Network-aware P2P file sharing over the wireless mobile networks

With the coming wireless mobile networks era and the popular use of P2P applications, how to improve the resource retrieval and discovery for P2P file sharing applications in wireless mobile networks becomes a critical issue. In this paper, we propose a novel network-aware P2P file architecture and related control schemes that can provide continuous resource retrieval and discovery for mobile users over the wireless network environment. The proposed architecture divides a P2P file sharing network into multiple network-aware clusters, in which peers are assigned to a network-aware cluster using a network prefix division. Accordingly, there are two designs for supporting mobile peers to retrieve files in wireless mobile networks. First, a novel file discovery control scheme named mobility-aware file discovery control (MAFDC) scheme is devised to obtain fresh status of shared peers and find the new resource providing peers in wireless mobile networks. Second, a resource provider selection algorithm is devised to enable a mobile peer to select new resource providing peers for continuous file retrieval     

一种新型P2P应用层并行路径选择机制

在网格业务网络或者点对点（P2P）网络中使用并行路径来实现文件传输业务时,为了仅依靠P2P层的技术在多条可行的并行路径间选择较优并行路径,切实提高业务的稳定性,可靠性和吞吐率,提出了＂弱相关路径＂的概念,采用被动测量方法,设计了P2P层并行路径间相关性的测量算法和测量机制;进而,设计了基于测量结果的路径选择机制。使用网络模拟器NS-2对此算法和机制进行了仿真实验,实验结果证明此算法和机制能够增强并行路径文件传输的平均性能。     

无线Ad-Hoc网络中P2P文件搜索机制的研究

对低移动性、频繁搜索文件的无线Ad-Hoc网络,提出一种新型P2P文件共享系统,介绍一种将文件查找和路由功能统一起来形成跨层的方案。所有共享文件采用全分布哈希表,在无线网络拓扑结构建立的同时存储和保留位置信息以及路由信息．通过节点间的树形逻辑结构解决共享文件的定位查询和下载问题。     

P2P文件共享系统中对等点发现机制的实现

由于P2P网络的动态性，如何有效和准确地进行对等点定位成为P2P网络中的关键技术。本文在分析现在P2P网络中几种常见的对等点发现机制的优点与不足的基础上，提出了利用IP多播技术和JXTA平台实现的对等点发现机制，并讨论了其在P2P文件共享系统中的实现方法。     

P2P文件共享系统中基于用户行为的搭便车抑制机制

In order to inhibit Free Riding in Peer-to-Peer (P2P) file-sharing systems, the Free Riding In-hibition Mechanism Based on User Behavior (IM-BUB) is proposed. IMBUB considers the regularity of user behavior and models user behavior by ana-lyzing many definitions and formulas. In IMBUB, Bandwidth Allocated Ratio, Incentive Mechanism Based on User Online Time, Double Reward Mech-anism, Incentive Mechanism of Sharing for Permis-sion and Inhibition Mechanism of White-washing Behavior are put forward to inhibit Free Riding and encourage user sharing. A P2P file system BITShare is designed and realized under the conditions of a campus network environment. The test results show that BITShare's Query Hit Ratio has a significant increase from 22% to 99% , and the sharing process in BITShare is very optimistic. Most users opt to use online time to exchange service quality instead of white-washing behavior, and the real white-ish-ing ratio in BITShare is lower than 1% . We confirm that IMBUB can effectively inhibit Free Riding be-havior in P2P file-sharing systems.     

基于公钥认证的P2P多点数据传输系统

近年来,多点数据传输成为一个热门话题,广泛应用于各种P2P网络中。随着网络资源的共享越来越被强化,由于对等网络缺乏集中化的管理,安全性难以保证,多点数据传输系统的大规模商业应用所面临的安全问题越来越突出。针对P2P网络的安全问题,设计了一种公钥认证模式来识别用户身份,并实现了一个多点数据传输系统,该系统包括文件分块下载、即时聊天及音频／视频服务等常见应用。     

P2P流媒体技术原理及应用

基于P2P的流媒体技术是一项非常有前途的技术,该技术有两方面的优点:不需要互联网路由器和网络基础设施的支持,因此性价比高且易于部署;流媒体用户不只是下载媒体流,而且还把媒体流上载给其他用户,因此,这种方法可以扩大用户组的规模,且由更多的需求带来更多的资源。由于P2P流媒体系统中节点存在不稳定性,因此P2P流媒体系统需要在文件定位技术、节点选择技术、容错以及安全机制方面有所突破。此外在如何管理节点并建立发布树、如何应付不可预知的节点失效、如何适应网络状态变化方面也面临着一些挑战。     

Exploiting scheduling and free‐riding for offline downloading in BitTorrent networks

Recently, the peer‐to‐peer (P2P) architecture has become a popular scheme for Internet users to rapidly exchange files. As reported in previous studies, P2P traffic accounts for a significant portion of overall Internet traffic. Many computing resources, for example, network bandwidth and disk space, may be consumed by P2P clients. Accordingly, in this paper, we devise a novel scheme that integrates advantageous features of both the conventional client–server and the P2P architectures to create an offline downloading service. Specifically, the proposed service acts as an agent that downloads required files from the BitTorrent network without consuming local computing resources. In other words, users can stay offline during the download process. Because the proposed scheme aims to provide service to numerous users at the same time, a proper scheduling technique is adopted to achieve better download performance. Moreover, a free‐riding mechanism is seamlessly incorporated with the proposed priority queuing to facilitate more effective bandwidth utilization. Empirical studies show that our scheme is promising in practical applications. Copyright © 2012 John Wiley & Sons, Ltd.     

