多QoS约束的层次多播路由算法框架

为了解决网络路由的扩展性问题。大型网络通常被划分成若干个不同的域。拓扑聚集是对这些域的拓扑状态信息进行汇总的过程。在拓扑聚集的基础上,QoS层次多播路由算法用来构造满足QoS要求的域闻多播树。现有的QoS层次多播路由算法在其拓扑聚集和路径计算的过程中都只考虑了存在两个QoS特征值的情况。本文提出了一种具有多QoS约束的层次多播路由算法框架HMRMQ（Hierarchical Multicast Routing with Multiple QoS constraints）,此算法框架不仅为基于多QoS特征值的拓扑状态聚集和状态信息表示提供了新的方法,而且提出了一种适应于多QoS约束的层次多播路由新算法。我们提出的状态信息表示法和拓扑聚集算法都具有很好的扩展性,分布式的路由算法也便于某些安全性策略的实施。理论分析和实验结果不仅证明了HMRMQ的正确性和有效性,同时也表明了HMRMQ在网络路由的扩展性、路由成功率、网络代价以及报文负载等方面都具有良好的性能。     

QoS动态多播路由协议

保证服务质量的QoS（Quality of Service）路由是网络中解决OoS问题的一项关键技术．具有OoS约束的多播路由技术已成为网络领域的一个重要研究课题．该文研讨了具有QoS约束的动态多播路由问题．文中描述了一种适应于QoS多播路由的网络模型，提出了一种QoS动态多播路由协议（QDMRP）．QDMRP只要求网络链路（或节点）的局部状态信息，不需要维护全局状态信息．QDMRP较好地减少构造一棵多播树的开销．仿真实验结果表明：QDMRP具有较低的控制信息开销和节点加入时延，较好地适合于网络状态变化比较频繁的环境以及实时多媒体应用．     

A QoS Multicast Routing Algorithm Working with Imprecise State Information

In large networks, maintaining precise global network state information is almost impossible. Many factors, including non-negligible propagation delay, infiequent link state update due to overhead concerns, link state update policy, and hierarchical topology aggregation, have impacts on the precision of the network state information. The existing QoS multicast routing algorithms do not provide satisfactory performance with imprecise state information. In this paper, we propose a distributed QoS multicast routing scheme based on traffic lights, called QMRI algorithm, which can probe multiple feasible tree branches, and select the optimal or near-optimal branch through the UR or TL mode for constructing a multicast tree with QoS guarantees if it exists. The proposed algorithm considers not only the QoS requirements but also the cost optimality of the multicast tree. Extensive simulations show that our algorithm achieves high call-admission ratio and low-cost multicast trees with modest message overhead. The algorithm can tolerate high degree of state information imprecision.     

A distributed QoS-Aware multicast routing protocol

This paper discusses the multicast routing problem with QoS constraints, and describes a network model that is suitable to research such routing problem. The paper mainly presents a distributed QoS-aware multicast routing protocol (QMRP). The QMRP can operate on top of the unicast routing protocol. It only requires the local state information of the link (or the node), but does not require any global network state to be maintained. The QMRP can significantly reduce the overhead for constructing a multicast tree with QoS constraints. In QMRP, a multicast group member can join or leave the multicast session dynamically, which can support dynamic membership. The protocol can search multiple feasible tree branches, and select the optimal or near-optimal branch for connecting the new receiver to the multicast tree if it exists. In this paper, the proof of correctness and complexity analysis of the QMRP are given, and the performance measures of the protocol are evaluated using simulation. The study shows that QMRP provides an available approach to multicast routing with QoS constraints and dynamic membership support.Received: 3 April 2003, Published online: 2 September 2003     

分布式QoS多播路由协议

研讨了具有QoS约束的分布式多播路由问题。描述了一种适应于QoS多播路由的网络模型,提出了一种分布式QoS多播路由协议（DQMRP）。DQMRP只要求网络链路（或节点）的局部状态信息,不需要维护全局状态信息。DQMRP可有效地减少构造一棵多播树的开销,多播组成员能动态地加入,退出一个多播会晤,且不干扰现有的多播树。给出了DQMRP的正确性证明。仿真实验结果表明：DQMRP具有较低的控制信息开销和节点加入时延,较其它协议更适合于网络状态变化比较频繁的环境以及实时多媒体应用。     

