共查询到18条相似文献,搜索用时 213 毫秒
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应用层多播(ALM)作为IP多播的替代在互联网中得到广泛的应用。提出一个新的基于优先级的动态分层应用层多播模型CDMP(The Classified Dynamic Model Based on the Priority in Application-Level Multicast),模型通过对不同性质的结点的分层来搭建整个架构,通过分域将性质接近的结点放在一起以保证数据传输的效率和数据共享的公正性,并且减少了结点寻找路由的代价,加快了当结点失败时的路由修复速度。通过分析和仿真实验证明,CDMP协议具有良好的上述性质。 相似文献
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为了解决现有多播存在的问题,加速多播的应用,近年来提出了应用层多播(ALM)。根据ALM构建转发树的策略,可以将应用层多播分成集中式和分布式两类。由于ALM的开放性带来了一定的安全隐患,我们引入RBAC来解决该问题。该文基于集中式ALM的特点,提出了相应的RBAC模型—CALM-RBAC,并对该模型进行了UML语言的描述。 相似文献
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为了解决基三分层互连网络(THIN)系统中的负载平衡问题,提出一种采用多播树技术提高节点间交换负载信息效率的动态负载平衡(DLB)算法--THINDLBA.设计了一套完整的DLB消息和各节点处的信息维护机制以辅助算法实现.重载节点的负载迁移请求消息沿着一棵以该节点为根的多播树传播,被该树覆盖的轻载节点均成为负载迁移的候选目标节点,可以沿着该树和重载节点交互负载信息,从而使重载节点能够在算法的一次执行中外迁最多的过载进程,尽快改善自身负载状态.算法设计中约束了多播树的构造过程,以避免因树间覆盖造成的消息误传或冗余.通过实验对比了4种DLB算法的性能,结果证明THINDLBA能更有效地缩减THIN系统处理计算密集型任务的时间. 相似文献
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覆盖多播在端系统间构建数据分发树.由于端系统随意地加入或退出多播组,其可靠性不如路由器.当分发树中的非叶节点退出或者节点失效时,其下游节点将受到影响.低代价而快速的节点失效检测能降低由于服务间断所带来的影响,同时也为后续的恢复工作提供一个良好的基础.在分析相关工作的基础上,提出了一种改进的节点失效检测机制,它能够兼顾节点失效检测时间和额外消息负载两个性能指标. 相似文献
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应用层多播越来越广泛应用于Internet,为了解决异构网络环境带来的异构性和传输实时性等许多问题,本文提出一种基于代理的自适应多播AALM系统(Agent-based Application-level Multicast),在局域范围内采用高效率的IP多播传输数据,每个IP多播域中设置一个代理服务器,代理服务器之间的主干网络通过应用层多播进行数据传输.AALM多播系统的模块划分和通信协议表的具体定义,进一步验证了AALM多播系统可以满足不同的应用需求,在异构环境下可以节省了大量网络资源,提高了视频服务质量. 相似文献
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刘余娇 《绵阳师范学院学报》2009,28(8):77-81
现有的应用层多播机制的特点是没有考虑角色的动态分配与动态授权,忽视了应用层多播系统上下文环境的动态性,该文从应用层多播系统的动态角色分配与动态角色授权角度出发,提出了基于应用层多播的角色分配与角色授权模型,利用用户-角色矩阵与角色-权限矩阵分析了ALM中角色分配与角色授权关系,在此基础上进一步讨论了ALM中的安全问题. 相似文献
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《实验室研究与探索》2016,(10):127-134
Wi Fi网络下的视频多播传输问题是目前的研究热点,针对当前视频多播传输方案使得处于区域边界处的用户享受到的服务质量较低、可靠性差这一不足,提出一种基于多访问点(AP)协作的视频多播可靠传输方案。通过在多个AP间展开协作,每个AP可传输完全不同或部分不同的FEC编码报文,多播接收器利用空间和时间分集来提升性能。此外,我们还提出一种支持FEC码率自适应的资源分配算法,有效地提高了有限无线资源的利用率和视频质量。最后,通过全面的仿真实验评估了本文算法的有效性,与传统的单AP点多播算法相比,本文算法使用户满意率提升了37.1%。 相似文献
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刘莞 《福建工程学院学报》2009,7(3)
提出一种新的基于代理的系统--应用层自适应多播AALM系统,改善网络的异构性和传输实时性.在局域范围内采用高效率的IP multicaat进行数据传输,每个多播域中设置一个代理服务器MAN,MAN之间的主干网络通过应用层多播进行数据传输,实现在Internet范围内的多点数据通信.采用了XML驱动的服务定制机制,可以满足不同应用需求,节省大量的网络资源,提供网络吞吐量,提高视频服务质量. 相似文献
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针对目前Internet安全组通信技术的现状,通过分析目前已有的应用层多播机制的特点,提出了应用层多播中涉及的角色分配与角色授权模型,利用用户一角色矩阵与角色一权限矩阵分析了ALM中角色分配与角色授权关系,在此基础上进一步讨论了ALM中的安全问题. 相似文献
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Multicasting is a communication service that allows an application to efficiently transmit copies of data packets to a set of destination nodes. The problem of finding a minimum cost multicast tree can be formulated as a minimum Steiner tree problem in networks, which is NP-completeness. MPH (minimum path cost heuristic) algorithm is a famous solution to this problem. In this paper,we present a novel solution TPMPH (two phase minimum path cost heuristic) to improve the MPH by generating the nodes and the edges of multicast tree separately. The cost of multicast tree generated by the proposed algorithm with the same time as MPH is no more than that of MPH in the worst case. Extensive simulation results show that TPMPH can effectively improve the performance on MPH, and performs better in large-scale networks and wireless networks. 相似文献
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Algorithm for Delay-Constrained Minimal Cost Group Multicasting 总被引:1,自引:0,他引:1
