基于Chord的域间组播解决方案

域间组播是大范围内部署组播时需要考虑的主要因素。该文提出了一种基于Chord查找协议的简单有效的域间组播方案。该方案具有良好的扩展性和负载平衡性,能够很好地支持任意源组播(ASM),并为主机移动组播提供了方便。不仅描述了该组播方案的构建,还分析了该方案所具有的特点及其自身的安全特性。     

应用层组播动态调整问题的研究

通过分析影响应用层组播性能的因素及这些因素的变化对组播性能的影响,指出了在组播过程中随着成员的加入退出、网络波动和结点处理能力的变化,组播的结构和性能都会发生变化。在组播开始时构建的组播树无法适应这些变化,导致了组播性能的下降。针对该问题提出了在组播过程中根据变化调整组播树的结构,并给出了一种改善组播性能的动态调整算法。实验结果表明,动态调整算法能够有效的反映组播的结构、网络状况和结点情况,改善组播的性能。     

Topology Design of Network-Coding-Based Multicast Networks

It is anticipated that a large amount of multicast traffic needs to be supported in future communication networks. The network coding technique proposed recently is promising for establishing multicast connections with a significantly lower bandwidth requirement than that of traditional Steiner-tree-based multicast connections. How to design multicast network topologies with the consideration of efficiently supporting multicast by the network coding technique becomes an important issue now. It is notable, however, that the conventional algorithms for network topology design are mainly unicast-oriented, and they cannot be adopted directly for the efficient topology design of network-coding-based multicast networks by simply treating each multicast as multiple unicasts. In this paper, we consider for the first time the novel topology design problem of network-coding-based multicast networks. Based on the characteristics of multicast and network coding, we first formulate this problem as a mixed-integer nonlinear programming problem, which is NP-hard, and then propose two heuristic algorithms for it. The effectiveness of our heuristics is verified through simulation and comparison with the exhaustive search method. We demonstrate in this paper that, in the topology design of multicast networks, adopting the network coding technique to support multicast transmissions can significantly reduce the overall topology cost as compared to conventional unicast-oriented design and the Steiner-tree-based design.     

On Bandwidth-Efficient Overlay Multicast

In this paper, we propose a new multicast delivery mechanism for bandwidth-demanding applications in IP networks. Our mechanism, referred to as multiple-destination overlay multicast (MOM), combines the advantages of IP multicast and overlay multicast. We formulate the MOM routing problem as an optimization problem. We then design an algorithm based on Lagrangian relaxation on our formulation and propose a distributed protocol based on the algorithm. For network operators, MOM consumes less network bandwidth than both IP multicast and overlay multicast. For users, MOM uses less interface bandwidth than overlay multicast.     

基于代理的覆盖网组播生成树算法研究

利用覆盖网组播技术构建组播服务平台是一种可行的提供组播服务的方案.基于代理的覆盖网组播兼具覆盖网组播的灵活性和IP组播的高效性的特点.结合节点的带宽、处理延迟和节点间的通信延迟给出一个完善的基于代理的覆盖网组播模型,根据此模型设计了求节点度受限的具有最小平均延迟的组播转发树生成算法.探讨了主机节点在进行数据分组复制转发时的转发顺序对平均延迟的影响,给出并证明了主机节点对数据分组复制转发的最优策略.通过仿真实验验证了所给算法和最优复制转发策略的有效性.     

