基于关键节点和多播节点的多播路由算法

在视频会议等多播应用中，降低多播树网络费用非常重要。本文提出了基于关键节点和目的节点的多播路由KDDMC算法。由于在算法中优先考虑采用关键节点，实现更多链路的共享，从而降低网络费用。在随机网络上的仿真结果表明，KDDMC算法的多播树网络费用优于SPH算法。同时证明了KDDMC算法的复杂度为O(n^3)，且利用所提出的路由表算法易于分布式实现。     

基于双向共享树的MPLS多播流聚合算法

可扩展性是影响多播在MPLS网络大规模使用的主要问题,为解决该问题提出了一种基于双向共享树的多播流聚合算法.它根据节点之间的关系计算多播流的可聚合度,然后将标记边缘路由器聚类生成共享树的叶子节点集,并由树管理服务器计算双向共享树的拓扑结构,最后将可聚合度大于指定阈值的多播流汇聚到树中.实验结果表明,该算法可以大幅缩小MPLS标记的占用,简化中间节点的处理过程,减少路由器的转发状态,大大提高了MPLS多播的可扩展性.     

最小代价多播生成树的快速算法

本文针对MPH（Minimum Path Cost Heuristic）等多播最小生成树算法存在的问题，通过改进最短路径节点的搜寻过程，以较小的存储空间为代价，获得了计算效率很高的快速最小代价多播生成树算法FMPH（Fast Minimum Path Cost Heuristic），且获得多播生成树与MPH算法完全相同，随机网络模型的仿真结果表明：FMPH算法快速、稳定，是一种值得推广使用的高效算法。     

无线Mesh网络可靠多播路由

无线Mesh网络多播路由是无线路由必须解决的关键技术。部分研究者对网络资源和服务质量（QoS）进行研究,提出了建立最短路径树、最小开销树、负载感知、信道分配多播等多播算法;有的算法考虑链路可靠性,建立备用路径。将结合网络资源和可靠性对多播路由算法进行研究,提出了建立可靠多播树（RT,Reliable Tree）的多播路由算法：可靠多播树是一个多树结构,由一棵首选多播树和一棵多径树构成,多径树提供可靠多路径,以提高网络吞吐量。     

基于SimCT的多播路由及故障恢复研究

在数据交换网络中,颜色树是一种通过节点不相交的多路径路由数据报文的有效方法。这种方法中组建两棵以某一节点为根节点的颜色树,即Red树和Blue树,网络中各节点到根节点的路径是节点不相交的。本文在分析和研究SimCT算法的基础上,提出了一种基于颜色树的多播树生成方法及单节点/链路故障的多播通信恢复方案。该方法根据SimCT算法构造的颜色树来组建一棵多播转发树,在多播树中单节点或单链路故障后,故障检测节点本地执行故障恢复方案,将受影响的故障节点的下游子树重新连接到多播树。仿真实验表明,本文所提出的多播树生成方案相比现有方案可以减少网络资源的浪费,并且故障恢复后的代价与原多播通信树相当。     

基于分层多播的视频传输拥塞控制算法研究

分层多播以多速率方式解决了多播接收者异构性问题,对于提高网络服务质量具有重要意义。本文分析了分层多播传输特性,通过提取MPEG视频流中的I帧、P帧、B帧组成3个帧流,分别放到分层多播的基层、增强层1和增强层2上传输,并在中间节点采用优先级队列机制,提出了一种面向视频流传输的分层多播拥塞控制(VLMCC)算法。仿真实验表明,本文提出的VLMCC算法能够适应视频多播接收者的异构性,大大提高了视频多播传输质量。     

高稳定的可扩展覆盖网多播算法

提出了一种高稳定的可扩展覆盖网多播（SOM-HS, scalable overlay multicast with high stability）算法。SOM-HS算法定义了节点稳定度因子以及链路权重,能保证高稳定的节点位于多播树骨干网中。在分层分簇构造过程中,SOM-HS算法限制节点出度,保证节点负载均衡。实验结论表明,与现有其他算法相比,在不同组规模下,使用SOM-HS算法时的最大多播延时都最小。     

