一种在Ad Hoc网络中基于地理位置的节约能量的组播路由算法

在移动adhoc网络中,设计节约能量的组播路由算法是非常重要的,这是由于网络中的节点运行时所需要的能量来自于电池的有限供给。由于节点是可以移动的,这就要求节约能量的路由协议在本质上是分布式的,对于当前的节点状态是自适应的。论文提出一种基于地理位置的节约能量的组播路由算法,使得在满足带宽的同时,组播的能量消耗尽可能的少。其基本思想是:先由基本的组播算法生成一棵组播树,然后由组播树的每个非叶子节点根据其邻居节点的地理位置,动态地选择一些转发点,通过这些点以较小功率转发时可节约能量,以此优化组播树。     

基于遗传算法的实时组播通信路由算法

组播通信路由技术是视频广播、计算机会议、CSCW()等新型分布式计算的关键技术.提出了基于分布式遗传算法的共享树组播路由算法,包括包交换的网络组播树的建立、组播树的动态维护和计算满足特定时延和时延抖动限制的近似斯坦利最小树算法等.利用它可以实现在给定网络和组播需求的情况下,在组成员间寻找动态的组播树,并使该树覆盖所有的成员,并约束网络费用达到最小.进而解决树状路由的建立以及树状路由的动态维护等问题.     

A Service-Centric Multicast Architecture and Routing Protocol

In this paper, we present a new multicast architecture and the corresponding multicast routing protocol for providing efficient and flexible multicast services over the Internet. Traditional multicast protocols construct and update the multicast tree in a distributed manner, which may cause two problems: first, since each node has only local or partial information on the network topology and group membership, it is difficult to build an efficient multicast tree and, second, due to the lack of complete information, broadcast is often used for sending control packets and data packets, which consumes a great deal of network bandwidth. In the newly proposed multicast architecture, a few powerful routers, called m-routers, collect multicast-related information and process multicast requests based on the information collected. The m-routers handle most of the multicast-related tasks, whereas other routers in the network only need to perform minimum functions for routing. The m-routers are designed to be able to handle simultaneous many-to-many communications efficiently. The new multicast routing protocol, called the Service-Centric Multicast Protocol (SCMP), builds a shared multicast tree rooted at the m-router for each group. The multicast tree is computed in the m-router by employing the Delay-Constrained Dynamic Multicast (DCDM) algorithm, which dynamically builds a delay-constrained multicast tree and minimizes the tree cost as well. The physical construction of the multicast tree over the Internet is performed by a special type of self-routing packets in order to minimize the protocol overhead. Our simulation results on ns-2 demonstrate that the new SCMP protocol outperforms other existing protocols and is a promising alternative for providing efficient and flexible multicast services over the Internet.     

AODV路由算法的多播通信

ah—hoc网络具有网络拓扑结构易变的特性，苒加上移动网络本身具有的通信带宽有限，电池能源有限等特性。使得设计适合ad-hoc的路由协议具有一定的难度。AODV（Ad Hoc On—demand Distance Vector）是现在被广泛应用于adhoc网络中的一种按需路由算法，并且还设计了多播功能。多播是指一次给一个有明确定义的组发送消息。AODV的多播功能是路由器通过建立多播书树的方法实现的。本文主要介绍AODV路由协议算法的多播通信，其中详细介绍了多播树的建立过程和维护过程。并且选取传输半径和发包率为参     

Performance analysis of multicast algorithms for mobile satellite communication networks

With the rise of mobile computing and an increasing need for ubiquitous high-speed data connections, Internet-in-the-sky solutions are becoming increasingly viable. To reduce the network overhead of one-to-many transmissions, the multicast protocol has been devised. The implementation of multicast in these low earth orbit (LEO) constellations is a critical component to achieving an omnipresent network environment. This paper examines the system performance associated with two terrestrial-based multicast mobility solutions, distance vector multicast routing protocol (DVMRP) with mobile IP and on demand multicast routing protocol (ODMRP). These protocols are implemented and simulated in a satellite LEO constellation. Results from the simulation trials show the ODMRP protocol provided greater than 99% reliability in packet deliverability, at the cost of more than 8 bits of overhead for every 1 bit of data for multicast groups with multiple sources. In contrast, DVMRP proved robust and scalable, with data-to-overhead ratios increasing logarithmically with membership levels. DVMRP also had less than 70 ms of average end-to-end delay, providing stable transmissions at high loading and membership levels.     

