Network aware P2P multimedia streaming: capacity or locality?

P2P content providers are motivated to localize traffic within Autonomous Systems and therefore alleviate the tension with ISPs stemming from costly inter-AS traffic generated by geographically distributed P2P users. In this paper, we first present a new three-tier framework to conduct a thorough study on the impact of various capacity aware or locality aware neighbor selection and chunk scheduling strategies. Specifically, we propose a novel hybrid neighbor selection strategy with the flexibility to elect neighbors based on either type of network awareness with different probabilities. We find that network awareness in terms of both capacity and locality potentially degrades system QoS as a whole and that capacity awareness faces effort-based unfairness, but enables contribution-based fairness. Extensive simulations show that hybrid neighbor selection can not only promote traffic locality but lift streaming quality and that the crux of traffic locality promotion is active overlay construction. Based on this observation, we then propose a totally decentralized network awareness protocol, equipped with hybrid neighbor selection. In realistic simulation environments, this protocol can reduce inter-AS traffic from 95% to 38% a locality performance comparable with tracker-side strategies (35%) under the premise of high streaming quality. Our performance evaluation results provide valuable insights for both theoretical study on selfish topologies and real-deployed system design. © 2011 IEEE.published_or_final_versionThe 2011 IEEE International Conference on Peer-to-Peer Computing (P2P 2011), Kyoto, Japan, 31 August-2 September 2011. In Proceedings of P2P, 2011, p. 54-6

On dynamic server provisioning in multichannel P2P live streaming

To guarantee the streaming quality in live peer-to-peer (P2P) streaming channels, it is preferable to provision adequate levels of upload capacities at dedicated streaming servers, compensating for peer instability and time-varying peer upload bandwidth availability. Most commercial P2P streaming systems have resorted to the practice of overprovisioning a fixed amount of upload capacity on streaming servers. In this paper, we have performed a detailed analysis on 10 months of run-time traces from UUSee, a commercial P2P streaming system, and observed that available server capacities are not able to keep up with the increasing demand by hundreds of channels. We propose a novel online server capacity provisioning algorithm that proactively adjusts server capacities available to each of the concurrent channels, such that the supply of server bandwidth in each channel dynamically adapts to the forecasted demand, taking into account the number of peers, the streaming quality, and the channel priority. The algorithm is able to learn over time, has full Internet service provider (ISP) awareness to maximally constrain P2P traffic within ISP boundaries, and can provide differentiated streaming qualities to different channels by manipulating their priorities. To evaluate its effectiveness, our experiments are based on an implementation of the algorithm, which replays real-world traces. © 2011 IEEE.published_or_final_versio

