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1组播技术概述组播(Multicast)又称为多播、多址广播、多地址广播和成组通信等,是相对于单播和广播方式而言的一种网络通信方式。IP组播技术作为IP网络中主机之间通信的一种模式,是通过组播地址寻址,向所有网络节点中某个确定子集(该子集被称为组播组)的成员发送数据包的技术。它的基本思想是源主机只需发送一份数据,属于该子集的所有接收者都可以收到相同的数据拷贝,而不属于该子集的主机则不能接收该数据拷贝。IP组播技术有效地解决了单点发送多点接收和多点发送多点接收等问题,实现了IP网络点到多点的高效数据传输。与传… 相似文献
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应用层组播是群组通信技术中的一个研究热点,针对未来数字化战场对多媒体信息传输的要求.设计并实现了一个基于代理的多源应用层组播系统PMALMS。该系统利用了基于代理的服务模式和P2P的网络技术.同时采用了经过优化的共享组播树构建和数据分发算法,有效地提高了多源应用层组播系统的性能和效率。 相似文献
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IP组播技术实现了IP网络中点到多点的高效数据传送。由于能够有效地节约网络带宽、降低网络负载,IP组播技术在实时数据传送、多媒体会议、数据拷贝、游戏和仿真等诸多方面都拥有广泛的应用前景。但是,目前中国运营商开展组播业务的实例并不多,主要是因为在现网中实施组播技术还存在一些问题,下面就分别对这些问题进行论述。 相似文献
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组播通信可以有效地减轻网络负担,避免资源浪费,是一种十分有效的通信方式。简要介绍IP组播技术的概念、原理及体系结构,描述IGMP Snooping协议在VOD系统中的应用,在此基础上设计基于IP组播技术的VOD系统。 相似文献
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IP网络组播技术的新发展 总被引:12,自引:1,他引:11
本文综述了IP网络中组播实现体制和技术的新发展。首先.对在IP层实现组播的体系结构——IP组播进行了深入的探讨,分析、比较了IP组播两种业务模型——标准业务模型和确定源节点业务模型,讨论了IP组播存在的问题和发展趋势。接着,对应用层实现组播的体系结构进行了讨论,描述了应用层组播体制的主要功能和机制,对主要的几个应用层组播方案进行了比较,探讨了应用层组播体制的优缺点。最后对未来Internet中组播业务的实现提出了一些看法。 相似文献
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IP 组播技术是一种可以把单个数据信息同时分发到不同的用户去的网络技术。卫星网络固有的广播信道特性使得它很适合组播应用。然而目前针对卫星网络的可靠组播服务研究很少,虽然已经有一些关于地面Internet组播协议建议,但他们并不适合于卫星网络。在卫星网络组播传输中的一个关键技术是传输协议设计。该文提出一种基于Agent的宽带卫星网络可靠组播传输协议(ASMTP)。该协议利用接收端Agent来实现卫星组播,采用分组级FEC和本地差错恢复纠正传播中的非相关错误和相关错误。在ASMTP中,还实现了流量控制和拥塞控制机制。仿真结果表明,在卫星网络环境中,ASMTP性能优于MFTP(Multicast File Transport Protocol),同时具有较好的网络可扩展性。 相似文献
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Many multicast applications, such as video‐on‐demand and video conferencing, desire quality of service (QoS) support from an underlying network. The differentiated services (DiffServ) approach will bring benefits for theses applications. However, difficulties arise while integrating native IP multicasting with DiffServ, such as multicast group states in the core routers and a heterogeneous QoS requirement within the same multicast group. In addition, a missing per‐flow reservation in DiffServ and a dynamic join/leave in the group introduce heavier and uncontrollable traffic in a network. In this paper, we propose a distributed and stateless admission control in the edge routers. We also use a mobile agents‐based approach for dynamic resource availability checking. In this approach, mobile agents act in a parallel and distributed fashion and cooperate with each other in order to construct the multicast tree satisfying the QoS requirements. 相似文献
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IP组播是一种高效的多目标传输机制.随着网络的发展,组播在网络的应用占据着越来越重要的地位,其应用不断扩展,技术日益成熟.目前,组播作为一个崭新的学术研究领域,在组播路由算法、流量控制、可靠传输等方面的研究已有很多成果,而对于组播安全问题的研究特别是组播通信密钥的研究还很不成熟.本文通过研究绀播通信安全进行深入的研究,对比各种密钥管理方法,研究了可扩展的密钥管理方法.该密钥管理体系采用分层管理结构,采用子管理中心对各个子域进行管理,不仅可以高效地处理组播组成员动态加入和退出,同时,大大减少了密钥管理中心的负担.使该方法可以应用于大型、动态的组播系统.此外,该方法根据现有的网络和组播系统的要求,提出了控制中心由计算机组进行统一调度管理,避免了单点故障的问题,增加了系统的鲁棒性. 相似文献
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Multicast communications concern the transfer of data among multiple users. Multicast communications can be provided at the network layer—an example is IP multicast—or at the application layer, also called overlay multicast. An important issue in multicast communications is to control how different users—senders, receivers, and delivery nodes—access the transmitted data as well as the network resources. Many researchers have proposed solutions addressing access control in IP multicast. However, little attention has been paid to overlay multicast. In this paper, we investigate the access control issues in overlay multicast and present OMAC: a new solution to address these issues. OMAC provides access control for senders, receivers, and delivery nodes in overlay multicast. The proposed architecture, which is based on symmetric key cryptosystem, centralizes the authentication process in one server whereas it distributes the authorization process among the delivery nodes. Moreover, delivery nodes are utilized as a buffer zone between end systems and the authentication server, making it less exposed to malicious end systems. To evaluate our work, we have used simulation to compare the performance of OMAC against previous solutions. Results of the simulation show that OMAC outperforms previous multicast access control schemes. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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This paper proposes a mechanism called a Multicast Handoff Agent (MHA) to reduce handoff latency for IP multicast. The MHA acts as a proxy for the Internet Group Management Protocol (IGMP) of mobile nodes and keeps information for members of multicast groups in a cell. When a mobile node moves to other cell, the MHA immediately sends unsolicited reports without waiting for the IGMP query. In addition, our mechanism may conserve battery power since it does not need to reply to a query.The mechanism is evaluated through simulation and analysis and compared with the IGMPv2 for mobility and IGMP traffic. Simulation results show that handoff latency can be largely reduced and the IGMP control traffic can be eliminated on the wireless links during the duration of membership. 相似文献
