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Recent studies have suggested that the stability of peer-to-peer networks may rely on persistent peers, who dwell on the network after they obtain the entire file. In the absence of such peers, one piece becomes extremely rare in the network, which leads to instability. Technological developments, however, are poised to reduce the incidence of persistent peers, giving rise to a need for a protocol that guarantees stability with non-persistent peers. We propose a novel peer-to-peer protocol, the group suppression protocol, to ensure the stability of peer-to-peer networks under the scenario that all the peers adopt non-persistent behavior. Using a suitable Lyapunov potential function, the group suppression protocol is proven to be stable when the file is broken into two pieces, and detailed experiments demonstrate the stability of the protocol for arbitrary number of pieces. We define and simulate a decentralized version of this protocol for practical applications. Straightforward incorporation of the group suppression protocol into BitTorrent while retaining most of BitTorrent’s core mechanisms is also presented. Subsequent simulations show that under certain assumptions, BitTorrent with the official protocol cannot escape from the missing piece syndrome, but BitTorrent with group suppression does. [ABSTRACT FROM AUTHOR]

Data transmission and IP telephony-based sound transmission are carried out via same network infrastructure in campus networks. In general, there are two types of traffics in network environment. The first one is the normal stream traffic which refers to data and sound. The second one is the background traffic which is considered as undesirable traffic and adversely affects IP-based sound packets. This adverse effect leads to delays and fluctuations and finally ends up with packet losses. This study investigates sound scrambling factors which result from network configurations and torrents. We carried sound packet over VLAN (Virtual network) defined in network devices. In this way, we enabled to transmit sound with more quality and without interruption in campus network. While Iperf tool was used for point-to-point tests, OPNET simulation software was used to evaluate VLAN performance. Tests conducted in multiple units of the campus indicate that fluctuations in sound packets remained between the range of 0-150 ms; sound packet delays remained between the range of 0-20 ms. [ABSTRACT FROM AUTHOR]

Fairness is one of the most important challenges that should be considered as a priority when designing a P2P file-sharing network. An unfair P2P network may attract free-riders, frustrate the majority of users, and consequently shorten the longevity of files. When BitTorrent protocol was first introduced, by suggesting new algorithms like tit-fortat or rarest-first and combining them with methods like choking and unchoking, it pushed fairness one step forward. However, BitTorrent did not bring a plenary solution and has its own shortcomings. For instance, neither this protocol nor other P2P protocols that we are aware of precisely indicate how seeders should be treated in their networks. Most of the time they dictate that seeders upload as much as possible. With this approach, seeders can easily be abused by free-riders. It gets even worse when we realize that for lack of a good infrastructure a lawful user may become a free-rider unknowingly. The purpose of this paper is to address this problem by suggesting a novel and universal method that can be implemented in current P2P networks. We show that by separating nodes into two groups of seeders and leechers and then implementing a simple pattern for seeders, we can improve fairness in P2P networks. Even though our algorithm is universal and not limited to a specific protocol, by implementing it on BitTorrent we show how it can be used in practice and how effective it is. [ABSTRACT FROM AUTHOR]

Most of the users of a BitTorrent community participate in multiple swarms, usually simultaneously as uploader and downloader. Thus the inter-swarm aspect of the bandwidth resource allocation has high relevance in the algorithm design of deployed BitTorrent clients. This inter-swarm connections among the users of a BitTorrent community can be represented by a flow network of special structure. Using this representation it has been demonstrated that de facto solutions to the resource allocation in BitTorrent communities are suboptimal. In this paper we investigate this conclusion in more details using graph measures and optimization techniques. We find that BitTorrent communities are sensitive for removal of highly contributing users, that the inter-swarm connectivity can lead to different performance results, and that torrent selection mechanisms can hardly improve the average download performance of users. Regarding the theoretical optimum of the discussed problem we show that it does not necessary comply with the BitTorrent protocol. [ABSTRACT FROM AUTHOR]