无线mesh网中最小编码代价低时延多播路由

提出了一种无线mesh网中最小网络编码代价低时延多播路由协议(MNCLDMR, minimal network coding and low delay multicast routing)。MNCLDMR的目标是选择合适的网络编码节点,最小化网络编码代价,降低网络时延。MNCLDMR主要思想是引入拓扑关键节点和网络编码关键节点的概念,以下一跳的节点是否是网络编码关键节点或拓扑关键节点作为路由判据,采用MNCLD算法构造多播树。仿真结果表明,MNCLDMR可以达到预定目标,合理形成网络编码机会,能实现最小网络编码代价低时延多播路由。     

多播光网络研究中几个问题的探讨

波分复用(WDM)技术的开发和应用使得网络中的信息容量得到了极大的提高，而网络中业务信息的多样化则促进了多播技术的应用和发展。多播的出现使网络的节点结构、虚拟拓扑连接方式及路由和流量疏导算法变得更加复杂多样。为此对光网络中各种多播方式及节点结构并对现有的路由和波长分配算法进行了评述。在此基础上提出了对这类光网络中的信息流量进行疏导时应遵循的几个基本原则，目的是提高波长容量的利用率，减少网络中所用的波长和分插复用器（ADM）数，降低网络的成本和费用。     

网络多播路由的改进编码软件设计与实现

传统网络多播路由编码方法采用多播分布树进行编码,但链路容量遭遇瓶颈,致使编码节点较多,导致浪费带宽资源的问题。在此提出基于Koetter指数时间的网络多播路由改进编码算法对编码软件进行设计,分析多播路由的总体设计,通过数据包编码转发模块在多播拓扑不相交路径上进行编码和转发多播数据包,利用输入模块实现网络多播路由和上游节点的信息交换,通过开关仲裁模块判断能够向特定输出端口传输信息的输入端口,利用死锁控制模块对出现死锁现象的路由节点进行检测,一段时间后使多播路由恢复正常的数据交换,通过输出模块对数据的输出进行管理。以降低带宽资源为目的,采用Koetter指数时间算法实现网络多播路由编码,并给出编码的详细代码。实验结果表明,所提方法不仅节省网络资源,而且显著降低多播路由时延,增强网络吞吐量。     

Distributed algorithms for multicast path setup in data networks

Establishing a multicast tree in a point-to-point network of switch nodes, such as a wide-area asynchronous transfer mode (ATM) network, can be modeled as the NP-complete Steiner problem in networks. In this paper, we introduce and evaluate two distributed algorithms for finding multicast trees in point-to-point data networks. These algorithms are based on the centralized Steiner heuristics, the shortest path heuristic (SPH) and the Kruskal-based shortest path heuristic (K-SPH), and have the advantage that only the multicast members and nodes in the neighborhood of the multicast tree need to participate in the execution of the algorithm. We compare our algorithms by simulation against a baseline algorithm, the pruned minimum spanning-tree heuristic that is the basis of many previously published algorithms for finding multicast trees. Our results show that the competitiveness (the ratio of the sum of the heuristic tree's edge weights to that of the best solution found) of both of our algorithms was, on the average, 25% better in comparison to that of the pruned spanning-tree approach. In addition, the competitiveness of our algorithms was, in almost all cases, within 10% of the best solution found by any of the Steiner heuristics considered, including both centralized and distributed algorithms. Limiting the execution of the algorithm to a subset of the nodes in the network results in an increase in convergence time over the pruned spanning-tree approach, but this overhead can be reduced by careful implementation     

一种改进的Steiner树启发式算法

最小Steiner树问题是NP完全问题，关于Steiner问题的启发式算法的研究具有重要理论和实际意义。本文在MPH算法基础上，对于经过某些关键节点的短路径优先考虑，提出了KBMPH算法，从而实现更多链路的共享。在随机网络上的仿真结果表明，极大多数情况下，在准Steiner树的网络费用KBMPH算法优于MPH算法，KBMPH算法的复杂度为O（n^3）。     

Destination-driven routing for low-cost multicast

We present a destination-driven algorithm that optimizes for applications, such as group video or teleconferencing, that require multicast trees with low total cost. The destination-driven algorithm uses a greedy strategy based on shortest-path trees and minimal spanning trees but biases routes through destinations. The performance of the algorithm is analyzed through extensive simulation and compared with several Steiner tree heuristics and the popular shortest-path tree (SPT) method. The algorithm is found to produce trees with significantly lower overall cost than the SPT while maintaining reasonable per-destination performance. Its performance also compares well with other known Steiner heuristics. Moreover, the algorithm does not suffer from high complexity common to most Steiner tree heuristics and builds a route by querying only incident links for cost information     