同源同宿SSM组播路由控制技术研究

由于组播报文总是沿着从组播接收者到组播发送者单播路由的相反方向进行转发,这决定了同一主机收到的同一组播源的不同组播流通常总是沿着相同的路径传送。针对某些应用场景中需要将这些报文人工分流到不同的链路传送的情况,在阐述组播转发原理的基础上,探讨了组播路径控制的关键技术,并提出了解决此类组播分流问题的思路,在现网上部署后满足了业务系统需求,同时方案简单和易于工程实现。     

TMCP: Two-layer multicast communication protocol for Bluetooth radio networks

Bluetooth is a low power, low cost, and short-range wireless technology developed for Personal Area Networks (PANs). A Bluetooth multicast group is a set of Bluetooth devices that desire for periodically receiving the multicast messages from the same source. For reducing the propagation delay and saving the bandwidth and energy consumptions, a multicast tree which connects all multicast members serves for the delivery of multicast messages. However, a given connected scatternet topology may not be appropriate for constructing an efficient multicast tree and hence causes power consumption and end-to-end delay. This paper develops a two-layer multicast communication protocol (TMCP) using role switching techniques for constructing an efficient multicast tree. The proposed TMCP collects as many as possible the members into the same piconet, reduces the length of multicast paths and assigns each member with a proper role. The constructed multicast tree has several features including as few as possible the non-member devices, the smallest tree level and the minimal propagation delay. Experiment results show that the TMCP offers efficient multicast service with low power consumption and small delay.     

Hydra: Efficient multicast routing in MANETs using sender-initiated multicast meshes

We present Hydra, the first multicast routing protocol for MANETs that establishes a multicast routing structure approximating the set of source-rooted shortest-path trees from multicast sources to receivers, without requiring the dissemination of control packets from each source of a multicast group. Hydra accomplishes this by dynamically electing a core for the mesh of a multicast group among the sources of the group, and aggregating multicast routing state in the nodes participating in multicast meshes, so that only control packets from the core are disseminated towards the receivers of a group. We prove that Hydra establishes correct routes from senders to receivers of a multicast group when multicast state information is aggregated. We also present simulation results illustrating that Hydra attains comparable or higher delivery ratios than the On-Demand Multicast Routing Protocol (ODMRP), but with considerably lower end-to-end delays and far less communication overhead. Results are shown for scenarios using 802.11 DCF and TDMA as the MAC layer protocols and using random waypoint and group mobility as mobility models.     

Internet TV中受控组播的设计与实现

在Internet TV中,为解决现有的组播协议不支持用户认证,缺乏对数据访问的控制,在流量扩散安全性,频道切换延时等方面上存在的问题,通过扩展现有的组播协议,提出了完整的网络接入认证流程,加入组播组流程,退出组播组流程,异常／强制退出组播组流程,断网流程,实现了受控组播协议,使得对数据的访问得到控制,整个服务完全受控于服务方,减少了频道切换的响应时间,并通过SR仿真试验,验证了受控组播协议在Internet TV中的可实用性。     

遗传算法在聚合组播问题优化中的应用

IP组播至今仍没有在Internet上被广泛应用,其中一个重要原因是组播转发状态的扩展性问题。聚合组播是一种减少组播转发状态的新技术,其主要目标是使网络中能够复合的组播组共用一棵组播分发树,从而减少转发状态,提高网络性能。采用遗传算法求解聚合组播问题。仿真结果表明,该算法对聚合组播问题有巨大的优化作用。     

动态层次小组多播路由的研究

在分析现有多播路由协议的基础上,本文提出了动态层次小组多播路由。多播数据源可以根据自治系统（AS）中接收者的多少而动态决定发送多播数据的方式。在一个AS中,对于一个特定的多播源,当多播数据接收者的数量较少时,用单播的方式;当自治系统中接收者较多时,用组地址的方式转发多播数据。同样,AS中的分枝节点亦可以根据该策略构造以分枝节点为根的动态管理方式,从而动态地构造层次多播路由体系结构。本文还定义了动态层次多播路由算法的数据结构以及功能模块,并从网络带宽与路由器计算两方面面分析了动态层次小组多播路由协议分发多播数据时的代价。     