To solve the problem that the free-riding behavior of a node will seriously affect the download progress of the common node and the whole network performance in the BT network， a new economic model (TTEM) was proposed based on the tit-for-tat mechanism. According to the commodity trading and credit system in the social life， the economic model was presented that consisted of the node wealth， the file blocks pricing and the node overdraft. Finally， the TTEM was proposed by deploying the economic model on the tit-for-tat. Resources spread between nodes as a transaction in TTEM. Nodes were traded by the price of the file blocks， making the wealth of the node change， if the node’s wealth is greater than the overdraft. The simulation results show TTEM is able to reduce the impact which the free-rider nodes make on the BT network than the pure tit-for-tat mechanism under the similar propagation velocity of the file resources. [ABSTRACT FROM AUTHOR]

Incentive schemes are designed to promote cooperation in distributed systems, in which peers are free to decide how much to contribute. A variety of incentive schemes have been proposed in peer-to-peer file-sharing systems, touted to have special advantages in certain scenarios. However, only little research has been done on comparing these incentive schemes under an identical scenario. Fairness is an important indicator to evaluate an incentive scheme, because good fairness can enable proper rewarding to collaborative peers and punishment to strategic peers. In this paper, the correlation map between return and investment of peers is used to depict the fairness degree of different incentive schemes. The fairness and efficiency of several representative incentive schemes are compared under rate-based metrics (all chunks have an identical value) and value-based metrics (different chunks have different values). [ABSTRACT FROM AUTHOR]

This paper proposes a new microblogging architecture based on peer-to-peer networks overlays. The proposed platform comprises three mostly independent overlay networks. The first provides distributed user registration and authentication and is based on the Bitcoin protocol. The second one is a Distributed Hash Table (DHT) overlay network providing key/value storage for user resources and tracker location for the third network. The last network is a collection of possibly disjoint ‘swarms’ of followers, based on the BitTorrent protocol, which can be used for efficient near-instant notification delivery to many users. By leveraging existing and proven technologies, twister provides a new microblogging platform offering security, scalability and privacy features. A built-in mechanism provides incentive for entities that contribute processing time to run the user registration network, rewarding such entities with the privilege of sending a single unsolicited (‘promoted’) message to the entire network. The number of unsolicited messages per day is defined in order to not upset users. Security and scalability assumptions have been confirmed in a real-world deployment. [ABSTRACT FROM AUTHOR]

Background: Our publication of the BitTorious portal [1] demonstrated the ability to create a privatized distributed data warehouse of sufficient magnitude for real-world bioinformatics studies using minimal changes to the standard BitTorrent tracker protocol. In this second phase, we release a new server-side specification to accept anonymous philantropic storage donations by the general public, wherein a small portion of each user's local disk may be used for archival of scientific data. We have implementated the server-side announcement and control portions of this BitTorrent extension into v3.0.0 of the BitTorious portal, upon which compatible clients may be built. Results: Automated test cases for the BitTorious Volunteer extensions have been added to the portal's v3.0.0 release, supporting validation of the "peer affinity" concept and announcement protocol introduced by this specification. Additionally, a separate reference implementation of affinity calculation has been provided in C++ for informaticians wishing to integrate into libtorrent-based projects. Conclusions: The BitTorrent "affinity" extensions as provided in the BitTorious portal reference implementation allow data publishers to crowdsource the extreme storage prerequisites for research in "big data" fields. With sufficient awareness and adoption of BitTorious Volunteer-based clients by the general public, the BitTorious portal may be able to provide peta-scale storage resources to the scientific community at relatively insignificant financial cost. [ABSTRACT FROM AUTHOR]

Recently, BitTorrent communities are rapidly evolving into private torrent sites (PT). PT sites have employed several incentive rules to improve the performance and availability of the system. Many studies have been dedicated for measuring and modeling the PT systems in order to better understand the new rules and their impact on the users' behavior in order to improve the usability of the system. These studies have been performed on different PT sites that differ in their implementation of the system and in their system's user incentive rules. Therefore, current measurement findings cannot reflect accurate results and, more importantly, the current conclusions may be biased. In this paper, we investigate the accuracy of previous measurement studies on PT sites, while emphasizing the incentive rules employed and the interplay between these rules and corresponding objective factors. We evaluate the behavior regulation policies of the front-end website and the tracker and examine the semantics of provided data. Using this information we have designed a new crawling methodology and conducted a large-scale measurement study across four representative PT sites over a year. Interestingly, we find that most reported measurements have neither considered design goals, nor thought through the incentive policies and their interplay. This lack of awareness in turn may lead to inaccurate conclusions of system properties. For example, the Seeder to Leecher Ratio (SLR), which is reported in most of the available measurements, is routinely at least 16-45 % less than the real SLR because the sites ignored the 'partial seeders' in their calculation. This study aims to offer fundamental insights into designing an accurate methodology when conducting measurement studies on PT sites. [ABSTRACT FROM AUTHOR]

