References of "Mathy, Laurent"
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See detailA Hybrid IP Lookup Architecture with Fast Updates
Luo, Layong; Xie, Gaogang; Xie, Yingke et al

in Annual International Conference on Computer Communications (2012, March)

As network link rates are being pushed beyond 40 Gbps, IP lookup in high-speed routers is moving to hardware. The TCAM (Ternary Content Addressable Memory)-based IP lookup engine and the SRAM (Static ... [more ▼]

As network link rates are being pushed beyond 40 Gbps, IP lookup in high-speed routers is moving to hardware. The TCAM (Ternary Content Addressable Memory)-based IP lookup engine and the SRAM (Static Random Access Memory)- based IP lookup pipeline are the two most common ways to achieve high throughput. However, route updates in both engines degrade lookup performance and may lead to packet drops. Moreover, there is a growing interest in virtual IP routers where more frequent updates happen. Finding solutions that achieve both fast lookup and low update overhead becomes critical. In this paper, we propose a hybrid IP lookup architecture to address this challenge. The architecture is based on an efficient trie partitioning scheme that divides the Forwarding Information Base (FIB) into two prefix sets: a large disjoint leaf prefix set mapped into an external TCAM-based lookup engine and a small overlapping prefix set mapped into an on-chip SRAM-based lookup pipeline. Critical optimizations are developed on both IP lookup engines to reduce the update overhead. We show how to extend the proposed hybrid architecture to support virtual routers. Our implementation shows a throughput of 250 million lookups per second (MLPS). The update overhead is significantly lower than that of previous work and the utilization ratio of most external TCAMs is up to 100%. [less ▲]

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See detailEditorial for Computer Networks special issue on “Measurement-based optimization of P2P networking and applications”
Fu, Xiaoming; Chen, Yang; Leduc, Guy ULg et al

in Computer Networks (2012), 26(3), 1077-1079

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See detailTowards TCAM-based Scalable Virtual Routers
Luo, Layong; Xie, Gaogang; Uhlig, Steve et al

in ACM CoNEXT 2012 Proceedings (2012)

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See detailImproved parallelism and scheduling in multi-core software routers
Egi, Norbert; Iannaccone, Gianluca; Manesh, Maziar et al

in Journal of Supercomputing (2011)

Recent technological advances in commodity server architectures, with multiple multi-core CPUs, integrated memory controllers, high-speed interconnects, and enhanced network interface cards, provide ... [more ▼]

Recent technological advances in commodity server architectures, with multiple multi-core CPUs, integrated memory controllers, high-speed interconnects, and enhanced network interface cards, provide substantial computational capacity, and thus an attractive platform for packet forwarding. However, to exploit this available capacity, we need a suitable software platform that allows effective parallel packet processing and resource management. In this paper, we at first introduce an improved forwarding architecture for software routers that enhances parallelism by exploiting hardware classification and multi-queue support, already available in recent commodity network interface cards. After evaluating the original scheduling algorithm of the widely-used Click modular router, we propose solutions for extending this scheduler for improved fairness, throughput, and more precise resource management. To illustrate the potential benefits of our proposal, we implement and evaluate a few key elements of our overall design. Finally, we discuss how our improved forwarding architecture and resource management might be applied in virtualized software routers. [less ▲]

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See detailBuilding virtual networks across multiple domains
Werle, C.; Bless, R.; Papadimitriou, P. et al

in Proceedings of the ACM SIGCOMM 2011 conference on SIGCOMM (2011)

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See detailForwarding Path Architectures for Multicore Software Routers
Egi, Norbert; Greenhalgh, Adam; Handley, Mark et al

in ACM CoNEXT 2010 Workshop Proceedings (2010, November)

Multi-core CPUs, along with recent advances in memory and buses, render commodity hardware a strong candidate for building fexible and high-performance software routers. With a forwarding plane physically ... [more ▼]

