Abstract

Most major operators use MPLS technology to manage their network via signalling and label distribution protocols. However, these protocols are complex to deploy, maintain and troubleshooting is often very difficult. The IETF has initiated the standardization of a segment routing architecture based on a simple control plane, lightweight, easyto-manage and instantiated on MPLS or IPv6. This architecture is based on the concept of source routing, in which the packet header carries the indications of the path to follow to reach its destination. Suitable for simple use cases and natively resistant to failure, more complex use cases require the resolution of technological issues for which we offer several solutions.In this thesis carried out within Orange Labs, we were interested in the instantiation of the Segment Routing architecture on the MPLS transfer plan and more particularly in traffic engineering, particularly with resource reservation. We have proposed solutions to the problems related to the hardware limitation of current routers that do not allow the expression of all constrained paths. This work is divided into two parts : (i) the proposal of algorithms for computing and encoding segment routing paths in order to bypass hardware limitations. (ii) the definition of architectural requirements and the construction of a functional proof of concept. Finally, this thesis proposes new research issues to consolidate traffic engineering tools for segment routing.; La majorité des grands opérateurs utilise la technologie MPLS pour gérer leur réseau via des protocoles de signalisation et de distributions de labels. Or, ces protocoles sont complexes à déployer, à maintenir et la résolution des pannes est souvent très difficile. L'IETF a initié la standardisation d'une architecture de routage par segments (Segment Routing) s'appuyant sur un plan de contrôle simple, léger, facile à gérer et instanciée sur MPLS ou IPv6. Cette architecture repose sur le concept de routage à la source, dans lequel l'en-tête des paquets transporte les indications du chemin à suivre pour atteindre sa destination. Adapté aux cas d'usages simples et offrant nativement une résistance aux pannes, les cas d'usages plus complexes exigent de résoudre des verrous technologiques pour lesquels nous proposons plusieurs solutions. Dans cette thèse effectuée au sein d'Orange Labs, nous nous sommes intéressés à l'instanciation de l'architecture Segment Routing sur le plan de transfert MPLS et plus particulièrement à l'ingénierie de trafic, notamment avec réservation de ressources. Nous avons proposé des solutions aux problèmes liés à la limitation matérielle des routeurs actuels ne permettant pas l'expression de tous les chemins contraints. Ce travail est divisé en deux parties : (i) la proposition d'algorithmes de calcul et d'encodage de chemins de routage par segment afin de contourner les limitations matérielles. (ii) la définition des exigences architecturales et la construction d'une preuve de concept fonctionnelle. Enfin, cette thèse propose de nouvelles pistes d'études afin de consolider les outils d'ingénierie de trafic pour le routage par segment.

Abstract

This project presents two contributions to the PCE implementation in Telefonica I+D: Segment Routing and the upgrade of the BGP-LS protocol to the 3rd version of the draft to support MPLS and GMPLS scenarios. Regarding the first contribution, this document is intended to assess the use of Segment Routing in centralised traffic-engineering scenarios. It will attempt to make a validation of such technology using the available IETF drafts and publications and trying, at all time, to back-up the use cases with experimental demonstrations. Moreover, the 3rd version of the BGP-LS protocol draft was implemented. This protocol opens the possibility to export the network’s topology and its Traffic Engineering parameters to external entities. The BGP-LS extensions developed enables to retrieve the TE parameters for MPLS and GMPLS networks. The development of the project was done in Telefonica R&D’s facilities within the Core Network Evolution group. The code extends Telefonica’s PCE and network protocols to support Segment Routing and the new version for BGP-LS. As such, both the PCEP and the BGP-LS protocols were enhanced with the latest IETF drafts that define the technology. Once the code was developed and debugged, a series of tests were run in order to validate that the format used followed all the proposed standards. These tests have been defined following the sections that constitute each draft in an attempt to proof the use of each protocol in the most exhaustive possible way. It is important to remark that the validation tests are done not only with Telefonica code, but also with external prestigious entities like Cisco, Telecom Italia, Centre Tecnològic Telecomunicacions Catalunya or Consorzio Nazionale Interuniversitario per le Telecomunicazioni. Ingeniería de Telecomunicación