Background Centralized silos of genomic data are architecturally easier to initially design, develop and deploy than distributed models. However, as interoperability pains in EHR/EMR, HIE and other collaboration-centric life sciences domains have taught us, the core challenge of networking genomics systems is not in the construction of individual silos, but the interoperability of those deployments in a manner embracing the heterogeneous needs, terms and infrastructure of collaborating parties. This article demonstrates the adaptation of BitTorrent to private collaboration networks in an authenticated, authorized and encrypted manner while retaining the same characteristics of standard BitTorrent. Results The BitTorious portal was sucessfully used to manage many concurrent domestic Bittorrent clients across the United States: exchanging genomics data payloads in excess of 500GiB using the uTorrent client software on Linux, OSX and Windows platforms. Individual nodes were sporadically interrupted to verify the resilience of the system to outages of a single client node as well as recovery of nodes resuming operation on intermittent Internet connections. Conclusions The authorization-based extension of Bittorrent and accompanying BitTorious reference tracker and user management web portal provide a free, standards-based, general purpose and extensible data distribution system for large 'omics collaborations. [ABSTRACT FROM AUTHOR]

Tens of millions of individuals around the world use decentralized content distribution systems, a fact of growing social, economic, and technological importance. These sharing systems are poorly understood because, unlike in other technosocial systems, it is difficult to gather large-scale data about user behavior. Here, we investigate user activity patterns and the socioeconomic factors that could explain the behavior. Our analysis reveals that (i) the ecosystem is heterogeneous at several levels: content types are heterogeneous, users specialize in a few content types, and countries are heterogeneous in user profiles; and (ii) there is a strong correlation between socioeconomic indicators of a country and users behavior. Our findings open a research area on the dynamics of decentralized sharing ecosystems and the socioeconomic factors affecting them, and may have implications for the design of algorithms and for policymaking. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Peer-to-Peer (P2P) streaming technology based on various service requirements often remains on the elusive benefits of user-friendly video streaming in cloud computing environments. Cloud-assisted P2P media streaming gives an opportunity to enhance on-demand, dynamic and easily accessible videos. This paper outlines the fundamental video block device (VBD) method for user-friendly viewing patterns that inherits from user access patterns and provides efficient delivery using an enhanced BitTorrent protocol. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we propose a modification to the BitTorrent protocol related to its peer unchoking policy. In particular, we apply a novel optimistic unchoking approach that improves the quality of inter-connections amongst peers, i.e., increases the number of directly-connected and interested-in-cooperation peers without penalizing underutilized and/or idle peers. Our optimistic unchoking policy takes into consideration the number of clients currently interested in downloading from a peer that is to be unchoked. Our conjecture is that peers having few clients interested in downloading data from them, should be favored with optimistic unchoke intervals. This enables the peers in question to receive data since they become unchoked faster and in turn, they will trigger the interest of additional clients. In contrast, peers with plenty of “interested” clients should enjoy a lower priority to be selected as planned optimistic unchoked, since these peers likely have enough data to forward; nevertheless, they receive enough data due to tit-for-tat peer reciprocation and are not in need of optimistic unchoking slots. Armed with this realization, we establish an analytical model and prove a significant performance improvement under our modified BitTorrent protocol. Experimental results, also, indicate that our approach significantly outperforms the existing optimistic unchoking policy in three important aspects: first, there is a higher number of interested-in-cooperation and directly-connected peers. Second, since leechers now act as data intermediaries, the load on seeders eases up considerably. Last, a shorter bootstrapping period for fresh peers is achieved. Hence, we claim that our approach helps implement an enhanced BitTorrent protocol and we name it “EnhancedBit”. [Copyright &y& Elsevier]