Multi-core CPUs, along with recent advances in memory and buses, render commodity hardware a strong candidate for building fexible and high-performance software routers. With a forwarding plane physically composed of many packet processing components and operations, resource allocation in multi-core systems is not trivial. Indeed, packets crossing cache hierarchies degrade forwarding performance, since the bottleneck is main memory access. Therefore, forwarding path allocation and input/output processing become challenging, especially when states and data structures have to be shared among multiple cores. In this context, we investigate a set of input/output processing architectures, as well as resource allocation strategies for forwarding paths. For each packet processing operation, we uncover the gains and possible implications by either running different components concurrently or replicating the same components across different cores. [less ▲]

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See detailAdaptive Virtual Network Provisioning
Houidi, Ines; Louati, Wajdi; Zeghlache, Djamal et al

in ACM SIGCOMM Workshops Proceedings (2010, September)

In the future, virtual networks will be allocated, maintained and managed much like clouds offering flexibility, extensibility and elasticity with resources acquired for a limited time and even on a lease ... [more ▼]

In the future, virtual networks will be allocated, maintained and managed much like clouds offering flexibility, extensibility and elasticity with resources acquired for a limited time and even on a lease basis. Adaptive provisioning is required to maintain virtual network topologies, comply with established contracts, expand initial allocations on demand, release resources no longer useful, optimise resource utilisation and respond to anomalies, faults and evolving demands. In this paper, we elaborate on adaptive virtual resource provisioning to maintain virtual networks, allocated initially on demand, in response to a virtual network creation request. We propose a distributed fault-tolerant embedding algorithm, which relies on substrate node agents to cope with failures and severe performance degradation. This algorithm coupled with dynamic resource binding is integrated and evaluated within a medium-scale experimental infrastructure. [less ▲]

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See detailA Platform for High Performance and Flexible Virtual Routers on Commodity Hardware
Egi, Norbert; Greenhalgh, Adam; Handley, Mark et al

in ACM SIGCOMM Computer Communication Review (2010, January)

Multi-core CPUs, along with recent advances in memory and buses, render commodity hardware a strong candidate for software router virtualization. In this context, we present the design of a new platform ... [more ▼]

Multi-core CPUs, along with recent advances in memory and buses, render commodity hardware a strong candidate for software router virtualization. In this context, we present the design of a new platform for virtual routers on modern PC hardware. We further discuss our design choices in order to achieve both high performance and flexibility for packet processing. [less ▲]

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See detailImproved Forwarding Architecture and Resource Management for Multi-Core Software Routers
Egi, Norbert; Greenhalgh, Adam; Handley, Mark et al

in NPC 2009 Proceedings (2009, October)

Recent technological advances in commodity server architectures, with multiple multi-core CPUs, integrated memory controllers, high-speed interconnects and enhanced network interface cards, provide ... [more ▼]

Recent technological advances in commodity server architectures, with multiple multi-core CPUs, integrated memory controllers, high-speed interconnects and enhanced network interface cards, provide substantial computational capacity and thus an attractive platform for packet forwarding. However, to exploit this available capacity, we need a suitable software platform that allows effective parallel packet processing and resource management. In this paper, we at first introduce an improved forwarding architecture for software routers that enhances parallelism by exploiting hardware classification and multi-queue support, already available in recent commodity network interface cards. After evaluating the original scheduling algorithm of the widely-used Click modular router, we propose solutions for extending this scheduler for improved fairness, throughput and more precise resource management. To illustrate the potential benefits of our proposal, we implement and evaluate a few key elements of our overall design. [less ▲]

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See detailCommutation de paquets logicielle sur routeurs PC multi-coeurs
Egi, Norbert; Greenhalgh, Adam; Handley, Mark et al

in Actes de CFIP 2009 (2009, October)

Les processeurs multi-coeurs sur PC, en même temps que les progrès récents sur la performance de la mémoire et des bus, suggèrent un candidat idéal pour la construction d’architectures de routeurs ... [more ▼]