Scenarios and system dynamics of mobile peer-to-peer content distribution

Vertaisverkkoteknologian menestys kiinteissä verkoissa on johtanut vertaisverkkototeutuksiin myös mobiileissa verkoissa. Mobiilin vertaisverkkoteknologian tulevaisuuden suhteen on tosin vielä paljon epävarmuutta, koska operaattorit ja muut sidosryhmän jäsenet, jotka kärsivät laittoman tiedostonvaihdon seurauksista kiinteän verkon puolella, pelkäävät saman tapahtuvan myös mobiileissa verkoissa. Täten he saattavat yrittää estää mobiilin vertaisverkkoteknologian kehittymistä. On myös epävarmaa onko mobiilille vertaisverkkoteknologialle tarvetta loppukäyttäjän näkökulmasta, eritoten kun mobiililaitteiden suorituskyvyt ovat huomattavasti alhaisempia kuin kiinteiden. Tämä diplomityö keskittyy mobiilin vertaisverkon sisällönjakeluun. Sisällönjakelu on jaettu tiedostonvaihtoon, sisällön suoratoistoon ja kaupallisiin sisältöjärjestelmiin. Työ antaa näkemystä mobiilin vertaisverkon sisällönjakelun olennaisimpiin skenaarioihin, sidosryhmän jäseniin ja heidän kannustimiin. Mobiilin vertaisverkon sisällönjakelun epävarmuutta rajataan käyttämällä skenaarioanalyysiä ja mallinnetaan systeemidynamiikalla. Olennaisimmat skenaariot rakennetaan Schoemakerin metodilla ja niiden mallinnusta yritetään systeemidynamiikan keinoin. Tuloksena saadaan neljä eri skenaariota, jotka on kehitetty brainstorming -tilaisuuksissa ja kirjallisuuskatsauksessa löydettyjen avaintrendien ja -epävarmuustekijöiden perusteella. Skenaarioiden kvantitatiivisen mallinnuksen sijaan mallinnetaan skenaarioihin perustuvan mobiilin vertaisverkon sisällönjakelujärjestelmän dynaamista käyttäytymistä. Vaikka joitakin mobiilia vertaisverkkoteknologiaa hyödyntäviä sovelluksia on jo kehitetty ja käytössä, sekä aihetta tutkittu laajasti, vieläkin on epävarmaa mikä teknologian vaikutus tulee olemaan. Tämä diplomityö esittää mahdollisia vaikutuksia teknologialle ja antaa lähtökohdan tulevalle mobiilien vertaisverkon sisällönjakelujärjestelmien kvantitatiiviselle mallinnukselle. Systeemidynamiikka on toteuttamiskelpoinen vaihtoehto tavallisemmille mallinnustekniikoille, kuten taulukkolaskentamallinnukselle, jonka etuna on järjestelmän takaisinkytkentäsilmukkojen mallintaminen. Kun mobiili vertaisverkkoteknologia kehittyy, enemmän dataa tulee saataville ja vaihtoehtoisten systeemidynamiikkamallien rakentaminen on suositeltavaa.The success of peer-to-peer technology in the fixed networks has led to peer-to-peer implementations in the mobile networks as well. There is, however, a lot of uncertainty regarding the future of mobile peer-to-peer technology as the operators and other stakeholders that were affected negatively by illegal peer-to-peer file sharing in the fixed networks are afraid that it might happen in the mobile domain as well. Thus they might try to prevent mobile peer-to-peer technology from emerging. There is also the question whether there really is a need for peer-to-peer technology in the mobile domain from the end users' perspective, especially as the mobile device capabilities are considerably lower compared to the fixed ones. This thesis concentrates on mobile peer-to-peer content distribution. Content distribution is divided to file exchange, content streaming and commercial content systems. The thesis provides insight to the most relevant scenarios, stakeholders and their incentives related to mobile peer-to-peer content distribution. The uncertainty regarding mobile peer-to-peer content distribution will be bounded using scenario analysis and modeled using system dynamics. The most relevant scenarios regarding mobile peer-to-peer content distribution are constructed using Schoemaker's method and modeling of these scenarios is attempted with system dynamics. As a result four different scenarios are developed based on the key trends and uncertainties discovered during the literature review and brainstorming sessions. Instead of modeling the scenarios quantitatively, the dynamic behavior of a mobile peer-to-peer content distribution system based on the scenarios is modeled with system dynamics. Although there are some mobile peer-to-peer content distribution applications already developed and used, and the topic is considerably researched, it is still uncertain what the outcome of the technology will be. This thesis presents possible outcomes for the technology and provides a starting point for further quantitative modeling of mobile peer-to-peer content distribution systems. System dynamics provides a viable alternative to more common modeling techniques such as spreadsheet modeling, with a distinctive benefit of modeling the feedback loops in a system when used proficiently. As the mobile peer-to-peer technology evolves, more data becomes available and the construction of alternative system dynamics models is encouraged

Peer-to-Peer Networks and Computation: Current Trends and Future Perspectives

This research papers examines the state-of-the-art in the area of P2P networks/computation. It attempts to identify the challenges that confront the community of P2P researchers and developers, which need to be addressed before the potential of P2P-based systems, can be effectively realized beyond content distribution and file-sharing applications to build real-world, intelligent and commercial software systems. Future perspectives and some thoughts on the evolution of P2P-based systems are also provided

Flexible Application-Layer Multicast in Heterogeneous Networks

This work develops a set of peer-to-peer-based protocols and extensions in order to provide Internet-wide group communication. The focus is put to the question how different access technologies can be integrated in order to face the growing traffic load problem. Thereby, protocols are developed that allow autonomous adaptation to the current network situation on the one hand and the integration of WiFi domains where applicable on the other hand

Flexible cross layer optimization for fixed and mobile broadband telecommunication networks and beyond

In der heutigen Zeit, in der das Internet im Allgemeinen und Telekommunikationsnetze im Speziellen kritische Infrastrukturen erreicht haben, entstehen hohe Anforderungen und neue Herausforderungen an den Datentransport in Hinsicht auf Effizienz und Flexibilität. Heutige Telekommunikationsnetze sind jedoch rigide und statisch konzipiert, was nur ein geringes Maß an Flexibilität und Anpassungsfähigkeit der Netze ermöglicht und darüber hinaus nur im begrenzten Maße die Wichtigkeit von Datenflüssen im wiederspiegelt. Diverse Lösungsansätze zum kompletten Neuentwurf als auch zum evolutionären Konzept des Internet wurden ausgearbeitet und spezifiziert, um diese neuartigen Anforderungen und Herausforderungen adäquat zu adressieren. Einer dieser Ansätze ist das Cross Layer Optimierungs-Paradigma, welches eine bisher nicht mögliche direkte Kommunikation zwischen verteilten Funktionalitäten unterschiedlichen Typs ermöglicht, um ein höheres Maß an Dienstgüte zu erlangen. Ein wesentlicher Indikator, welcher die Relevanz dieses Ansatzes unterstreicht, zeichnet sich durch die Programmierbarkeit von Netzwerkfunktionalitäten aus, welche sich aus der Evolution von heutigen hin zu zukünftigen Netzen erkennen lässt. Dieses Konzept wird als ein vielversprechender Lösungsansatz für Kontrollmechanismen von Diensten in zukünftigen Kernnetzwerken erachtet. Dennoch existiert zur Zeit der Entstehung dieser Doktorarbeit kein Ansatz zur Cross Layer Optimierung in Festnetz-und Mobilfunknetze, welcher der geforderten Effizienz und Flexibilität gerecht wird. Die übergeordnete Zielsetzung dieser Arbeit adressiert die Konzeptionierung, Entwicklung und Evaluierung eines Cross Layer Optimierungsansatzes für Telekommunikationsnetze. Einen wesentlichen Schwerpunkt dieser Arbeit stellt die Definition einer theoretischen Konzeptionierung und deren praktischer Realisierung eines Systems zur Cross Layer Optimierung für Telekommunikationsnetze dar. Die durch diese Doktorarbeit analysierten wissenschaftlichen Fragestellungen betreffen u.a. die Anwendbarkeit von Cross Layer Optimierungsansätzen auf Telekommunikationsnetzwerke; die Betrachtung neuartiger Anforderungen; existierende Konzepte, Ansätze und Lösungen; die Abdeckung neuer Funktionalitäten durch bereits existierende Lösungen; und letztendlich den erkennbaren Mehrwert des neu vorgeschlagenen Konzepts gegenüber den bestehenden Lösungen. Die wissenschaftlichen Beiträge dieser Doktorarbeit lassen sich grob durch vier Säulen skizzieren: Erstens werden der Stand der Wissenschaft und Technik analysiert und bewertet, Anforderungen erhoben und eine Lückenanalyse vorgenommen. Zweitens werden Herausforderungen, Möglichkeiten, Limitierungen und Konzeptionierungsaspekte eines Modells zur Cross Layer Optimierung analysiert und evaluiert. Drittens wird ein konzeptionelles Modell - Generic Adaptive Resource Control (GARC) - spezifiziert, als Prototyp realisiert und ausgiebig validiert. Viertens werden theoretische und praktische Beiträge dieser Doktorarbeit vertiefend analysiert und bewertet.As the telecommunication world moves towards a data-only network environment, signaling, voice and other data are similarly transported as Internet Protocol packets. New requirements, challenges and opportunities are bound to this transition and influence telecommunication architectures accordingly. In this time in which the Internet in general, and telecommunication networks in particular, have entered critical infrastructures and systems, it is of high importance to guarantee efficient and flexible data transport. A certain level of Quality-of-Service (QoS) for critical services is crucial even during overload situations in the access and core network, as these two are the bottlenecks in the network. However, the current telecommunication architecture is rigid and static, which offers very limited flexibility and adaptability. Several concepts on clean slate as well as evolutionary approaches have been proposed and defined in order to cope with these new challenges and requirements. One of these approaches is the Cross Layer Optimization paradigm. This concept omits the strict separation and isolation of the Application-, Control- and Network-Layers as it enables interaction and fosters Cross Layer Optimization among them. One indicator underlying this trend is the programmability of network functions, which emerges clearly during the telecommunication network evolution towards the Future Internet. The concept is regarded as one solution for service control in future mobile core networks. However, no standardized approach for Cross Layer signaling nor optimizations in between the individual layers have been standardized at the time this thesis was written. The main objective of this thesis is the design, implementation and evaluation of a Cross Layer Optimization concept on telecommunication networks. A major emphasis is given to the definition of a theoretical model and its practical realization through the implementation of a Cross Layer network resource optimization system for telecommunication systems. The key questions answered through this thesis are: in which way can the Cross Layer Optimization paradigm be applied on telecommunication networks; which new requirements arise; which of the required functionalities cannot be covered through existing solutions, what other conceptual approaches already exist and finally whether such a new concept is viable. The work presented in this thesis and its contributions can be summarized in four parts: First, a review of related work, a requirement analysis and a gap analysis were performed. Second, challenges, limitations, opportunities and design aspects for specifying an optimization model between application and network layer were formulated. Third, a conceptual model - Generic Adaptive Resource Control (GARC) - was specified and its prototypical implementation was realized. Fourth, the theoretical and practical thesis contributions was validated and evaluated

BitTorrent locality and transit trafficreduction: When, why, and at what cost?

