P2P—对等网络的未来

P2P(Peer-to-Peer)引导网络计算模式从集中式向分布式偏移,网络应用的核心从中央服务器向网络边缘的终端设备扩散。P2P是一种基于互联网的新的应用型技术,主要为软件技术。主要介绍了P2P技术的背景起源,关键技术和应用趋势,并重点分析了SUN公司提出的P2P平台:JXTA的体系机构。

Auto Distribution of Tag Table in P2P Control System

In control system, tag table is like a dictionary mapping tagname to address. Therefore, applications on workstation may use tagname to access different data in system. Normally tag table generated by configuration software will transfer to other workstation in system manually after system configuration, which is inconvenient and failible. The development of peer-to-peer （P2P） network technology and the realization of control system based on P2P network make the auto distn＇bution of tag table possible. In this paper based on file sharing technology the presented method realizes the auto distn＇bution of tag table.

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.

MCloudSim:modeling and simulating distributed clouds

Many distributed clouds which try to integrate the advantages of centralized clouds and distributed systems have been studied in recent years.Traditional cloud simulators focus on large scale data centers with virtualized servers,and cannot meet the needs of distributed cloud simulations.This paper introduces a generalized and extensible simulation framework,named MCloudSim,which is used for modeling and simulating distributed clouds.MCloudSim has the following characteristics;(1)the overlay protocol in MCloudSim can be freely replaced without affecting the function of other modules;(2) a Petri net workflow theory based task model is proposed to simulate distributed tasks;(3) a distributed cloud can be easily built by assembling and expanding the basic resource entities provided by MCloudSim.Finally,simulation results of scenarios with a 3-tier central-controlled distributed cloud and a P2 P based cloud prove that MCloudSim has high efficiency and satisfies performance in supporting large scale experiments and different distributed clouds.

Strategies of Collaboration in Multi-Swarm Peer-to-Peer Content Distribution

In modern Peer-to-Peer （P2P） content distribution applications, multiple swarms typically exist, each corresponding to the dissemination of one content among interested peers. A common design in the existing P2P applications is to allow peers in one swarm to help each other, while different swarms are only coupled when sharing the upload bandwidth at the dedicated content servers/publishers. In recent years, a number of proposals have emerged which advocate inter-swarm collaboration and resource sharing, where peers in one swarm may contribute their storage and bandwidth resources to help peers in the swarm of another content. Such inter-swarm collaboration can improve content availability and optimize resource uti- lization in the entire system, at the cost of additional overhead for content preloading and inter-swarm coor- dination. This paper presents a survey of studies on effective inter-swarm collaboration mechanisms in the existing literature. This paper first discusses strategies of collaboration in P2P file sharing applications, and then presents multi-channel collaborative design for P2P live and Video-on-Demand （VoD） streaming. In particular, this paper elaborates our recent design of collaboration strategies among multiple streaming channels in a P2P VoD system, and shows that the server cost can be reduced by up to 25% while high streaming qualities are guaranteed in the entire system, even during extreme scenarios such as unexpected flash crowds. This paper also discusses representative approaches to implement inter-swarm collaborations in various P2P content distribution systems.

PChord:a distributed hash table for P2P network

As a solution for data storage and information sharing for peer-to-peer(P2P)networks,a novel distributed hash table(DHT)structure called PChord is presented in this paper.PChord adopts a bi-directional searching mechanism superior to Chord and enhances the structure of the finger table.Based on Hilbert space filling curve,PChord realizes the mapping mechanism for multikeyword approximate searching.Compared with the Chord and Kademlia protocols,PChord evidently increases speed on resource searching and message spreading via theoretic proof and simulation results,while maintaining satisfactory load balance.

P2P energy trading via public power networks:Practical challenges,emerging solutions,and the way forward

Peer-to-peer(P2P)energy trading is an emerging energy supply paradigm where customers with distributed energy resources(DERs)are allowed to directly trade and share electricity with each other.P2P energy trading can facilitate local power and energy balance,thus being a potential way to manage the rapidly increasing number of DERs in net zero transition.It is of great importance to explore P2P energy trading via public power networks,to which most DERs are connected.Despite the extensive research on P2P energy trading,there has been little large-scale commercial deployment in practice across the world.In this paper,the practical challenges of conducting P2P energy trading via public power networks are identified and presented,based on the analysis of a practical Local Virtual Private Networks(LVPNs)case in North Wales,UK.The ongoing efforts and emerging solutions to tackling the challenges are then summarized and critically reviewed.Finally,the way forward for facilitating P2P energy trading via public power networks is proposed.