Les processeurs multi-coeurs sur PC, en même temps que les progrès récents sur la performance de la mémoire et des bus, suggèrent un candidat idéal pour la construction d’architectures de routeurs purement logicielles qui soient flexibles et en même temps performantes. Dans cet article, nous présentons une architecture de commutation de paquets pour les routeurs logiciels ou virtuels dont l’objectif principal est de prévenir des accès mémoire coûteux tout en utilisant les ressources CPU disponibles au mieux pour traiter et commuter les paquets. Nous présentons premièrement le principe d’arbre de commutation dont la fonction est de garder les paquets commutés dans la même hiérarchie de cache du processeur. Nous identifions ensuite la source de contention principale des performances de commutation comme l’accès concurrent aux interfaces de sorties puis analysons les gains potentiels de performance en utilisant un verrou sur les interfaces de sortie ainsi qu’un mécanisme de retour sur l’état des queues du routeur. Finalement, nous proposons et évaluons une modification des arbres de commutation qui permet de contourner la contention due au partage des interfaces de sortie par les arbres [less ▲]

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See detailExtending Routers Utilisability and Life Cycle through Automated Configuration Management
Rodriguez, Francisco; Hoerdt, Mickael; Mathy, Laurent ULg

in IPOM '09 Proceedings (2009, October)

We present the design of a distributed router platform aimed at consolidating multiple hardware routers. The goal of the approach is twofold: firstly decouple the logical routing and forwarding ... [more ▼]

We present the design of a distributed router platform aimed at consolidating multiple hardware routers. The goal of the approach is twofold: firstly decouple the logical routing and forwarding functionality from the limitations of the hardware that runs it, through automated configuration management only; and secondly, give component routers a longer lease of life, as constituting parts of a larger router system. We focus on the logical intra-domain routing function provided by routers, and show the need for a centralized intra-domain route server. [less ▲]

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See detailNetwork Virtualization Architecture: Proposal and Initial Prototype
Schaffrath, Gregor; Werle, Christoph; Papadimitriou, Panagiotis et al

in ACM SIGCOMM Workshops Proceedings (2009, August)

The tussle between reliability and functionality of the Internet is firmly biased on the side of reliability. New enabling technologies fail to achieve traction across the majority of ISPs. We believe ... [more ▼]

The tussle between reliability and functionality of the Internet is firmly biased on the side of reliability. New enabling technologies fail to achieve traction across the majority of ISPs. We believe that the greatest challenge is not in finding solutions and improvements to the Internet's many problems, but in how to actually deploy those solutions and re-balance the tussle between reliability and functionality. Network virtualization provides a promising approach to enable the coexistence of innovation and reliability. We describe a network virtualization architecture as a technology for enabling Internet innovation. This architecture is motivated from both business and technical perspectives and comprises four main players. In order to gain insight about its viability, we also evaluate some of its components based on experimental results from a prototype implementation. [less ▲]

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See detailCertified Internet Coordinates
Kaafar, Mohamed Ali; Mathy, Laurent ULg; Barakat, Chadi et al

in ICCCN '09 Proceedings (2009, August)

We address the issue of asserting the accuracy of coordinates advertised by nodes of Internet coordinate systems during distance estimations. Indeed, some nodes may lie deliberately about their ... [more ▼]

We address the issue of asserting the accuracy of coordinates advertised by nodes of Internet coordinate systems during distance estimations. Indeed, some nodes may lie deliberately about their coordinates to mount various attacks against applications and overlays. Our proposed method consists in two steps: 1) establish the correctness of a node’s claimed coordinate (which leverages our previous work on securing the coordinates embedding phase using a Surveyor infrastructure); and 2) issue a time limited validity certificate for each verified coordinate. Validity periods are computed based on an analysis of coordinate inter-shift times observed on PlanetLab, and shown to follow a long-tail distribution (lognormal distribution in most cases, or Weibull distribution otherwise). The effectiveness of the coordinate certification method is validated by measuring the impact of a variety of attacks on distance estimates. [less ▲]

