基于能力因子的P2P邻居节点随机可变选择算法

在分析固定随机选择邻居节点算法的基础上,提出了一种适用于混合式P2P直播系统的邻居节点随机可变选择算法,新算法通过能力因子来衡量节点的良好度,对不同类的节点有不同的邻居数量的最大值,使得良好度高的节点能发挥更大的作用,仿真表明算法能降低数据传输的延迟,提高网络系统的性能。     

基于蚁群算法的对等网络自适应寻径协议

针对现有的蚁群算法在对等网络寻径中,不能根据访问的对等体状况去自适应克隆转发相应数目的蚂蚁,自适应设置克隆蚂蚁的TTL的问题,给出一种面向对等网络的自适应寻径模型,提出一种基于蚁群算法的对等网络自适应寻径协议AARP,描述蚁群在对等网络中自适应的克隆、寻径过程。分析和仿真实验结果表明,AARP能够以较低的寻径开销、较短的寻径时延,实现较高的寻径效率。     

Distributed Downloads of Bulk,Replicated Grid Data

Data-sharing scientific communities use storage systems as distributed data stores by replicating content. In such highly replicated environments, a particular dataset can reside at multiple locations and can thus be downloaded from any one of them. Since datasets of interest are significantly large in size, improving download speeds either by server selection or by co-allocation can offer substantial benefits. In this paper, we present an architecture for co-allocating Grid data transfers across multiple connections, enabling the parallel download of datasets from multiple servers. We have developed several co-allocation strategies comprising of simple brute-force, predictive and dynamic load balancing techniques as a means both to exploit rate differences among the various client–server links and to address dynamic rate fluctuations. We evaluate our approaches using the GridFTP data movement protocol in a wide-area testbed and present our results.     

A congestion-aware search protocol for heterogeneous peer-to-peer networks

Peer-to-Peer (P2P) file sharing is the hottest, fastest growing application on the Internet. When designing Gnutella-like applications, the most important consideration is the scalability problem, because P2P systems typically support millions of users online concurrently. Gnutella suffers from poor scaling due to its flooding-based search, resulting in excessive amounts of repeated query messages. Therefore, a good search protocol plays an important role in a system’s scalability. However, congestion, due to large query loads from users, definitely impacts on the performance of search protocols, and this consideration has received little attention from the research community. In this paper, we propose a congestion-aware search protocol for unstructured P2P networks. Our protocol consists of three parts—Congestion-Aware Forwarding, Random Early Stop and Emergency Signaling. The aim of our protocol is to integrate congestion control and object discovery functionality so that the search protocol can achieve good performance under congested networks and flash crowds. We perform extensive simulations to study our proposed protocol. The results show that our protocol can significantly reduce the hit delay while maintaining the high hit rate and also the congestion problems such as query loss and the peer overloading problem can be effectively alleviated.     

一种媒体点播系统资源对等搜索模型

媒体点播是网络教育中重要的教学方式,但是目前存在标准不同、共享困难等问题。为此引入P2P技术解决资源共享问题。P2P网络是一种自组织、适应性强、负载均衡、可靠性好的网络,目前被广泛运用于文件共享等领域。文中介绍利用P2P技术实现多个媒体点播系统互联,为用户提供可扩展的查询服务和资源共享平台。通过分析得出互联后的媒体点播系统较单个系统具有许多优点。     

Peer-to-Peer文件共享系统的测量研究

Peer-to-Peer(P2P)技术的发展引发了Internet应用模式的变革.为了寻求网络运营商、内容提供商和Internet用户三方共赢的解决方案,必须从他们各自的角度出发对P2P应用进行系统的测量与分析.首先概述了P2P测量的研究内容,并将现有的P2P测量研究划分为P2P拓扑特征的测量、P2P流量特征的测量、P2P可用性的测量3类.在对P2P测量方法进行对比分析之后,详细综述了P2P测量的研究现状,对现有的各种测量方案以及研究成果进行了深入的分析,指出了其中存在的问题和缺陷.最后讨论了P2P测量未来的研究方向.     

P2P网络中蠕虫传播与防治模型的研究

本文提出了一种P2P网络主动蠕虫的传播模型。同时，针对不同结构的P2P网络拓扑，给出了各自的用良性蠕虫对抗恶性蠕虫的防治策略和防治模型，并在Matlab环境下对这些模型进行了仿真，评估了P2P网络蠕虫传播的特点以及蠕虫防治效果的优劣。     

P-Chord:一种基于分区的Chord路由模型

在P2P系统中,有效地定位分布在网络中不同节点的数据资源一直是研究的重点。结构化P2P网络Chord的路由表存在着严重的信息冗余,影响了整个系统的效率。针对这种情况,文中在Chord的基础上提出了一种基于分区的Chord路由模型(P-Chord),通过对Chord的分区,将节点的路由表进行改造,消除了冗余信息,增加了有效信息。试验结果表明,P-Chord在保持Chord其他性能的前提下,减少了平均查找跳数,提高了查找效率。     

Enhancing Computational Grids with Peer-to-Peer Technology for Large Scale Service Discovery

Within computational Grids, some services (typically software components, e.g., linear algebra libraries) are made available by some servers to some clients. In spite of the growing popularity of such Grids, the service discovery, although efficient in many cases, does not reach several requirements. Among them, the flexibility of the discovery and its efficiency on wide-area dynamic platforms are two major issues. Therefore, it becomes crucial to propose new tools coping with such platforms. Emerging peer-to-peer technologies provide algorithms allowing the distribution and the retrieval of data items while addressing the dynamicity of the underlying network. Whereas merging peer-to-peer technology and Grid infrastructures has been widely suggested, very few implementations are available. The contribution of this paper is twofold. First, we present the design, the implementation and the experimentation of the first architecture, to our knowledge, extending traditional Network-Enabled Servers (NES) systems with an unstructured peer-to-peer network. This extension allows to dynamically connect distributed agents thus providing to clients an entry point to servers geographically distributed. Our implementation is based on the Diet middleware and the JXTA toolbox and experimentation have been conducted on a high speed network. Then, we study the service discovery in a pure peer-to-peer environment. We describe a new trie-based approach for the peer-to-peer service discovery service, supporting range queries while providing fault-tolerance and taking into account the topology of the underlying network. We validate this approach both by analysis and simulation. This work has been supported in part by the ANR project LEGO (ANR-05-CIGC-11).     

Data Management in the APPA System

Combining Grid and P2P technologies can be exploited to provide high-level data sharing in large-scale distributed environments. However, this combination must deal with two hard problems: the scale of the network and the dynamic behavior of the nodes. In this paper, we present our solution in APPA (Atlas Peer-to-Peer Architecture), a data management system with high-level services for building large-scale distributed applications. We focus on data availability and data discovery which are two main requirements for implementing large-scale Grids. We have validated APPA’s services through a combination of experimentation over Grid5000, which is a very large Grid experimental platform, and simulation using SimJava. The results show very good performance in terms of communication cost and response time. Work partially funded by ARA “Massive Data” of the French ministry of research and the European Strep Grid4All project.