一种基于分群的移动自组网多播路由协议

为提高多播协议的可扩展性,提出一个基于分群的高效多播路由协议(ECMRP)。采用改进的基于权重的分群算法对移动自组网中的移动节点进行分层管理,并应用软状态方法在群首间建立多播树,减小当网络拓扑结构动态变化时重构、维护多播树结构的控制开销。仿真实验结果表明,该算法在路由开销和分组投递率上均优于多播按需距离矢量和按需多播路由协议,更适合于高动态、大规模的自组网。     

基于MPH的时延约束Steiner树算法

为了在时延约束务件下进一步优化组播树代价,并降低算法计算复杂度,研究了时延受限的Steiner树问题.分析了MPH(minimum path heuristic)算法的计算复杂度;在此基础上设计了一个时延约束Steiner树算法DCMPH(delay-constrained MPH)用于构造时延约束最小代价组播树.该算法中每个目的结点通过与当前组播树有最小代价的路径加入组播树;若时延不满足要求,则通过合并最小时延SPT(shortest path tree)树进而产生一个满足时延约束的最小代价组播树.仿真实验表明,DCMPH算法生成的组播树在保证时延要求的情况下,与同类算法相比取得了很好的代价性能和较低的计算复杂度.     

Scalable multimedia communication using IP Multicast andlightweight sessions

This survey describes the roots of IP Multicast, the evolution of the Internet Multicast Backbone, or Mbone, and the technologies that have risen around the Mbone to support large-scale Internet-based multimedia conferencing. The author explains the technical rationale for design decisions that underlay the Mbone tools, describes the evolution of this work from early prototypes into Internet standards, and outlines the open challenges that remain and must be overcome to realize a ubiquitous multicast infrastructure     

Vxworks下组播路由体系研究与实现

随着Internet上多媒体尤其是网络视频、网络会议以及远程直播等应用的发展,组播技术已经变得越来越重要,它可以帮助用户节约宝贵的带宽资源,有效地解决单点发送多点接收问题。在介绍了组播路由基本原理的基础上,对Vxworks下组播路由体系结构进行了研究,并以DVMRP和PIM两个协议为例,从总体设计、组播任务、IP协议栈内核以及组播任务和内核的交互等几个方面给出了它的初步实现。     

Multicast communication in multicomputer networks

Efficient routing of messages is a key to the performance of multicomputers. Multicast communication refers to the delivery of the same message from a source node to an arbitrary number of destination nodes. While multicast communication is highly demanded in many applications, most of the existing multicomputers do not directly support this service; rather it is indirectly supported by multiple one-to-one or broadcast communications, which result in more network traffic and a waste of system resources. The authors study routing evaluation criteria for multicast communication under different switching technologies. Multicast communication in multicomputers is formulated as a graph theoretical problem. Depending on the evaluation criteria and switching technologies, they study three optimal multicast communication problems, which are equivalent to the finding of the following three subgraphs: optimal multicast path, optimal multicast cycle, and minimal Steiner tree, where the interconnection of a multicomputer defines a host graph. They show that all these optimization problems are NP-complete for the popular 2D-mesh and hypercube host graphs. Heuristic multicast algorithms for these routing problems are proposed     

主动层次多目通信路由模型

许多应用需要IP多目通信.在Internet大规模应用IP Multicast时,有效的路由是关键.这样的多目路由协议必须是有效的、可伸缩的和增量可配置的.但是传统的Internet路由对性能是不敏感的,不能平衡负载和处理拥塞.现有的大多数多目通信路由协议不仅负责数据转发,还负责路由树的构造,这给路由器带来了极大的复杂性,而且协议的配置是手动的、费时费钱的工作.该文提出一个主动层次式Multicast路由的体系结构,采用主动网络技术将多目通信路由协议的数据转发和控制机制分开,根据链路的状态信息用主动报文控     

基因池操作遗传算法的应用层组播路由优化

在应用层组播系统中，负责数据转发的终端节点不具备线速转发能力，较重的转发负载会引起拥塞。以拥塞节点为根的整个子路由树将与源节点失联。为解决由拥塞导致应用层组播稳定性差的问题，将构造最优组播树的过程抽象为有度约束的最小代价Steiner树问题。提出了一种用于构造节点转发能力受限应用层组播树的遗传算法，算法以组播树上各节点的直接前驱对其进行遗传表达，便于节点出度的统计。为使遗传操作适用于直接前驱编码，引入了“基因池”的概念并以此为基础实现了交叉与变异。针对度约束导致产生非可行解的问题，提出将组播树对度约束的超出量作为一个新的优化目标，从而以多目标优化的方式得到Pareto前沿，并从Pareto前沿上截取满足度约束的解作为最终输出，避免了使用惩罚函数法的求得非可行解的风险。仿真实验表明，提出的遗传算法能够构造节点转发能力受限的应用层组播路由树，具有良好的求解可靠性。     

基于PIM-DM的区分服务组播路由协议

区分服务和组播是下一代网络需要支持的两种关键技术。但是,在区分服务中支持组播需要解决被忽略的预约子树(NRS)和组成员异构性问题。解决这两个问题需要对传统的组播路由协议进行修改,使其满足区分服务网络的要求。论文改进了域内组播路由协议PIM-DM,解决了该协议在区分服务网络中应用时遇到的NRS和组成员异构性问题。由于PIM-DM和DVMRP都是工作在密集模式下数据驱动的组播路由协议,因此论文的方法同样适用于DVMRP协议。该方法在ns-2模拟器上进行了验证。     

A distributed multicast routing protocol for real-time multicast applications

Multicast routing is establishing a tree which is rooted from the source node and contains all the multicast destinations. A delay bounded routing tree is a tree in which the accumulated delay from the source node to any destination along the tree does not exceed a pre-specified bound. This paper presents a distributed routing protocol which constructs delay bounded routing trees for real-time multicast connections. A constructed routing tree has a near optimal network cost under the delay bound constraint. The proposed algorithm is fully distributed, efficient in terms of the number of messages required, and flexible in multicast membership changes. A large number of simulations have been done to show the network cost of the routing trees generated by our method is better than the other major existing algorithms.     

