TYPHOON: mobile distributed hash tables

TYPHOON is a capability-aware peer-to-peer (P2P) system. It exploits the heterogeneity of nodes in the system based on the concept of virtual homes. Nodes participating in the system are classified as good and inactive. TYPHOON uses resources provided by good peers. It is thus more reliable and agile than a naive structured P2P system. When a good peer is overloaded, it picks a suitable inactive node and migrates some loads (i.e., virtual homes) to that node. However, migration of virtual homes may cause instability in the system. TYPHOON thus incorporates a mechanism for tracking virtual homes. A migrated home can receive states of relevant homes using an adaptive, logical tree structure that can also react to system heterogeneity, node loading and network locality. A migrated home can also proactively discover the state of an interested home to ensure the correctness of lookup. We evaluate TYPHOON using theoretical and simulation analysis. We also benchmark TYPHOON using a prototype system on 34 desktop PCs. The results all confirm the effectiveness of TYPHOON.     

An adaptive super-peer selection algorithm considering peers capacity utilizing asynchronous dynamic cellular learning automata

Super-peer networks refer to a class of peer-to-peer networks in which some peers called super-peers are in charge of managing the network. A group of super-peer selection algorithms use the capacity of the peers for the purpose of super-peer selection where the capacity of a peer is defined as a general concept that can be calculated by some properties, such as bandwidth and computational capabilities of that peer. One of the drawbacks of these algorithms is that they do not take into consideration the dynamic nature of peer-to-peer networks in the process of selecting super-peers. In this paper, an adaptive super-peer selection algorithm considering peers capacity based on an asynchronous dynamic cellular learning automaton has been proposed. The proposed cellular learning automaton uses the model of fungal growth as it happens in nature to adjust the attributes of the cells of the cellular learning automaton in order to take into consideration the dynamicity that exists in peer-to-peer networks in the process of super-peers selection. Several computer simulations have been conducted to compare the performance of the proposed super-peer selection algorithm with the performance of existing algorithms with respect to the number of super-peers, and capacity utilization. Simulation results have shown the superiority of the proposed super-peer selection algorithm over the existing algorithms.     

EMMP: a highly efficient membership management protocol

Gossip (or epidemic) algorithms have recently become popular solutions to multicast message dissemination in peer-to-peer systems. Nevertheless, it is not straightforward to apply gossip to on-demand streaming because it often fails to achieve a timely delivery. To solve this problem and taking into account the characteristic of peers randomly joining and leaving in peer-to-peer systems, an Efficient Membership Management Protocol (EMMP) has been presented. Every node only needs to keep contact with O (log(N)) nodes, and EMMP can support the reliable dissemination of messages. Considering the “distance” between peers, it causes the major data to be transmitted in a local area and reduces the backbone’s traffic, and speeds up the dissemination of messages between peers. This paper has adopted the “goodfriend” mechanism to reduce the influence on the system when a peer fails or leaves. Simulation results show that EMMP is highly efficient, and both the redundancy and the delay of the system are well solved.     

Reputation management algorithms for DHT-based peer-to-peer environment

This paper addresses the problem of integration of reputation management mechanisms into data look-up and routing processes to cope with some specific security problems in peer-to-peer (P2P) networks based on Distributed Hash Tables (DHT). The goal is to find a mode for “good” peers to cooperate in order to withstand malicious activity of single malevolent peers and their collusions as well.We start from consideration of individual instruments for reputation evaluation that every single peer should be provided with to autonomously define the level of its own trust towards others. We also propose a possible scenario of integration of some existing reputation management techniques and routing mechanisms in a P2P network based on the popular Kademlia algorithm. Then, we present an interaction algorithm that allows peers to obtain the global trust value for each single node through exchanging opinions in the form of local trust values independently calculated by every peer with other members of the community. Such collaboration between peers is indispensable to cope with malicious activity of inconsistent nature specific to DHT-based environment. To render the algorithm resilient to the presence of malicious participants we propose to apply solutions for Byzantine Agreement to exchange opinions among peers. We also provide mathematical evaluations concerning the complexity and computational costs of the proposed algorithm that evidence apparent improvements over the previous one.     