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See detailImplementing Network Virtualization for a Future Internet
Papadimitriou, Panagiotis; Maennel, Olaf; Greenhalgh, Adam et al

in 20th ITC Specialist Seminar on Network Virtualization Proceedings (2009, May)

The Internet has become an essential communication medium upon which billions of people rely every day. However, necessary evolution of the Internet has been severely limited by reliability constrains and ... [more ▼]

The Internet has become an essential communication medium upon which billions of people rely every day. However, necessary evolution of the Internet has been severely limited by reliability constrains and social-economic factors. Experts fear that current growth rates will threaten the future of the Internet as a whole, despite the fact that new core technologies already exist. Network virtualization presents a promising approach to overcome ossification and facilitate service deployment for a future Internet. Exploring this approach, we present a prototype implementation which realizes a subset of the 4WARD virtual network (VNet) architecture, allowing multiple VNets to coexist on top of a shared physical infrastructure. We discuss the functionality of our prototype and demonstrate experimental results to assess its performance. [less ▲]

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See detailFlow Processing and the Rise of Commodity Network Hardware
Greenhalgh, Adam; Huici, Felipe; Hoerdt, Mickael et al

in ACM SIGCOMM Computer Communication Review (2009)

The Internet has seen a proliferation of specialized middlebox devices that carry out crucial network functionality such as load balancing, packet inspection and intrusion detection. Recent advances in ... [more ▼]

The Internet has seen a proliferation of specialized middlebox devices that carry out crucial network functionality such as load balancing, packet inspection and intrusion detection. Recent advances in CPU power, memory, buses and network connectivity have turned commodity PC hardware into a powerful network platform. Furthermore, commodity switch technologies have recently emerged offering the possibility to control the switching of flows in a fine-grained manner. Exploiting these new technologies, we present a new class of network architectures which enables flow processing and forwarding at unprecedented flexibility and low cost. [less ▲]

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See detailFlowstream Architectures
Greenhalgh, Adam; Handley, Mark; Hoerdt, Mickael et al

in Electronic Communications of the EASST (2009)

The Internet has seen a proliferation of specialized middlebox devices that carry out crucial network functionality such as load balancing, packet inspection or intrusion detection, amongst others ... [more ▼]

The Internet has seen a proliferation of specialized middlebox devices that carry out crucial network functionality such as load balancing, packet inspection or intrusion detection, amongst others. Traditionally, high performance network devices have been built on custom multi-core, specialized memory hierarchies, architectures which are well suited to packet processing. Recently, commodity PC hardware has experienced a move to multiple multi-core chips, as well as the routine inclusion of multiple memory hierarchies in the so-called NUMA architectures. While a PC architecture is obviously not specifically targeted to network applications, it nevertheless provides high performance cheaply. Furthermore, a few commodity switch technologies have recently emerged offering the possibility to control the switching of flows in a rather fine grained manner. Put together, these new technologies offer a new network commodity platform enabling new flow processing and forwarding at an unprecedented flexibility and low cost. [less ▲]

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See detailDesigning a Platform for Flexible and Performant Virtual Routers on Commodity Hardware
Egi, Norbert; Greenhalgh, Adam; Handley, Mark et al

in Electronic Communications of the EASST (2009)

Multi-core CPUs, along with recent advances in memory and buses, render commodity hardware a strong candidate for software router virtualization. In this context, we present the design of a new platform ... [more ▼]

Multi-core CPUs, along with recent advances in memory and buses, render commodity hardware a strong candidate for software router virtualization. In this context, we present the design of a new platform for virtual routers on x86 hardware. We also elaborate on our design choices in order to achieve both high performance and flexibility for packet processing. [less ▲]

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See detailCharacterising and Exploiting Workloads of Highly Interactive Video-on-Demand
Brampton, Andrew; MacQuire, Andrew; Fry, Michael et al

in Multimedia Systems (2009)

