基于Region多层结构P2P计算网络模型

分布式P2P网络Gnutella模型中共享信息查询的路由协议为"洪泛"算法,其协议机制仅在应用层实现,缺乏对Internet底层通信子网路由资源的利用,存在可扩展性、性能与效率不高的问题.以"小世界和幂规律"模型为理论基础,以层和域为基本逻辑管理单位,按用户需求和共享目的组织域,提出了基于Region多层结构P2P网络模型RLP2P(region-layer P2P),实现了其系统原型;实现了一个优化的Multilayer Light-Gossip分级路由策略;量化分析了表征模型数据通道质量指标的压力和伸展率,提出了综合考虑压力和伸展率的思想.模拟分析表明,RLP2P模型可以有效地解决可扩展性、性能与效率不高问题,且网络规模越大,其综合性能的优越性越明显.因此,模型是合理、有效的.     

一个基于P2P高性能计算的高效数据传输协议

针对基于对等网络的高性能计算平台P2HP，设计了一个高效的数据传输协议FDTP.FDTP是一个基于连接的数据管道传输协议，其网络传输通道包括传输控制消息的消息信道和传输任务数据的数据信道．它将数据传输过程分为构建通道、数据传输、关闭通道3步，定义了数据请求方式和数据传输格式，并对传输过程中的数据通道进行管理和容错控制．FDTP通过简化传输控制和减少通信次数来降低通信延迟，进而提高数据传输效率，并最终提高P2HP的运行效率．     

基于P2P的时移电视传输策略

针对新兴的时移电视业务,提出了基于P2P技术的时移电视传输策略．将视频点播中的补丁技术与P2P技术相结合，节省了视频服务器及主干网络的资源，同时对服务规模没有限制．理论分析及仿真结果表明，该策略可以有效地减轻视频服务器的压力．     

分组P2P网络模型分包传输策略分析

Internet的飞速发展使对等网络(P2P)及其相关领域的研究成为热点,但是当前P2P网络的结构并不完善。文中介绍了几种P2P模型,并在综合这几种模型优点的基础上,针对P2P网络的动态特性提出了一种分组P2P模型。P2P的网络应用在正不断发展,P2P中的一个重要核心思想是分包传输,它所采用的分包算法对于我们开发P2P软件具有重要的参考价值.我们在本文中分析它的分包传输算法,并且结合参考Coolstreaming和沸点网络电视系统中的策略,对在P2P网络中进行视频、音频等多媒体流数据的传输的方法和性能进行分析。     

利用多级局部性实现可扩展的无结构P2P 搜索

无结构P2P网络拓扑随着规模的增大会出现一定的统计特性,充分应用该现象提出了一种多级局部覆盖网络(multi-level local overlay,简称ML2O)的无结构P2P覆盖网,对ML2O中节点间的连接进行恰当的数学控制后,就能使产生的拓扑具有从微观到宏观的多个粒度上的局部性.理论分析表明,ML2O的网络直径和节点平均度都是网络规模n的对数,为其上建立可扩展的无结构P2P搜索奠定了基础.给出了应用ML2O多粒度局部特性的索引机制:首先以局部为单位建立信息索引;然后在局部索引的基础上建立更大粒度局部的索引,从而形成一棵索引树;最后提出了一种局部渗透定向搜索算法(local pervasion and directed search,简称LPDS).LPDS用局部渗透收集到的信息建立部分索引树,并在树上找到更接近搜索目标的下一跳.理论分析表明,LPDS搜索算法的平均搜索跳数和通信负载都是O(logn).模拟实验结果表明,ML2O上LPDS的可扩展性接近结构化P2P搜索,其鲁棒性接近无结构P2P搜索.     

基于P2P系统信任机制的DRM模型

P2P技术的成熟同时也给数字内容的版权保护带来更大的挑战.传统C/S模式下的DRM已不能满足P2P环境下的数字版权保护.结合现阶段网络技术中P2P技术的实际应用情况和新一代数字版权管理(DRM)技术,提出了基于P2P系统信任机制的版权管理模型.该模型通过秘密共享思想将许可证密钥分发给P2P网络中的可信任节点,为基于P2P技术的数字内容分发提供了必要的安全保障.通过分析与仿真实验表明,该模型较现有数字版权管理模型在传输的容错性、入侵容忍性与安全性方面都有较大的提高.     