基于节点服务能力的自适应P2P模型

P2P网络的节点在处理能力、存储能力、网络带宽、兴趣域等特性上存在着明显的异构性,在早期的研究中,这种异构性往往被忽略或者仅仅简单、单一地被考虑。综合利用节点的这些异构性,提出基于节点服务能力的自适应P2P模型。模型中,节点通过服务能力自主选择邻居进行聚类,根据网络的需求和动态变化自适应地调整聚类的规模和节点间的连接。仿真实验结果表明,该模型减少了网络拓扑失配和freerider现象,有效地提高了网络的搜索效率。     

面向半分布式P2P系统的可靠节点交换机制

P2P系统中广泛使用的来源交换(PEX)技术为系统用户提供了丰富的节点资源,加快了节点交换速度,同时也带来了不可避免的安全隐患,恶意节点可以通过来源交换对正常节点的邻居列表进行污染。首先分析了现有来源交换技术存在的安全隐患,讨论了导致这些安全隐患的核心因素;其次,以来源交换的安全性分析为基础,提出了一种面向半分布式P2P系统的安全节点交换机制。该机制借鉴基于信任评估的激励技术,通过给出超级节点的信任评估方案,引入节点来源信任的概念,以节点的来源交换信任值为支撑,控制节点间的来源交换。最后,对提出机制进行了实验性能分析。实验结果表明,由于网络异构性所存在的信任值错误计算问题,所提出的交换机制虽然会导致约2.5%比例正常的节点交换失效,但可大幅度降低正常节点参与恶意节点传播和污染的情况,从而在总体上提升了P2P系统的可靠性。     

一个非结构化P2P网络中基于信誉的激励机制

在P2P网络中,freerider节点和恶意节点的不合作行为严重影响了P2P服务的可用性。为此,本文提出了一个应用于非结构化P2P环境下基于信誉的激励机制。该机制通过有限的信任信息的共享,实现信任评估和推荐信任度评估;并以此为基础,通过有效的拓扑构造和服务选择策略及服务请求冲突解析策略的选择,实现对合作节点的激励和对freerider和恶意节点的遏制及惩罚。分析及仿真实验表明,本文提出的基于信誉的激励机制是简单有效的。     

P2P网络中基于增量学习的节点聚类

本文研究了p2p网络中基于内容的节点聚类。基于文件名关键词精确匹配的查询没有考虑文本语义及内容相似性。如果能够根据节点发布内容的相似性,建立节点聚类,信息查询在类内进行,必将提高查询效率。本文提出了一种基于增量学习的节点聚类方法,通过兴趣爬虫代理计算节点得分,据此判断一个节点是否可以加入节点簇。实验表明,节点簇的建立可以有效地提高 p2p 网络的查询效率。     

Future indoor network with a sixth sense: Requirements,challenges and enabling technologies

Wireless connectivity will soon enable people to consume augmented and virtual reality content anywhere and cloud-connected mobile robots to perform complex tasks collaboratively. This connectivity will come to enterprises, factory floors and digital homes first, powered by indoor networks that offer much higher data rates, greater reliability, and lower latency than today’s networks. In addition to providing traditional communication capabilities, the future indoor network will have a “sixth sense” that enables it to provide sensory information and insights to meet physiological needs such as lighting, heating, health and safety. It will serve as the core infrastructure for smart buildings and help enterprises operate more efficiently by further enabling capabilities such as immersive virtual workplaces, indoor navigation and asset tracking.This paper reviews current technologies, examines the enabling technologies of the future indoor network and presents our latest research results and our vision for implementing them in commercial and residential environments.     

Reducing query overhead through route learning in unstructured peer-to-peer network

In unstructured peer-to-peer networks, such as Gnutella, peers propagate query messages towards the resource holders by flooding them through the network. This is, however, a costly operation since it consumes node and link resources excessively and often unnecessarily. There is no reason, for example, for a peer to receive a query message if the peer has no matching resource or is not on the path to a peer holding a matching resource. In this paper, we present a solution to this problem, which we call Route Learning, aiming to reduce query traffic in unstructured peer-to-peer networks. In Route Learning, peers try to identify the most likely neighbors through which replies can be obtained to submitted queries. In this way, a query is forwarded only to a subset of the neighbors of a peer, or it is dropped if no neighbor, likely to reply, is found. The scheme also has mechanisms to cope with variations in user submitted queries, like changes in the keywords. The scheme can also evaluate the route for a query for which it is not trained. We show through simulation results that when compared to a pure flooding based querying approach, our scheme reduces bandwidth overhead significantly without sacrificing user satisfaction.     

Under storage constraints of epidemic backup node selection using HyMIS architecture for data replication in mobile peer-to-peer networks

The attainment of high reliability and availability is very difficult to be achieved in very complex wireless infrastructureless networks. Reliability concept describes essentially the transmission characteristics of infrastructureless networks, such as packet loss probability, packet duplication, data misinsertion, and corruption of packets. Some other metrics nowadays, aggregate and contribute to the aggravation of end to end reliability. In this work a new scheme for end to end reliable file/resource sharing is studied, among mobile peer-to-peer users. The proposed scheme uses the Hybrid Mobile Infostation System (HyMIS) to maintain and enhance the reliability of file/resource sharing process among wireless devices. Under various storage constraints the epidemic backup node selection is adopted, merging the advantages of epidemic file dissemination through purely mobile Infostations, using the HyMIS architecture. Examination through simulation is performed, taking into account many newly introduced storage metrics, for the performance evaluation of the proposed scheme. These storage metrics are tuned into certain bounded values to enable high packet delivery ratio. Results show that this scheme under certain storage requirements offer a reliable and robust solution for sharing resources of any capacity in dynamic mobile peer-to-peer wireless environments.     

