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．     

IP多播路由技术研究

随着高性能网络技术的不断发展,IP多播路由技术已经成为网络领域的一个重要研究课题,对未来网络发展有重要意义。本文论述了IP多播路由技术的研究情况及IP多播路由技术的发展现状,介绍了几种重要的IP多播路由协议并简单进行了对比,同时介绍了几种IP多播路由算法及其分类,最后给出了IP多播路由技术的应用领域和待研究的问题。     

计算机网络中的多播路由问题

在计算机网络中，多播是目前研究最多、应用最广的连接方式。就目前存在的多播路由算法及路由协议进行了分析与总结，给出了解决多播问题的一般方法，提出了在光网络中推行多播的必要性。     

基于QoS约束的多播路由研究

该文给出了多播路由的定义和多播树的分类,描述了一种适用于研究QoS多播路由的网络模型,对多播路由算法进行了分类,介绍了典型的基于QoS约束的多播路由协议和算法,对每个算法的性能特性和适应范围进行了客观的评价,提供了QoS多播路由算法复杂度的比较,对QoS多播路由技术的进一步研究进行了展望。     

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。     

计算机网络中的多播路由问题

本文探讨了多播路由的定义,对多播路由的算法进行了简单分类,最后对每个算法的性能进行了客观的评价,对多播路由技术的进一步研究进行了展望。     

基于MANET的QoS多播路由协议研究

在自组织网络上运行多媒体应用，正在成为随遇计算和随遇通信环境中的一个完整部分，同时提出了对QoS和多播的需求，如何设计有效的QoS多播路由协议已经成为当前研究的热点问题。本文介绍了自组网QoS多播路由协议研究方面的一些最新进展，并对该研究所提出的路由算法进行了比较和分析，有助于进一步改进和完善自组网的QoS多播路由技术。     

AdHoc网络多播路由协议研究进展分析

基于AdHoc网络的特殊性,固定网络中已有的多播路由协议已经难以有较好的适应度,怎样在移动无线自组织网络中实现效率较高的多播路由已成为一个极具挑战性的问题。分析了移动无线自组织网络中多播路由协议所具有的问题以及相应的设计要求;详细阐述了现有的移动无线自组织网络多播路由协议,并对该网络中不同多播路由的方法进行了分析和比较;对移动无线自组织网络中的多播路由协议的使用进行了总结。     

基于主动网络的可靠多播路由协议

主动网络是一种允许用户对网络中间节点进行编程的新型网络结构，该文在多播网络系统模型基础上，探讨了主动网络可靠多播协议的特点和多播路由问题，提出了一个基于主动网络的可靠多播路由协议模型，该协议较好地减少了网络中大量的路由重构和分组的重传，缩短了错误发现和恢复时间。最后，利用仿真实验作了相关计算，给出了RMRPA协议的性能分析及与不可靠多播协议的比较。研究结果表明RMRPA协议为多媒体多播传输提供了一种新的有效途径。     

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。     

面向混合网络的半覆盖组播路由协议

组播已在多个协议层上分别实现,但现有协议仍未兼顾对灵活性与效率的共同需求.总的来说,硬件组播和IP组播较为高效,而覆盖组播则更为灵活.在混合网络中,底层技术的差异使这一问题变得更为突出.为此提出了一种动态自组织的半覆盖组播路由协议HOMR(half overlay multicast routing).该协议把基于组内区域广播的IP组播、基于地址端口转换的覆盖组播以及对各类硬件组播的调用融入单一的模型,在各层组播间按需转换.HOMR具有与全覆盖组播相似的灵活性,模拟实验表明,HOMR在保持较低协议开销的同时,获得了与完全IP组播相近的转发效率.     

