Peer-to-peer (P2P) streaming has recently received much research attention, with successful commercial systems showing its viability in the Internet. Despite the remarkable popularity in real-world systems, the fundamental properties and limitations are not yet well understood from a theoretical perspective, as there exists a significant gap between the fundamental limits and the performance achieved in practice. In this thesis, we seek to provide an in-depth analytical understanding of fundamental properties and limitations of P2P streaming systems, with a particular spotlight on the performance gap. We first identify the major problem in existing streaming protocols and show that this problem accounts for most of the gap separating the actual and optimal performances of the streaming systems. We then propose a remedy based on network coding to address this problem and show that the gap to the fundamental limits can be significantly reduced.

Companies that sell digital products such as software and movies transfer large amounts of data to its customers. In order to send this amount of data using FTP or HTTP and still maintain a high speed transfer rate it is required that the company have a large number of servers and a huge bandwidth. Servers and bandwidth costs money which means they have great costs on the distribution of their products. In order to reduce distribution costs, P2P technology can be used and the most powerful technology to transmit popular files is called BitTorrent.BitTorrent requires users to share their bandwidth. Nowadays, BitTorrent is frequently used to transfer products that are free of charge; one example is the Linux distribution Ubuntu. In these BitTorrent systems different incentives exist to motivate the users to share their bandwidth. If a company uses BitTorrent to save money and put the distribution cost on their customers, does the customers motivation to share their bandwidth disappear?To give the reader a clear picture of the subject, literature on how BitTorrent works and its different concepts have been acquired and processed. In addition to literature, a survey has been carried out in which BitTorrent users were asked about their willingness to share their bandwidth and what motivates them most in a possible commercial BitTorrent system.The result of this study shows that a marked increase in the propensity to share bandwidth appears as additional incentives are implemented to a BitTorrent system. These incentives may be of financial or functional value. Economic incentives proved to be the most requested implementation. / Företag som säljer digitala produkter så som mjukvara och film skickar stora mängder data till dess kunder. För att kunna överföra dessa mängder med FTP eller HTTP i hög hastighet till kunderna krävs det att företaget har ett stort antal servrar och enorm bandbredd. Servrar och bandbredd kostar pengar vilket betyder att företagen har stora kostnader på distribution av deras produkter. För att minska distributionskostnader kan P2P-teknik användas och den kraftfullaste tekniken för att överföra populära filer heter BitTorrent.BitTorrent kräver att användare delar med sig av sin bandbredd. I dag används BitTorrent ofta för att överföra produkter som är gratis, ett exempel är Linuxdistributionen Ubuntu. I dessa BitTorrent-system motiveras användarna att bidra med sin bandbredd för att ge tillbaka någonting till gemenskapen. För att spara pengar kan företaget sprida ut kostnader för distribution till kunderna. Vad händer med kundens motivation att dela med sig av sin bandbredd i detta fall?Litteratur om hur BitTorrent fungerar och dess olika begrepp har samlats in och bearbetats. Utöver tidigare litteratur har en enkätundersökning genomförts där BitTorrent-användare tillfrågats om deras relation till att bidra med bandbredd och vad som motiverar dem mest i ett eventuellt kommersiellt BitTorrent-system.Resultatet av undersökningen visar att en tydlig ökning av benägenhet att dela med sig av bandbredd infinner sig då ytterligare incitament tillförs i BitTorrent-system. Dessa incitament kan vara ekonomiska eller funktionella värden. Ekonomiska incitament visade sig dock vara de mest efterfrågade.