An adaptive secure communication framework for mobile peer-to-peer environments using Bayesian games

Peers in Mobile P2P (MP2P) networks exploit both the structured and unstructured styles to enable communication in a peer-to-peer fashion. Such networks involve the participation of two types of peers: benign peers and malicious peers. Complexities are witnessed in the determination of the identity of the peers because of the user mobility and the unrestricted switching (ON/OFF) of the mobile devices. MP2P networks require a scalable, distributed and light-weighted secure communication scheme. Nevertheless, existing communication approaches lack the capability to satisfy the requirements above. In this paper, we propose an Adaptive Trusted Request and Authorization model (ATRA) over MP2P networks, by exploiting the limited historical interaction information among the peers and a Bayesian game to ensure secure communication. The simulation results reveal that regardless of the peer’s ability to obtain the other such peer’s trust and risk data, the request peers always spontaneously connect the trusted resource peers and the resource peers always preferentially authorize the trusted request peers. Performance comparison of ATRA with state-of-the-art secure communication schemes over MP2P networks shows that ATRA can: (a) improve the success rate of node typing identification, (b) reduce time required for secure connections found, (c) provide efficient resource sharing, and (d) maintain the lower average cost.     

HAMS: Scalable peer-to-peer multimedia streaming model in heterogeneous networks

In a peer-to-peer (P2P) overlay network, a large number and various types of peer processes are interconnected in networks and are cooperating by using multimedia contents like movies and music. Here, multimedia contents are in nature distributed to peers in various ways like downloading and caching to the peers. Multimedia streaming is a key technology to realize multimedia applications in networks. In multimedia streaming applications, multimedia contents are required to be reliable and continuously delivered to processes in a real-time manner. Some contents peer may not send packets of a content at a required rate due to limited computation resource and a communication channel may not support enough Quality of Service (QoS) due to congestions and faults. Thus, P2P overlay networks are in nature heterogeneous. In this paper, we newly discuss a heterogeneous asynchronous multi-source streaming (HAMS) model where multiple contents peers transmit packets of a multimedia content to a requesting leaf peer to increase the throughput, reliability, and scalability in P2P overlay networks. Here, some pair of channels between contents and leaf peers may support different QoS. Peers may be faulty and some pair of contents peers may have different transmission rates. Finally, we show the HAMS model can support higher throughput and shorter transmission time than the other models in the evaluation.     

An Effective P2P Search Scheme to Exploit File Sharing Heterogeneity

Although the original intent of the peer-to-peer (P2P) concept is to treat each participant equally, heterogeneity widely exists in deployed P2P networks. Peers are different from each other in many aspects, such as bandwidth, CPU power, and storage capacity. Some approaches have been proposed to take advantage of the query forwarding heterogeneity such that the high bandwidth of powerful nodes can be fully utilized to maximize the system capacity. In this paper, we suggest using the query answering heterogeneity to directly improve the search efficiency of P2P networks. In our proposed differentiated search (DiffSearch) algorithm, the peers with high query answering capabilities will have higher priority to be queried. Because the query answering capabilities are extremely unbalanced among peers, a high query success rate can be achieved by querying only a small portion of a network. The search traffic is significantly reduced due to the shrunken search space. Our trace analysis and simulation show that the DiffSearch algorithm can save up to 60 percent of search traffic     

Introducing artificial evolution into peer-to-peer networks with the distributed remodeling framework

A peer-to-peer (P2P) network is a complex system whose elements (peer nodes, or simply peers) cooperate to implement scalable distributed services. From a general point of view, the activities of a P2P system are consequences of external inputs coming from the environment, and of the internal feedbacks among nodes. The reaction of a peer to direct or indirect inputs from the environment is dictated by its functional structure, which is usually defined in terms of static rules (protocols) shared among peers. The introduction of artificial evolution mechanisms may improve the efficiency of P2P networks, with respect to resource consumption, while preserving high performance in response to the environmental needs. In this paper, we propose the distributed remodeling framework (DRF), a general approach for the design of efficient environment-driven peer-to-peer networks. As a case study, we consider an ultra-large-scale storage and computing system whose nodes perform lookups for resources provided by other nodes, to cope with task execution requests that cannot be fulfilled locally. Thanks to the DRF, workload modifications trigger reconfigurations at the level of single peers, from which global system adaptation emerges without centralized control.     