In the area of network performance and discovery, network tomography focuses on reconstructing network properties using only end-to-end measurements at the application layer. One challenging problem in network tomography is reconstructing available bandwidth along all links during multiple source/multiple destination transmissions. The traditional measurement procedures used for bandwidth tomography are extremely time consuming. We propose a novel solution to this problem. Our method counts the fragments exchanged during a BitTorrent broadcast. While this measurement has a high level of randomness, it can be obtained very efficiently, and aggregated into a reliable metric. This data is then analyzed with state-of-the-art algorithms, which correctly reconstruct logical clusters of nodes interconnected by high bandwidth, as well as bottlenecks between these logical clusters. Our experiments demonstrate that the proposed two-phase approach efficiently solves the presented problem for a number of settings on a complex grid infrastructure. [ABSTRACT FROM AUTHOR]

Piece-related algorithms, including piece revelation, selection, and queuing, play a crucial role in the BitTorrent (BT) protocol, because the BT system can be viewed as a market where peers trade their pieces with one another. During the piece exchanging, a peer selects some pieces revealed by neighbors, and queues them up for downloading. In this paper, we provide a deep understanding of these algorithms, and also propose some improvements to them. Previous study has shown that the piece revelation strategy is vulnerable to under-reporting. We provide a game-theoretic analysis for this selfish gaming, and propose a distributed credit method to prevent it. Existing piece selection strategies, though long believed to be good enough, may fail to balance piece supply and demand. We propose a unified strategy to shorten the download time of peers by applying utility theory. The design of the piece queuing algorithm has a conflict with that of piece selection strategy, because it is not possible to assume that the queued requests for a selected piece can always be available on multiple neighbors. We give a possible fix to address the conflict by allowing peers to dynamically manage their unfulfilled requests. To evaluate the performance of the proposed algorithms, we run several experiments in a live swarm. Our primary results show that they can achieve fast individual and system-wide download time. [ABSTRACT FROM PUBLISHER]

In the area of network performance and discovery, network tomography focuses on reconstructing network properties using only end-to-end measurements at the application layer. One challenging problem in network tomography is reconstructing available bandwidth along all links during multiple source/multiple destination transmissions. The traditional measurement procedures used for bandwidth tomography are extremely time consuming. We propose a novel solution to this problem. Our method counts the fragments exchanged during a BitTorrent broadcast. While this measurement has a high level of randomness, it can be obtained very efficiently, and aggregated into a reliable metric. This data is then analyzed with state-of-the-art algorithms, which correctly reconstruct logical clusters of nodes interconnected by high bandwidth, as well as bottlenecks between these logical clusters. Our experiments demonstrate that the proposed two-phase approach efficiently solves the presented problem for a number of settings on a complex grid infrastructure. [ABSTRACT FROM AUTHOR]

Abstract: BT system modeling has great importance for understanding the system performance and improving the protocol design. The challenge of accurate BT system modeling lies in the complicated peer behavior in the dynamic and heterogeneous system. In this paper, we propose a bottom-up model to simplify the performance analysis and increase the modeling accuracy, in which local transitions of the system lead to global macroscopic descriptions by integration. To be specific, we evaluate the download rate of each individual peer by estimating the probability of a connection being made, and the probability of a peer being unchoked, and then later integrate the analysis of each individual peer into the description of the whole system. Such a model characterizes both core parts of the protocol and main features of the system and requires far fewer restrictive assumptions than that used before. By using the model, we provide some interesting insights into setting of parameters, power of free-riding, effect of bandwidth distribution and effectiveness of unchoking. We also validate our model through both simulations and experiments. The preliminary experimental results show that our model is significantly more accurate than existing ones. [Copyright &y& Elsevier]

