Posts Tagged - tech-report

Tech Report: Peer-to-Peer Traffic

Date Completed: August 2009

This Tech Report deals with Peer-to-Peer protocols. We start by giving a brief account of history of P2P applications and then cite from some of the P2P traffic measurement studies. P2P traffic identification methods and the recent P2P traffic optimization schemes constitute the core of this report, in which we examine the state-of-the-art in this field.

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Tech Report: BitTorrent

Date Completed: July 2009

BitTorrent protocol has emerged as the most popular P2P protocol over the past years. The core BitTorrent protocol has been designed and implemented by Bram Cohen in 2001.

The protocol is especially useful for distributing large popular files (like open-source operating system distributions) as its performance improves as the number of interested connected peers increases. The way in which BitTorrent operates lessens the burden (hardware costs and bandwidth resources) of servers hosting the files and distributes that burden among all the peers currently connected, reducing costs significantly for original content distributors as a result. Connected peers share the task of serving the content to newly-connected peers and a “tit-for-tat” mechanism ensures fairness among all the peers. This method of content sharing also improves redundancy in the overlay network (formed around that specific content), as a probable malfunctioning of the original content provider does not render the content unavailable. In this Tech Report, we explain the functionality of the BitTorrent protocol and its various system components.

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Tech Report: Congestion Avoidance and Control

Date Completed: June 2009

In this Tech Report, we start by introducing the principles of congestion control and its importance in the stability of the Internet. We then move on to provide some background information on TCP’s congestion control algorithms as well as on Explicit Congestion Notification (ECN). Afterwards, we explain the concepts behind the major Active Queue Management (AQM) mechanisms and explore their designs. We conclude the report by stating our opinion regarding “fairness” and will reinforce our position by introducing the “re-ECN” initiative.

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Tech Report: IEEE 802.11 and Propagation Modeling: A Survey and a Practical Design Approach

Technical Report, Masood Khosroshahy (2007)

Abstract—Due to known difficulties of researchers in the networking domain regarding experimentation of their ideas in actual networks, network simulators have become indispensable tools for investigating and validating various ideas in all layers of the network. In this survey, we inspect the implementations of IEEE 802.11 PHY-MAC and propagation models of some of the well-known, open-source network simulators. The chosen simulators are: NS-2, OMNeT++, GloMoSim, J-Sim and JiST/SWANS. The study concentrates on the availability and implementation flexibility of MAC modes, physical layer features and propagation models. This survey could help the research community in determining the state-of-the-art of IEEE 802.11 implementations and, to the best of our knowledge, is the first such study published in the open literature. To facilitate the ongoing and future network simulator developments, we also present our design and implementation approaches in successfully developing a prototype of a detailed IEEE 802.11a PHY layer along with the propagation models.

Index Terms—IEEE 802.11, Network Simulators, Propagation Models, WiFi

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