publications : Internal working papers not available.

Performance study of multilayers networks protected by p-cycles

Person in charge :     Diane Prisca ONGUETOU In IP networks, the restoration is achieved by using one of the two following methods: the ring protection and the meshed protection. The ring protection method is based on the double-ring principle and it offers a quick restoration if there is a simple failure but it does not give any guarantee of restoration in case of multiple failures. Furthermore, it requires a larger bandwidth to work with; and thus, a high cost. As regards the meshed protection method, it provides a shared protection by using a dynamic routing. It can restore multiple failures and the restoration's speed depends on the convergence of the routing algorithm. A third method, namely the p-cycles (or ring protection in WDM meshed networks), can be derived by a combination of the two methods mentioned above. The p-cycles can restore efficiently and quickly simple or multiple failures. It is obvious that this method has an important impact on the reliability of a network. Our main goal is to study such an impact on the performance of integrated networks at the IP level. Specifically, we want to define some networks topology using p-cycles to protect the optical layer, against some predefined failures. We will design data transfer and measure the performance of the network. Given the fact that there does not exist any mathematical models that we can use for our analysis, we will work with simulation methods. The project is divided in two parts. Firstly, we will set up an integrated network simulator and, secondly, we will use the simulator to achieve the performance measurement required. Publications : Internal working papers not available.