【作者】 于婧；

【导师】 汪斌强；

【作者基本信息】 解放军信息工程大学 ， 通信与信息系统， 2007， 博士

【摘要】 为提高边缘网对流媒体业务的的承载服务能力,满足流媒体业务可控制、可管理和可运营的综合要求,国家863计划高性能宽带信息网(3Tnet)启动了重大子项课题——“大规模接入汇聚路由器(ACR)系统性能和关键技术研究”。ACR对端口的可控制、可管理的特性以及带宽预留的功能,使得ACR可以实现对用户流量的监控、管理以及计费。作为“十一五”国家高科技发展支撑计划“中国互动新媒体网络与新业务科技工程”中的重要设备,ACR必须能够支持当前互联网应用最广泛的对等网络(P2P)技术,目标就是对P2P流量进行有效管理与监控,解决P2P的带宽高占用率以及计费困难等问题。而此项工作的前提就是要深入研究当前P2P技术及其应用的关键技术及思想。故针对ACR的研发需求,本文以结构化P2P网络路由模型为研究课题,依托ACR项目开展研究工作。本文结合当前互联网以及P2P网络的特性,提出一种基于主题和物理位置相近原则新型结构化P2P网络路由模型,并研究影响结构化P2P网络路由性能的拓扑一致性问题、hotspot]问题以及异构节点的负载均衡问题在新模型下的解决方案,该方案可以推广应用到其它结构化P2P网络。本文主要包括如下几个方面的工作：1、分析了当前P2P网络路由模型的两大分支,即非结构化P2P网络路由模型以及结构化P2P网络路由模型。由于结构化P2P网络路由模型定位算法效率高,可扩展性、可靠性和可维护性好等特点,成为未来P2P网络发展的方向。通过对当前流行的结构化P2P网络几大拓扑构成的分析,总结出结构化P2P网络路由模型面临拓扑一致性、hotspot以及负载均衡等方面的问题,这些问题严重影响了结构化P2P网络的路由性能。通过研究还发现,当前结构化P2P网络构建过程中存在由于没有充分考虑当前互联网的特征而导致无法优化实际运作过程中的路由性能的问题。2、基于Internet网络架构以及节点兴趣区域化分布的特性构建基于主题和物理位置相近原则的新型结构化P2P网络路由模型(TPPH)。将兴趣相近物理距离也相近的节点组织在一起,提高节点近距离定位资源的成功率,同时降低节点定位资源的延迟。TPPH结构将相同主题的节点组织在一起构成主题区域,并在同一个主题区域内部将物理位置相近的节点构成组群。这种覆盖网络构建方式符合拓扑一致性原则,基于DHT机制组织构建的系统、主题、组群三级结构能够有效提高网络的查询性能。创新性的提出了标识符分段表示的方法,该方法可以简单高效的对系统内节点按照所包含资源情况归入对应的主题,并且可以将发布的资源也按照其归属主题存储在对应主题区域内。这种基于主题的标识符分段表示的方法是结构化P2P网络模型TPPH构建主题区域的基础。通过主题区域的构建,加速了系统内资源的查询过程,提高了系统的性能。3、基于拓扑一致性问题的研究,根据覆盖网络层路由引发实际物理网络路由产生物理链路重复使用的问题,以实际网络路出为基本出发点,提出检测并降低重复链路使用的拓扑一致性解决方案(DDL),解决TPPH结构拓扑一致性问题。通过检测三点间路由经历的实际物理链路的重复利用情况,在满足一定条件下,向源节点发送重定向报文,建立源和目的节点之间的直接连接,降低路由过程经历的实际物理链路数目,减少骨干网络流量,节约系统带宽,提高路由性能。对重复链路的探测并通过修改覆盖网络层路由的方法可以做到一定程度上的拓扑匹配。在TPPH结构中利用DDL机制,获取临近节点信息,并将邻近节点在覆盖网络层面组织在一起,实现TPPH结构中主题内组群划分以及建立主题间超链接。4、基于物理位置相近的节点感兴趣文件内容相似性也偏大的性质,针对query hotspot问题,基于TPPH结构,以组群为单位,提出了分布式资源发布及搜索机制。考虑到节点对资源的索取呈现地域趋势,将组群内节点查询过的资源在本组群范围内进行资源发布,在组群内其它节点发起对同一资源的查询时可以在本组群内得到响应,从而降低组群内其它节点对该资源查询的响应时间。基于DHT的组群构成方式使得节点可以在本组群内进行资源的高效查找,提高了系统的查询性能。同时该机制对资源的存储进行了分散,降低了系统范围内资源放置点唯一性导致的hotspot问题的发生。5、针对TPPH结构中节点的异构性问题,提出了考虑节点异构性的结构化P2P网络负载均衡方案。通过资源分片降低大资源对单一节点的占用,解决单点失效问题。将资源分片通过DHT机制放置在根据系统内定义的HASH函数序列顺序计算得到的对应的节点上,可以有效的提高资源分片查找的效率；提出了异构网络负载均衡的衡量指标——负载平滑度,并在资源分片及放置策略基础上,以资源的节点标识符向量为范围,提出了基于负载平滑度的负载转移方案,带动整个系统逐步达到负载均衡状态。更多还原

