基于可用带宽测量的应用层组播算法

针对组播分发树建立过程的特性和需求,提出一种基于可用带宽测量的应用层组播算法。该算法以组播数据作为测试源,建立输入数据率和单向时延的关系模型,融合可用带宽测量与组播分发树的建立,以降低测量开销和对网络的影响,仿真实验表明,生成的组播树具有高吞吐量和低链路压力的特点。     

基于分层结构的Ad Hoc网络应用层组播路由研究

提出了一种基于分层结构的Ad Hoc网络应用层组播路由协议HALMP,将网络划分为多个子网,利用虚拟成员节点和延迟响应机制优化子网内共享组播树,以最小生成树方式构建子网间的源-群首组播树,数据分组转发时对组成员节点分布密集的区域引入本地广播机制。仿真结果表明,这些策略的采用优化了组播树,提高了分组转发效率,协议具有较好的可扩展性。     

Ad hoc网络中基于标号的组播路由算法

针对Ad hoc网络中最小带宽消耗组播路由问题,给出一个基于标号优化的启发式算法(LOHA),介绍标号规则及修改节点间邻接关系规则,通过修改组播树中节点的标号来减少树中的转发节点数,从而最小化带宽消耗。该算法的时间复杂度为O(n3),从转发节点个数和平均跳数2个方面比较LOHA及广度优先搜索算法所生成的组播树。实验结果表明,LOHA得到的组播树带宽消耗较少。     

应用层组播转发树节点选择策略研究

应用层组播解决了网络层组播难于部署的问题,但是效率不及网络层组播。针对如何构建一棵高效的应用层组播转发树的问题,重点研究了基于最小路径延迟、基于最大链路带宽、基于最近网络拓扑三种父母节点选择策略对转发树通信效率的影响。仿真实验结果证明,在约束节点度前提下,不同的网络规模中,基于最小路径延迟方法生成树的平均延迟、平均加入时间最小,更适合于延迟敏感型的应用。     

基于决策图贝叶斯优化算法的QoS组播路由算法

组播通信路由技术是视频广播、网络会议等分布式计算的关键技术 ,其目的是要寻找连接源节点和一组目的节点的一棵组播树 ,使得总体代价最小 .提出了一种基于决策图贝叶斯优化算法 (Bayesian Optim ization Algorithmwith Decision Graphs,简称 DBOA)的 Qo S组播路由算法 ,该算法利用新的编码和解码方法以及适当的适应度函数来求解带宽、时延及时延差别等 Qo S限制下最小代价组播路由问题 .仿真结果表明了该算法的可行性和有效性     

应用层组播树性能的测量研究*

针对应用层组播中构建组播树的三种不同算法对组播树性能影响进行了研究,包括各节点的吞吐量和组播树的稳定性,在PlanetLab分布式实验床上进行了实际的测量和分析。结果表明最大带宽组播树算法构建的组播树有最好的吞吐量和稳定性;最短路径树算法也有很高的稳定性,其吞吐量比随机组播树算法有所提高,但差于最大带宽组播树算法。     

一个单源的应用层组播协议的设计和实现

提出了一个单源的应用层组播的协议SSALM。SSALM协议采用树优先的构造策略,在组成员之间构造基于源的组播分发树,并在源树的基础上建立叠加网。成员可以独立地加入组和退出组,并在组播树中进行切换。给出了该协议的主要算法和实现模型。在现有的Internet环境下使用该协议能有效地节省网络带宽。     

基于改进克隆策略的整体优化组播路由算法

提出一种基于改进克隆策略的整体优化组播路由算法,该算法优先考虑延时,同时在满足延时约束的条件下考虑延时、带宽、代价这三个性能指标,在三者之间进行权衡约束,专门用一个参数Q作为衡量组播路由综合性能的指标,并且对树内路径进行了基因优化从而很快得到最优个体。仿真结果表明,得出的组播树代价和延时较小,带宽较大,大大改善了组播路由的整体服务质量,且该算法收敛速度快,可靠性和稳定性高。     

一种基于SSM的多源组播路由协议

为满足参与方同时为收发方的组播通信模式,该文提出了一种新的基于特定源组播的多源组播路由协议SSM-MSM,该协议利用特定源组播形成的单向组播转发树维护一个与之并行的用于多方通信的双向转发树,其路由状态、树建立和控制消息开销和组播包转发时延较小,可综合几种已有的基于SSM多方通信方案的优势。     

可扩展的基于MPLS的稀疏模式IP组播算法

提出了一种可扩展性较好的基于MPLS的稀疏模式的IP组播算法，利用分枝节点和隧道相结合的原理，实现了共享树的组播。通过使用隧道技术，实现多点到多点的MPLS共享树组播，解决了MPLS组播中的关键问题：mp2mp的标签分配。基于网络仿真软件NS-2，实现了该算法的仿真模块。实验证明，该算法是可行和有效的。     

基于启发式遗传算法的QoS组播路由问题求解

研究了带宽、延时抖动和包丢失率约束以及费用最小的QoS组播路由问题,并提出一种启发式遗传算法。该算法有以下特点：（1）预处理机制;（2）树结构编码;（3）启发式交叉策略;（4）指导性变异过程,最后通过仿真实验证明该算法快速有效。     

A tree-based particle swarm optimization for multicast routing

QoS multicast routing is a non-linear combinatorial optimization problem. It tries to find a multicast routing tree with minimal cost that can satisfy constraints such as bandwidth, delay, and delay jitter. This problem is NP-complete. The solution to such problems is often to search first for paths from the source node to each destination node and then integrate these paths into a multicast tree. Such a method, however, is slow and complex. To overcome these shortcomings, we propose a new method for tree-based optimization. Our algorithm optimizes the multicast tree directly, unlike the conventional solutions to finding paths and integrating them to generate a multicast tree. Our algorithm also applies particle swarm optimization to the solution to control the optimization orientation of the tree shape. Simulation results show that our algorithm performs well in searching, converging speed and adaptability scale.     