一种媒体直播的P2P自适应网络快速传输模型磁

为解决媒体流在网络直播的低延迟与可扩展性,结合P2P的特点,研究了一种基于P2P的自适应网络快速传输模型。该模型首先对网络节点状态进行分类,通过一种位索引机制实现节点状态的识别,接着在MST 覆盖网络基础上,探讨了一种面向请求节点构建MST的P2P媒体直播系统,并提出了一种自适应网络快速传输控制算法。数学模型分析与模拟结果表明提出的模型能较大程度地缩短端到端传播的延迟时间,且减少跳点数与服务负载,从而进一步提升了媒体播放的流畅性,为采用P2 P技术实现媒体的快速直播提供了很好的参考与借鉴。     

分组P2P网络模型分包传输策略分析

Internet的飞速发展使对等网络（P2P）及其相关领域的研究成为热点,但是当前P2P网络的结构并不完善.文中介绍了几种P2P模型,并在综合这几种模型优点的基础上,针对P2P网络的动态特性提出了一种分组P2P模型.P2P的网络应用在正不断发展,P2P中的一个重要核心思想是分包传输,它所采用的分包算法对于我们开发P2p软件具有重要的参考价值.我们在本文中分析它的分包传输算法,并且结合参考Coolstreaming和沸点网络电视系统中的策略,对在P2P网络中进行视频、音频等多媒体流数据的传输的方法和性能进行分析.     

基于SCTP多路径传输的P2P系统设计与实现

流控制传输协议（SCTP）是一种面向连接、提供可靠数据传输服务的传输层协议,其多宿特性非常适合对传输性能要求较高的各类网络服务。文中在详细介绍SCTP传输协议的基础上,充分利用其多宿特性,结合P2P分布式网络数据分发的高效性优势,设计了基于SCTP的P2P分布式系统的模型和体系架构,并实现了新型的P2P数据传输系统。通过在实际网络环境中搭建系统进行测试,验证了两者结合的可行性。所得结论为在多路径环境下利用SCTP增强系统传输性能提供了参考。     

动态自组织P2P僵尸网络的构建及其防御

僵尸网络作为大规模攻击活动的基础平台,严重威胁网络空间安全,从预测的角度对其开展研究具有重要的现实意义。针对现有研究在终端感知、身份识别和动态对抗中存在的不足,本文概括僵尸网络生命周期,总结P2P结构僵尸网络的脆弱点,建立P2P僵尸网络动态对抗模型,分析节点真实性判断和网络拓扑优化重构的重要性。在此基础上,从攻击者视角提出一种新颖的动态自组织P2P僵尸网络模型DSBot。该模型在架构设计上可扩展至各类目标设备,通过基于可信度矩阵和真实性验证的节点安全性评估机制增强终端对抗性,并提出分阶段感染策略。借鉴无线自组网和多智能体的思路和方法,刻画节点属性多维表示和基于状态标识的动态网络框架,以此为基础设计O(N_i)更新算法、均匀连接算法和节点主动移除算法,并结合相应的初始化和调整机制提出网络自组织重构策略,从而进一步提升网络的健壮性。其中,O(N_i)更新算法确保节点的可信度,均匀连接算法降低网络暴露风险,节点主动移除算法实时移除可疑节点。从平均等待时间、命令可达率、网络连接度和重构稳定时间等方面对DSBot模型进行评估。实验结果表明,DSBot模型在效率和韧性上可满足僵尸网络命令控制机制的基本需求。最后,从终端清除、命令控制服务器打击和命令控制过程等方面讨论了可能的防御策略。本文旨在通过预测新型僵尸网络模型来完善防御解决方案。     

Compact Routing Schemes for Dynamic Ring Networks

We consider the problem of routing in an asynchronous dynamically changing ring of processors using schemes that minimize the storage space for the routing information. In general, applying static techniques to a dynamic network would require significant re-computation. Moreover, the known dynamic techniques applied to the ring lead to inefficient schemes. In this paper we introduce a new technique, Dynamic Interval Routing, and we show tradeoffs between the stretch factor, the adaptation cost, and the size of the update messages used by routing schemes based upon it. We give three algorithms for rings of maximum size N: the first two are deterministic, one with adaptation cost zero but worst case stretch factor \lfloor N/2 \rfloor, the other with worst case adaptation cost O(N) update messages of O(log N) bits and stretch factor 1. The third algorithm is randomized, uses update messages of size O(k log N), has adaptation cost O(k), and expected stretch factor 1+1/k, for any integer k 3. All schemes require O(log N) bits per node for the routing information and all messages headers are of O(log N) bits.     

