P2P覆盖网中的聚类研究综述*

首先对P2P覆盖网中的聚类技术进行了分类,在此基础上介绍了各种典型的聚类方法并进行了对比分析;最后指出了P2P覆盖网中聚类技术的未来研究趋势。     

无标度异构网络中的层次化P2P覆盖网设计

针对P2P应用系统中存在的负载不均衡,拓扑不匹配等问题,提出在无标度网络中的节点上分别实现路由和服务索引维护这两种功能的覆盖网设计思想,以Chord为例设计节点成簇和成环算法,实现三层覆盖网体系和二维地址空间结构,并提出节点负载分析模型。仿真结果表明,相比以往2层的以Chord为中心的覆盖网,新提出的覆盖网在查询路径长度、负载、查询成功率等多个性能指标上都有很大的优化。     

Receiving-peer-driven multi-video-source scheduling algorithms in mobile P2P overlay networks

This paper proposes two algorithms for multi-video-source in a new mobile P2P architecture for streaming media systems. One is serial, and the other is parallel. When the service peer set providing expected QoS is not empty, the former is called, otherwise the latter is called. The former triggers the video source change event, re-selects a video source, and synchronizes the multi-video-source by the time model of the streaming sequence when QoS is degraded. The latter allows the multiple video sources to concurrently send the data to the receiving peer according to the assigned transmission. Compared to the existing papers, the contribution of this paper is fourfold: (1) the serial and parallel scheduling algorithms, correctly switched according to the actual situation, are firstly proposed; (2) the mobile feature of peers are firstly considered and validated; (3) the client nodes have better and smoother video quality; (4) our algorithms have shorter run time, which is a crucial factor for an on-line system.     

An optimal inherently stabilizing routing algorithm for star P2P overlay networks

Star graphs possess many desirable properties such as scalable node degrees and diameters, which are essential to facilitate reduced routing table sizes and low maximum path length for routing in large P2P networks. In addition, because a large number of disjoint paths are available and each data/replica in an n‐star can be placed in an (n − 1)‐star, load balancing and alleviation of network bottlenecks can be implemented in star P2P overlay networks. Therefore, star networks have been proposed as viable alternatives to existing overlay topologies for large P2P networks. In this paper, we propose an optimal stabilizing and inherently stabilizing algorithm for routing messages over all disjoint paths between two peers in a star P2P overlay network. The algorithm is optimal in terms of its time complexity in rounds and the length of the longest path traversed by the messages, and fault tolerant due to being stabilizing and inherently stabilizing, allowing the system to withstand transient faults. The algorithm can be used to increase network reliability and survivability in P2P networks. In addition, the usage of all disjoint paths to route messages between two peers leads to increased network bandwidth while distributing the communication overhead across the network and eliminating network bottlenecks in P2P networks. Copyright © 2016 John Wiley & Sons, Ltd.     

A distributed data clustering algorithm in P2P networks

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.     

DisCoP2P: an efficient P2P computing overlay

CodiP2P and DisCoP are two peer-to-peer (P2P) computing overlays aimed at sharing computing resources (CPU, Memory, etc.) to execute parallel applications. Their component nodes are basically PC’s and a wide range of computer servers, desktops or laptops. This paper joins these two platforms into a new one, DisCoP2P, to combine the features from both overlays. CodiP2P is highly scalable, and DisCoP has an efficient searching mechanism and the ability to classify computing resources. The new platform takes advantage of these features and uses them to offer new facilities to schedule and execute parallel applications efficiently. This is accomplished at null cost because the platform is made up of nodes that share resources for free. This research field can also be classified in desktop computing. The success of this platform depends greatly on the added overhead. This overhead is produced mainly in searching for resources and system administration. The obtained results in a preliminary prototype, although not sufficiently conclusive, demonstrate the applicability of DisCoP2P in the real world, i.e. Internet.     