As computers become pervasive and better connected, the popularity of peer-to-peer computing has grown immensely. The sharing of unused resources at peers is desirable and practically important because they can collectively comprise a powerful system. The potential benefit, however, can be undermined by uncooperative behavior of some peers because they are managed individually and hence may not follow the expected protocols. To build robust systems, we must incorporate proper trust and incentive mechanisms so that peers would rather cooperate. In this dissertation, we demonstrate that building robust peer-to-peer information dissemination systems is important and viable, using four concrete cases. First, we investigate the incentive mechanism of BitTorrent, an exchange-based file distribution protocol. Our framework based on iterated prisoner's dilemma provides an insight into users' tension between eagerness to download and unwillingness to upload. By using both analytical and experimental approaches, we show that the current incentive mechanism of BitTorrent is susceptible to free riding. We propose an improved mechanism that punishes free riders effectively. Second, we present a trust-aware overlay multicast system that performs well in the presence of uncooperative nodes, which may block, delay, fabricate, or forge the messages they forward. We develop (1) a set of protocols that detect uncooperative behavior, (2) a scheme of trust value assignment according to the behavior of nodes, and (3) an algorithm that adapts the multicast tree based on trust values, all of which allows the system to remain stable and responsive over time. Third, we propose an alternative news feed dissemination system, called FeedEx, in which feed subscribers mesh into a network and exchange news feeds with neighbors. The collaborative exchange in FeedEx, with the help of the incentive-compatible design using the pair-wise fairness principle, reduces the server load and hence increases the scalability. Fourth, we introduce a new concept of peer-to-peer computing, that is, continual service using ephemeral servers. To this end, we develop a system model for the concept and implement a discrete-time simulator to find the conditions and the system support for eliciting cooperation. All four cases are substantiated by experimental results.

With the extremely rapid development of the Internet in recent years, emerging peer-to-peer network overlays are meeting the requirements of a more sophisticated communications environment, providing a useful substrate for applications such as scalable file sharing, data storage, large-scale multicast, web-cache, and publish-subscribe services. Due to its design flexibility, peer-to-peer networks can offer features including self-organization, fault-tolerance, scalability, load-balancing, locality and anonymity. As the Internet grows, there is an urgent requirement to understand real-time network performance degradation. Measurement tools currently used are ping, traceroute and variations of these. SNMP (Simple Network Management Protocol) is also used by network administrators to monitor local networks. However, ping and traceroute can only be used temporarily, SNMP can only be deployed at certain points in networks and these tools are incapable of sharing network measurements among end-users. Due to the distributed nature of networking performance data, peer-to-peer overlay networks present an attractive platform to distribute this information among Internet users. This thesis aims at investigating the desirable locality property of peer-to-peer overlays to create an application to share Internet measurement performance. When measurement data are distributed amongst users, it needs to be localized in the network allowing users to retrieve it when external Internet links fail. Thus, network locality and robustness are the most desirable properties. Although some unstructured overlays also integrate locality in design, they fail to reach rarely located data items. Consequently, structured overlays are chosen because they can locate a rare data item deterministically and they can perform well during network failures. In structured peer-to-peer overlays, Tapestry, Pastry and Chord with proximity neighbour selection, were studied due to their explicit notion of locality. To differentiate the level of locality and resiliency in these protocols, P2Psim simulations were performed. The results show that Tapestry is the more suitable peer-to-peer substrate to build such an application due to its superior localizing data performance. Furthermore, due to the routing similarity between Tapestry and Pastry, an implementation that shares network measurement information was developed on freepastry, verifying the application feasibility. This project also contributes to the extension of P2Psim to integrate with GT-ITM and link failures.

Zugl.: Oldenburg, Universiẗat, Diss., 2008.

Hermes é um arcabouço para a programação de aplicações P2P. Com ele, pode-se criar diversos tipos de aplicações distribuídas, sem se preocupar com a camada de comunicação. O Hermes não é uma implementação de uma rede de sobreposição P2P, e sim uma camada acima das implementações já existentes. O desenvolvedor da aplicação fica isolado da implementação da rede de sobreposição utilizada. Esse isolamento é feito de forma tal que não há limitações quanto à arquitetura de rede utilizada pela implementação, seja ela centralizada, descentralizada, distribuída estruturada ou distribuída não-estruturada. Entre os serviços oferecidos pelo Hermes estão: troca de mensagens, busca, comunicação em grupo e armazenamento distribuído. Geralmente, no início do desenvolvimento de uma aplicação distribuída, tem-se poucas informações sobre o seu tamanho final ou perfil de utilização. O Hermes possibilita ao desenvolvedor da aplicação adiar, até o momento da efetiva implantação do sistema, a decisão sobre qual arquitetura de rede ou qual implementação de rede de sobreposição são as mais apropriadas para suas necessidades. Possibilita também, quando o perfil de utilização muda com o tempo, a troca da implementação utilizada por uma outra que se adeque mais ao novo perfil sem alterações no código da aplicação. / Hermes is a framework for P2P application programming. Using it, one can create several kinds of distributed applications without worrying about the underlying network. Hermes is not a P2P overlay network implementation, but a shell envolving existing implementations. The application developer is isolated from the implementation of the overlay network in use. This isolation is done in a way that poses no limitations on the network architecture used, which may be centralized, decentralized, structured or unstructured. Amongst the services offered by Hermes are: message exchange, search, group communication, and distributed storage. In the early stages of the development of a distributed application, information as to its final size or utilization profile is often unknown. Hermes gives the application developer the possibility of delaying, until the actual moment of system deployment, the decision as to which network architecture or which overlay network implementation is the most appropriate. It also gives the developer the choice, when utilization profile changes over time, of replacing the network implementation with one more suitable to the application needs, without changes on the application code.