Solving an algebraic path problem and some related graph problemson a hyper-bus broadcast network

The parallel computation model upon which the proposed algorithms are based is the hyper-bus broadcast network. The hyper-bus broadcast network consists of processors which are connected by global buses only. Based on such an improved architecture, we first design two O(1) time basic operations for finding the maximum and minimum of N numbers each of size O(log N)-bit and computing the matrix multiplication operation of two N×N matrices, respectively. Then, based on these two basic operations, three of the most important instances in the algebraic path problem, the connectivity problem, and several related problems are all solved in O(log N) time. These include the all-pair shortest paths, the minimum-weight spanning tree, the transitive closure, the connected component, the biconnected component, the articulation point, and the bridge problems, either in an undirected or a directed graph, respectively     

Providing service differentiation in pure IP-based networks

The lack of an effective cooperation between the data, control and management plane of QoS routing solutions presented so far, prevents the implementation of service differentiation in the context of pure IP-based networks. Most of paths calculation proposals performed by the control plane are unaware of service characteristics of each flow. Scalable data plane QoS proposals ignore the issue about selecting the best paths to route the traffic. Proposed management plane schemes do not perform the network state maintenance and service level monitoring. Multi-service routing is a flow-based forwarding protocol that implements the service differentiation in pure IP-based networks, using a straight cooperation between data, control and management plane. This cooperation is accomplished by a data plane supporting the DiffServ model and performs route selection based on flows service class, which is exploited by the management plane to carry out the network state maintenance, and performance monitoring by using the RTCP protocol, to provide service metrics to control plane for route calculation. Simulation experiments show better performance results achieved by Multi-service routing compared to those obtained by traditional link state protocol with the DiffServ model and QoS routing in heavy loaded network scenarios of mixed traffic having different service requirements.     

Efficient techniques and tools for intra‐domain traffic engineering

Intra‐domain routing protocols are based on Shortest Path First (SPF) routing, where shortest paths are calculated between each pair of nodes (routers) using pre‐assigned link weights, also referred to as link metric. These link weights can be modified by network administrators in accordance with the routing policies of the network operator. The operator's objective is usually to minimize traffic congestion or minimize total routing costs subject to the traffic demands and the protocol constraints. However, determining a link weight combination that meets a network operator's objectives is a difficult task. In this paper, we study the link weight optimization problem in intra‐domain networks. This problem is proved to be NP‐hard with hard protocol constraints, e.g., a flow is evenly distributed along the shortest paths between its origin and destination nodes. We present two fast heuristic approaches to generate efficient link metrics for intra‐domain routing. Some promising experimental results are reported.     

Conventional and early token release scheduling models for the IEEE 802.5 token ring

We develop analyticalscheduling models for both the original IEEE 802.5 token ring protocol and a recent extension to the original protocol that allows early token release (ETR). A scheduling model is an abstraction that supports reasoning about the timing correctness of a given set of real-time messages scheduled on the network. Scheduling analysis of the original IEEE 802.5 token ring protocol has previously been discussed in Strosnider and Marchok (1989) and Pleinevaux (1992) in the context of improving responsiveness of soft deadline aperiodic messages. In contrast, this paper develops schedulability conditions for arbitrary periodic message sets. The main contributions of this work are: Scheduling models for both the original protocol and ETR protocol; comparison for maximum achievable utilizations for the two protocols; comparison between the original protocol and ETR from a schedulability viewpoint. We also demonstrate the utility of our scheduling models to select network operating parameters such as maximum packet size, and to quantify effects of parameters such as the number of stations, and network size on schedulability.     

