P2P技术在IPTV中的应用

P2P打破了传统C／S模式服务器对网络资源的集中化管理和提供,解放了服务器响应的压力和降低了带宽负载,应用于IPTV系统。然而P2P技术为IPTV业务实现带来灵活和高效率等优点的同时也带来一些问题,比如时延、网络不可控等。本文就P2P技术在IPTV中的应用及相关问题进行了分析。     

Distributed Throughput Maximization in P2P VoD Applications

In peer-to-peer (P2P) video-on-demand (VoD) systems, a scalable source coding is a promising solution to provide heterogeneous peers with different video quality. In this paper, we present a systematic study on the throughput maximization problem in P2P VoD applications. We apply network coding to scalable P2P systems to eliminate the delivery redundancy. Since each peer receives distinct packets, a peer with a higher throughput can reconstruct the video at a higher quality. We maximize the throughput in the existing buffer-forwarding P2P VoD systems using a fully distributed algorithm. We demonstrate in the simulations that the proposed distributed algorithm achieves a higher throughput compared to the proportional allocation scheme or the equal allocation scheme. The existing buffer-forwarding architecture has a limitation in total upload capacity. Therefore we propose a hybrid-forwarding P2P VoD architecture to improve the throughput by combining the buffer-forwarding approach with the storage-forwarding approach. The throughput maximization problem in the hybrid-forwarding architecture is also solved using a fully distributed algorithm. We demonstrate that the proposed hybrid-forwarding architecture greatly improves the throughput compared to the existing buffer-forwarding architecture. In addition, by adjusting the priority weight at each peer, we can implement the differentiated throughput among different users within a video session in the buffer-forwarding architecture, and the differentiated throughput among different video sessions in the hybrid-forwarding architecture.      

基于JXTA的P2P应用程序开发方法

P2P技术是目前计算网络领域的研究热点。JXTA是开发P2P应用程序的流行平台，使用JXTA开发的P2P程序具有很好的开放性和可移植性。本文介绍了基于JXTA的P2P应用程序的开发方法和过程，并给出一个应用实例。     

基于JXTA的P2P应用程序开发方法

P2P技术是目前计算网络领域的研究热点,JXTA是开发P2P应用程序的流行平台,使用JXTA开发的P2P程序具有很好的开放性和可移植性。本文介绍了基于JXTA的P2P应用程序的开发方法和过程,并给出一个应用实例。     

Nonmonotonic Trust Management for P2P Applications

Community decisions about access control in virtual communities are non-monotonic in nature. This means that they cannot be expressed in current, monotonic trust management languages such as the family of Role Based Trust Management languages (RT). To solve this problem we propose RT, which adds a restricted form of negation to the standard RT language, thus admitting a controlled form of non-monotonicity. The semantics of RT is discussed and presented in terms of the well-founded semantics for Logic Programs. Finally we discuss how chain discovery can be accomplished for RT.     

Peer-to-Peer典型应用安全需求分析

在介绍P2P网络及其应用的基础上,对P2P典型应用的安全性进行具体的分析,得出了每种应用的详细安全需求,总结了P2P应用的一般安全需求,并明确了其中的核心安全需求——信任关系。     

浅析P2P技术在校园网络中的应用

随着网络与信息资源的飞速发展,P2P文件共享系统等分布式网络应用已经成为人们获取网络资源信息的重要途径本文围绕P2P技术的结构模式及其特点进行了分析,并举例说明P2P网络应用。     

A Containment-Based Security Model for Cycle-Stealing P2P Applications

ABSTRACT

P2P networks and the computations they enable hold great potential in creating the next generation of large-scale distributed applications. However, the P2P phenomenon has largely left untouched large organizations and businesses that have stringent security requirements and are uncomfortable with the anonymity and lack of centralized control/censorship which are the features of P2P systems. Hence, there is an urgent need to address the security concerns in deploying P2P systems which can leverage the underutilized compute resources in organizations across the world. This article proposes a containment-based security model (CBSM) for cycle-stealing P2P applications, based on the Secure Linux (SE Linux) Operating System, which alleviates existing security concerns, allowing peers to host untrusted or even hostile applications. Our approach is suitable for pure P2P applications and requires no message exchanges or trust computations in ensuring security. Testing via deployment of potentially malicious remote code proves the effectiveness of the proposed system.     