Minimization of Multicast Traffic and Ensuring Its Fault Tolerance in Software-Defined Networks

In recent years, the widespread TCP/IP computer network model has been replaced by the software-defined network model, where the control plane is separated from the data plane and is logically centralized. The new model requires a revision of traditional network control protocols. One group of such revised protocols consists of multicast routing protocols. In this paper, the multicast routing protocols used in traditional TCP/IP networks are analyzed, and their basic disadvantages and difficulties in their application in software-defined networks are revealed. Multicast routing algorithms that use the capabilities of software-defined networks and ensure the optimization and reliability of routes in multicast routing are described. These algorithms are exempt from the drawbacks of traditional networks. The proposed algorithms are implemented as an application for the RunOS controller. This experimental study shows that the delays due to the use of the proposed algorithms for restructuring routes satisfy the requirements of telecommunications operators of large regional networks.     

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     

Traffic Engineered Multicast Content Delivery Without MPLS Overlay

Multicast traffic engineering (TE) has recently attracted significant attention given the emergence of point-to-multipoint multimedia content delivery over the Internet. Existing multicast resource provisioning solutions tend to use explicit-routing based TE with multiprotocol label switching (MPLS) tunnels. In this paper, we shift away from this overlay approach and address native IP multicast traffic engineering based on link state routing protocols. The objective is that, through plain protocol independent multicast-sparse mode (PIM-SM) shortest path routing with optimized multitopology IGP (MT-IGP) link weights, the resulting multicast trees are geared towards minimal consumption of bandwidth resources. We apply genetic algorithms (GA) to the calculation of optimized MT-IGP link weights that specifically cater for engineered PIM-SM routing with statistical bandwidth guarantees in multimedia content delivery. Our evaluation results show that GA-based multicast traffic engineering consumes significantly less bandwidth in comparison to conventional IP approaches while also exhibiting higher service availability     

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.     

IP多址广播路由研究

ＩＰ多址广播路由是Ｉｎｔｅｒｎｅｔ协议研究的一个重要的方向,随着Ｉｎｔｅｒｎｅｔ上多址广播的应用和需求不断增长,ＩＰ多址广播路由的研究与实现也变得更加重要和迫切。本文讨论了ＩＰ多址广播路由协议的定义与分类,深入分析了常见ＩＰ多址广播路由协议的算法与实现。     

支持Internet实时多媒体应用的Overlay技术研究

目前出现的大规模（large-scale）的多媒体应用对Internet提出了新的挑战。传统的IP组播（IP multicast，IPM）由于实现技术的复杂性，很难在Internet上推广。相反，基于叠加网络（overlay network，ON）的解决方案则受到各方面的关注。本文针对大规模实时多媒体应用需求，通过建立评价参数模型对ON协议进行研究。尤其时overlay组播（overlay multicast，OM）的QoS控制、可靠性以及可伸缩性机制进行了分析。与IPM相比，OM虽然有性能代价（performance penalty）问题，但是OM能方便、灵活地利用多种高层的功能实现，基于hop-by-hop方式有效地提供E2E（end—to-end）的可靠性和QoS保障，并且较好地支持TCP-friendliness，具有良好的可伸缩性。此外，0M的基础网络（infrastructure／underlay network）无关性，也使其容易在Internet中进行配置。以上特性使得OM成为支持Internet上大规模实时多媒体应用的最具前景的技术．     

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.     

ACOM: Any-source Capacity-constrained Overlay Multicast in Non-DHT P2P Networks

rdquoApplication-level multicast is a promising alternative to IP multicast due to its independence from the IP routing infrastructure and its flexibility in constructing the delivery trees. The existing overlay multicast systems either support a single data source or have high maintenance overhead when multiple sources are allowed. They are inefficient for applications that require any-source multicast with varied host capacities and dynamic membership. This paper proposes ACOM, an any-source capacity-constrained overlay multicast system, consisting of three distributed multicast algorithms on top of a non-DHT overlay network with simple structures (random overlay with a non-DHT ring) that are easy to manage as nodes join and depart. The nodes have different capacities, and they can support different numbers of direct children during a multicast session. No explicit multicast trees are maintained on top of the overlay. The distributed execution of the algorithms naturally defines an implicit, roughly balanced, capacity-constrained multicast tree for each source node. We prove that the system can deliver a multicast message from any source to all nodes in expected O(log_c n) hops, which is asymptotically optimal, where c is the average node capacity and n is the number of members in a multicast group.