基于层次结构的P2P网络模型研究

基于Gnutella模型的"洪泛"算法,存在向前咨询的盲目性以及仅在应用层实现,缺乏对底层通信子网路由资源的利用,存在可扩展性不高等问题.本文提出以层和域为基本逻辑管理单位构成的多层模型,从路由策略以及多播协议中采用的压力和伸展率指标综合考虑,此模型能有效地解决可扩展性等问题.     

基于攻击图的网络安全度量研究

随着现代社会对网络系统依赖程度的日益增强,网络安全问题受到普遍关注。网络安全度量是指在理解网络环境的基础之上,建立合适指标体系和度量方法,评估网络的安全性。本文采用攻击图这种网络脆弱性分析技术,在对目标网络和攻击者建模的基础之上,根据两者之间的相互关系生成攻击图模型,分析不同的攻击路径。借鉴CVSS对单一漏洞的量化指标,以及节点间概率转换关系,提出攻击伸缩性机理。结合CVSS指标和攻击图,计算攻击伸缩性数值,并以此作为网络安全度量的方法,最后总结了当前网络安全度量的发展现状以及面临的挑战。     

Fuzzy particle swarm optimization algorithms for the open shortest path first weight setting problem

The open shortest path first (OSPF) routing protocol is a well-known approach for routing packets from a source node to a destination node. The protocol assigns weights (or costs) to the links of a network. These weights are used to determine the shortest paths between all sources to all destination nodes. Assignment of these weights to the links is classified as an NP-hard problem. The aim behind the solution to the OSPF weight setting problem is to obtain optimized routing paths to enhance the utilization of the network. This paper formulates the above problem as a multi-objective optimization problem. The optimization metrics are maximum utilization, number of congested links, and number of unused links. These metrics are conflicting in nature, which motivates the use of fuzzy logic to be employed as a tool to aggregate these metrics into a scalar cost function. This scalar cost function is then optimized using a fuzzy particle swarm optimization (FPSO) algorithm developed in this paper. A modified variant of the proposed PSO, namely, fuzzy evolutionary PSO (FEPSO), is also developed. FEPSO incorporates the characteristics of the simulated evolution heuristic into FPSO. Experimentation is done using 12 test cases reported in literature. These test cases consist of 50 and 100 nodes, with the number of arcs ranging from 148 to 503. Empirical results have been obtained and analyzed for different values of FPSO parameters. Results also suggest that FEPSO outperformed FPSO in terms of quality of solution by achieving improvements between 7 and 31 %. Furthermore, comparison of FEPSO with various other algorithms such as Pareto-dominance PSO, weighted aggregation PSO, NSGA-II, simulated evolution, and simulated annealing algorithms revealed that FEPSO performed better than all of them by achieving best results for two or all three objectives.     

Distributed transactional memory for metric-space networks

Transactional Memory is a concurrent programming API in which concurrent threads synchronize via transactions (instead of locks). Although this model has mostly been studied in the context of multiprocessors, it has attractive features for distributed systems as well. In this paper, we consider the problem of implementing transactional memory in a network of nodes where communication costs form a metric. The heart of our design is a new cache-coherence protocol, called the Ballistic protocol, for tracking and moving up-to-date copies of cached objects. For constant-doubling metrics, a broad class encompassing both Euclidean spaces and growth-restricted networks, this protocol has stretch logarithmic in the diameter of the network. Supported by NSF grant 0410042 and by grants from Intel Corporation and Sun Microsystems.     

Rendezvous based routing protocol for wireless sensor networks with mobile sink

In wireless sensor networks, the sensor nodes find the route towards the sink to transmit data. Data transmission happens either directly to the sink node or through the intermediate nodes. As the sensor node has limited energy, it is very important to develop efficient routing technique to prolong network life time. In this paper we proposed rendezvous-based routing protocol, which creates a rendezvous region in the middle of the network and constructs a tree within that region. There are two different modes of data transmission in the proposed protocol. In Method 1, the tree is directed towards the sink and the source node transmits the data to the sink via this tree, whereas in Method 2, the sink transmits its location to the tree, and the source node gets the sink’s location from the tree and transmits the data directly to the sink. The proposed protocol is validated through experiment and compared with the existing protocols using some metrics such as packet delivery ratio, energy consumption, end-to-end latency, network life time.