共查询到20条相似文献,搜索用时 15 毫秒
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PZP存储系统具有可扩展性好、容错性高等优势,是近年来学术界的研究热点.但是由于P2P存储系统的复杂性高,搭建起来比较困难,使得系统并没有随着研究发展而流行起来.尤其是在广域网中,由于节点的高动态性,使得系统的部署和维护更加困难.介绍了一个开放式的P2P存储平台架构,可以在封闭的机房系统里,利用稳定的服务器搭建存储系统,也可以在开放的广域网环境下,利用动态性高的个人电脑来搭建存储系统.上层应用开发者可方便地使用该平台来创建各种服务,从而能将P2P存储系统在实际应用中推广开来. 相似文献
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网络信誉系统是一个用于综合运算、记录并发布各个客户端以往行为表现的系统。在P2P开放网络资源共享系统中,网络信誉系统起到了两个重要的作用:向用户提供信息以决定对方是否可信,激励交易双方在交易中保持良好的表现以提高自身的信誉度。该文介绍了P2P开放网络与信誉管理系统的概念,分析了现有的信誉系统、模型及其算法。在此基础上设计了新的模型,该模型以信任链方式查询节点信誉度,提出把信誉度分层的方法,通过Java实现了该系统,展望了网络信誉系统的发展方向。 相似文献
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The tremendous growth of public interest in Peer-to-Peer (P2P) networks in recent years has initiated a lot of research work on how to design efficient overlay structures for P2P systems. Scalable overlay networks such as Chord, CAN, Pastry, and Tapestry provide no control over where data is stored and the location of the peers and resources is determined by the hash values of their identifiers and keys respectively. As a result, these overlays cannot support range queries and other proximity-aware complex queries directly.In this paper, we present a hierarchical P2P overlay network called SkipCluster, which is capable of supporting both exact-match and multi-dimensional range queries efficiently without consumption of extra memory space. SkipCluster is derived from skip graphs and SkipNet, but it has a two-tier hierarchical architecture.In both tiers, peers are connected in sequence according to the order of their peer IDs, and related resources are stored near each other without hashing of their resource keys. We design a novel data structure called Triple Linked List (TLL) to store each super-peer’s pointers in the higher tier, which can be used to find the longest prefix and speed up query routing of inter-cluster. In the lower tier, each intra-cluster peer’s routing table contains pointers with exponentially incremental distance. Experimental results show that SkipCluster can speed up both exact-match and range queries in different network sizes. 相似文献
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Yi Hu Laxmi N. BhuyanAuthor VitaeMin FengAuthor Vitae 《Journal of Parallel and Distributed Computing》2012
Motivating peers to contribute services is critical to the success of peer-to-peer (P2P) systems. Incentive protocols use reciprocity to enforce contributions. Indirect reciprocity schemes are more efficient than direct reciprocity schemes for large-scale P2P systems under high churn rate. In this paper, we propose an indirect reciprocity scheme, called FairTrade, in which peers issue personal currencies to trade services in a P2P system. Personal currency enables indirect reciprocity without relying on any central banks or authorities. It wins extra robustness over global currency as well as much improved trading flexibility and efficiency over direct reciprocity schemes. The acceptance degree of a personal currency depends on the issuer’s service capability and reliance. Peer credit limit is introduced to represent the amount of personal currency that will be accepted by other peers. Every peer as a creditor applies a Bayesian network model to setting peer credit limit for a trading partner peer as a creditee. The Bayesian network model learns the creditee’s capability and reliability and anticipates the associated profits and risks for credit setting. Using simulations on a file-sharing P2P system, we demonstrate that FairTrade achieves 100% success rate of download requests without malicious peers, and maintains over 90% success rate even with 50% malicious nodes. The system warms up quickly and does not assume any altruistic service or other kind of help. On average, the system traffic stabilizes before peers issue their second download requests. All these good performances are achieved with extremely low trading overhead, which takes up less than 1% of the total traffic. 相似文献
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Loránd Jakab Albert Cabellos-Aparicio Thomas Silverston Marc Solé Florin Coraş Jordi Domingo-Pascual 《Computer Networks》2010,54(18):3388-3401