多约束QoS动态多播路由算法

YAM和QoSMIC是支持QoS动态多播路由算法,允许多播组成员动态地加入/退出,同时为接收方提供多个可选择的多播接入路径,以满足不同应用的QoS需求。该文在分析这些算法的基础上,研讨了具有延迟、延迟抖动、带宽和代价等多约束QoS的多播路由问题,描述了一种适应于研究QoS多播路由的网络模型,提出了一种具有多约束QoS的动态多播路由算法(MQDMR),MQDMR试图有效地减少生成多约束QoS的多播树的开销。在MQDMR中,一个多播组成员能动态地加入/退出一个多播会晤,且不干扰现有的多播树。仿真实验结果表明,MQDMR比YAM和QoSMIC具有较小的延时和较少的代价。     

基于遗传算法的多约束QoS多播路由优化算法

随着大量新型的多媒体在高性能网络、移动网络及Internet中的应用，满足QoS约束的多播路由问题成为越来越重要，它吸引了许多爱好者．本文讨论了多约束QoS多播路由问题，主要包含延迟、延迟抖动、带宽和分组丢失率等QoS约束，文中描述了一种在动态网络环境及不确定参数下适应于研究QoS多播路由的网络模型．提出了一种在网络规模、可行性方面为Imernet、移动网络和高性能网络下基于遗传算法的多约束QoS多播路由优化算法（MQMRGA）．仿真结果表明该算法收敛速度快、可靠性高．MQMRGA为QoS多播路由提供了一种新的有效途径．     

Performance evaluation of a mesh-evolving quality-of-service-aware multicast routing protocol for mobile ad hoc networks

The tremendous amount of multimedia applications running across the wireless communication medium makes quality of service (QoS) a fundamental requirement for mobile ad hoc networks. However, it is not easy to incorporate QoS into these networks. Moreover, the growing number of group-oriented applications also necessitates the efficient utilisation of network resources. The multicast model is a promising technique which can achieve this efficiency by facilitating the inherent broadcast capability of the wireless medium. The mesh-evolving ad hoc QoS multicast (MAQM) routing protocol is developed to address the resource efficiency and QoS problems with one, integrated solution. MAQM achieves multicast efficiency by tracking the availability of resources for each node within its neighbourhood. The QoS status is monitored continuously and announced periodically to the extent of QoS provision. Using these features, MAQM nodes can make their decisions on joining a new multicast session based on the sustainability of their perceived QoS. MAQM also evolves the initial multicast tree into a mesh during the course of an ongoing session to achieve a more robust network topology. Thus, MAQM integrates the concept of QoS-awareness into multicast routing in mobile ad hoc networks. Since ad hoc networks require the protocol control overhead to be as small as possible, we analyse the multicast session establishment process of MAQM to see its impact on the protocol performance in terms of system control overhead. We also evaluate the performance of MAQM through computer simulations using various qualitative and quantitative criteria. The simulation results validate our mathematical analysis of the control overhead and show that MAQM significantly improves multicast efficiency through its QoS-aware admission and routing decisions with an acceptably small overhead. Thus, MAQM shows that QoS is not only essential for, but also applicable to mobile ad hoc networks.     

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.     

一种新的QoS约束的多播路由协议

网络技术和多媒体技术的发展使得未来的Internet对具有QoS(Quality of Service)需求的多播应用的支持变得更加迫切．为了解决现有QoS多播路由协议消息复杂度高、寻路成功率低以及连接建立时间比较长等问题，作者提出了一种新的QoS多播约束路由协议MRPQoS(Multicast Routing Protocol with QoS constraints)．它完全分布式运行，将局部搜索与全局搜索、单分支搜索与多分支搜索有机地结合在一起，较好地解决了上述问题．仿真结果证明：MRPQoS较其它协议更适合于网络状态变化比较频繁的环境以及实时多媒体应用．     

一种基于遗传算法的多约束QoS多播路由优化算法

随着Internet、移动网络和高性能网络的不断发展,在网络和不确定参数下具有多约束QoS多播路由优化技术已成为网络及分布式系统领域的一个重要研究课题,这也是下一代Internet和高性能网络的难题。它吸引了许多爱好者。论文研讨了具有多约束QoS多播路由问题,其中主要包含延迟、延迟抖动、带宽、分组丢失率等QoS约束,文中描述了一种适应于研究QoS多播路由的网络模型。论文在网络环境及不确定参数下,提出了一种在网络规模、可行性方面优化Internet、移动网络和其他高性能网络的基于遗传算法的多约束QoS多播路由优化算法(MQROGA)。MQROGA在网络环境及不确定参数下能够优化网络资源,如带宽、延迟、分组丢失率等得到一个最优解和次优解。仿真实验结果表明,MQROGA为QoS多播路由提供了一种新的有效途径。     

基于遗传模拟退火算法的多约束QOS组播路由优化算法

组播路由问题在计算机网络中是著名的Steiner树问题,是NP完全问题.通过考虑组播通信服务质量需求与网络资源约束,研究了基于服务质量的组播路由选择算法问题,首次提出了一个基于遗传算法和模拟退火算法的多约束组播路由优化算法,该算法在满足带宽、延时、延时抖动及包丢失率约束条件下寻找代价最小的组播树.     