Group multicast routing algorithms satisfying quality of service requirements of real-time applications are essential for high-speed networks. A heuristic algorithm was presented for group multicast routing with bandwidth and delay constrained. A new metric was designed as a function of available bandwidth and delay of link, And source-specific routing trees for each member were generated in the algorithm by using the metric, which satisfy member's bandwidth and end-to-end delay requirements. Simulations over random network were carried out to compare the performance of the proposed algorithm with that from literature. Experimental results show that the algorithm performs better in terms of network cost and ability in constructing feasible multicast trees for group members. Moreover,the algorithm can avoid link blocking and enhance the network behavior efficiently. 相似文献
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1 Introduction Withthedevelopmentofcomputernetworkandmultimediatechnologies ,thereisanincreasingnum berofapplicationssuchassoftwaredistribution ,au dio/videoconference ,andaudio/videobroadcastswheredataisdistributedtomultiplereceivers[7] .Animportanttechniqu… 相似文献
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Li Bao-Hong Hou W-Bin 《重庆大学学报(英文版)》2005,4(3):154-157
1 Introduction a Many secure multicast systems, such as stock quotes, video conferencing, should provide mechanisms for recipients to authenticate messages they received. Packet authentication in multicast environments is a challenge for two reasons. First, the standard Message Authentication Code (MAC) technique is no longer available because of the fact that all members in a multicast group share the same session key. Another obvious way is to sign each packet using the sender’s private … 相似文献
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In order to share multimedia transmissions in mesh networks and optimize the utilization of network resources, this paper presents a Two-stage Evolutionary Algorithm (TEA), i.e., unicast routing evolution and multicast path composition, for dynamic multicast routing. The TEA uses a novel link-duplicate-degree encoding, which can encode a multicast path in the link-duplicate-degree and decode the path as a link vector easily. A dynamic algorithm for adding nodes to or removing nodes from a multicast group and a repairing algorithm are also covered in this paper. As the TEA is based on global evaluation, the quality of the multicast path remains stabilized without degradation when multicast members change over time. Therefore, it is not necessary to rearrange the multicast path during the life cycle of the multicast sessions. Simulation results show that the TEA is efficient and convergent. 相似文献
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王竞 《重庆大学学报(英文版)》2005,4(2):96-101
1 Introduction 1 Multiparty applications based on group communication such as video conference, remote education and so on are expected to become widespread in the Internet in the future. Now, the network transmission mode is unicast with a single receiver. If there are multiple receivers, the sender has to transmit multiple copies of the same data. Obviously, the unicast is inefficient for increasing one-to-many and many-to-many network applications. Multicast (RFC1112) is one of the effect… 相似文献
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采用一种神经网络算法——径向基函数来选择无线传感器网络的节点簇首,它具有并行处理能力、分布式存储以及快速学习等优点.通过分析得出与节点作为簇首相关的4个因素:节点的剩余能量,周围分布的节点的数目,中心度和距离基站的位置.把这4个因素作为神经网络的输入变量,输出变量就是该节点作为簇首的适应度值.根据网络规模的大小,基站选出一组作为簇首的节点,然后广播作为簇首的节点号的消息.如果一个节点被选为簇首,就向周围广播自己的身份并成立一个新簇,周围的非簇首节点要求加入该簇并成为它的成员.每簇中由簇首负责管理它的成员并执行数据融合等功能.实验结果表明,与其他算法相比,该算法能显著地延长传感器网络的生命. 相似文献