Enhancing scalability of peer-to-peer energy markets using adaptive segmentation method

This paper proposes an adaptive segmentation method as a market clearing mechanism for peer-to-peer(P2P)energy trading scheme with large number of market players.In the proposed method,market players participate in the market by announcing their bids.In the first step,players are assigned to different segments based on their features,where the balanced k-means clustering method is implemented to form segments.These segments are formed based on the similarity between players,where the amount of energy for trade and its corresponding price are considered as features of players.In the next step,a distributed method is employed to clear the market in each segment without any need to private information of players.The novelty of this paper relies on developing an adaptive algorithm for dividing large number of market players into multiple segments to enhance scalability of the P2P trading by reducing data exchange and communication overheads.The proposed approach can be used along with any distributed method for market clearing.In this paper,two different structures including community-based market and decentralized bilateral trading market are used to demonstrate the efficacy of the proposed method.Simulation results show the beneficial properties of the proposed segmentation method.

Hybrid Collaborative Management Ring on Mobile Multi-agent for Cloud-P2P

In order to fully utilize all potential available network resources and make the interoperability of systems possible, we propose to integrate cloud computing and peer-to-peer （P2P） computing environments together. We utilize the mobile multi-agent technology to construct an effective hierarchical integration model named Cloud-P2P. As the original management mechanisms for traditional cloud computing and P2P computing systems are no longer applicable to Cloud-P2P, we propose a novel hybrid collaborative management ring based on mobile multi-agent in order to ensure the efficiency and success rate of task implementation in the Cloud- P2P environment. This mechanism needs to divide the system into core ring, cloud inner rings and several peer rings. In each ring, every node is in collaboration with its neighbor nodes with multi-agent, or uses mobile agent moving from node to node with string or parallel methods to monitor the statuses and performances of all nodes, in order to avoid problems of performance bottleneck and single point failure. This paper analyses the node conditions of cloud computing and P2P computing environments in-depth, then elaborates on Cloud-P2P and the hybrid collaborative management ring based on mobile multi-agent （HCMRMMA）. After that, the construction method of the network ring topology for Cloud-P2P is introduced. Finally, experimental results and performance analysis of HCMRMMA are presented.

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 Internet. 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 Internet, 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.

BulkTree: an overlay network architecture for live media streaming

Peer-to-peer (P2P) systems are now very popular. Current P2P systems are broadly of two kinds, structured and unstructured. The tree structured P2P systems used technologies such as distributed hash tables (DHT) and hierarchical clustering can search the required target quickly, however, in a tree, the internal node has a higher load and its leave or crash often causes a large population of its offspring's problems, so that in the highly dynamic Internet environment the tree structure may still suffer frequent breaks. On the other hand, most widely used unstructured P2P networks rely on central directory servers or massive message flooding, clearly not scalable. So, we consider both of the above systems' advantages and disadvantages and realize that in the P2P systems one node may fail easily, but that when a number of nodes organized as a set, which we call "super node", the set is robust. Super nodes can be created and updated aware of topology-aware, and used with simple protocol such as flooding or "servers" to exchange information. Furthermore the entire robust super node can be organized into exquisite tree structure. By using this overlay network architecture, P2P systems are robust, efficient, scalable and secure. The simulation results demonstrated that our architecture greatly reduces the alteration time of the structure while decreasing the average delay time, compared to the common tree structure.

Control DHT maintenance costs with session heterogeneity

The maintaining overheads of Distributed Hash Table (DHT) topology have recently received considerable attention. This paper presents a novel SHT (Session Heterogeneity Topology) model, in which DHT is reconstructed with session hetero- geneity. SHT clusters nodes by means of session heterogeneity among nodes and selects the stable nodes as the participants of DHT. With an evolving process, this model gradually makes DHT stable and reliable. Therefore the high maintaining overheads for DHT are effectively controlled. Simulation with real traces of session distribution showed that the maintaining overheads are reduced dramatically and that the data availability is greatly improved.

TEES:topology-aware execution environment service for fast and agile application deployment in HPC

High-performance computing(HPC)systems are about to reach a new height:exascale.Application deployment is becoming an increasingly prominent problem.Container technology solves the problems of encapsulation and migration of applications and their execution environment.However,the container image is too large,and deploying the image to a large number of compute nodes is time-consuming.Although the peer-to-peer(P2P)approach brings higher transmission efficiency,it introduces larger network load.All of these issues lead to high startup latency of the application.To solve these problems,we propose the topology-aware execution environment service(TEES)for fast and agile application deployment on HPC systems.TEES creates a more lightweight execution environment for users,and uses a more efficient topology-aware P2P approach to reduce deployment time.Combined with a split-step transport and launch-in-advance mechanism,TEES reduces application startup latency.In the Tianhe HPC system,TEES realizes the deployment and startup of a typical application on 17560 compute nodes within 3 s.Compared to container-based application deployment,the speed is increased by 12-fold,and the network load is reduced by 85%.