【Abstract】 To enhance the carrying capacity of edge network and to meet the controllable, manageable and operational requirements of streaming media traffic, "High Performance Broadband Information Networks" (3Tnet) of the National High-Tech Research and Development Program of China (863 Program) launches the project of "System Performance and Key Technology Researches on the Access and Convergence Router (ACR)". ACR can control the ports and reserve the bandwidth for each port, which makes it possible to monitor the user traffic. As the core equipment of "China Interactive New Media Network and New Business Projects" which belongs to "11th Five-Year Plan" National High-Tech Development Program, ACR must be able to support P2P technology which is used most extensively on the internet. It aims at effectively managing and monitoring the P2P traffic and solving the P2P high bandwidth occupancy and billing problems. And the premise of this work is to study in depth the current P2P technology and its applications. So against the development needs of ACR, this paper studied on structured P2P routing network based on ACR project.Considering the features of internet and P2P network, this paper proposed a structured P2P network routing model based on topic and physical proximity principle. It also studied the solutions of topology-aware, hotspot and load balancing which affect the routing performance of structured P2P network in the new model. This program can be applied to other structured P2P network. This paper includes the following aspects:1、To analyze the two major branches of P2P network routing model, that are unstructured and structured P2P network routing model. As structured P2P network routing model is with efficiency, scalability, reliability and maintainability features, it is becoming the future direction of the development of P2P networks. Based on the analysis of the popular structured P2P network topologies, it is concluded that structured P2P network routing topology model faces topology-aware, hotspot and load balancing problems, which affect the routing performance of structured P2P network deeply. There also exists a problem that the absence of full consideration of internet characteristics during the construction of structured P2P networks leads to incapable of optimizing routing performance in the process of routing.2、A new structured P2P network routing model based on topic and physical proximity principle (TPPH) was constructed considering the internet framework and regional distribution of nodes’ interests. To organize nodes with similar interests and short physical distances together to enhance the success rate of searching within short distance and deduce the delay. TPPH organized nodes with same topic together into a topic area and made physically adjacent nodes within a topic area form into a cluster. The construction of overlay network is consistent with the topology-aware principle. Three levels of overlay network, that is system, topic and cluster, which are organized based on DHT, can improve network performance effectively. An innovative sub-identifier proposal was presented. It can classify the nodes according to its resources simply, and also store the resources to the corresponding topic area. The sub-identifier proposal is the basis of topic area construction of TPPH. Construction of the topic area accelerates the process of searching and improves routing performance.3、Based on researches on topology-aware, considering the duplicate physical links triggered by overlay routing, detect and decrease links overlapped (DDL) solution was proposed. It aimed at resolving topology-aware problem of TPPH. By detecting the overlapped physical links during routing among three nodes, redirect message was sent to the source when needed, thus established a direct link between the source and the destination. DDL can decrease the actual physical links traversed and reduce backbone network traffic, thus save system bandwidth and improve routing performance. The detection of duplicate links and modification of overlay routing can make overlay network and physical network topology-aware. TPPH connected adjacent nodes into cluster or with hyperlinks from the detection information.4、Based on the feature that adjacent nodes have similar interests, in view of query hotspot issues, distributed resource publishing and searching mechanism was proposed on the basis of TPPH structure. Considering the regional distribution of nodes’interests, resources which had been searched by a node in cluster were republished within the cluster, therefore when the other node in this cluster searched for the same resource, it will be answered within the cluster, thus the response time is decreased. The cluster was constructed according to DHT principle which makes it possible for nodes to search efficiently within the cluster. At the same time, this mechanism decentralized the storage of resources and reduced the possibility of hotspot issues deduced by the single resource storage point in system-wide area.5、Against the problem of heterogeneous nodes in TPPH structure, a load balancing mechanism considering the heterogeneous nodes for structured P2P network was proposed. Resource fragmenting can reduce the occupation of large resource to single node, thus resolve the single failure problem. Resource fragments were placed on the corresponding nodes according to DHT principle which were calculated from a sequence of HASH functions defined in system. A load balancing measure indicator of heterogeneous network—load smoothness was brought forward. Based on resource fragment and placement strategy, within the scope of node identifier vector, we proposed a load transfer program to lead the entire system to load balancing state step by step.更多还原