一种面向结构化P2P网络的基于闲谈的资源发现方法

 结构化P2P网络下的多属性资源发现一直是一个公开问题.本文针对当前一种新颖的、优于传统方法的多属性资源发现方法－PIRD,深入分析了其在网络动态变化时可能出现的低查询效率问题,并提出一种解决方法:基于闲谈的PIRD(Gossip-based PIRD,G-PIRD).G-PIRD通过闲谈算法估计网络规模,动态调整资源索引的发布以保证高的查询效率.同时针对G-PIRD可能导致的负载不均衡问题,提出一种基于有界LSH(Bounded LSH,B-LSH )的负载均衡策略.试验证明:G-PIRD能动态适应网络变化,保证高效率的多属性资源发现;以及G-PIRD的负载均衡策略在保证高查询效率的同时,大大地降低了节点的索引负载.     

结构化P2P网络资源搜索Chord算法研究与改进方案

针对结构化P2P网络资源搜索技术中Chord算法进行深入研究和分析,分别从路由信息冗余、节点延迟划分、查询路径判断等3个方面对传统Chord系统进行讨论和改进,提出了相应的改进方案,并通过仿真实验对方案进行性能测试和验证分析,证明改进方案减少了资源查询路径长度,降低了信息的转发次数,减轻了网络的负担,从而能更好提高资源搜索效率.     

一种分层的P2P网络模型

基于分布式哈希表(DHT)的结构化P2P网络是目前研究热点,但是DHT机制实现比较复杂,更重要的是节点频繁的加入或退出所造成的网络动荡会对系统的网络造成巨大的压力,网络系统的稳定性很差。文章提出了一种层次化的P2P网络模型,该网络模型分为两层,其中上层是结构化Chord网络,下层中心化网络,该网络结合了结构化和中心化P2P网络的优点,弱化或克服了两者的缺点,在稳定性、可扩展性和查询效率等方面的性能都有一定的提高。     

结构化P2P资源搜索算法及其在未来光网络中的应用

推进绿色节能光网络是未来光网络面临的重要挑战之一。基于DHT的结构化P2P资源搜索算法因为可扩展性、鲁棒性、负载均衡、查询效率高等特点更适用于具有云计算、物联网、移动互联网等特点的未来光网络中的资源搜索。研究结构化P2P资源搜索算法的特点,从降低能耗角度分析算法对未来光网络产生的影响,提出在名址分离架构的未来网中快速资源搜索设计方法,最后探讨P2P资源搜索算法在未来光网络中面临的挑战。     

云计算环境中一种基于Hash环的P2P网络模型研究

P2P技术的应用在现代网络系统中越来越普及,而云计算的出现给IT界带来了全新的挑战,因此,针对目前网络的发展现状,对P2P技术和云计算技术进行研究,提出了一种云计算环境中的P2P网络模型,这是云计算技术与P2P技术的一种结合。通过对使用P2P技术的网络中节点的处理能力、拥有的资源量、占据的带宽大小等进行评估,得出网络中各节点的层次结构并形成Hash环,然后利用一致性Hash算法在系统中对资源进行快速搜索。利用这种方法,由于每个节点只需要更新少量的信息就可以完成查询路由,从而实现了网络中资源的快速定位,提高了网络资源搜索的效率。     

一种针对P2P网络优化的Kademlia路由算法

为了加快P2P网络中热点查询的速度,针对Kademlia算法在查询效率和高速缓存策略方面存在的不足,文中采用快表技术和加权设置策略对该算法进行改进,避免了在高刷新频率缓存中查询效率低下的问题,为更高的查询命中率提供了更集中的热点资源.模拟实验证明此改进算法具有更短的查询延时和更少的平均路由跳数.     

基于结构化P2P网络的CORBA交易服务

交易服务能够在分布式环境下为用户提供发现网络中服务的能力。文章提出了一种在CORBA环境下基于结构化P2P网络的交易服务结构（DHT-Trader），该体系结构不仅具有结构化P2P网络的可扩展性和健壮性，还支持类型相关查询，包括基于属性查询和语义查询。文章着重分析了类型相关查询和语义查询的难点．提出了在结构化P2P网络中实现类型相关查询和语义查询的解决方案。通过使用DHT-Trader，出口者可以为一个服务发布若干名字．进口者仅根据其中之一就可以得到服务以及该服务类型的所有子类型。     

基于MP2P网络的内容分发机制研究

针对目前MP2P网络因节点频繁移动带来的扰动性,及节点有限的计算、存储能力等限制因素,提出分区管理的灵活策略,将节点按标准进行功能划分,每个子网由超级节点管理。采用部分网络编码技术处理数据,加快数据传输及更替效率。并提出跨子网查询算法加强子网间信息的交互及资源定位。实验结果表明,该策略可以有效地提高资源下载成功率与命中率,减少资源传输延时,改善了MP2P网络的内容分发效率,同时也增强了系统的顽健性。     