P2P缓存系统中总开销最小的协作缓存策略

为降低P2P缓存系统中的全局开销,提出一种基于总开销最小的协作缓存策略。该策略综合考虑P2P缓存系统中的传输开销和存储开销,使用跨ISP域间链路开销、流行度、文件大小、存储开销来衡量文件的缓存增益。需要替换时,首先替换掉缓存增益最小的内容。实验结果表明,所提策略能够有效降低系统的总开销。     

Resource-Cardinality Based Scheme to Reduce Resource Lookup Cost in Structured P2P Networks

A P2P (peer-to-peer) network is a distributed system dependent on the IP-based networks, where independent nodes join and leave the network at their drive. The files (resource) are shared in distributed manner and each participating node ought to share its resources. Some files in P2P networks are accessed frequently by many users and such files are called popular files. Replication of popular files at different nodes in structured P2P networks provides significant reduction in resource lookup cost. Most of the schemes for resource access in the structured P2P networks are governed by DHT (Distributed Hash Table) or DHT-based protocols like Chord. Chord protocol is well accepted protocol among structured P2P networks due to its simple notion and robust characteristics. But Chord or other resource access protocols in structured P2P networks do not consider the cardinality of replicated files to enhance the lookup performance of replicated files. In this paper, we have exploited the cardinality of the replicated files and proposed a resource cardinality-based scheme to enhance the resource lookup performance in the structured P2P networks. We have also proposed the notion of trustworthiness factor to judge the reliability of a donor node. The analytical modelling and simulation analysis indicate that the proposed scheme performs better than the existing Chord and PCache protocols.

     

P2P network traffic control mechanism based on global evaluation values

Peer-to-peer (P2P) computing technology has been widely used on the Internet to exchange data. However, it occupies much network bandwidth, and thus greatly influences traditional business on the Interact. Besides, problems about free-riders and 'tragedy of the commons' in the P2P environment estrange from it P2P users who constantly contribute to the network with quality resources. This article proposes a new P2P network traffic control mechanism based on global evaluation values. It aims to help individual users to avoid peak traffic time as much as possible, ease network congestion and protect traditional business on the Interact, as well as differentiating priority grades of peers according to their contributions and stimulating them to share their valuable resources actively. This article first analyzes the current state of network traffic, and then elaborates on P2P network traffic control policies and proposes the peer's priority level differentiation mechanism based on global evaluation values. Finally,after the testing results and analysis of the proposed P2P network traffic control mechanism are discussed, conclusions are drawn.     

Authentication with P2P Agents

The problem of network security is now heavily focused on user and agent authentication. In particular, higher levels of automated management and autonomous behaviour are economically necessary within security services. This work focuses on a peer-to-peer (P2P) network architecture in support of an authentication service application. The paper considers whether the key properties of P2P systems, such as scalability, robustness and resilience, may be of significant value in the context of designing a secure agent-based user authentication service. The task of authenticating legitimate network users across distributed systems and services remains a challenging process. The proposed solution is to use a distributed agent-based application to address the process of client authentication and the maintenance of user credentials. Using an agent-to-agent platform, an autonomous and scalable defence mechanism has been constructed. The agent architecture provides a number of security services with the goal of automating the process of user authentication and trust management. In particular, the agents handle all password, encryption keys and certificate management. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cross-layer design of P2P file sharing over mobile ad hoc networks

Peer-to-peer file sharing over mobile ad hoc networks (MANET) has become a popular application due to the rapid growing number of mobile devices. However, the fact that mobile nodes in a MANET dynamically alter their locations and join/leave the P2P system has posted many challenges in designing a robust and scalable P2P system. Although, in the literature, flooding-based P2P approach has been shown to be robust in a highly dynamic network, it leads to poor efficiency in terms of bandwidth usage and scalability. A new design is required in which cross-layer designs and cognitive approaches could be applied such that it could interact with the requests of users and respond to dynamic change of network topology. In this paper, we propose an efficient and scalable P2P file sharing system over MANET based on Swarm Intelligence, referred to as P2PSI. By applying the cognitive behaviour of the real ant colonies, P2PSI owns the capability of adaptive learning of routing path and is able to cope with mobility problem without flooding. Moreover, P2PSI also adopts cross-layer design to reduce the redundant message overhead and query latency. Performance of P2PSI is evaluated and compared to two existing cross-layer design service discovery protocols through simulations. Our simulation results show that P2PSI achieves better performance in terms of control overhead and request success ratio.     