In this paper, we conduct an in-depth study on the feasibility of using network coding to ameliorate the content availability of BitTorrent swarms. We first perform mathematical analysis on the potential improvement in the content availability and bandwidth utilization induced by two existing network coding schemes. It is found that these two coding schemes either incur a very high coding complexity and disk operation overhead or cannot effectively leverage the potential of improving the content availability. In this regard, we propose a simple sparse network coding scheme in which both the drawbacks mentioned before are precluded. To accommodate the proposed coding scheme into BitTorrent, a new block scheduling algorithm is also developed based on the original rarest-first block scheduling policy of BitTorrent. Through extensive simulations and performance evaluations, we show that the proposed coding scheme is very effective in terms of improving the content availability of BitTorrent swarms when compared with some existing methods. [ABSTRACT FROM PUBLISHER]

Internet-enabled file sharing via peer-to-peer (P2P) systems is a transglobal activity involving millions of people circulating vast amounts of information. 'Anonymous peers' exchange data via autonomous networks that are simultaneously external to, and embedded within, market structures. A transnational alliance of technology and media industries and governments employs technological barriers, legal instruments and, belatedly, commercial alternatives to constrain the phenomenon. Such 'digital enclosures' trigger productive rebellious acts by programmers, intellectual property activists and file sharers inhabiting overlapping informal networks. Escalating cycles of retaliation and resistance spawn further disorder in the informational domain. The period 2009-12 has been a watershed for technological trends, landmark legal battles and supranational treaties. However, scant attention is paid to how 'digital piracy' disturbs the logic of capital by instituting material practices that tolerate contradictory positions on free culture and electronic freedom, creating new contexts for social experimentation and recomposition. [ABSTRACT FROM AUTHOR]

This paper reveals the power saving potential of P2P file sharing in two cases; popular and unpopular files. For popular files, we derive, with regard to BitTorrent, an expression for the optimal time seeders should support leechers. For unpopular files, we extend an existing model by taking into account leechers' power consumption dependent on the load. Leechers are assumed to build a temporary cluster within the P2P-overlay. We determine the required number of active leechers to cope with a given load and compare results from an analytical model to simulation. We demonstrate that it is possible to reach almost optimal energy efficiency for the download scenario by comparing the local case without cooperation with the distributed case where leechers cooperate. [ABSTRACT FROM AUTHOR]

We propose a BitTorrent-like protocol based on an online learning (reinforcement learning) mechanism, which can replace the peer selection mechanisms in the regular BitTorrent protocol. We model the peers' interactions in the BitTorrent-like network as a repeated stochastic game, where the strategic behaviors of the peers are explicitly considered. A peer that applies the reinforcement learning (RL)-based mechanism uses the observations on the associated peers' statistical reciprocal behaviors to determine its best responses and estimate the corresponding impact on its expected utility. The policy determines the peer's resource reciprocations such that the peer can maximize its long-term performance. We have implemented the proposed mechanism and incorporated it into an existing BitTorrent client. Our experiments performed on a controlled Planetlab testbed confirm that the proposed protocol 1) promotes fairness and provides incentives to contributed resources, i.e., high capacity peers improve their download completion time by up to 33 percent, 2) improves the system stability and robustness, i.e., reduces the peer selection fluctuations by 57 percent, and (3) discourages free-riding, i.e., peers reduce their uploads to free-riders by 64 percent as compared to the regular BitTorrent protocol. [ABSTRACT FROM PUBLISHER]

Abstract: Two case studies explore the reciprocal influence between technological change and Internet governance. Both focus on the use by Internet service providers of a new capability known as deep packet inspection (DPI). DPI was used by major network operators in the U.S. and Canada to block or restrict the speed of peer to peer file sharing traffic by their customers. In both cases, DPI implementations led to public protests, litigation and major regulatory proceedings. In both cases, network neutrality norms were used to challenge DPI deployments. The paper''s descriptive comparison is supplemented by quantitative data drawn from the use of Glasnost, a network test that allows third parties to detect BitTorrent throttling via DPI. The paper asks whether the use of DPI by ISPs disrupted the way the Internet is regulated, and whether political and institutional factors alter or constrain DPI use. It finds that the power to shape traffic flows redistributes control among actors in the Internet ecosystem, generating broad political economy debates about efficiency, fairness, innovation and transparency. But the actual results of those conflicts are indeterminate, reflecting institutional and historical contingencies. [Copyright &y& Elsevier]