Abstract

Optimizing the way traffic is routed over networks has been of interest since we first started using computer networks to communicate and exchange information. Network technologies are constantly evolving and so do the underlying problems that need to be solved. This thesis focus on studying the recently proposed segment routing technology. In a traditional IP network, packets are routed using shorted paths according to weights that are configured on the network links. Segment routing offers a new way of routing traffic by allowing packets to do some detours on their way. Between these detours, traditional shortest path routing is used, making this technology have almost no usage overhead. We aim at providing a mathematical formalization of segment routing and showcase several of its use cases. We believe that such a formalization is going to help advance the research of the algorithmic aspects of segment routing by providing a solid mathematical foundation and notations which can serve as a starting point for others to research this topic. We leverage segment routing to solve traffic engineering problems, perform network monitoring and provide traffic duplication services that are robust to link failures. (FSA - Sciences de l'ingénieur) -- UCL, 2020

Abstract

National audience; This research paper proposes IEEE802.3az incorporated green algorithmic schemes on the software defined networking-based segment routing (SDN-based SR) centralized network. The proposed schemes are the green (i.e. the EAGER and CARE metrics) SDN-based SR networks with and without traffic engineering (TE) tunneling. Green metrics extend the IEEE 802.3az energy saving to the whole network, while tunneling avoids the load sharing mechanism included in the segment routing that is not convenient for energy saving purpose. The findings of emulation revealed that the energy efficiency under the EAGER-tunneling strategy is comparable to the conventional metric with TE tunneling, and the saving realized under the CARE-tunneling scheme is twofold in comparison with the LEGACY-tunneling strategy. Meanwhile, the energy saving performance achieved with all three metrics under TE non-tunneling was inferior to those with tunneling. Nonetheless, the lower end-to-end delay and lower maximum link utilization (MLU) were achievable with the non-tunneling strategy.

Abstract

International audience; Energy consumption has become a limiting factor for deploying large-scale distributed infrastructures. This work 1 seeks to improve the energy efficiency of backbone networks by providing an intra-domain Software Defined Network (SDN) approach to selectively turn off a subset of links. We propose the STREETE framework (SegmenT Routing based Energy Efficient Traffic Engineering) that dynamically adapts the number of powered-on links to the traffic load. The core of the solution relies on SPRING, a novel protocol being standardized by IETF. It is also known under the name of Segment Routing. The algorithms have been implemented and evaluated using the OMNET++ simulator. Experimental results show that the consumption of 44% of links can be reduced while preserving good quality of service.

Abstract

Segment Routing (SR) combines the simplicity of Link-State routing protocols with the flexibility of Multiprotocol Label Switching (MPLS). By decomposing forwarding paths into segments, identified by labels, SR improves Traffic Engineering (TE) and enables new solutions for the optimization of network resources utilization. This work proposes an Evolutionary Computation approach that enables Path Computation Element (PCE) or Software-defined Network (SDN) controllers to optimize label switching paths for congestion avoidance while using at the most three labels to configure each label switching path. This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT Fundac¸˜ao para a Ciˆencia e Tecnologia within the Project Scope: UID/CEC/00319/2013. info:eu-repo/semantics/publishedVersion

Abstract

International audience; Abstract: Segment Routing is a new architecture that leverages the source routing mechanism to enhance packet forwarding in networks. It is designed to operate over either an MPLS (SR-MPLS) or an IPv6 control plane. SR-MPLS encodes a path as a stack of labels inserted in the packet header by the ingress node. This overhead may violate the Maximum SID Depth (MSD), the equipment hardware limitation which indicates the maximum number of labels an ingress node can push onto the packet header. Currently, the MSD varies from 3 to 5 depending on the equipment manufacturer. Therefore, the MSD value considerably limits the number of paths that can be implemented with SR-MPLS, leading to an inefficient network resource utilization and possibly to congestion. We propose and analyze SR-LEA, an algorithm for an efficient path label encoding that takes advantage of the existing IGP shortest paths in the network. The output of SR-LEA is the minimum label stack to express SR-MPLS paths according to the MSD constraint. Therefore, SR-LEA substantially slackens the impact of MSD and restores the path diversity that MSD forbids in the network.