Efficient data dissemination for Wi-Fi peer-to-peer networks by unicasting among Wi-Fi P2P groups

Recently, the Wi-Fi peer-to-peer (Wi-Fi P2P) technology is discussed to be able to support communications in infrastructure-less network scenarios. In many of such application scenarios, disseminating data (or information) to all network devices is an important issue. According to the Wi-Fi P2P specification, a device can communicate with other devices after joining a Wi-Fi P2P group. A Wi-Fi P2P group is a star network (rooted at a group owner). The group owner can disseminate data to all network devices by broadcasting. However, the Wi-Fi P2P broadcasting mechanism cannot guarantee successful delivery of packets. In order to disseminate data reliably, a possible solution is to disseminate packets to network devices by unicasting. But, by this manner, the group owner will run out of its energy quickly and the time needed to disseminate data to network devices will be lengthened. To consider the above factors, in this paper, we formally define a Wi-Fi P2P data dissemination (WPDD) problem, and prove that this problem is NP-complete. Instead of using one Wi-Fi P2P group to connect all network devices, we propose to divide devices into multiple groups. We then propose a tree-based dissemination scheme and a ring-based data dissemination scheme to achieve data dissemination among groups. The proposed schemes can be compatible with the Wi-Fi P2P specification. We evaluate the performance and effectiveness of the proposed schemes by simulation programs and prototyping implementations.     

SSDHT：基于社交网络的DHT安全增强机制

P2P系统在文件共享等领域中得到了广泛的应用,但DHT（distributed hash table）网络无中心、无认证、缺乏节点身份验证机制,使得现有的基于DHT的P2P系统易受到Sybil攻击等外部攻击。提出一种基于社交网络的DHT安全增强机制,将社交网络中节点的信任关系引入DHT网络中提高对Sybil节点的识别能力。以KAD（Kademlia）算法为例进行了实验验证,基于Facebook和Twitter数据集的实验结果表明本文提出的安全机制适用于大规模动态的网络,能够有效防御Sybil攻击。     

P2P发展现状与运营方案

P2P技术和应用发展迅速,对电信业务和运营造成了巨大冲击。运营商需精细化管道运营,发展特色P2P业务,遵循互联网业务的规律,结合在网络、资源、用户等方面的优势设计可管理可运营的P2P解决方案,使用户获得更好的P2P业务体验。中兴通讯可运营可管理的P2P解决方案,可根据运营商的要求进行鉴权和计费,利用现网得到广泛使用的宽带业务管理平台进行开发,系统稳定可靠。     

A new statistical approach to estimate global file populations from local observations in the eDonkey P2P file sharing system

In this paper, we propose a new statistical approach, also known in biology under the name capture–recapture methods in order to estimate global population statistics from local observations. Evaluating population sizes in P2P systems has received much attention lately as these may be useful to set system parameters, to derive other system statistics, or to predict system performance. As these systems are very large, encompassing several millions of users and since they are highly distributed estimating population sizes is a challenging task. More precisely, we are interested in estimating the number of file replicas in the system, i.e., the size of the population of users possessing given files. To this end, we propose a capture–recapture method which is both computationally efficient and accurate. The method proposed allows deriving global population statistics from local and time-limited observations. We apply the method on a measurement data set of several days on a residential network. We compare the results obtained from direct counting procedures with those derived with the proposed methodology.     

An economic mechanism for request routing and resource allocation in hybrid CDN–P2P networks

Hybrid content delivery networks (HCDN) benefit from the complementary advantages of P2P (Peer to Peer) networks and CDNs (Content Delivery Network). In order to extend a traditional CDN and enable it to offer hybrid content delivery service, we have modified a traditional domain name system‐based request routing mechanism. The proposed scheme relies on an oligopolistic mechanism to balance the load on the edge servers and employs a truthful profit‐maximizing auction to maximize the contribution of users in the P2P content delivery. In particular, economics of content delivery in HCDNs is studied, and it is shown that through our request routing mechanism, it is possible to deliver higher quality of service to majority of end‐users, increase the net profit of the HCDN provider and decrease the content distribution cost at the same time. Copyright © 2015 John Wiley & Sons, Ltd.     

网络编码在P2P网络中的应用

网络编码是信息论领域的一个重要突破,它不同于信源编码和信道编码,将网络编码应用到P2P网络中是当前研究热点之一,其中具有分布式特点的随机网络编码可广泛应用于P2P网络。对具有非实时性的P2P文件下载应用,为降低随机网络编码引入的复杂性,可对文件分块进行分代,然后采用代内或代间网络编码技术。对具有实时性的P2P流媒体直播和点播,则需要采用具有优先级意识的网络编码技术,包括分层网络编码,或与推拉技术相结合来实现高效率的P2P流媒体分发。     

基于双层P2P架构的VoD系统

本文提出的视频点播系统基于双层P2P架构实现,由城域网与驻地网媒体内容分发构成2级数据分发服务平台,用户终端点播并接受视频服务的同时,还能为其他用户提供数据服务,双层P2P架构有效地扩展了系统带宽,增强了服务能力,降低了系统成本,并提供QoS保证.