The rapid growth of broadband access has popularized multimedia services, which nowadays contribute to a large part of Internet traffic. Among this content, the broadcasting of live events requires streaming from a single source to a large set of users. For such content, network-layer multicast is the most efficient solution, but it has not found wide-spread adoption due to its high deployment cost. As a result, several application-layer solutions have been proposed based on large-scale P2P systems. These solutions however, are unable to provide a satisfactory quality of experience to all users, mainly because of the variability of the peers and their limited upload capacity. In this paper we advocate for a network-layer solution that circumvents the prohibitive deployment costs of previous approaches, taking advantage of the rare window of opportunity offered by the locator/identifier separation protocol (LISP). This new architecture, motivated by the alarming growth rate of the default-free zone (DFZ) routing table, is developed within the IETF, and aims to upgrade the current inter-domain routing system. We present CoreCast, an efficient inter-domain live streaming architecture operating on top of LISP. LISP involves upgrading some Internet routers and our proposal can be introduced along with these new deployments. To evaluate its feasibility in terms of processing overhead in networking equipment we have implemented CoreCast in the Linux kernel. Further, we compare the performance of CoreCast to the popular P2P streaming services both analytically and experimentally. The results show that CoreCast reduces inter-domain bandwidth consumption and that introduces negligible processing overhead in network equipment. 相似文献
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一种有效的簇集主干点P2P网络结构模型 总被引:3,自引:0,他引:3
文中提出一种有效的簇集主干点P2P网络结构模型,克服了非结构化P2P系统中存在的扩展性不好和搜索效率不高的问题。该模型根据拓扑优先级把对等点聚类成簇形层级结构,从CN中选出GN充当簇的中心和服务提供者,实现定位查询和信息交互。为了衡量由主干点组成的骨干网的路由,文中设计了一种适用于应用级广播协议的路由算法。实验利用Java平台和仿真工具模拟实时网络环境,比较层级结构结合主干点骨干协议的系统模型和Gnuteua系统的代价。实验结果证明这种层级结构的簇集P2P模型,加上骨干网协议支持,在系统性能和可扩展性上带来了明显地提升,并可在大范围非结构化的P2P环境中得到应用推广。 相似文献
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Available resources in peer-to-peer (P2P) systems depend strongly on resource contributions made by individual peers. Empirical data shows that in the absence of incentives, a majority of the participating peers do not contribute resources. Modeling interactions between individual peers is often difficult as the number of peers in the system can be very large, and the relationships among them can be very complex. In this paper, we propose a new solution for P2P systems, where peers upload and download content to and from the contributing peers based on agreed-upon/determined sharing rates. We propose a P2P solution that deters free-riders by imposing constraints on participating peers; specifically, a peer is allowed access to new content only as long as its own content contribution exceeds an adaptively set threshold. The constraints are enforced either by a central authority (e.g., a tracker) or by a decentralized coalition of peers in a swarm, social network, etc. We derive optimal upload policies for the peers given their estimated future download requirements and their previous contribution (credit) to the other peers. Our results show considerable improvement in the cost-benefit tradeoff for peers that deploy such an optimal policy as compared to heuristic upload policies. We also propose mechanisms based on which the coalition of peers can provide incentives or penalties to participating peers to adjust their policies such that the availability of content and/or number of peers contributing content is maximized. 相似文献
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张洪军 《计算机工程与设计》2006,27(24):4767-4769
P2P(peer to peer)技术在分布计算时代发挥着越来越重要的作用,但在数据管理方面,P2P的应用表现出较大的局限性。作为一种快速高效的P2P信息系统P-Grid,它能够极大地减少其它P2P系统所需要的网络带宽。P-Grid系统的构造和维护严格依照本地交互的随机算法,即使在不可靠的节点也能提供可靠的访问,并且能够较好地衡量存取和通信代价。 相似文献
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P2P网络(Peer toPeer,对等网)已经以飞快的速度发展成为internet中最重要的应用系统之一。P2P网络开放、匿名的特性使得任何人在任何时候都也可加入网络为其他人提供内容和服务,同时也可以从网络中查找并获得所需要的资源。然而,也正是因为这种特点,节点之间缺乏信任、恶意节点随意终止服务,造成了网络的利用率低下,信任管理就显得十分必要。然而传统的单向信任管理机制难以有效地对自私节点和恶意节点进行控制。鉴于此,本文在研究P2P网络的信任管理机制的基础上,引入了双向信任机制,实现节点之间的双向评估。 相似文献
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Thao P. Nghiem Kiki Maulana Kinh Nguyen David Green Agustinus Borgy Waluyo David Taniar 《Journal of Parallel and Distributed Computing》2014
The increasing use of mobile communications has raised many issues of decision support and resource allocation. A crucial problem is how to solve queries of Reverse Nearest Neighbour (RNN). An RNN query returns all objects that consider the query object as their nearest neighbour. Existing methods mostly rely on a centralised base station. However, mobile P2P systems offer many benefits, including self-organisation, fault-tolerance and load-balancing. In this study, we propose and evaluate 3 distinct P2P algorithms focusing on bichromatic RNN queries, in which mobile query peers and static objects of interest are of two different categories, based on a time-out mechanism and a boundary polygon around the mobile query peers. The Brute-Force Search Algorithm provides a naive approach to exploit shared information among peers whereas two other Boundary Search Algorithms filter a number of peers involved in query processing. The algorithms are evaluated in the MiXiM simulation framework with both real and synthetic datasets. The results show the practical feasibility of the P2P approach for solving bichromatic RNN queries for mobile networks. 相似文献