Denna studie undersöker om peer-to-peer-investeringar (P2P) kan fungera som en fördelaktig diversifiering för investerare. Med fokus på P2P-lån emitterade via den svenska plattformen Savelend under tidsperioden januari 2014 till december 2023 uppskattar analysen den riskjusterade avkastningen och korrelationen med andra investeringsformer, som aktiemarknadsindex, obligationsfonder, hedgefonder och statsobligationer. Analysen använder sig av både en kvantitativ och kvalitativ struktur med hjälp av data från P2P-plattformen och intervjuer med branschexperter. Resultaten syftar till att informera potentiella investerare om lönsamheten i att inkludera P2P-lån i en diversifierad investeringsportfölj, med tanke på deras resultat under olika ekonomiska cykler och som helhet under de senaste tio åren. Resultaten från studien visar att peer-to-peer-investeringar (P2P) via Savelend från januari 2014 till december 2023 erbjuder fördelaktig riskjusterad avkastning jämfört med mer traditionella investeringar och alternativa investeringar. P2P-lån har potential för hög avkastning och låg korrelation med stora marknader, vilket ökar diversifieringen i investeringsportföljer. Resultat från intervjuerna visar att diversifiering genom inkluderandet av P2P-lån i en investeringsportfölj kan vara fördelaktigt men att vara medveten om likviditets- och plattformsrisker. P2P-lån kan vara värdefulla men kräver noggrant övervägande av tillhörande risker. / This study investigates whether peer-to-peer (P2P) investments might serve as a beneficial diversification for investors. Focusing on P2P-loans issued through the Swedish platform Savelend during the timeframe January 2014 to December 2023, the research estimates the risk-adjusted returns and correlation with other investment forms like stock-market indexes, bond funds, hedge funds and government bonds. The analysis uses both a quantitative and qualitative structure using data from the P2P-platform and interviews with industry experts. The findings aim to inform potential investors about the viability of including P2P-loans in a diversified investment portfolio, considering their performance during different economic cycles and as a whole during the last ten years. The results from the study reveals that peer-to-peer (P2P) investments via Savelend from January 2014 to December 2023 offer competitive risk-adjusted returns compared to more traditional investments and alternative investments like stock-market indexes, bonds, hedge funds and government bonds. P2P-loans show potential for high returns and low correlation with major markets, enhancing portfolio diversification. Results from the interviews show that diversification through the incorporation of P2P-loans into an investment portfolio might be advantageous but to be aware of liquidity and platform risks. P2P-loans can be valuable but require careful consideration of associated risks.

The primary goal of this thesis is to implement peer to peer technology in vehicular communication. The emerging concept of Vehicular Communication including road side infrastructure is a promising solution to avoid accidents and providing live traffic data. There is a high demand for the technologies which ensure low latency communication. Modern vehicles equipped with computing, communication and storage and sensing capabilities eased the transmission of data. To achieve deterministic bounds on data delivery, ability to be established anywhere quickly, and efficiency of data query we have chosen to implement a structured peer to peer overlay model in a cluster of vehicles. The vehicles in the cluster exchange information with the cluster head. The cluster head acts as a leader of the cluster, it fetches the data from the Road-side unit and other cluster heads. We have implemented Pyramid Tree Model in structured peer to peer models. A pyramid tree is group of clusters organized in a structured format with the data links between the clusters. The core concepts behind the pyramid tree model is clustering the nodes based on interest.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Telemetry recorders have historically been used as standalone systems with each user responsible for operation and data interpretation on that system. Utilizing the latest peerto- peer networking technologies, telemetry recorders can now be linked to provide instantaneous communication between systems. This fully distributed, network-based architecture can be used for command and control of multiple recorders, as well as message passing between them. A centralized server is no longer required, resulting in considerable logistical and cost savings. The peer-to-peer communication topology can efficiently connect telemetry recorder “islands of information”.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy