The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Performance Evaluation of Multicast Networks and Service Differentiation Mechanisms in IP Networks

Eeva Nyberg-Oksanen

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Auditorium S5 at Helsinki University of Technology (Espoo, Finland) on the 13th of January, 2006, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-7993-2)   [918 KB]
Dissertation is also available in print (ISBN 951-22-7992-4)

Abstract

The performance of a communication network depends on how well the network is designed in terms of delivering the level of service required by a given type of traffic. The field of teletraffic theory is concerned with quantifying the three-way relationship between the network, its level of service and the traffic arriving at the network. In this thesis, we study three different problems concerning this three-way relationship and present models to assist in designing and dimensioning networks to satisfy the different quality of service demands.

In the first part of the thesis, we consider service differentiation mechanisms in packet-switched IP networks implementing a Differentiated Services (DiffServ) architecture. We study how bandwidth can be divided in a weighted fair manner between persistent elastic TCP flows, and between these TCP flows and streaming real-time UDP flows. To this end, we model the traffic conditioning and scheduling mechanisms on the packet and the flow level. We also model the interaction of these DiffServ mechanisms with the TCP congestion control mechanism and present closed-loop models for the sending rate of a TCP flow that reacts to congestion signals from the network.

In the second part, we concentrate on non-persistent elastic TCP traffic in IP networks and study how flows can be differentiated in terms of mean delay by giving priority to flows based on their age. We study Multi Level Processor Sharing (MLPS) disciplines, where jobs are classified into levels based on their age or attained service. Between levels, a strict priority discipline is applied; the level containing the youngest jobs has the highest priority. Inside a particular level, any scheduling discipline could be used. We present an implementation proposal of a two-level discipline, PS+PS, with the Processor Sharing discipline used inside both levels. We prove that, as long as the hazard rate of the job-size distribution is decreasing, which is the case for Internet traffic, PS+PS, and any MLPS discipline that favors young jobs, is better than PS with respect to overall mean delay.

In the final part, we study distribution-type streaming traffic in a multicast network, where there is, at most, one copy of each channel transmission in each network link, and quantify the blocking probability. We derive an exact blocking probability algorithm for multicast traffic in a tree network based on the convolution and truncation algorithm for unicast traffic. We present a new convolution operation, the OR-convolution, to suit the transmission principle of multicast traffic, and a new truncation operator to take into account the case of having both unicast and multicast traffic in the network. We also consider different user models derived from the single-user model.

This thesis consists of an overview and of the following 8 publications:

  1. Eeva Nyberg and Samuli Aalto. How to achieve fair differentiation. In Proceedings of Networking 2002, pages 1178-1183, Pisa, Italy, May 2002. © 2002 Springer Science+Business Media. By permission.
  2. Samuli Aalto and Eeva Nyberg. Flow level models of DiffServ packet level mechanisms. In Proceedings of the 16th Nordic Teletraffic Seminar, pages 194-205, Espoo, Finland, August 2002. © 2002 by authors.
  3. Eeva Nyberg and Samuli Aalto. Differentiation and interaction of traffic: a flow level study. In Proceedings of International Workshop Art-Qos 2003, pages 276-290, Warsaw, Poland, March 2003. © 2003 Springer Science+Business Media. By permission.
  4. Konstantin Avrachenkov, Urtzi Ayesta, Patrick Brown, and Eeva Nyberg. Differentiation between short and long TCP flows: predictability of the response time. In Proceedings of IEEE INFOCOM 2004, volume 2, pages 762-773, March 2004. © 2004 IEEE. By permission.
  5. Samuli Aalto, Urtzi Ayesta, and Eeva Nyberg-Oksanen. Two-Level Processor-Sharing scheduling disciplines: Mean delay analysis. In Proceedings of ACM SIGMETRICS - PERFORMANCE 2004, pages 97-105, June 2004. © 2004 Association for Computing Machinery (ACM). By permission.
  6. Samuli Aalto, Urtzi Ayesta, and Eeva Nyberg-Oksanen. M/G/1/MLPS comapred to M/G/1/PS. Operations Research Letters, 33 (5): 519-524, September 2005. © 2005 Elsevier Science. By permission.
  7. Eeva Nyberg, Jorma Virtamo, and Samuli Aalto. An exact algorithm for calculating blocking probabilities in multicast networks. In Proceedings of Networking 2000, pages 275-286, Paris, France, May 2000. © 2000 Springer Science+Business Media. By permission.
  8. Eeva Nyberg, Jorma Virtamo, and Samuli Aalto. An exact end-to-end blocking probability algorithm for multicast networks. Performance Evaluation, 54 (4): 311-330, December 2003. © 2003 Elsevier Science. By permission.

Errata of publications 3, 4 and 5

Keywords: TCP, QoS, DiffServ, fairness, scheduling, PS, MLPS, delay, multicast, blocking probability, OR-convolution

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© 2006 Helsinki University of Technology

Last update 2011-05-26