Abstract: BitTorrent is a popular peer-to-peer file sharing system and a target file shared through BitTorrent is partitioned into pieces and downloaded from multiple peers in parallel in order to shorten the download process. However, due to peer dynamics in P2P networks, rare pieces may be lost and thus lead to the so-called last piece problem. BitTorrent employs rarest-first piece selection algorithm to deal with this problem, but its efficacy is limited because each peer only has a local view of piece rareness. In this paper, we propose an Interest-Intended Piece Selection (IIPS) algorithm aiming at better alleviating the last piece problem while maintaining stable cooperation between peers. IIPS is named interest intended in that every IIPS peer favors pieces that, if downloaded, would increase the probability of being interesting to its cooperating peers. Simulation results show that IIPS achieves less occurrences of piece loss under tough conditions and slightly outperforms the BitTorrent’s rarest-first algorithm in terms of higher piece diversity. [Copyright &y& Elsevier]

Abstract: At present, BitTorrent protocol packets constitute a large part of peer-to-peer application traffic on the Internet. Due to the increasing amount of BitTorrent traffic, it has become inevitable to take into account its effects on network management. Generally, studies on BitTorrent traffic measurement have involved analysis with packets transmitted via IPv4 protocol. However, with several facilities provided by IPv6 protocol, its traffic volume in operational networks is increasing day by day. New features of IPv6 enhance packet processing speeds over routers, switches and end systems. We consider that traffic features and packet traffic characteristics are likely to be affected with increasing amount of IPv6 protocol traffic. Therefore, it becomes significant to explore IPv6 packet traffic characteristics and application traffic features over IPv6. In this study, we investigate the IPv6 BitTorrent packet traffic characteristics in terms of autocorrelation, power spectral density and self similarity of packet size and packet interarrival time. We also perform distribution modeling for IPv4 and IPv6 BitTorrent packet traffic. With these models, efficient packet traffic traces are generated for network simulation studies. A detailed comparison is performed to determine differences between IPv4 and IPv6 BitTorrent packet traffic. [Copyright &y& Elsevier]

In the past few years, P2P file distribution applications (e.g., BitTorrent) are becoming so popular that they are the dominating source of Internet traffic. This creates significant problems to Internet Service Providers (ISPs), not only because of the added complexity in traffic engineering, but the increase of traffic, in particular on the cross-ISP links, implies congestion and a higher operating cost. In this paper, we consider an ISP-friendly file distribution protocol which uses the "exploiting-the-locality principle" (ELP) to reduce the cross-ISP traffic. To show its benefit, we derive an upper and lower bound of cross-ISP traffic for the protocols which rely on ELP and show that the cross-ISP traffic can be reduced significantly when the number of peers within an ISP increases. To carry out realistic study, we design and implement our ISP-friendly protocol (which is compatible with the current BitTorrent protocol) and carry out large scale experiments on PlanetLab to measure the reduction of the cross ISP-traffic and the file downloading time. More important, we also show how the proposed ISP-friendly protocol can handle the "black-hole" security attack. This paper sheds light on the merits and design direction of ISP-friendly content distribution protocols. [ABSTRACT FROM AUTHOR]

Abstract: In Technics and Time, 1, Bernard Stiegler (1998) challenged the prevalent philosophical distinction between tekhnē and ēpistēmē, arguing that humans are fundamentally technical beings. According to Stiegler, the industrialization of civilization led to a disequilibrium in the evolution of culture and the evolution of technics, with technics evolving more quickly than culture. Stiegler''s discussions of technics, culture, time, and memory provide a useful theoretical framework for understanding some of the cultural implications of copyright issues, which are often viewed in terms of economics, legality, and/or ethics. In this article, I focus on the intellectual property debate as it pertains to peer-to-peer networks and the music industry. Drawing from Technics and Time, I theoretically frame these issues as a problem of temporality, memory, and a disconnect in the evolution of culture and technology. I then use small-scale/observational ethnographic analysis to examine a private torrent community to consider how torrent communities are cultural phenomena, the implications of this assumption, and how these considerations might inform or extend existing approaches to issues of intellectual property. More broadly, I ask, what are the affordances of thinking about these economic, legal, and political issues from a cultural framework? [Copyright &y& Elsevier]

