Design of congestion control mechanism for multimedia

gegeben und mich bei meinen Vorhaben immer wieder in die richtige Richtung gelenkt. Dr. Trier hat mir etliche Reisen zu internationalen Tagungen ermöglicht, auf denen ich Anschluss an die weltweit verteilte Gemeinde der Internet-Netzforscher finden konnte. Professor Dr. Evi Nemeth hat mich auf einigen dieser Reisen unterstützt, indem sie mich als ” MBone-Slave “ beschäftigt und dadurch zur Reisefinanzierung beigetragen hat, und, indem sie mich mit interessanten Leuten in Kontakt gebracht hat. Für beides bin ich ihr sehr dankbar. Den vielen Kollegen aus unserem Rechenzentrum einschließlich des ehemaligen Kollegen Axel Clauberg, die mir bei zahlreichen technischen Fragen geholfen haben, gilt mein herzlichster Dank. Nur durch die besondere Infrastruktur unseres Rechenzentrums und das offene, freundliche Arbeitsklima ist die vorliegende Arbeit überhaupt möglich geworden. Auch mussten sie mehr als einmal die Beschwerden und Beschuldigungen der ” Opfer “ meiner Messungen entgegennehmen und an mich weiterleiten. Nicole Lyscom und Roland Franzen danke ich für ihre überaus wertvolle Hilfe bei der englischsprachigen Formulierung der Teilpublikationen. Ein besonderer

This thesis studies performance and performance analysis of TCP/IP networks, and presents a hybrid TCP/IP performance measurement environment. Central to this measurement environment is DLR, an IP-network simulator. TCP/IP protocol suite is the set of protocols that all communication in the Internet uses. The performance analysis of TCP/IP systems is a complex issue due to the heterogeneity of the IP-networks, the dynamic nature of the network characteristics, and the complex interaction between various network entities. There are basically three approaches to the performance analysis: analytic modeling, simulation and direct measurement. The measurement environment aims at comb...

Abstract We characterize a TCP implementation by a function, called a profile, that expresses the instantaneous throughput at the source in terms of the instantaneous roundtrip time and instantaneous loss rate for bulk transfers. We empirically obtain profiles of several TCP implementations, accurately enough to distinguish not only the TCP version but also the implementation (BSD, Windows, etc).

With a new United States Army initiative to exploit commercially developed information technology, there is a heightened interest in using Internet protocols over the military’s geosynchronous satellite links. TCP is the dominant Internet protocol used for reliable data exchange, but its own design limits performance when used over long delay network links such as satellites. Initially this research set out to compare TCP with another proposed protocol, the Satellite Transport Protocol (STP). However through a series of tests, we found that STP does not fulfill its claims of increased throughput over TCP and uncovered a flaw in STP’s founding research. In addition, this thesis proposes and demonstrates novel performance enhancing techniques that significantly improve transport protocol throughput. iii Acknowledgements First, I would like to thank my advisor, Prof. David Cyganski, for sharing his insights in physics, electrical engineering, and the art behind successful presentations. Next, I would like to thank my thesis committee, Prof. Brian King and Prof. William Michalson, for their time and helpful suggestions, and I would like to thank Raytheon’s Network Centric Systems Division for sponsoring the research project which provided ample thesis material

Embedded systems such as smart cards or sensors are now widespread, but are often closed systems, only accessed via dedicated terminals. A new trend consists in embedding Web servers in small devices, making both access and application development easier. In this paper, we propose a TCP performance model in the context of embedded Web servers, and we introduce a taxonomy of the contents possibly served by Web applications. The main idea of this paper is to adapt the communication stack behavior to application contents properties. We propose a strategies set fitting with each type of content. The model allows to evaluate the benefits of our strategies in terms of time and memory charge. By implementing a real use case on a smart card, we measure the benefits of our proposals and validate our model. Our prototype, called Smews, makes a gap with state of the art solutions both in terms of performance and memory charge.

exploring delay-based tcp congestion control a thesis submitted to the national university of ireland for the degree of

ii This thesis is dedicated to my parents who made my education priority and to my wife who made it a pleasure. i ACKNOWLEDGMENTS I would like to acknowledge those who helped make this thesis transition from thought to action: First and foremost, My supervisor Prof. Douglas Leith whose guidance helped me steer in the right direction and find the way on the long journey, and whose insight helped me tackle some seemingly dead-ends. Prof. Robert Shorten for his help during the research and the writing stages. Prof. Barak Pearlmutter for watering the seed of thought of going for a Masters degree and his help to make this effort bear fruits. Rosemary Hunt and Kate Moriarty for all their administrative help that let me focus on my work rather than form filings. And also my friends at the Hamilton Institute who made my stay in Ireland much more

We present a novel, practical, and effective mechanism for identifying the IP address of Tor clients. We approximate an almost-global passive adversary (GPA) capable of eavesdropping anywhere in the network by using LinkWidth, a novel bandwidth-estimation technique. LinkWidth allows network edge-attached entities to estimate the available bandwidth in an arbitrary Internet link without a cooperating peer host, router, or ISP. By modulating the bandwidth of an anonymous connection (e.g., when the destination server or its router is under our control), we can observe these fluctuations as they propagate through the Tor network and the Internet to the end-user’s IP address. Our technique exploits one of the design criteria for Tor (trading off GPA-resistance for improved latency/bandwidth over MIXes) by allowing well-provisioned (in terms of bandwidth) adversaries to effectively become GPAs. Although timing-based attacks have been demonstrated against non-timing-preserving anonymity networks, they have depended either on a global passive adversary or on the compromise of a substantial number of Tor nodes. Our technique does not require compromise of any Tor nodes or collaboration of the end-server (for some scenarios). We demonstrate the effectiveness of our approach in tracking the IP address of Tor users in a series of experiments. Even for an underprovisioned adversary with only two network vantage points, we can accurately identify the end user (IP address) in many cases. 1