可扩展组播及其在数据中心网络中的应用

文章认为组播协议的可扩展性一直是阻碍组播技术广泛部署的重要因素之一,为此文章探讨了互联网环境下几种可扩展组播的解决方案:基于组成员稀疏分布的可扩展组播方案、基于布鲁姆过滤器的可扩展组播方案、基于聚合组播树的可扩展组播方案;数据中心网络中可扩展组播面临的新挑战主要来自于硬件限制导致无法同时容纳大量的组播组,同时基于组成员稀疏分布的可扩展组播方案和聚合组播树的方案在数据中心网中应用受限,为此文章探讨了数据中心网络环境下混合使用组播和单播的可扩展组播方案、基于布鲁姆过滤器的可扩展组播方案。摘要:     

固定组成员的应用层组播树不稳定问题

传统的组播树稳定性研究一般都是基于组播成员的动态变化的.但在应用层组播中,由于组播树的组成节点是应用层的端系统节点,组播成员可以通过欺骗以企图在组播树上占据更有利的位置,从而在组播成员不变时也会造成组播树的不稳定.本文建立了应用层组播节点的欺骗模型,并讨论了在固定组成员的情况下,节点欺骗引起的组播树不稳定问题.模拟实验结果表明,节点欺骗对应用层组播树的稳定性有极大的负面影响.     

无线传感器与执行器网络组播技术研究

组播是将给定消息从一个源节点发送到若干个目标节点的通信模式。在组播中,给定消息沿着路由从一个节点发送到多个目标节点,这些目标节点的位置是任意的,且分布在整个网络内。文章给出了WSAN(无线传感器与执行器网络)中组播的定义与数学描述,分析了Ad hoc网络组播协议以及基于树与网格的组播协议特征与思路,描述了LAM(轻量级自适应组播)、DDM(差异目标组播)、GMP(地理组播协议)、PBM(基于位置的组播)、GMR(地理组播路由)、HRPM(分层汇聚点组播)、HGMR(分层地理组播路由)等地理组播协议的工作原理。     

基于IPv6的特定源组播的组播侦听发现技术

随着组播技术的发展,特定源组播已经作为一种切实可行的通信模型.本文在探讨特定源组播和组播侦听发现协议的工作原理和体系结构的基础上,研究了基于组播侦听者的组播侦听发现协议的实现机制和内核流程,并针对现存的组播接口状态转换问题,给出了解决方案.     

IP组播技术研究与实现

主要介绍了IP组播技术、IP组播协议的分类及域内组播路由协议比较;详细地给出了综合业务交换机上IP组播软件的实现框架,并对PIM-SM组播路由模块、IGMP协议模块和组播数据转发模块的设计进行了简要的说明。IP组播技术的应用将不断得到重视和扩大。     

IP组播技术及其应用

本文介绍了IP组播技术体系的结构、组播的IP地址和组播的各种协议,并结合实际介绍了组播的各种应用。     

基于IP组播的MPLS组播架构

介绍一种多标签交换协议（MPLS）组播架构的实现。此种方案主要根据网络协议（IP）组播的工作原理和MPLS组播树（MMT）的管理方式,不仅可以快速的实现MPLS组播,与IP组播衔接良好,并且便于MPLS组播管理。通过IP组播路由表与MPLS层路由表建立一一映射关系,实现组播路径（M_LSP）的建立;采用上游按需分配的标签分配方式实现MPLS组播成员的加入和退出,解决了MPLS组播的扩展性问题。最终,实现基于IP组播的MPLS组播,并且通过仿真软件（OMNET＋＋）仿真实现进行验证。     

无线窄带组播实现技术

组播业务是网络中的一项重要应用,通过组播技术可极大减小网络的开销,然而由于无线窄带网络的特点,常用的组播技术无法直接应用在无线窄带环境中。文章概述了组播技术的原理,归类总结了目前有线网络中常用的组播技术,并对无线自组网络中的组播技术进行了对比分析。最后根据无线窄带网络的特点,提出了基于源路由多目地址机制的组播实现技术及在话音组播上的改进,详细分析了实现过程。     

EPON接入网中的组播实现

简要介绍了EPON技术及IP组播技术,然后阐述了EPON设备的组播实现原理和动态组播控制技术,并基于国内运营商的城域网架构,给出了城域网的EPON组播部署方案。     

无线窄带网络组播实现技术

组播业务是网络中的一项重要应用,通过组播技术可极大减小网络的开销,然而由于无线环境的限制,常用的组播技术无法直接应用在无线窄带网络中。本文通过概述组播技术的原理,归类总结了目前有线网络中常用的组播技术,并对无线自组网络中的组播技术进行对比分析,最后根据无线窄带网络的特点,提出了基于源路由多目地址机制的组播实现技术及在话音组播上的改进。     

一种组播路由算法

随着组播业务的急剧增多,组播技术(Multicast)日益重要.在组播技术中组播路由算法是一项关键技术.主要介绍了两种组播路由算法,一种是适用于任意网络拓扑的启发式路由算法(RST),另一种是基于Mesh网络拓扑的启发式路由算法.     

