基三分层网络中的受限多播路由算法

多播路由算法对互连网络的通信性能和多处理机系统性能的发挥起着重要作用。针对基三分层互连网络,在权衡性能、成本和实现的基础上,提出一种基于树的受限多播路由算法TRMA。该算法充分利用基三分层互连网络的层次特性和节点编码中所含的网络拓扑信息实现消息路由,算法设计简单,易于硬件实现。和其他基于树的多播路由算法相比,TRMA算法不需要源节点在发送消息前构建多播树,并将多播树的信息存放在消息中,大大降低了源节点的工作负载,提高整个系统的性能。通过仿真比较了TRMA和基于单播的多播路由算法,结果表明TRMA具有较低的网络延迟和较小的网络流量。     

一种基于分发树切分的分布式聚集多播协议

随着网络组通讯应用的广泛开展,IP多播将由于路由状态信息爆炸以及控制信息爆炸而面临严重的扩展性问题。在主干网中,这种状态可扩展性问题尤为严重。为了提高主干网中多播状态的可扩展性,本文提出了一种基于数据分发树切分的聚集多播协议——BEAMBTS(Bi-dirEctional Aggregated Multicast Based on Tree Splitting)。BEAMBTS是一种简单而易于实现的、使用双向树的分布式协议。仿真试验显示,BEAMBTS可以更好地改善状态可扩展性。     

基于多树的移动自组织网多播路由协议

由于移动节点能量耗尽严重影响了移动自组织网(MANET)路由性能,有效地使用移动节点的能量是非常重要的。为此,提出基于多树的移动自组织网多播路由协议(MTMR)。MTMR协议先计算移动节点能量,将能量低于门限值的节点不参与路由。然后,将参与路由的节点构建不同的树,源节点通过这些树向目的节点传输数据,从而实现多播路由。仿真结果表明,提出的MTMR协议有效地提高了数据传输率,降低了端到端传输时延。     

一种新的QoS覆盖多播路由协议的研究

研究了QoS覆盖多播路由问题,对度约束模型进行扩展,提出了一个新的支持QoS路南的覆盖多播网络模型．基于此模型,提出丁一个新的QoS覆盖多播路南协议QOS覆盖多播树协议（QOMTP）．该协议采用分布式和树优先的策略,使多播组成员之间能自组织地构建一棵基于源的、满足QoS约束的覆盖多播树．该协议采用了一种新的启发式局部优化算法,通过调节启发因子,能灵活地在延时和带宽之间进行均衡．仿真实验表明,采用按请求带宽转发媒体流,并选择适当的启发因子,QOMTP协议能减少多播树上节点的网络资源占用越,同时获得较高的节点接纳率和较好的动态适心性,从而证明了该协议机制及其算法的有效性．     

一种基于遗传算法的半动态应用层多播协议

将半动态应用层多播通信分解为静态起始和动态维护两种阶段交替出现的过程．在起始阶段．采用基于遗传算法的多播路由机制构建优化的静态多播树;在维护阶段,采用拓扑维护机制、路由性能监控机制和路由更新机制．对多播拓扑的动态进行快速响应．仿真结果表明．该协议同时具备优化多播树性能和快速维护多播拓扑的能力,改善了通信过程中多播树的整体性能．     

一种支持多QoS约束的多播路由协议

在分析YAM、QoSMIC和QMRP协议的基础上,讨论了包括延时、延时抖动、带宽和代价约束的多播路由问题,描述了一种适用于多QoS约束的多播路由的网络优化模型,提出了一种支持多QoS约束的多播路由协议（MRPMQoS）,构建在NS2下该协议的仿真模块.该协议只要求网络链路（或节点）的局部状态信息,不需要维护全局状态信息,多播组成员可动态地加入/退出多播会晤.该协议采用单路径寻径和多路径寻径相结合的搜索方式,有效地减少构造一棵多播树的开销,降低结点加入延时和提高寻径成功率.NS2仿真结果证明,该协议的可用性和有效性,可用于不同规模网络,具有良好的可扩展性.     

基于移动代理的QoS多播路由技术研究

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约束的多播路由协议越来越重要.针对目前多播路由协议无法同时满足可扩展性和高成功率,提出了一种新的以移动代理为基础的QoS多播路由协议(MAQMR).该方法允许多播协议在移动代理间实现并在代理所访问的每个结点得到动态应用.不同于单播路由,移动代理以并行和分布形式协作方式来构建多播树,同时使消息开销最小化并满足QoS要求.     

基于欧氏最小生成树的无线Ad Hoc网络容量研究

无线Adhoc网络容量是当前的一个研究热点。在Gupta和Kumar提出的协议模型和物理模型基础上,推导了无线Adhoc网络基于欧氏最小生成树的单播、多播容量,且指出当多播组尺寸小于总的网络节点数时,多播容量比单播容量大。基于NS-2的仿真实验验证了多播容量上限是有效的。     

移动Ad Hoc网络中基于NACK的可靠多播协议

如何采用有效的机制来保证多播数据的可靠传输是移动Ad Hoc网络中的一个难题.针对IEEE 802.11 MAC层进行改进,提出了一种基于使用NACK消息的可靠多播协议,该协议仅当数据分组传输出错时才发送NACK消息要求重传数据.仿真结果表明使用该协议能提高多播路由传输数据的吞吐量,同时降低了平均时延.     