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.     

基于状态稳定性更新的距离向量路由算法

为了满足多种业务需求、优化网络资源,QoS路由需要具备较准确的网络状态信息计算路径。受到网络开销等诸多方面的限制,现有的距离向量等算法难以及时、准确地描述网络状态统计特征,状态的不确定性成为了服务质量研究的难点。该文提出了一种基于状态稳定性更新的距离向量路由算法（SSB-DV）,改进了对距离向量算法的周期更新方式。通过分析和仿真实验表明,SSB-DV算法能够在确保网络有效利用等重要的路由性能的基础上,以较小的代价使具有显著变化的网络状态得到及时的更新和通告。     

不确定信息下QoS多播路由问题研究

QoS(Quality of Service)多播路由是保证网络服务质量的重要组件。但是网络状态信息具有固有的不确定性,因此有必要研究不确定信息对QoS多播路由的影响。假设网络带宽和延时为符合某种分布的随机变量,建立了问题的机会约束规划模型,并采用并行遗传算法对模型进行了求解,仿真结果证明该算法收敛速度快,可靠性高,能够满足多媒体网络对实时性的要求。     

基于免疫遗传算法的多约束QoS组播路由选择方法

以具有精英保留的免疫遗传算法（IGAE）为基础,提出了一种新的用来求解带宽、时延、时延抖动受限,费用最小的QoS组播路由选择问题的方法。首先采用预处理机制,将网络结构中不满足带宽约束的链路去掉,利用Dijkstra第k最短路径算法建立编码空间的备选路径集;然后采用基于路径的树结构编码来随机产生初始群体,使种群中的每个个体都代表组播路由问题的一个候选解;最后利用IGAE算法对种群进行优化,最终求得满足QoS要求的组播路由。仿真实验结果表明,该算法具有较好的性能,能以较快的速度搜索到满足QoS要求的费用最小的组播树。     

多QoS约束的自适应组播路由协议*

在多加性QoS约束的自适应组播路由基础上,提出了一种基于多QoS约束的自适应组播路由协议MQDMRP。采用多路径寻路和受限泛播策略,有效限制了控制报文开销;对MQDMRP与传统协议进行仿真研究,表明新协议的接入成功率比传统协议要好。     

基于QoS的多播路由综述

瓦联网络上的多媒体应用如视频会议、远程教育、协同工作和视频点播等具有服务质最QoS(Quality of Service)要求,如链路带宽、传输延迟、节点处碰延迟、料动以及丢失率等,考虑不同应用的不同QoS请求,就多播应用中多播路由树的构造算法／协议进行综述,介绍厂日前任多播领域的研究现状,并就各种方法和其优缺点进行厂比较分析最后给出了多播路由的研究方向。     

基于受限泛播技术的可伸缩性QoS组播路由协议

随着远程会议、远程教育和交互式仿真等分布式多媒体应用的兴起,组播技术受到网络研究人员的重视.而这些应用的QoS(quality of service)需求又进一步推动了QoS敏感的组播路由协议的发展.在已提出的各种QoS组播路由协议中,如何提高呼叫成功率、增强规模伸缩性、降低控制报文开销,仍然是一个有待探索的问题.提出了一个新的QoS组播路由协议,其基本思想是使路由器只存储其两层邻居节点的可达性信息以及链路的QoS状态信息,以减少路由器存储开销,提高协议的规模伸缩性(scalability).协议采用受限的泛播技术,构造了一个接受节点发起的、采用多路径技术的、分布式路由算法.描述了协议的数据结构、组播树的构造算法,并给出了模拟实验结果.分析表明,基于受限泛播技术的组播路由协议具有节点存储开销小、呼叫接收成功率高等特点.虽然该协议付出了泛播引起的额外带宽开销较大的代价,但是由于协议所需要的控制数据总量不大,加上两层存储结构在一定程度上限制了泛播通信量,因此该方案具有很好的性能.