Island Multicast: Combining IP Multicast With Overlay Data Distribution

Traditional overlay protocols use unicast connections to form delivery trees. While it can achieve global multicast across the Internet, it is not as efficient as IP multicast. In this paper, we integrate IP multicast into overlay data distribution to improve delivery efficiency. We investigate island multicast where unicast connections are used to connect multicast domains and IP multicast is used within multicast domains. We first explore a centralized island multicast protocol (termed CIM), which relies on a central server to construct a delivery tree. We then study a distributed protocol (termed DIM), where hosts can distributedly join islands and form a delivery tree. We study the key issues in both protocols. We also discuss how to apply these protocols to media streaming applications. We have evaluated both protocols on Internet-like topologies. We have also implemented a prototype for CIM and tested it on PlanetLab. The results show that our approaches can significantly im prove network performance as compared to pure overlay protocols. Our study shows that it is important to consider local multicast capability when designing overlay protocols.     

基于组播网关的可靠组播体系结构

保证组播通信的可靠性是许多Internet上的组播应用的前提.针对IP组播在Internet中难以规模化部署的现状,提出了一种使用组播网关将IP组播岛与应用层组播(ALM)区域连接起来的可靠组播(RM)体系结构,对组标识、组播网关、组管理、差错控制和拥塞控制等关键问题给出了解决方案,并设计了组播网关竞争算法.该结构能够屏蔽底层组播技术差异,从而支持Internet上统一化的可靠组播服务部署.     

BGP/MPLS VPN组播链路恢复方案

BGP/MPLS VPN组播链路失效后,一棵组播树会断开成不相连的子树。为此,使用备用路径连接子树,重构组播树,减少备用链路上的离线概率加权主机数。找出备用路径建立时失效链路对组播树的影响因子,设计组播备用路径算法,使该影响因子最小化,从而提高组播树的健壮性。分析结果表明,该算法能实现组播链路的快速恢复。     

Nonblocking k-fold multicast networks

Multicast communication involves transmitting information from a single source to multiple destinations and is a requirement in high-performance networks. Current trends in networking applications indicate an increasing demand in future networks for multicast capability. Many multicast applications require not only multicast capability, but also predictable communication performance such as guaranteed multicast latency and bandwidth. In this paper, we present a design for a nonblocking k-fold multicast network, in which any destination node can be involved in up to k simultaneous multicast connections in a nonblocking manner. We also develop an efficient routing algorithm for the network. As can be seen, a k-fold multicast network has significantly lower network cost than that of k copies of ordinary 1-fold multicast networks and is a cost effective choice for supporting arbitrary multicast communication.     

负载均衡的聚合组播技术研究

聚合组播技术是近年来针对组播状态可扩展性问题提出的热点方案,但现有的聚合组播算法和协议缺乏网络流量的负载均衡机制,使网络整体利用效率下降,并容易因聚合产生拥塞。为此,提出一种基于负载均衡的聚合组播协议AMPLB,仿真结果表明其在保证聚合性能的同时使网络流量分布更加均衡,降低出现拥塞的风险,可较好地改善大规模组播网络的性能。     

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     

基于MPLS的按需分枝组播方法

提出一种新的基于MPLS的组播方法--按需分枝组播方法.该方法采用一种全新的组播树维护方式,即组播树上只有分枝节点处的路由器和本地链路上有组成员的路由器需要保存组播树的有关信息,并参加组播树的维护过程,组播树上的其它路由器只是以普通单播的路由方式组播数据包,无须维护组播树的任何信息.网络仿真实验和与其它算法性能比较分析表明,该方法可有效地提高IP组播的可量测性和减少转发状态.     

用于超大Infiniband网络的负载均衡多播路由

高性能计算中,硬件支持的多播操作对应用程序性能具有至关重要的影响.Infiniband网络中现有的两类多播路由算法中,MINIHOP-MC未考虑路由均衡性问题,导致链路edge forwarding index(EFI)指数很大,严重影响多播消息性能;SSSP-MC虽然部分考虑了路由均衡性问题,但其运行时间很长,不能满...