论P2P网络信任机制的影响因素

P2P网络具有开放性、匿名性和自治性等特点。信任的缺乏导致节点之间的交易存在风险,阻碍了P2P网络的进一步发展。针对P2P网络所建立的信任机制能确保节点间正常交易,但由于P2P网络的特点和网络的复杂性,使P2P信任机制的部署不易实施。为此,分析了P2P网络中信任机制面临的网络攻击,详细研究了相关的影响因素,发现信誉值的计算不仅应关注上传节点,还应该关注下载节点。从上传节点和下载节点两个角度给出了影响因素的分布。这些影响因素的研究有助于对P2P信任机制的进一步研究。     

Peer sampling gossip-based distributed clustering algorithm for unstructured P2P networks

Clustering, as an unsupervised learning method and an important process in data mining, is an aspect of large and distributed data analysis. In many applications, such as peer-to-peer systems, huge volumes of data are distributed between multiple sources. Analysis of these volumes of data and identifying appropriate clusters is challenging due to transmission, processing and storage costs. In this paper, a gossip-based distributed clustering algorithm for P2P networks called Efficient GBDC-P2P is proposed, based on an improved gossip communicative approach by combining the peer sampeling and CYCLON protocol and the idea of partitioning-based data clustering. This algorithm is appropriate for data clustering in unstructured P2P networks, and it is adapted to the dynamic conditions of these networks. In the Efficient GBDC-P2P algorithm, distributed peers perform clustering operation in a distributed way only through local communications with their neighbors. Our approach does not rely on the central server to carry out data clustering task and without the need to synchronize operations. Evaluation results verify the efficiency of our proposed algorithm for data clustering in unstructured P2P networks. Furthermore, comparative analyses with other well-established distributed clustering approaches demonstrate the superior accuracy of the proposed method.

     

MANET adaptive structured P2P overlay

This paper presents an efficient structured P2P overlay over MANET which better matches to the physical network in term of routing. This feature is achieved by locally building up the minimum-spanning tree (MST) at each peer using the information of the peer’s logical neighbors which are either directly connected (1-hop) or 2-hops away. Using this interconnection structure among the peers, we design a new algorithm to distribute the contents information in the overlay by partitioning the identifier (ID) space among the peers. In this algorithm, each peer maintains a disjoint portion of the ID space. The ID space at a peer may be non-contiguous and each contiguous part is consecutive to the ID space of its directly connected neighbor peers. To route the file-lookup query, each peer builds up a binary search tree (BST) using the knowledge of the ID space of itself and of its directly connected neighbor peers. Simulation results show that our approach outperforms the existing approaches in term of routing overhead, average file-discovery delay, false-negative ratio and average path-stretch value.     

Subscriber mobility management for a P2P publish/subscribe overlay in mobile tactical networks

P2P (Peer-to-Peer) overlay is a promising distributed computing and communication paradigm that allows for a group of participants to share information and coordinate their resources. Dissemination of information among end users can also be greatly facilitated by the publish/subscribe model. In this paper, we employ the publish/subscribe model in a P2P mobile tactical networking environment. Considering the particular requirements for mobile tactical networks, we investigate the problem of subscriber mobility management and propose a novel proactive handoff approach for improved system responsiveness and reliability. A comprehensive performance evaluation of the proposed mechanism is presented. The obtained results demonstrate significant performance benefits of the proposed scheme.

一种网络敏感的结构化小世界P2P覆盖网络*

近年来人们对结构化P2P覆盖网络进行了大量的研究,在结构化P2P网络的构建中,下层的网络拓扑结构并没有得到考虑,因此在端到端的通信中,尽管覆盖网上所反映出路径跳数很少,但实际的延迟却会很大。针对此问题,结合小世界理论提出一种网络敏感的新P2P覆盖网络,使实际网络中邻近的节点能聚集到同一簇中,并利用小世界网络平均距离小和大簇系数特性进行路由选择和拥塞控制。仿真实验表明,与经典的P2P覆盖网络相比,该网络具有更高的查询效率。     

On the impact of routing matrix inconsistencies on statistical path monitoring in overlay networks

Overlay networks can be used to find working paths when direct underlay paths are anomalously slow, e.g. because of a network fault. Overlay paths should not use links that are involved in a fault, so choosing which overlay path to use often requires path monitoring, which introduces an overhead. By using a routing matrix ‘M’ to define which links are used in each path, and sorting the matrix according to the degree of independence of paths, we can choose a reduced set of paths to monitor, and so reduce overheads. The state of the unmonitored paths are then predicted using statistical estimation techniques based on information inferred from the monitored paths. However, such methods assume knowledge of routing matrix. We investigate the impact on such methods when knowledge of the routing matrix is only approximate, e.g. as obtained using simple tools like traceroute which have been previously blamed for incorrect mapping of the topology of real world IP networks. This paper investigates the impact of routing matrix errors on such statistical path estimation approaches. We show that mitigation or removal of such errors leads to improved path metric prediction and anomaly detection.     