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We propose and analyze a multicast algorithm named Dynamic Agent-based Hierarchical Multicast (DAHM) for wireless mesh networks that supports user mobility and dynamic group membership. The objective of DAHM is to minimize the overall network cost incurred. DAHM dynamically selects multicast routers serving as multicast agents for integrated mobility and multicast service management, effectively combining backbone multicast routing and local unicast routing into an integrated algorithm. As the name suggests, DAHM employs a two-level hierarchical multicast structure. At the upper level is a backbone multicast tree consisting of mesh routers with multicast agents being the leaves. At the lower level, each multicast agent services those multicast group members within its service region. A multicast group member changes its multicast agent when it moves out of the service region of the current multicast agent. The optimal service region size of a multicast agent is a critical system parameter. We propose a model-based approach to dynamically determine the optimal service region size that achieves network cost minimization. Through a comparative performance study, we show that DAHM significantly outperforms two existing baseline multicast algorithms based on multicast tree structures with dynamic updates upon member movement and group membership changes. 相似文献
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Traditionally, wireless cellular communication systems have been engineered for voice. With the explosive growth of Internet applications and users, there is an increasing demand on providing Internet services to mobile users based on the voice-oriented cellular networks. However, Internet services add a set of radically different requirements on to the cellular wireless networks, because the nature of communication is very different from voice. It is a challenge to develop an adequate network architecture and necessary systems components to meet those requirements.This paper describes our experience on developing Internet services, in particular, mobile and multicast IP services, in PACS (Personal Access Communication Systems). Our major contributions are five-fold: (i) PACS system architecture that provides wireless Internet and Intranet access by augmenting the voice network with IP routers and backbone links to connect to the Internet; (ii) simplified design of RPCU (Radio Port Controller Unit) for easy service maintenance and migration to future IP standards such as IPv6; (iii) native PACS multicast to efficiently support dynamic IP multicast and MBone connectivity; (iv) optimization and incorporation of Mobile IP into PACS handoff mechanism to efficiently support roaming within a PACS network as well as global mobility between PACS networks and the Internet; (v) successful prototype design of the new architecture and services verified by extensive performance measurements of IP applications. Our design experience and measurement results demonstrate that it is highly feasible to seamlessly integrate the PACS networks into the Internet with global IP mobility and IP multicast services. 相似文献
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Y. Desmedt 《BT Technology Journal》2006,24(3):77-83
It is a myth the Internet has been designed to withstand a denial of service attack. At the BlackHat 2005 conference it was
shown that potential attacks against routers are far from hypothetical. These attacks are about compromising the integrity
of routers and hence the Internet. Current TCP/IP protocols, even including IPsec, do not have the resilience to deal with
routers taken over by the adversary. Indeed, IPsec only provides point-to-point cryptography–hence if a point is compromised,
it fails.
We survey the research done in the area of how to communicate reliably and/or privately in the presence of different types
of adversary, particularly denial of service attacks against nodes/routers. Evidently, if the adversary can control all nodes
(routers) in the network, no solution exists. The nodes that can be attacked by the adversary can be described using a threshold,
or by what is called an adversary structure. The types of network in question can be point-to-point or broadcast/multicast. 相似文献
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Supporting IP Multicast for Mobile Hosts 总被引:6,自引:0,他引:6
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互联网组播技术可以从根本上改善网络带宽的利用率,使发送者和路由器的处理消耗以及发送延迟降到最低的程度。IGMP是一种应用比较广泛的组播用户组管理协议,但是本身没有认证功能。PAP(密码认证协议)提供了一种简单的可以使端对端使用2次握手建立身份验证的协议。论文提出一种IGMP改进方案,把PAP认证协议添加在IGMP v3协议的扩展字段中,用于组播路由的最后一跳认证。 相似文献
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IP组播技术是新兴的网络技术,依托卫星网络的组播业务更是下一代Internet为用户提供的主流服务。文章详细介绍IP组播技术,对其在卫星网络应用中存在的主要问题、解决方法及常用的卫星组播网络拓扑结构进行阐述和分析。 相似文献