Présentation de Lamine Lamali au GT Algodist le lundi 10 octobre 2016 à 14h en salle 178 du LaBRI

Bonjour à tous,

Lamine Lamali présentera un exposé au GT Algodist, le lundi 10 octobre 2016 à 14h en salle 178, intitulé : "Calcul de chemins dans les réseaux multicouches : une approche par la théorie des langages".

Résumé :
Les réseaux multicouches sont des réseaux où plusieurs protocoles coexistent sur différentes couches. Néanmoins, plusieurs architectures réseaux définissent des fonctions de conversion, encapsulation et désencapsulation de protocoles pour pallier cette hétérogénéité. Les algorithmes classiques de calcul de chemins dans les graphes ne peuvent être appliqués dans ce contexte car ils ne prennent pas en compte ces (dés)encapsulations. De plus, les plus courts chemins dans ce type de réseaux ont des caractéristiques non triviales : ils peuvent comporter des boucles et n’ont pas de sous-structure optimale.
Après avoir constaté que les séquences de protocoles associées à un chemin dans un réseau multicouche forment un langage à contexte libre, nous proposons un nouveau modèle de réseau basé sur les automates à pile, ainsi que des algorithmes issus de la théorie des langages pour calculer le(s) plus court(s) chemin(s) dans ce type de réseaux. Nous montrons également que sous contrainte de bande passante, le calcul de chemins devient NP-complet, même dans un réseau symétrique et avec seulement deux protocoles.

Tout le monde est le bienvenu.

Sémi-doc on June 22nd 2016 at 1.30pm in the LaBRI about Service Chain Modeling and Embedding for NFV-based Content Delivery

Dear all,

There will be a presentation on June 22nd, 2016 at 1.30pm (in the main amphitheater of the LaBRI) by Nicolas Herbaut on:
Service Chain Modeling and Embedding for NFV-based Content Delivery

Increasing over-the-top video consumption endangers the sustainability of content delivery over the Internet. Internet Service Providers (ISP) face difficulties in competing on value-added services with content providers and Content Delivery Network (CDN) operators. In this respect, we propose a new model for the collaboration between content delivery actors, where CDN operators can deploy their software in ISP infrastructures using Network Function Virtualization (NFV) techniques.
As the ISP network topology and utilization is deemed confidential, we use a high-level Service Level Agreement (SLA) for the negotiation of both computing resources and connectivity, allowing the ISP to optimize server selection, while providing at the same time sufficient flexibility to the CDN operators for content delivery.
Furthermore, we present a linear programming formulation and an algorithm for service chain embedding. Our simulations results show significant gains of the algorithm in terms of request acceptance rate and resource consumption. Finally, we validate the efficiency of the proposed service chain model for Virtual CDN management.
Everyone is welcome.
See you there,

Mini-GT Comet aujourd'hui à 14H30 en salle 073 / Comet mini-WG today at 2.30pm in room 073

Hi everyone,

There will be a workgroup meeting today for our Comet group at 14H30 - 2.30pm in room 073 of the Labri.

Nicolas Herbaut and Joachim Bruneau-Queyreix will present their work in progress.

The information of Nicolas' talk is given below:

Title: Content Delivery Networks as a Virtual Network Function: a win-win ISP-CDN collaboration

Abstract: The switch in video delivery from traditional medium to Over-the-Top based services has been a game changer for stakeholders of the media delivery ecosystem.  It has changed the value chain enabling Content Delivery Networks and Content Providers to take the lion's share at the expense of Internet/Network Service Providers. Even if establishing collaboration between them naturally appears as the key to provide good Quality of Service to the end-users, they struggle in finding efficient and fair ways to do so.
This paper directly tackles this problem and proposes a new model for Content Delivery Actors to collaborate over a Virtualized Infrastructure, fairly balancing the revenue stream created. We list the main challenges and the new technical opportunities to solve them, among which the deployment of a distributed Network Function Virtualization platform at the edge of the Internet Service Provider's network where a virtual Content Delivery Network is deployed.

See you soon!


Semi-doc on the 10th of September 2015 at LaBRI on the paper entitled "Migrating to a NFV-based Home Gateway: introducing a Surrogate vNF approach"

On Sept 10th, Nicolas Herbaut will give a talk on "Migrating to a NFV-based Home Gateway: introducing a Surrogate vNF approach"


Virtualizing network functions is becoming a major trend in today's research on cloud computing. Among networking elements, the Home Gateway appears to be one with the most diverse functions to handle and thus, with great potential for virtualization. To this end, the paper proposes a solution to ease adoption by Service Providers of the latest breakthroughs in cloud computing technologies towards a virtualized Home Gateway. Although the NFV approach globally pretends bringing operational advantages in terms of CAPEX and OPEX, it is essential to prove them for Home Gateways scenarios where compatibility and versatility are strong requirements. To achieve this goal, we introduce the concept of Surrogate vNF, which makes Home Gateways NFV aware. The paper highlights a migration path towards full Home Gateway virtualization and proves its concept through a real implementation and a simulated evaluation on a practical use case related to video content distribution.

Presentation of the research paper WiseReplica by Nicolas Herbaut on Tuesday 19/05 14h room 071 at the Labri

Dear all,

Nicolas Herbaut will give a talk on Tuesday 19/05, 14h, room 071 at the Labri on the paper:

Boosting Streaming Video Delivery with WiseReplica
by Guthemberg Silvestre, David Buffoni, Karine Pires, Śebastien Monnet , and Pierre Sens

link to the paper -->

Abstract. Streaming video consumption has risen sharply over the last years. It has not only reshaped the Internet traffic, it has also changed the manner of watching videos. Users are progressively moving from the old-fashioned scheduled television to video-on-demand (VoD) services. As broadcasting future seems to be online, customers have become more sensitive to VoD quality, expecting ever-higher bitrates and lower rebuffering. In this context, average bitrate is a key quality of service (QoS) metric. Therefore, content delivery networks (CDNs) and content providers must be committed to enforce average bitrate through
service-level agreement (SLA) contracts. Adaptive content replication is a promising technique towards this goal. However, this still offers a major challenge for CDN providers, particularly as they aim to avoid waste of resources. In this work, we introduce WiseReplica, an adaptive replication scheme for peer-assisted VoD systems that enforces the average bitrate for Internet videos. Using an accurate machine-learned ranking, WiseReplica saves storage and bandwidth from the vast majority of non-popular contents for the most watched videos. Simulations using YouTube traces suggest that our approach meets users  expectations efficiently. Compared to caching, WiseReplica reduces the required replication degree for the most-watched videos by two orders of magnitude, and under heavy load, it increases the average bitrate by roughly 85 %.

Best regards,