A substantial amount of work has recently gone into localizing BitTorrent traffic within an ISP in order to avoid excessive and often times unnecessary transit costs. Several architectures and systems have been proposed and the initial results from specific ISPs and a few torrents have been encouraging. In this work we attempt to deepen and scale our understanding of locality and its potential. Looking at specific ISPs, we consider tens of thousands of concurrent torrents, and thus capture ISP-wide implications that cannot be appreciated by looking at only a handful of torrents. Second, we go beyond individual case studies and present results for few thousands ISPs represented in our data set of up to 40K torrents involving more than 3.9M concurrent peers and more than 20M in the course of a day spread in 11K ASes. Finally, we develop scalable methodologies that allow us to process this huge data set and derive accurate traffic matrices of torrents. Using the previous methods we obtain the following main findings: i) Although there are a large number of very small ISPs without enough resources for localizing traffic, by analyzing the 100 largest ISPs we show that Locality policies are expected to significantly reduce the transit traffic with respect to the default random overlay construction method in these ISPs; ii) contrary to the popular belief, increasing the access speed of the clients of an ISP does not necessarily help to localize more traffic; iii) by studying several real ISPs, we have shown that soft speed-aware locality policies guarantee win-win situations for ISPs and end users. Furthermore, the maximum transit traffic savings that an ISP can achieve without limiting the number of inter-ISP overlay links is bounded by “unlocalizable” torrents with few local clients. The application of restrictions in the number of inter-ISP links leads to a higher transit traffic reduction but the QoS of clients downloading “unlocalizable” torrents would be severely harmed.The research leading to these results has been partially funded by the European Union's FP7 Program under the projects eCOUSIN (318398) and TREND (257740), the Spanish Ministry of Economy and Competitiveness under the eeCONTENT project (TEC2011-29688-C02-02), and the Regional Government of Madrid under the MEDIANET Project (S2009/TIC-1468).Publicad

Incentive-driven QoS in peer-to-peer overlays

A well known problem in peer-to-peer overlays is that no single entity has control over the software, hardware and configuration of peers. Thus, each peer can selfishly adapt its behaviour to maximise its benefit from the overlay. This thesis is concerned with the modelling and design of incentive mechanisms for QoS-overlays: resource allocation protocols that provide strategic peers with participation incentives, while at the same time optimising the performance of the peer-to-peer distribution overlay. The contributions of this thesis are as follows. First, we present PledgeRoute, a novel contribution accounting system that can be used, along with a set of reciprocity policies, as an incentive mechanism to encourage peers to contribute resources even when users are not actively consuming overlay services. This mechanism uses a decentralised credit network, is resilient to sybil attacks, and allows peers to achieve time and space deferred contribution reciprocity. Then, we present a novel, QoS-aware resource allocation model based on Vickrey auctions that uses PledgeRoute as a substrate. It acts as an incentive mechanism by providing efficient overlay construction, while at the same time allocating increasing service quality to those peers that contribute more to the network. The model is then applied to lagsensitive chunk swarming, and some of its properties are explored for different peer delay distributions. When considering QoS overlays deployed over the best-effort Internet, the quality received by a client cannot be adjudicated completely to either its serving peer or the intervening network between them. By drawing parallels between this situation and well-known hidden action situations in microeconomics, we propose a novel scheme to ensure adherence to advertised QoS levels. We then apply it to delay-sensitive chunk distribution overlays and present the optimal contract payments required, along with a method for QoS contract enforcement through reciprocative strategies. We also present a probabilistic model for application-layer delay as a function of the prevailing network conditions. Finally, we address the incentives of managed overlays, and the prediction of their behaviour. We propose two novel models of multihoming managed overlay incentives in which overlays can freely allocate their traffic flows between different ISPs. One is obtained by optimising an overlay utility function with desired properties, while the other is designed for data-driven least-squares fitting of the cross elasticity of demand. This last model is then used to solve for ISP profit maximisation

CHORUS Deliverable 2.1: State of the Art on Multimedia Search Engines

Based on the information provided by European projects and national initiatives related to multimedia search as well as domains experts that participated in the CHORUS Think-thanks and workshops, this document reports on the state of the art related to multimedia content search from, a technical, and socio-economic perspective. The technical perspective includes an up to date view on content based indexing and retrieval technologies, multimedia search in the context of mobile devices and peer-to-peer networks, and an overview of current evaluation and benchmark inititiatives to measure the performance of multimedia search engines. From a socio-economic perspective we inventorize the impact and legal consequences of these technical advances and point out future directions of research