P2P模型构造及资源搜索算法研究

Peer-to-Peer(P2P)对于分布式文件共享具有很好的前景,但当前的P2P系统仍然缺乏有效的信息搜索机制。针对P2P网络中资源查找以及其自身存在的问题,提出了一种分布式二叉树索引模型,通过度量网络中结点属性相似性,对所有结点进行渐近分组,形成层次性逻辑二叉树覆盖网络。在信息搜索时,查询只路由到相关的结点上,减少信息搜索时的平均搜索路径长度,从而改善搜索效率。     

无线Ad Hoc网络中支持P2P应用的研究

无线Ad Hoc网络和P2P技术近年来发展迅速,已经成为宽带无线网络技术领域的研究热点.相关研究表明.在现有的无线Ad Hoc网络中直接应用P2P技术.会造成系统开销大量增加,分组传输效率及查询成功率下降,从而影响整个网络的性能.本文针对上述问题进行分析,采用跨层设计的方法,提出了在无线Ad Hoc网络中实现P2P应用的解决思路和方案,满足无线Ad Hoc网络中各种P2P应用的不同QoS需求.     

一种非结构化P2P网络的资源搜索算法

本文针对非结构F2P网络中利用洪泛搜索机制来进行资源搜索的盲目性问题，提出一种利用节点经验积累和cache技术相结合来指导资源搜索的算法。在访搜索算法中，节点记录收到的查询主题和满足该主题的邻居节点，建立主题与邻居节点的对应关系表，当再次收到该主题时，节点就利用该表来指导资源搜索。为了加快搜索速度，将常见查询主题的记录放到cache中。该算法利用一个相似度函数来判断本地文档是否满足查询主题。仿真实验表明，该算法有效地改进了资源搜索的盲目性。减少查询带来的网络流量，提高了查询成功率。     

SKIP:an efficient search mechanism in unstructured P2P networks

Search efficiency and accuracy of resource are important considerations for search algorithm in peer-to-peer(P2P)network.Most search algorithms use flooding among neighbor nodes to search relevant resource.However,this usually causes great amount of redundant messages,which results in high search costs and low search precision.In this paper,we use vector space model(VSM)and relevance ranking algorithms to construct overlay network,and a novel search mechanism search with K-iteration preference(SKIP)based on semantic group for P2P networks is proposed to efficiently solve these problems.The key idea of SKIP is to reorder the semantic neighbors of nodes according to relevant scores and to utilize preference selection during the process of query.We analysis and implement the scheme and reveal that the SKIP provides a low overhead on topology maintenance,which can be effectively used in P2P searching and verify it outperformanee in higher precision and lower search cost by comparing with current semantic-based searching mechanism gnutella-like efficient searching system(GES).     

Distributed upload bandwidth assigning algorithm in P2P VoD system

In a peer-to-peer(P2P) live streaming system,each peer uses greedy strategy to download chunks as many as possible so as to assure smooth playback and promote the chunk propagation.However,diversity of video playback rate,heterogeneity of peer downlink bandwidth and no prefetching limitation determine that greedy strategy is not the best strategy for P2P video-on-demand(VoD) system though this strategy performs well in P2P live system.To reasonably assign upload bandwidth among peers,we first present a stochastic model to relate expected downloading speed(EDS) with buffered data amount(BDA,the amount of data has been fetched in buffer,however has not been played yet by the peer),video playback rate and fluency(the probability of no interruption in a viewing process).On the base of this model,we design an equal fluency bandwidth assigning algorithm(EFBAA).In this algorithm,requesting peers compute EDS according to several local parameters(such as BDA,video playback rate and fluency) dynamically and independently and send the EDS to neighbor peers together with buffer map.Then the neighbor peer proportionally partitions and assigns its upload bandwidth to requesting peers according to their EDS.Extensive simulations demonstrate that EFBAA outperforms greedy strategy in terms of server load and startup latency.     

移动P2P网络中能量有效连续查询研究

在移动P2P网络中一个基本应用问题是访问分布式空间数据库中的数据对象,同时节省电量.文中提出了在移动P2P网络中能量有效连续查询处理（Energy Efficient Continuous Query Processing,EECQP）算法,包括范围查询和k个最近邻居节点查询（k-nearest-neighbor queries, k-NN）.EECQP算法能够提供移动用户找到一个有质量保证的连续查询结果.EECQP算法主要的想法是允许用户与节点合作,持续保存查询结果,而不是总是从头开始处理查询,从而减少通信开销.实验结果表明所提出的EECQP算法对于范围查询和k个最近邻居节点查询在通信开销和QoS保证是能量有效和可扩展的.     