Current infrastructures for Volunteer Computing follow a centralized architecture for data distribution, creating a potential bottleneck when tasks require large input files or the central server has limited bandwidth. In this paper we propose two new data models for Berkeley Open Infrastructure for Network Computing (BOINC): an approach based on the popular BitTorrent protocol; and a Content Delivery Network approach. While the latter remains on a theoretical level, we developed a prototype that adds BitTorrent functionality for task distribution and conducted medium-scale tests of the environment. Our preliminary results indicate that the BitTorrent client had a negligible influence on the BOINC client's computation time. The BOINC server showed an unexpectedly low bandwidth output when seeding the file, as well as spikes on CPU usage. This paper discusses the tests that were performed, how they were evaluated, as well as some improvements that could be made in future research on both approaches. [ABSTRACT FROM AUTHOR]

BitTorrent has emerged as a very popular peer-to-peer file sharing system, which uses an embedded set of incentive mechanisms to encourage contribution and prevent free-riding. However, BitTorrent's ability to prevent free-riding needs further study. In this paper, we present a fluid model with two different classes of peers to capture the effect of free-riding on BitTorrent-like systems. With the model, we find that BitTorrent's incentive mechanism is successful in preventing free-riding in a system without seeds but may not succeed in producing a disincentive for free-riding in a system with a high number of seeds. The reason for this is that BitTorrent does not employ any effective mechanisms for seeds to effectively guard against free-riding. Therefore, we propose a seed bandwidth allocation strategy for the BitTorrent system to reduce the effect of seeds on free-riding. Finally, simulation results are given that validate what we have found in our analysis and demonstrate the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

The fast-growing traffic of Peer-to-Peer (P2P) applications, most notably BitTorrent (BT), is putting unprecedented pressure to Internet Service Providers (ISPs). P2P locality has, therefore, been widely suggested to mitigate the costly inter-ISP traffic. In this paper, we for the first time examine the existence and distribution of the locality through a large-scale hybrid PlanetLab-Internet measurement. We find that even in the most popular Autonomous Systems (ASes), very few individual torrents are able to form large enough local clusters of peers, making state-of-the-art locality mechanisms for individual torrents quite inefficient. Inspired by peers' multiple torrent behavior, we develop a novel framework that traces and recovers the available contents at peers across multiple torrents, and thus effectively amplifies the possibilities of local sharing. We address the key design issues in this framework, in particular, the detection of peer migration across the torrents. We develop a smart detection mechanism with shared trackers, which achieves 45 percent success rate without any tracker-level communication overhead. We further demonstrate strong evidence that the migrations are not random, but follow certain patterns with correlations. This leads to torrent clustering, a practical enhancement that can increase the detection rate to 75 percent, thus greatly facilitating locality across multiple torrents. The simulation results indicate that our framework can successfully reduce the cross-ISP traffic and minimize the possible degradation of peers' downloading experiences. [ABSTRACT FROM AUTHOR]

The success of BitTorrent has fostered the development of variants to its basic components. Some of the variants adopt greedy approaches aiming at exploiting the intrinsic altruism of the original version of BitTorrent in order to maximize the benefit of participating to a torrent. In this work, we study BitTyrant, a recently proposed strategic client. BitTyrant tries to determine the exact amount of contribution necessary to maximize its download rate by dynamically adapting and shaping the upload rate allocated to its neighbors. We evaluate in detail the various mechanisms used by BitTyrant to identify their contribution to the performance of the client. Our findings indicate that the performance gain is due to the increased number of connections established by a BitTyrant client, rather than to its subtle uplink allocation algorithm; surprisingly, BitTyrant reveals to be altruistic and particularly efficient in disseminating the content, especially during the initial phase of the distribution process. The possible gain of a single BitTyrant client, however, disappears in the case of a widespread adoption: our results indicate a severe loss of efficiency that we analyze in detail. [ABSTRACT FROM PUBLISHER]

Although still being used, peer-to-peer technology appears to be declining in popularity compared to other approaches for accessing content over the Internet. [ABSTRACT FROM PUBLISHER]