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Algorithmes exacts et heuristiques pour le chainage de services réseaux virtualisés

Omar Houidi 1, 2, 3
Abstract : Network Function Virtualization (NFV) is an innovative emerging concept that decouples network functions (such as firewalls, DNS, NATs, load balancers, etc.) from dedicated hardware devices (the traditional expensive middleboxes). This decoupling enables hosting of network services, known as Virtualized Network Functions (VNFs), on commodity hardware (such as switches or servers) and thus facilitates and accelerates service deployment and management by providers, improves flexibility, leads to efficient and scalable resource usage, and reduces costs. This paradigm is a major turning point in the evolution of networking, as it introduces high expectations for enhanced economical network services, as well as major technical challenges.One of the main technical challenges in this domain is the optimal placement of the VNFs within the hosting infrastructures. This placement has a critical impact on the performance of the network, as well as on its reliability and operation cost. The VNF Placement and Chaining Problem is NP-Hard and there is a need for placement approaches that can scale with problem size and find good solutions in acceptable times. The overarching goal of this thesis is to enable dynamic virtual network resources provisioning to deal with demand fluctuation during the virtual network lifetime, and to enhance the substrate resource usage. Reserving a fixed amount of resources is inefficient to satisfy the VNF resource requirements. To cope with these problems, we propose dynamic resource management strategies.In this thesis, both exact and heuristic algorithms are designed and evaluated in terms of optimality, complexity, ability to scale, and compared with the state of the art. Elastic mechanisms and scaling algorithms are first presented to improve adaptation and deployment of virtualized network functions in NFV infrastructures to support increasing demand while increasing provider's revenue. Since network providers not only need to control, classify and steer user and application traffic flows in their dedicated slices but also want to extend their already acquired and operational virtual networks or slices with additional service graphs, the thesis proposes extension algorithms of already hosted network functions graphs without disrupting initially deployed and active service instances. The proposed algorithms extend already deployed network services and functions graphs to respond to new demands while taking into account the constraint of minimizing the impact on the original service graphs. The extension algorithms are particularly useful and suitable for situations where already deployed graphs need to be enhanced with new features and properties (adding new functions) and modified to react to degradation and attacks such as removing a fraction of the graph and replacing with new complex and composed functions into more capable and uncompromised graphs.The thesis also addresses the VNF placement and chaining problem in an online and in a batch mode to improve performance in terms of longer time reward. An enhanced Reinforcement Learning-based approach is also proposed to improve the long term reward beyond what the previous methods can achieve. This is analyzed and realized for a load balancing objective but can be adjusted for other criteria.
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Submitted on : Thursday, July 23, 2020 - 4:57:12 PM
Last modification on : Tuesday, August 25, 2020 - 3:22:59 AM


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  • HAL Id : tel-02905778, version 1


Omar Houidi. Algorithmes exacts et heuristiques pour le chainage de services réseaux virtualisés. Réseaux et télécommunications [cs.NI]. Institut Polytechnique de Paris, 2020. Français. ⟨NNT : 2020IPPAS005⟩. ⟨tel-02905778⟩



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