共享路径优先组播路由算法

求解开销最小组播树在数学上归结为Steiner树问题,但由于寻找最优的Steiner树问题是NP-Complete问题,因此在组播应用中,采用启发式算法获得次优的组播树是常见的方法。该文提出了一种新的的启发式组播路由算法(Shared Path First Heuristic,SPFH)该算法在选择目的节点加入组播树时,既考虑到目的节点到树上的距离,又考虑到先加入的节点对后续加入节点的影响。算法从距离当前组播树近的目的节点中挑选节点加入组播树,选择的规则是,把能够减小其它目的节点加入组播树开销的节点先加入树。仿真结果表明,SPFH算法能找到开销接近于最优解的组播树。     

A novel efficient multicast routing algorithm in sparse splitting optical networks

The advances in wavelength-division multiplexing (WDM) technology are expected to facilitate bandwidth-intensive multicast applications through light splitting. Due to complexity and cost constraints, light splitting (or optical multicast) nodes are sparsely configured in a practical WDM network. In this article, we investigate the multicast routing problem under the sparse light-splitting constraint. An efficient sparse splitting constrained multicast routing algorithm called Multicast Capable Node First Heuristic (MCNFH) is proposed. The key idea of MCNFH is to include the shortest path, that includes most of the multicast capable nodes, for configuring the multicast tree. Simulations and comparisons are used to demonstrate the performance of MCNFH. Simulation results and analysis show that MCNFH builds multicast trees with the least wavelength channel cost and with the smallest number of wavelengths used per link. In addition, MCNFH requires only one transmitter at the source node.     

多播路由算法MPH的时间复杂度研究

多播通信是从一个源点同时向网络中的多个成员发送分组的通信服务,一个最小代价的多播路由算法是NP完全的,在时间敏感的应用中其运行时间是一个关键问题.MPH(Minimum Path Cost Heuristic)算法是一个著名的启发式最小代价多播路由算法,本文对该算法进行了理论分析和证明,并做了广泛的仿真实验,结果表明其时间复杂度是O(m²n)而不是过去文献中所给出的O(m²n+e).     

Improved heuristics for multicast routing in wireless mesh networks

Multicast is a communication technique that allows a source to transmit data to a set of recipients in an efficient manner. Therefore, the primary objective of a multicast routing protocol would be to minimize number of transmissions to conserve bandwidth. The problem of computing multicast trees with minimal bandwidth consumption is similar to Steiner tree problem and has shown to be NP-complete. So, heuristic based algorithms are suitable to approximate such bandwidth optimal trees. This paper proposes a multicast routing protocol based on minimum number of transmission trees using an heuristic approach. The simulation results show that the proposed algorithm offers better performance over existing protocols, even in the worst-case scenario when the set of multicast receivers are sparsely distributed across the network.     

Optimization of splitting node placement in wavelength-routed optical networks

This paper addresses the placement of multicast nodes in wavelength-routed all-optical networks. This problem is motivated by the expected high cost of optical multicast cross-connects due to fabrication complexity and power considerations. An analytical model for the approximate blocking probability in multicast networks is developed. The blocking performance is used to guide an iterative algorithm, Multicast-ADD, for the placement of multicast nodes. We provide validation of the model and the techniques used. In addition, a simulation study is provided to evaluate the performance of the heuristic. Insights obtained from the simulation results reveal that: (1) only a subset of the nodes (found to be 50%) need to be multicast-capable for acceptable blocking performance; (2) the blocking performance of Multicast-ADD outperforms that of random placement; and (3) employing alternate routing trees is not helpful in the optimization procedure.     

基于灰狼算法的无线网络组播路由优化

针对无线网络中资源受限的组播路由问题,考虑网络节点的节点度限制和网络链路的带宽约束,以最小化组播路由开销为目标,提出了一种二进制编码方式的基于灰狼优化算法的组播路由策略.在给定的网络拓扑下,基于灰狼优化算法的组播路由策略可以迅速找到一棵包含源和目的节点的最小开销组播树.仿真结果表明,相比于遗传算法,所提出的基于灰狼优化...