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Approximation models for the evaluation of TCP/AQM networks

Marek Dariusz, Domański Adam, Domańska Joanna, Szyguła Jakub, Czachórski Tadeusz, Klamka Jerzy, Filus Katarzyna

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 4

art. no. e141986

EN

The article proposes a model in which Diffusion Approximation is used to analyse the TCP/AQM transmission mechanism in a multinode computer network. In order to prevent traffic congestion, routers implement AQM (Active Queue Management) algorithms. We investigate the influence of using RED-based AQM mechanisms and the fractional controller PIγ on the transport layer. Additionally, we examine the cases in which the TCP and the UDP flows occur and analyse their mutual influence. Both transport protocols used are independent and work simultaneously. We compare our solution with the Fluid Flow approximation, demonstrating the advantages of Diffusion Approximation.

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Modelowanie dynamiki przesyłów TCP/IP z uwzględnieniem mechanizmu RED

Nycz M., Czachórski T.

Studia Informatica

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2012

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Vol. 33, nr 3A

49-62

PL

W pracy przedstawiono wyniki modelowania wybranych scenariuszy współczesnych sieci komputerowych. W badaniach zastosowano model matematyczny aproksymacji fluid flow, opisujący wpływ zmiennego w czasie natężenia ruchu pakietów na przełączniki sieciowe i generowanie strat pakietowych, zgodnie z założeniami mechanizmu RED stosowanego w routerach . Przeprowadzone doświadczenia obejmowały wpływ początkowych ustawień parametrów na zachowanie układu.

EN

The paper presents the results of modeling of selected modern computer networks scenarios. The study used a mathematical model of fluid flow approxmiation, describing the effects of time varying packet traffic on the network switches and packet loss generation by the assumptions of the RED mechanism used in routers. The carried out esperiments included the influence of tlie parameters initial settings on the behavior of a whole system.

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Modelling Time-dependent Flows of Virtual Connections in ATM Networks

Czachórski T., Pekergin F.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2000

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Vol. 48, nr 4

619-628

EN

The paper discusses the use of diffusion and fluid flow approximations in modelling the time-varying flows of cells which belong to different connections but are routed through the same ATM network switch. When the cells are leaving the switch, their class should be known to define the next routing. In steady-state queueing models the probability that customer belongs to a class k is obtained as the ratio of the class k through put to the whole throughput passing the node. We are interested in transient analysis where the throughputs are changing and the composition of multiclass flow at the entrance of a queue is not the same as at the output: we should consider the delay introduced by the queue the distribution of which is also changing with time. Numerical examples, validated by simulation, testify that diffusion approximation approach gives satisfactionary results in the solution of this problem. The fluid flow approximation is much simpler to implement and needs relatively less computation effort but gives worse results: the reason of it is that in the modelling the delay introduced by a switch queue, the distribution of the queue is important and the reasoning based only on its mean value is oversimplified.