This paper presents a detailed character- isation of user behaviour for a series of interactive video experiments over a 12 month period, in which we served popular sporting and musical content. In ad ... [more ▼]

This paper presents a detailed character- isation of user behaviour for a series of interactive video experiments over a 12 month period, in which we served popular sporting and musical content. In ad- dition to generic VCR-like features, our custom-built Video-on-Demand application provides advanced inter- activity features such as bookmarking. The dramatic impact of such functionality on how users consume con- tent is studied and analysed. We discuss in detail how this user behaviour can be exploited by content dis- tributors to improve user experience. Speci cally, we study how simple dynamic bookmark placement and interactivity-aware content pre-fetching and replication can reduce the impact of highly interactive media on CDN performance. [less ▲]

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See detailTowards a Two-Tier Internet coordinate system to mitigate the impact of Triangle Inequality Violations
Kaafar, Mohamed Ali ULg; Gueye, Cheikh Ahmadou Bamba ULg; Cantin, François ULg et al

in Lecture Notes in Computer Science (2008, May), 4982

Routing policies or path inflation can give rise to violations of the Triangle Inequality with respect to delay (RTTs) in the Internet. In network coordinate systems, such Triangle Inequality Violations ... [more ▼]

Routing policies or path inflation can give rise to violations of the Triangle Inequality with respect to delay (RTTs) in the Internet. In network coordinate systems, such Triangle Inequality Violations (TIVs) will introduce inaccuracy, as nodes in this particular case could not be embedded into any metric space. In this paper, we consider these TIVs as an inherent and natural property of the Internet; rather than trying to remove them, we consider characterizing them and mitigating their impact on distributed coordinate systems. In a first step, we study TIVs existing in the Internet, using different metrics in order to quantify various levels of TIVs’ severity. Our results show that path lengths do have an effect on the impact of these TIVs. In particular, the shorter the link between any two nodes is, the less severe TIVs involved in are. In a second step, we do leverage our study to reduce the impact of TIVs on coordinate systems. We focus on the particular case of the Vivaldi coordinate system and we explore how TIVs may impact its accuracy and stability. In particular, we observed correlation between the (in)stability and high effective error of nodes’ coordinates with respect to their involvement in TIVs situations. We finally propose a Two-Tier architecture opposed to a flat structure of Vivaldi that do mitigate the effect of TIVs on the distances predictions. [less ▲]

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See detailExplication et réduction de l’impact des violations d’inégalités triangulaires dans Vivaldi
Cantin, François ULg; Gueye, Cheikh Ahmadou Bamba ULg; Kaafar, Mohamed Ali ULg et al

in CFIP'2008 (2008, March)

Les systèmes de coordonnées sont des systèmes distribués ayant pour but, à partir de mesures de distance (par exemple RTT) entre certaines paires de noeuds, d’associer des coordonnées à chaque noeud dans ... [more ▼]

Les systèmes de coordonnées sont des systèmes distribués ayant pour but, à partir de mesures de distance (par exemple RTT) entre certaines paires de noeuds, d’associer des coordonnées à chaque noeud dans un espace métrique. Toutefois, de tels systèmes ne fonctionnent pas correctement lorsque les distances mesurées ne respectent pas les inégalités triangulaires. Or, les violations de ces inégalités, appelées TIV, sont fréquentes dans l’Internet. Nous proposons une étude approfondie de l’impact des TIV sur le système de coordonnées Vivaldi. Nous quantifions et expliquons les erreurs de prédiction de distance et l’instabilité des coordonnées causées par les TIV selon leur fréquence et leur sévérité. Nous montrons aussi que la distance entre deux noeuds, mesurée par le RTT, est corrélée à la probabilité d’existence d’une TIV. Enfin, nous recommandons un système de coordonnées hiérarchique, et nous montrons, par des simulations sur une matrice de délais réelle, qu’une telle approche réduit l’impact des TIV. [less ▲]

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