A novel diffusion process with jumps to study an electronic-optical edge router

The article presents a diffusion approximation model applied to investigate the process of filling a large optical packet by smaller and coming irregularly electronic packets. The use of diffusion approximation enables us to include the general distributions of interarrival times, also the self-similarity of the input process, as well as to investigate transient states. We propose a novel diffusion process with jumps representing the end of the filling the buffer due to arrival of too large packet and we give the transient solution to this process. The model allows us to study the distribution of interdeparture times and the distribution of the space occupied in the optical packet

Implementation of modified AQM mechanisms in IP routers

The article is an attempt to answer the question if it makes sense to modify the way of choosing packets to reject inAQM mechanisms. Simulation and analytical research of RED and DSRED mechanisms shows that their efficiency grows when packet is received from the front of the queue. It is especially conspicuous when taking into account the self-similarity of traffic. However implementation of the above mentioned mechanisms in real router does not corroborate such a clear advantage over Drop-From-Front strategy. In this article the results of analytical, simulation and real router research based on the Linux operating system have been presented

Diffusion approximation as a modelling tool in congestion control and performance evaluation

Tutoria

A diffusion approximation model of an electronic-optical node

Designing of smart edge routers and shaping the self-similar traffic in optical switched networks arise recently a lot of interest. Here, we propose an analytical approach which we consider useful in modelling and dimensioning of buffers in the edge routers between electronic and optical networks. We study a single buffer where packets of various sizes, classified by the class of service and the destination, are stored to build an optical packet of a fixed size. We already studied this problem with the use of simulation model, remarking that self-similar traffic at the entrance of such a buffer remains self-similar when leaving it. Now we are building analytical model based on diffusion approximation. and our previous contributions to this approach, i.e. a method to solve transient diffusion models. The model is used to analyse the process of buffer filling and a a numerical example proves that this approach may give reasonable results in relatively short (compared to simulation, especially simulation of transient states) time

Transport Time Distribution for Optimal Deflection Routing on an Odd Torus

International audienc

Stability and Dynamics of TCP-NCD (DCR) Protocol in Presence of UDP Flows

International audienceThe fluid-flow approximation models investigate with much success the dynamics and stability of TCP/RED connections. Their main assumption is that the fluctuations of variables characterizing the behaviour of the connections are relatively small, that enables the linearization of model and the use of traditional control analysis tools to obtain such measures as Bode gain, phase margins, tracking error or delay margin. In this article, preserving linear fluid-flow model, we propose its extension to the case when a network is composed of wired and wireless part. We consider a variant of TCP algorithm (TCP-DCR or its new version TCP-NCR) and fluid-flow differential equations representing the size of congestion window, mean queue at the bottleneck router and loss probability at a RED queue are supplemented with terms representing constant loss probability due to transmission in wireless part and probability that a fraction of these errors is recovered by a link level mechanism. The decrease of congestion window due to TCP mechanism is delayed to allow the link protocol to deal with the errors. The model considers the presence of uncontrollable UDP flows

Forming optical packets, a diffusion approximation and simulation models

Designing of smart edge routers and shaping the self-similar traffic in optical switched networks arise recently a lot of interest. Here, we propose an analytical approach which we consider useful in modelling and dimensioning of buffers in the edge routers between electronic and optical networks. We study a single buffer where packets of various sizes, classified by the class of service and the destination, are stored to build an optical packet of a fixed size. We already studied this problem with the use of simulation model, remarking that self-similar traffic at the entrance of such a buffer remains self-similar when leaving it. Now we are building analytical model based on diffusion approximation. and our previous contributions to this approach, i.e. a method to solve transient diffusion models. The model is used to analyse the process of buffer filling and a a numerical example proves that this approach may give reasonable results in relatively short (compared to simulation, especially simulation of transient states) time

Modèle analytique du mécanisme partial buffer sharing pour des arrivées de paquets de taille variable

In order to control and manage the high speed networks congestion phenomena in general and Frame Relay (FR) congestion problem in particular, priority-based mechanisms are proposed in the litterature for fixed length data units. In this report, we have proposed a markovian model related to Partial Buffer Sharing (PBS) mechanism for variable length data units. The thorough performance evaluation for $M^{(1)} + M^{(2)}$/D/1/N with PBS mechanism queue has been conducted. We have shown the best performance of this mechanism compared with those of $M^{(1)} + M^{(2)}$/D/1/N without PBS mechanism queue. We have also discussed the parameters model choice.Dans le but de contrôler et de gérer le problème de congestion dans les réseaux haut débit en général et les réseaux Frame Relay (FR) en particulier, des mécanismes à rejets sélectifs ont été proposé dans la littérature pour des unités de données de taille fixe. Dans ce rapport, nous proposons premièrement, un modèle markovien du mécanisme Partial Buffer Sharing (PBS) pour des unités de données de taille variable. Une étude de performance de la file $M^{(1)} + M^{(2)}$/D/1/N avec mécanisme PBS est ensuite présenté montrant les bonnes performances de celui ci comparé à ceux de la file $M^{(1)} + M^{(2)}$/D/1/N sans mécanisme PBS. Le choix des paramètres du modèle est également discuté dans ce rapport

Packet Loss Analysis in Optical Packet-Switched Networks with Limited Deflection Routing

International audienc

Preliminary Results of Packet Loss Analytilis in Optical Packet-Switched Networks with Limited Deflection Routing

International audienc