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Existing live video streaming systems can be classified as server (cloud) based or as peer-to-peer (P2P). The client–server approach promises stability and (Quality of Service) QoS by incurring expensive bandwidth provision cost on the server. On the other hand, P2P architecture is scalable with low bandwidth and maintenance cost. Here we propose a cloud assisted P2P live streaming architecture which is scalable and stable. In order to achieve this we have developed: (i) a scalable gossip protocol that monitors dynamically the total available bandwidth resources of the participating peers, (ii) a control strategy that dynamically allocates the bandwidth that is required.The first step towards this direction is to create a theoretical model that captures the dynamic relationship between the total bandwidth surplus/deficit and peers’ bandwidth utilization in order to be able to apply a control theoretical approach. Moreover, we quantify the impact of monitoring inaccuracies and peers’ dynamic bandwidth changes and we calculate analytically, as a function of them, the minimum amount of bandwidth overprovision that ensures the undisturbed distribution of the stream. System is evaluated through a detailed simulator of a complete P2P live streaming system and testified the uninterrupted and complete stream delivery even in very adverse bandwidth changes. 相似文献
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在目前已广泛应用的P2P网络中,由于缺乏信任机制,存在着许多欺诈等恶意行为,节点的资源共享处于自愿,可能随时退出,系统的有效性和可用性难以保证。由于P2P网络节点的匿名性和贡献资源的自愿性,绝大多数节点缺乏提供服务积极性,从而引发了P2P网络中的搭便车问题。提出了一种新的激励机制,可有效解决一部分问题。 相似文献
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Many reputation systems have been proposed to distinguish malicious peers and to ensure the quality of the service in P2P file sharing systems. Most of those reputation systems implicitly assumed that normal peers are always altruistic and provide their resources unconditionally when requested. However, as independent decision makers in real networks, peers can be completely altruistic (always cooperative, ALLC), purely selfish (always defective, ALLD), or reciprocal (R). In addition, those systems do not provide an effective method to reduce free-riders in P2P networks. To address these two problems, in this paper, we propose an EigenTrust evolutionary game model based on the renowned EigenTrust reputation model. In our model, we use evolutionary game theory to model strategic peers and their transaction behaviors, which is close to the realistic scenario. Many experiments have been designed and performed to study the evolution of strategies and the emergence of cooperation under our proposed EigenTrust evolutionary model. The simulation results showed that rational users are inclined to cooperate (enthusiastically provide resources to other peers) even under some conditions in which malicious peers try to destroy the system. 相似文献
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Clustering is one of the important data mining issues, especially for large and distributed data analysis. Distributed computing environments such as Peer-to-Peer (P2P) networks involve separated/scattered data sources, distributed among the peers. According to unpredictable growth and dynamic nature of P2P networks, data of peers are constantly changing. Due to the high volume of computing and communications and privacy concerns, processing of these types of data should be applied in a distributed way and without central management. Today, most applications of P2P systems focus on unstructured P2P systems. In unstructured P2P networks, spreading gossip is a simple and efficient method of communication, which can adapt to dynamic conditions in these networks. Recently, some algorithms with different pros and cons have been proposed for data clustering in P2P networks. In this paper, by combining a novel method for extracting the representative data, a gossip-based protocol and a new centralized clustering method, a Gossip Based Distributed Clustering algorithm for P2P networks called GBDC-P2P is proposed. The GBDC-P2P algorithm is suitable for data clustering in unstructured P2P networks and it adapts to the dynamic conditions of these networks. In the GBDC-P2P algorithm, peers perform data clustering operation with a distributed approach only through communications with their neighbours. The GBDC-P2P does not need to rely on a central server and it performs asynchronously. Evaluation results demonstrate the superior performance of the GBDC-P2P algorithm. Also, a comparative analysis with other well-established methods illustrates the efficiency of the proposed method. 相似文献