Optimal Prefetching Scheme in P2P VoD Applications With Guided Seeks

Most existing peer-to-peer (P2P) video-on-demand (VoD) systems have been designed and optimized for the sequential playback. In practice, users often want to seek to the positions they are interested in. Such frequent seeks raise greater challenges to the design of the prefetching scheme. In this work, we first propose the concept of guided seeks. With the guidance, users can perform more efficient seeks to the desired positions. The guidance can be obtained from collective seeking statistics of other peers who have watched the same title in the previous and/or concurrent sessions. However, it is very challenging to aggregate the statistics efficiently, timely and in a completely distributed way. We design the hybrid sketches that not only capture the seeking statistics at significantly reduced space and time complexity, but also adapt to the popularity of the video. From the collected seeking statistics, we estimate the segment access probability, based on which we further develop an optimal prefetching scheme and an optimal cache replacement policy to minimize the expected seeking delay at every viewing position. Through extensive simulations, we demonstrate that the proposed prefetching framework significantly reduces the seeking delay compared to the sequential prefetching scheme.     

机器学习在P2P流量检测中的研究

P2P流量逐渐成为了互联网流量的重要组成部分,在对Internet 起巨大推动作用的同时,也带来了因资源过度占用而引起的网络拥塞以及安全隐患等问题,妨碍了正常的网络业务的开展.文中提出了基于机器学习的P2P流量识别方案,并运用FCBF(Fast Correlation-Based Filter)特征选择算法形成了流量特征子集,构建了机器学习P2P流量识别模型并对比了几种常见的机器学习算法在流量识别方面的性能.测试实验结果表明,C4.5算法和贝叶斯网络算法都适合于P2P流量检测,其个别模型达到了90%以上的识别率.     

P2P即时网络通信技术在医院检验科的应用模式初探

P2P网络通信技术作为信息社会时代出现的一种新媒体技术,在社会生活的方方面面都得到了广泛应用。本文旨在通过寻找可能的应用模式,探究P2P即时网络通信技术与检验数据传递融合的办法。     

Network Awareness of P2P Live Streaming Applications: A Measurement Study

Early P2P-TV systems have already attracted millions of users, and many new commercial solutions are entering this market. Little information is however available about how these systems work, due to their closed and proprietary design. In this paper, we present large scale experiments to compare three of the most successful P2P-TV systems, namely PPLive, SopCast and TVAnts. Our goal is to assess what level of "network awareness" has been embedded in the applications. We first define a general framework to quantify which network layer parameters leverage application choices, i.e., what parameters mainly drive the peer selection and data exchange. We then apply the methodology to a large dataset, collected during a number of experiments where we deployed about 40 peers in several European countries. From analysis of the dataset, we observe that TVAnts and PPLive exhibit a mild preference to exchange data among peers in the same autonomous system the peer belongs to, while this clustering effect is less intense in SopCast. However, no preference versus country, subnet or hop count is shown. Therefore, we believe that next-generation P2P live streaming applications definitively need to improve the level of network-awareness, so to better localize the traffic in the network and thus increase their network-friendliness as well.     

Free-Riding on BitTorrent-Like Peer-to-Peer File Sharing Systems: Modeling Analysis and Improvement

BitTorrent has emerged as a very popular peer-to-peer file sharing system, which uses an embedded set of incentive mechanisms to encourage contribution and prevent free-riding. However, the capability BitTorrent has of preventing free-riding needs further study. In this paper, we present a fluid model with two different classes of peers to capture the effect of free-riding on BitTorrent-like systems. With the model, we find that BitTorrent's incentive mechanism is successful in preventing free-riding in a system without seeds, but may not succeed in producing a disincentive for free-riding in a system with a high number of seeds. The reason for this is that BitTorrent does not employ any effective mechanisms for seeds to effectively guard against freeriding. Therefore, we propose a seed bandwidth allocation strategy for the BitTorrent system to reduce the effect of seeds on free-riding. Finally, simulation results are given, which validate what we have found in our analysis and demonstrate the effectiveness of the proposed strategy.     