移动分组无线网多播协议的设计与实现

提出了用于移动分组无线网的多播路由协议。在移动分组无线网环境中，多播路由协议起着非常重要的作用。传统的应用于有线网络的多播方法无法适应移动分组无线网具有的拓扑结构变化和带宽有限等特点。在协议中不需要维护全局的路由信息，而采用按需路由发现策略，动态建立路由信息及维持多播组成员关系。仿真实验显示协议在带宽较低、多播组成员数量变化较大的移动分组无线网环境中，具有较好的可靠性和工作效率。     

多QoS约束的多播路由协议

随着高性能网络、移动网络及Internet的不断发展,具有QoS约束的多播路由技术已成为网络及分布式系统领域的一个重要研究课题.研讨了具有多QoS约束的多播路由问题,其中主要包含延迟、延迟抖动、带宽、代价等QoS约束.描述了一种适应于研究QoS多播路由的网络模型,提出了一种具有多QoS约束的多播路由协议(multicast routing protocol with multiple QoS,简称MRPMQ).MRPMQ试图有效减少生成多QoS约束的多播树的开销.在MRPMQ中,一个多播组成员能够动态地加入/退出一个多播会晤,且不干扰现有的多播树.给出了该协议的正确性证明和复杂性分析.仿真实验结果表明,MRPMQ为多QoS约束多播路由提供了一种新的有效途径.     

基于分簇结构的无线移动网络多播路由协议

移动自组网（MANET,Mobile Ad hoc Networks）是一种特殊的、应用前景广阔的新型移动无线网络。特有的网络特性使它在诸如灾难救助、战场、传感器网络、分布式计算等领域有着广泛的应用前景。结合在移动自组网络中应用最为广泛的分层结构——簇结构的特点,提出了一种基于簇结构的移动自组网多播波路由协议。协议通过对移动自组网进行簇划分,形成由簇头、簇间节点和簇内节点构成的分簇网络结构,并且在由簇头和簇间节点形成的虚拟骨干网基础上,对其进行回路检测和冗余剪枝算法处理,最终得到一个能满足多播要求的多播树,从而实现在移动自组网中的多播路由。通过对仿真实验结果的分析,该协议具有稳定的数据包发送率和较低的路由建立时间。     

An efficient distributed algorithm for generating and updating multicast trees

As group applications are becoming widespread, efficient network utilization becomes a growing concern. Multicast transmission represents a necessary lower network service for the wide diffusion of new multimedia network applications. Multicast transmission may use network resources more efficiently than multiple point-to-point messages; however, creating optimal multicast trees (Steiner Tree Problem in networks) is prohibitively expensive. This paper proposes a distributed algorithm for the heuristic solution of the Steiner Tree Problem, allowing the construction of effective distribution trees using a coordination protocol among the network nodes. Furthermore, we propose a novel distributed technique for dynamically updating the multicast tree. The approach proposed has been implemented and extensively tested both in simulation, and on experimental networks. Performance evaluation indicates that the distributed algorithm performs as well as the centralized version, providing good levels of convergence time and communication complexity.     

A QoS multicast routing protocol for dynamic group topology

Multicast routing is establishing a tree which is rooted from the source node and contains all the multicast destinations. A multicast routing tree with multiple QoS constraints may be the tree in which the delay, delay-jitter, packet-loss and bandwidth should satisfy the pre-specified bounds. This paper discusses the multicast routing problem with multiple QoS constraints, which may deal with the delay, delay-jitter, bandwidth and packet-loss metrics, and describes a network model for researching the routing problem. It presents a QoS multicast routing protocol with dynamic group topology (QMRPD). The QMRPD attempts to significantly reduce the overhead of constructing a multicast tree with multiple QoS constraints. In MPRMQ, a multicast group member can join or leave a multicast session dynamically, which should not disrupt the multicast tree. It also attempts to minimize overall cost of the tree, and satisfy the multiple QoS constraints and least cost's (or lower cost) requirements. In this paper, the proof of correctness and complexity analysis of the QMRPD are also given. Simulation results show that QMRPD is an available approach to multicast routing decision with dynamic group topology.     

一个主动组播路由协议的设计与实现

该文提出一个基于主动网络的主动组播路由协议AMRP(ActiveMulticastRoutingProtocol),AMRP建立一棵以主动路由器为中间节点的动态主动组播树,支持组成员的动态加入和退出、多点对多点通信和子组的划分。