A new scalable multicast routing algorithm for interactive real-time applications

Quality of service (QoS) provisioning generally assumes more than one QoS measure that implies that QoS routing can be categorized as an instance of routing subject to multiple constraints: delay jitter, bandwidth, cost, etc. We study the problem of constructing multicast trees to meet the QoS requirements of real-time interactive applications where it is necessary to provide bounded delays and bounded delay variation among the source and all destinations while keeping overall cost of the multicast tree low. The main contribution of our work is a new strategy for constructing multiconstrained multicast trees. We first derive mathematically a new delay-variation estimation scheme and prove its efficiency. Thereafter, we propose a simple and competitive (in terms of running time) heuristic algorithm, for delay and delay variation constrained routing problem based on the proposed delay-variation estimation scheme and using the Extended Prim-Dijkstra tradeoffs’ algorithm. Our contribution also extends previous works in providing some properties and analyses of delay bounded paths satisfying delay variation constraints. Extensive simulation results show that our algorithm outperforms DVDMR in terms of multicast delay variation with the same time complexity as DVDMR.     

Dynamic Multicast in Overlay Networks with Linear Capacity Constraints

In a peer-to-peer overlay network, the phenomenon of multiple overlay links sharing bottleneck physical links leads to correlation of overlay link capacities. We are able to more accurately model the overlay by incorporating these linear capacity constraints (LCCs). We formulate the problem of maximizing bandwidth in overlay multicast using our LCC model. We show that finding a maximum bandwidth multicast tree in an overlay network with LCC is NP-complete. Therefore, an efficient heuristics algorithm is designed to solve the problem. Extensive simulations show that our algorithm is able to construct multicast trees that are optimal or extremely close to optimal, with significantly higher bandwidth than trees formed in overlays with no LCC. Furthermore, we develop a fully distributed algorithm for obtaining near-optimal multicast trees, by means of gossip-based algorithms and a restricted but inherently distributed class of LCC (node-based LCC). We demonstrate that the distributed algorithm converges quickly to the centralized optimal and is highly scalable.     

分布式蚁群QoS组播路由算法

为寻找满足带宽、延迟等约束的最小代价组播路由树的QoS组播路由,提出一种分布式蚁群优化算法。在蚂蚁行动过程中形成组播树的森林。若在某步结束时森林中仅剩1棵树,则蚂蚁达到目标,停止行动。仿真实验结果表明,该算法在结果和收敛速度方面都有良好的表现。     

聚合组播及组-树映射算法的研究

对一种新颖的减少组播状态的方法 -聚合组播进行了研究 ,它使多个组播组共享同一棵分布树 ,从而在损耗一定带宽的情况下 ,减少了组播状态和核心路由器上的树管理开销 .同时提出了一种组 -树映射算法 ,该算法将组播组指定到具有可控带宽的分布树上 ,在牺牲带宽的基础上 ,大大降低了额外的隧道开销和扩展开销     

双邻域查找组播聚合算法

光传输网络中聚合组播问题是一个完全NP 难问题,提出了一种解决聚合组播问题的双邻域查找算法.该算法使得生成的聚合树数量在满足波长约束的前提下,带宽浪费比率尽可能地小.基于贪婪策略定义了一种优先聚合规则以生成初始解;定义了两种邻域结构,使邻域查找具有效率;提出了跳坑策略以跳出局部最优解并且将查找引向有希望的方向.模拟实验结果表明:该算法可以有效地进行组播树的聚合,当轻载时,组播组阻塞比率始终为0;当重载时,与其他算法相比,平均带宽浪费比率降低25%以上.因此,对不同的网络状况都能获得较好的性能.     

On bandwidth adjusted multicast communications in pipeline router architecture

We have developed a novel algorithm to adjust link-bandwidths of a given multicast tree, which sends a message with sizer from a source to a multiple destinations taking into consideration pipelined router. The algorithm that we have developed tries to minimize the end-to-end delay time and resources such as bandwidths of a multicast tree, and performs admirably well in any given multicast tree. Our evaluation shows that the proposed algorithm dramatically reduces the end-to-end delay time and resources reserved to satisfy the time-constraints. This work was supported in parts by BK21 and the Ministry of Information and Communication, Korea. Corresponding author: H. Choo.     

On Bandwidth Adjusted Multicast Communications in Pipeline Router Architecture

We have developed a novel algorithm to adjust link-bandwidths of a given multicast tree, which sends a message with size r from a source to a multiple destinations taking into consideration pipelined router. The algorithm that we have developed tries to minimize the end-to-end delay time and resources such as bandwidths of a multicast tree, and performs admirably well in any given multicast tree. Our evaluation shows that the proposed algorithm dramatically reduces the end-to-end delay time and resources reserved to satisfy the time-constraints. This work was supported in parts by BK21 and the Ministry of Information and Communication, Korea. Corresponding author: H. Choo.     

基于局部信息的时延和时延差约束的组播路由

组播通信是从一个源节点同时向网络中的多个目的节点发送分组的通信服务,它一般提供一个以上的端到端的服务约束,实际的路由算法在应用时可以受到多重约束,解决这类问题的组播路由算法是NP完全的。在研究了构建组播树的相关算法后,提出了一种新的时延和时延差约束的低代价组播路由算法-DDVMC。该算法采用基于贪婪策略的Dijkstra最小生成树算法,利用局部信息来构建低代价组播树,很好地平衡了树的代价、时延和时延差。仿真表明,该算法能正确地构造出满足约束的组播树,同时还具有较低的代价和计算复杂度。