非结构化P2P覆盖网络通信协议研究

针对各种基于流言机制的通信协议在构造非结构化P2P覆盖网络中,其适用范围缺乏广泛的实证问题,提出了一个通用的协议框架——基于流言机制的节点采样服务,以执行高效和可靠的节点采样服务。在这种协议框架下通过实验分析了8种通信协议的差异。实验表明,采用不同的通信协议,所构造的非结构化P2P覆盖网络就表现出多种不同的行为特性,为构造非结构化P2P覆盖网络中选取通信协议提供了重要的参考依据。     

一种基于Small World的P2P覆盖网络的研究

Small World网络的两个主要特性是平均路径长度小和聚集系数大,参照Small World网络的两个主要特性,提出了一种基于Small World的P2P覆盖网络模型（SWPP）,并在SWPP中定义了一套DHT协议,以该协议为基础,提出了SWPP的路由算法及路由容错算法,分析了路由长度及路由优化方法,最后通过数值实验分析了SWPP性能。     

基于层次化P2P覆盖网络的多播模型

提出一种新的层次化覆盖网络模型HMCON,它是建立在二层P2P覆盖网络上的分布式的可扩展的自组织模型。该模型通过在所有的参与节点上构造多棵“互补”结构的多播树来协同流媒体信号的传输,以平衡各个节点的负载,保证QoS。为了测试网络的延迟和丢包率对HMCON模型的影响,采用ITU-T E-Model对模型进行了仿真,结果表明HMCON模型在网络延迟较大时也能保证良好的通信质量。     

基于P2P覆盖树网络的流媒体传输技术优化研究

PeerCast是一个基于P2P网络的流媒体传输系统,各节点被组织成树状来进行数据的分发.但没有一个有效的机制来维护树的平衡和保证所选取的父节点是最佳的节点.在此基础上,对该系统进行优化,在媒体数据包上加一个字节用来标识当前节点与根节点的距离,并对节点间响应消息进行优化.实验结果表明,这些优化措施能够有效的维护树的平衡和降底数据传输时延.     

GrouPeer: Dynamic clustering of P2P databases

Sharing structured data in a P2P network is a challenging problem, especially in the absence of a mediated schema. The standard practice of answering a consecutively rewritten query along the propagation path often results in significant loss of information. On the opposite, the use of mediated schemas requires human interaction and global agreement, both during creation and maintenance. In this paper we present GrouPeer, an adaptive, automated approach to both issues in the context of unstructured P2P database overlays. By allowing peers to individually choose which rewritten version of a query to answer and evaluate the received answers, information-rich sources left hidden otherwise are discovered. Gradually, the overlay is restructured as semantically similar peers are clustered together. Experimental results show that our technique produces very accurate answers and builds clusters that are very close to the optimal ones by contacting a very small number of nodes in the overlay.     

基于P2P网络的动态QoS多源多播模型

针对服务质量(QoS)约束的覆盖网络多播问题,提出了一个适合有多个数据源的多播模型。该模型中每个数据源不必维护一个以它为根的多播树,每个节点只需维护局部状态信息,多播信息以类似洪泛的方式传输。通过控制,信息的传输路径形成树型结构,多播树可动态调整来适应以不同源节点发起的满足QoS要求的多播应用。实验结果表明,该模型的节点多播覆盖率高,通过控制节点的子节点数,可使多播树的调整代价达到最低。     

一种分层分簇的P2P流媒体覆盖网络模型

提出一种新型的分层分簇结构的P2P覆盖网络模型HCPON。该模型根据能力对节点分层处理,分簇聚合,分别应用不同方案优化覆盖网络结构,兼顾了节点的能力差异性和位置特性。仿真实验表明,该模型具有很好的可扩展性和鲁棒性,能够满足大规模流媒体服务需求。     

Service-based P2P overlay network for collaborative problem solving

This paper describes a service-based P2P overlay network architecture to support a collaborative environment for solving complex business processes over the network. In the proposed architecture, autonomic service providers corresponding to various activities that occur in the processes reside on the overlay network and are discovered dynamically during the execution of the process. To consummate a specific process, a set of services that map into the business process are federated together and executed in a choreographed sequence. All services have standardized interfaces and this allows any service to be seamlessly replaced with another service without affecting the performance of the federation. The paper presents two cases of application of this architecture, namely, business-to-business collaboration in an engineering environment (General Electric) and multiparty financial transactions (mortgage).