改进的非结构化P2P网络搜索算法

如何高效地搜索资源是P2P网络中最为关键的问题.非结构化的对等网络,一般以广播方式作为其搜索的基本策略,引发较大的网络流量.针对以上问题,提出了一种利用节点积累的经验指导节点传播查询的路由搜索算法.在该算法中,通过记录节点关注的主题、主题的信息量大小和满足主题的目标节点,并建立对应关系表.当节点收到查询后,就利用该表来指导节点选择查询,以便更快地找到查询结果.仿真结果表明,该算法有效地减少了查询带来的网络流量,提高了查找的成功率.     

基于随机性和文件块相似性的结点选择策略

为了提高对等网文件共享系统的服务性能,增强文件共享过程的延续性,通过对比分析目前典型的P2P网络应用BitTorrent和基于临近节点聚类的Bit Torrent文件共享系统中的邻居节点选择策略的优点和不足,提出了一个优化的邻居结点选择策略,服务器tracker为结点优先选择与其具有相近文件块数的结点作为其邻居结点的同时,采用基于随机性的策略来提高文件共享过程的延续性.最后,模拟实验结果表明,该策略提高了共享系统的延续性和服务性能,具有很好的文件共享效率,有效地抑制了"搭便车行为".     

Traceable P2P record exchange: a database-oriented approach

In recent years, peer-to-peer (P2P) technologies are used for flexible and scalable information exchange in the Internet, but there exist problems to be solved for reliable information exchange. It is important to trace how data circulates between peers and how data modifications are performed during the circulation before reaching the destination for enhancing the reliability of exchanged information. However, such lineage tracing is not easy in current P2P networks, since data replications and modifications are performed independently by autonomous peers—this creates a lack of reliability among the records exchanged. In this paper, we propose a framework for traceable record exchange in a P2P network. By managing historical information in distributed peers, we make the modification and exchange histories of records traceable. One of the features of our work is that the database technologies are utilized for realizing the framework. Histories are maintained in a relational database in each peer, and tracing queries are written in the datalog query language and executed in a P2P network by cooperating peers. This paper describes the concept of the framework and overviews the approach to query processing.     

Optimizing transmission time of scalable coded images in peer-to-peer networks

In this paper, we study how to optimize image transmission time in peer-to-peer networks by considering the property of bitstreams generated by image coding algorithms. Images can be either scalable coded or nonscalable coded. Since transmission of nonscalable coded images is well understood, we focus on the transmission of scalable coded images in this paper. Because scalable coding embeds lower bit-rate bitstreams into higher bit-rate bitstreams, there exists a many-to-one relationship between supplying and requesting peers. When a requesting peer asks for an image coded in a particular bit rate, multiple peers with the same image but coded in different bit rates can supply to the requesting peer. This enables us to assign the task of image transmission to multiple supplying peers, split the traffic among these peers, and then reduce overall transmission time. Therefore, when we transmit scalable coded images over peer-to-peer networks, it is important to design optimal peer assignment algorithms to minimize the overall transmission time for the requesting peer. In this paper, we first formally define the peer assignment problem and then establish a sufficient condition on the optimality of peer assignment. Based on this condition, we propose an optimal peer assignment algorithm in continuous space (OPA-CS) and then derive a suboptimal peer assignment algorithm in integer space (SOPA-IS). Finally, we carry out extensive experiments to verify the superior performance of the proposed peer assignment algorithms by comparing with two simple heuristic schemes.     

DGTM: a dynamic grouping based trust model for mobile peer-to-peer networks

The special characteristics of the mobile environment, such as limited bandwidth, dynamic topology, heterogeneity of peers, and limited power, pose additional challenges on mobile peer-to-peer (MP2P) networks. Trust management becomes an essential component of MP2P networks to promote peer transactions. However, in an MP2P network, peers frequently join and leave the network, which dynamically changes the network topology. Thus, it is difficult to establish long-term and effective trust relationships among peers. In this paper, we propose a dynamic grouping based trust model (DGTM) to classify peers. A group is formed according to the peers’ interests. Within a group, mobile peers share resources and tend to keep stable trust relationships. We propose three peer roles (super peers, relay peers, and ordinary peers) and two novel trust metrics (intragroup trust and intergroup trust). The two metrics are used to accurately measure the trust between two peers from the same group or from different groups. Simulations illustrate that our proposed DGTM always achieves the highest successful transaction rate and the best communication overhead under different circumstances.