基于预算机制的非结构化P2P网络分段搜索策略

在非结构化P2P网络中,降低消息冗余,提高搜索的效率,一直是资源搜索的关键问题.目前非结构化P2P网络均采用生存时间（Time-To-Live）机制控制搜索算法的深度,但是同时产生了大量的冗余消息,严重影响了网络的利用率.为了能够在保持高搜索效率的前提下减少冗余消息的数量,提出了一种基于预算机制的非结构化P2P网络分段搜索策略DBudgetSearch.DBudgetSearch将搜索过程分为两个阶段,并在每个阶段中使用预算机制来控制消息转发的数量和导向,根据邻居节点的连接度大小来选择消息的转发对象.分析和试验结果表明,DBudgetSearch导向性好,算法搜索效率高,能够有效减少冗余消息.     

SNMS: an intelligent transportation system network architecture based on WSN and P2P network

With the development of city road networks, the question of how to obtain information about the roads is becoming more and more important. In this article, sensor network with mobile station (SNMS), a novel two-tiered intelligent transportation system (ITS) network architecture based on wireless sensor network (WSN) and peer-to-peer (P2P) network, is proposed to provide significant traffic information about the road and thereby, assist travelers to take optimum decisions when they are driving. A detailed explanation with regard to the strategy of each level as well as the design of two main components in the network, sensor unit (SU) and mobile station (MS), is presented. Finally, a representative scenario is described to display the operation of the system.     

P2P流量识别与管理技术

P2P流量在推动Internet宽带化的同时也带来了资源过度占用和网络安全等问题.本文调查和研究了P2P流量识别和策略控制的最新技术及相关设备,总结出P2P流量综合控制模型,并指出进一步的研究方向.     

Improving Resilience against DDoS Attack in Unstructured P2P Networks

In unstructured peer-to-peer （P2P） systems such as Gnutella, a general routing search algorithm is used to blindly flood a query through network among peers. But unfortunately, malicious nodes could easily make use of the search approach launching distributed denial of service （DDoS） attack which aims at the whole network. In order to alleviate or minimize the bad effect due to behavior of malicious nodes using the flooding search mechanism, the paper proposes a Markov-based evaluation model which exerts the trust and reputation mechanism to computing the level of trustworthy of nodes having the information requested by evaluation of the nodes＇ history behavior. Moreover, it can differentiate malicious nodes as early as possible for isolating and controlling the ones＇ message transmitted. The simulation results of the algorithm proposed show that it could effectively isolate malicious nodes, and hold back the transmission of vicious messages so that it could enhance tolerance of DDoS based on flooding in Guutella-like P2P network.     

P2P流量管理技术研究

近年来,P2P(peer-to-peer)技术的应用类型、用户规模和网络流量均呈爆发式增长,但P2P应用的兴起,也打破了网络运营商原有的运营和商业模式.为了更好地管理P2P流量,业界进行了多层次的探索,主要包括:一是通过DPI(深度数据包检测)技术进行流量识别和管控,二是进行流量本地化的优化,其中P2P缓存与Peer选择优化是两个主要方向.基于对上述技术的分析,本文提出一种将P2P缓存技术与Peer选择优化技术相结合的P2P承载架构,并以此承载架构为基础,对用户的管理、认证、计费、安全进行综合考虑,从而实现电信级的P2P分发网络.     

Model of downloading strategy from peers and server for saving server bandwidth in P2P VoD system

In peer-to-peer(P2P)video on demand(VoD)system,once the P2P downloading rate cannot satisfy the need of playback,server is quickly referred to for help in providing enough bandwidth.Thus the switch of downloading from other peers(P2P)and server(HTTP)exists.This paper uses the proportion of P2P downloading amount(PPDA)during the video watching process to measure server load.This article is interested in finding a better strategy or switch rule between P2P and HTTP downloading for saving server bandwidth.The authors suggest and model a kind of switch rule based on local buffer amount,using mathematical theory of Brownian motion.It can effectively alleviate the impact of P2P rate fluctuation,reduce the switch times and improve the PPDA by at least 3%-5% on the basis of the former switch rule,which means substantial cost can be saved.Particularly the PPDA is related with the ratio of playback bit rate to the HTTP downloading rate which means the PPDA can be restricted by controlling the ratio in the real-world system.Though the result comes from constant bit rate(CBR)video supposition,it provides perspective and method for variable bit rate(VBR)application,and valuable insights for the future development of P2P VoD system.