基于贪婪策略的高效可靠多播路由协议

无线Mesh多播路由协议多数是通过建立多播树实现,导致一些相邻链路上可利用的传输被忽略。另外,建立多播树的过程需要占用较多的时间和空间资源,以及整个网络的全局信息。为进一步提高网络性能,在Mesh网络多播路由中采用贪婪策略,不建立多播树,而是让在局部区域内发送效率最高的节点发送数据,充分利用无线Mesh网络中的有效链路,且仅需相邻节点间的局部信息即可实现完全分布式。仿真实验结果表明,基于该策略的路由协议比Pacifier协议的性能有较大提高。     

Reconfigurable multicast routing for Networks on Chip

Several unicast and multicast routing protocols have been presented for MPSoCs. Multicast protocols in NoCs are used for cache coherency in distributed shared memory systems, replication, barrier synchronization, or clock synchronization. Unicast routing algorithms are not suitable for multicast, as they increase traffic, congestion and deadlock probability. Famous multicast schemes such as tree-based and path-based schemes have been proposed originally for multicomputers and recently adapted to NoCs. In this paper, we propose a switch tree-based multicast scheme, called STBA. This method supports tree construction with a minimum number of routers. Our evaluation results reveal that, for both synthetic and real traffic loads, the proposed scheme outperforms the baseline tree-based routing scheme in a conventional mesh by up to 41% and reduces power consumption by up to 29%.     

Efficient Internet Multicast Routing Using Anycast Path Selection

A novel efficient and dynamic multicast routing protocol based on anycast routing techniques is presented. The contributions of the protocol differ from well-known shared-tree systems in two aspects: (1) Off-tree anycast routing: The nodes in the shared tree are formed into a virtual anycast group and multicast sources use anycast routing to select a better path from the source to one router in the group to achieve short delay and fault-tolerance. (2) On-tree dynamic routing: The shared-tree approach is extended with capability of alternative path selections. If a node becomes absent from the shared tree, some predefined backup path(s) is (are) used to bypass the node and enable dynamic multicast routing to continue. The protocol requires only the routers near the faulty node to be reconfigured, thus reducing the runtime overhead as compared with global reconfiguration. The simulation data demonstrates the efficiency of our routing protocol.     

一种基于内容的双向共享组播路由协议

针对组播协议在大规模分布式交互系统应用中面临的可扩展性问题,提出一种基于内容的双向共享组播路由协议CBSMRP(content-based bi-directional shared multicast routing protocol).该协议结合运用了主动路由思想和基于内容的发布-订购模式,在基于CBT(core-based tree)结构的双向共享组播树中,根据数据包的内容实现主动路由和双向过滤,不仅解决了组播地址的维护和分配等问题,而且能够有效地减轻系统的网络负载.仿真实验及实际应用表明,该协议具有较好的扩展性,能够满足大规模分布式交互系统的网络通信要求.     

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.     

An efficient fault-tolerant multicast routing protocol withcore-based tree techniques

In this paper, we design and analyze an efficient fault-tolerant multicast routing protocol. Reliable multicast communication is critical for the success of many Internet applications. Multicast routing protocols with core-based tree techniques (CBT) have been widely used because of their scalability and simplicity. We enhance the CBT protocol with fault tolerance capability and improve its efficiency and effectiveness. With our strategy, when a faulty component is detected, some pre-defined backup path(s) is (are) used to bypass the faulty component and enable the multicast communication to continue. Our protocol only requires that routers near the faulty component be reconfigured, thus reducing the runtime overhead without compromising much of the performance. Our approach is in contrast to other approaches that often require relatively large tree reformation when faults occur. These global methods are usually costly and complicated in their attempt to achieve theoretically optimal performance. Our performance evaluation shows that our new protocol performs nearly as well as the best possible global method while utilizing much less runtime overhead and implementation cost     

Improving source routing reliability in mobile ad hoc networks

In this paper, we propose a novel on-demand routing protocol called backup source routing (BSR) to establish and maintain backup routes that can be utilized after the primary path breaks. The key advantage of BSR is the reduction of the frequency of route discovery flooding, which is recognized as a major overhead in on-demand protocols. We define a new routing metric, called the route reliability, and use it to provide the basis for the backup path selection. We use a heuristic cost function to develop an analytical model and an approximation method to measure this metric. Various algorithms for our BSR protocol in the route discovery phase and route maintenance phase have been designed based on this cost function. Extensive simulations demonstrated that our routing strategy has two interesting features: 1) in less stressful situations of lower mobility, BSR has similar performance to DSR, 2) in more challenging situations of high mobility, BSR can improve the performance significantly.     

一种移动因特网中层次型QoS多径组播路由协议

提出了一种移动因特网中满足QoS约束的组播路由协议QoSHMM．基于“同层成环、异层构树”的原则,该协议建立一棵特殊的QoSHMM组播环树,从而在目的节点与源节点之间形成一条具有最短时延的路径和多条满足时延受限成本较小的路径．模拟结果显示。QoSHMM组播环树在平均切换延迟方面表现出了很好的性能。同时由于采用三态传输机制,该协议也具有很好的容错性．     

结合集中式与分布式特征的多路径QoS组播路由协议

提出了一个结合集中式算法与分布式算法优点的多路径启发式QoS组播路由算法和协议,它以单播路由协议OSPF传播链路的代价信息为基础,运用最小代价Dijkstra算法计算端节点到当前在树节点的最小代价路径,然后启动一个分布式计算过程得到一个可选路径集,加入节点通过一个综合性启发式选择其中的最佳路径连接到组播树．算法能够有效地支持延时和带宽受限的代价优化组播树构造,具有无环选路、呼叫接收成功率高、呼叫建立时间短、伸缩性好等特点．