Mathieu Goutelle

Study of a non-intrusive method for measuring the end-to-end capacity and useful bandwidth of a path

Studies and tools development for applications sensitive to data rates is a very active research field. Tools for measuring the end-to-end performance of a link between two hosts are very important for distributed application performance optimization. Bandwidth evaluation methods aim to provide a realistic view of the raw capacity but also of the dynamic behaviour of the interconnection that may be very useful to evaluate the time of bulk data transfer. Existing methods differs according to the measurements strategies and the evaluated metric. This paper analyses the available bandwidth measurements and the total capacity measurements approaches. None of the proposed tools permit to evaluate both metrics while giving an overview of the link topology. An approach using a hop-by-hop packet pair method and a fine analysis of the measurements can provide such informations. The principles of this hop-by-hop measurement of the capacity and available bandwidth method are exposed in this paper. This proposition has been validated in simulation, then implemented in Linux and validated experimentally. We compared our method with the others to define its limits and the potential utilisations on the developed tool.

Experiments with equivalent differentiated services in a grid context

Grids generally rely on a complex interconnection of Internet Protocol (IP) domains that offer heterogeneous services and unpredictable performance characteristics, particularly at the local area network/wide area network boundary. The total lack of end-to-end resource control in IP networks is responsible for performance problems that may affect the whole Grid environment. An end-to-end service differentiation architecture that controls heterogeneous communication performance is thus needed. We propose the Equivalent Differentiated Services (EDS) architecture, based on a layer-4 service differentiation solution exploiting a new layer-3 relative DiffServ model. In this paper, we present the EDS packet forwarding principles, the router mechanisms and two adaptive packet marking algorithms. As a proof of concept, we have implemented the EDS architecture in Linux and performed experiments on a transoceanic testbed.

Approches alternatives pour la différenciation de services IP

This article studies the problem of service differentiation in IP networks. The limits of the standard models are analysed and alternative solutions like the proportional differentiation and the non-elevated services are presented. These services are simpler to set up but need adaptation layers to insure correct end-to-end performances. To illustrate these approaches the EDS model from the INRIA/RESO team and the QBSS-LBE model of the internet2 project are explored and their properties studied practically. This study highlights the benefit of a global approach of Quality of Service in internet and open many perspectives of research on the transport layer.