P2P技术原理与应用软件

P2P的对等结构是互联网本质的回归，以P2P技术为支撑的网络应用目前席卷了整个网络产业。诸如BitTorrent、Thunder、Skype，P2P应用已成为当前网络技术领域的一颗明星。本文介绍了P2P社术基本原理和基于P2P技术的主流软件。     

P2P技术原理与应用软件

P2P的对等结构是互联网本质的回归,以P2P技术为支撑的网络应用目前席卷了整个网络产业。诸如BitTorrent、Thunder、Skype,P2P应用已成为当前网络技术领域的一颗明星。本文介绍了P2P技术基本原理和基于P2P技术的主流软件。     

From P2P to reliable semantic P2P systems

Current research to harness the power of P2P networks involves building reliable Semantic Peer-to-Peer (SP2P) systems. SP2P systems combine two complementary technologies: P2P networking and ontologies. There are several types of SP2P systems with applications to knowledge management systems, databases, the Semantic Web, emergent semantics, web services, and information systems. Correct semantic mapping is fundamental for success of SP2P systems where semantic mapping refers to semantic relationship between concepts from different ontologies. Current research on SP2P systems has emphasized semantics at the cost of dealing with the traditional issues of P2P networks of reliability and scalability. As a result of their lack of resilience to temporary mapping faults, SP2P systems can suffer from disconnection failures. Disconnection failures arise when SP2P systems that use adaptive query routing methods treat temporary mapping faults as permanent mapping faults. This paper identifies the disconnection failure problem due to temporary semantic mapping faults and proposes an algorithm to resolve it. To identify the problem, we will use a simulation model of SP2P systems. The Fault-Tolerant Adaptive Query Routing (FTAQR) algorithm proposed to resolve the problem is an adaptation of the generous tit-for-tat method originally developed in evolutionary game theory. The paper demonstrates that the reliability of an SP2P system increases by using the algorithm.     

StegoP2P:一种基于P2P网络的隐蔽通信方法

随着互联网的发展,隐私保护问题越来越突出,现有的匿名通信系统如Tor,Freenet等能够隐藏用户的身份,但是不能够隐藏通信的事实.以BitTorrent,emule为代表的P2P文件分享软件已经成互联网的主要应用,而且其用户规模庞大,分布在全球各地.在此基础之上提出一种新的隐蔽通信方法——StegoP2P,该方法不依赖于任何单一的系统或者接入点,而是利用P2P协议的隐蔽通道;并设计一个有效的隐蔽握手协议,让P2P网络中互为好友(合谋)但素未谋面的节点隐蔽握手,秘密交换信息,从而绕过网络审查.实验结果和安全性分析表明我们的系统具有较高的性能和健壮性,并能够抵御常见的流量审查.     

IS-P2P:一种基于索引的结构化P2P网络模型

在分析无结构与有结构P2P网络结构的基础上,提出了一种新的基于索引的有结构P2P网络模型IS-P2P（Index-based Structured P2P Networks）.IS-P2P网络采用两层混合结构,上层由比较稳定的索引节点组成有结构索引网络,使用文档路由搜索机制,提供资源的发布和查找功能.下层由普通节点组成分布式网络.IS-P2P模型充分利用P2P网络中节点的性能差异,具有高效的查找性能,且能适应P2P网络高度动态性.进一步计算IS-P2P模型中索引网络路由性能、查询处理速度、索引节点索引数据库大小以及索引节点转发查询消息代价表明,IS-P2P具有良好的性能.     

P2P畅想曲

P2P是一种技术,但更多的是一种思想,有着改变整个互联网基础的潜能的思想。     

Self-managed topologies in P2P networks

The problem of efficient resource location is an important open issue in P2P systems. This paper introduces DANTE, a self-adapting P2P system that changes its peer links to form topologies where resources are located in an efficient manner via random walks. Additionally, this same self-adaptation capacity makes DANTE capable of reacting to events like changes in the system load or attacks on well-connected nodes by adjusting the topology to the new scenario. This adaptive behavior emerges as the global result of the individual work of nodes, without the intervention of any central entity or the need for global knowledge. Simulations show that this adaptation process makes the system scalable, resilient to attacks, and tolerant to a high transitivity of peers. Simulations are also used to compare this solution with other well-known self-adapting P2P system. From these results it can be concluded that the topologies achieved by DANTE offer better performance.