基于数字证书的树型结构安全多播方案

该文提出一种基于数字证书的安全多播方案，采用树型的多播拓扑结构。多播树中的每个节点都有一个标识其身份的数字证书，除了成员身份认证外，还可以安全地分发会话密钥和实现会话数据的认证，因而减少了多播群密钥管理的复杂度；由于采用分层的树型多播结构，成员加入和退出有了更大的可扩展性。     

无线mesh网中最小编码代价低时延多播路由

提出了一种无线mesh网中最小网络编码代价低时延多播路由协议(MNCLDMR, minimal network coding and low delay multicast routing)。MNCLDMR的目标是选择合适的网络编码节点,最小化网络编码代价,降低网络时延。MNCLDMR主要思想是引入拓扑关键节点和网络编码关键节点的概念,以下一跳的节点是否是网络编码关键节点或拓扑关键节点作为路由判据,采用MNCLD算法构造多播树。仿真结果表明,MNCLDMR可以达到预定目标,合理形成网络编码机会,能实现最小网络编码代价低时延多播路由。     

A scalable multicast key management scheme for heterogeneous wireless networks

Secure multicast applications require key management that provides access control. In wireless networks, where the error rate is high and the bandwidth is limited, the design of key management schemes should place emphasis on reducing the communication burden associated with key updating. A communication-efficient class of key management schemes is those that employ a tree hierarchy. However, these tree-based key management schemes do not exploit issues related to the delivery of keying information that provide opportunities to further reduce the communication burden of rekeying. In this paper, we propose a method for designing multicast key management trees that match the network topology. The proposed key management scheme localizes the transmission of keying information and significantly reduces the communication burden of rekeying. Further, in mobile wireless applications, the issue of user handoff between base stations may cause user relocation on the key management tree. We address the problem of user handoff by proposing an efficient handoff scheme for our topology-matching key management trees. The proposed scheme also addresses the heterogeneity of the network. For multicast applications containing several thousands of users, simulations indicate a 55%-80% reduction in the communication cost compared to key trees that are independent of the network topology. Analysis and simulations also show that the communication cost of the proposed topology-matching key management tree scales better than topology-independent trees as the size of multicast group grows.     

A ring-based multicast routing topology with QoS support in wireless mesh networks

Wireless mesh networking (WMN) is an emerging technology for future broadband wireless access. The proliferation of the mobile computing devices that are equipped with cameras and ad hoc communication mode creates the possibility of exchanging real-time data between mobile users in wireless mesh networks. In this paper, we argue for a ring-based multicast routing topology with support from infrastructure nodes for group communications in WMNs. We study the performance of multicast communication over a ring routing topology when 802.11 with RTS/CTS scheme is used at the MAC layer to enable reliable multicast services in WMNs. We propose an algorithm to enhance the IP multicast routing on the ring topology. We show that when mesh routers on a ring topology support group communications by employing our proposed algorithms, a significant performance enhancement is realized. We analytically compute the end-to-end delay on a ring multicast routing topology. Our results show that the end-to-end delay is reduced about 33 %, and the capacity of multicast network (i.e., maximum group size that the ring can serve with QoS guarantees) is increased about 50 % as compared to conventional schemes. We also use our analytical results to develop heuristic algorithms for constructing an efficient ring-based multicast routing topology with QoS guarantees. The proposed algorithms take into account all possible traffic interference when constructing the multicast ring topology. Thus, the constructed ring topology provides QoS guarantees for the multicast traffic and minimizes the cost of group communications in WMNs.     

基于灰狼算法的无线网络组播路由优化

针对无线网络中资源受限的组播路由问题,考虑网络节点的节点度限制和网络链路的带宽约束,以最小化组播路由开销为目标,提出了一种二进制编码方式的基于灰狼优化算法的组播路由策略.在给定的网络拓扑下,基于灰狼优化算法的组播路由策略可以迅速找到一棵包含源和目的节点的最小开销组播树.仿真结果表明,相比于遗传算法,所提出的基于灰狼优化算法的组播路由策略可以得到一棵开销更小的组播树,并且在相同的时间复杂下具有更强的算法稳定性.     

Multicast multi-granular grooming based on integrated auxiliary grooming graph in optical networks

In order to improve the bandwidth utilization efficiency and reduce the blocking probability for multicast requests in optical networks, the multicast traffic grooming approach was proposed to groom a lot of low-speed traffic to a few of high-speed light-trees. At the same time, in order to save the ports and the cost of optical cross-connect, the multicast waveband grooming approach was proposed to groom multiple light-trees to a few of waveband tunnels. However, the existing approaches all did not consider the joint performances of improving bandwidth utilization efficiency, reducing blocking probability and saving ports for multicast requests. Therefore, in this article, we propose a new multicast multi-granular grooming approach to perform the hierarchical sequential grooming to improve the joint performances based on a newly developed integrated auxiliary grooming graph (IAGG) that includes multiple wavelength integrated grooming graphs (WIGGs) and one waveband virtual topology layered graph (BVLG) to support both the multicast traffic grooming and multicast waveband grooming. In order to achieve the map of light-tree to the virtual topology layer in WIGG or BVLG, we present a light-segment map method, where a light-tree will be divided to several light-segments each of which will be independently mapped to the virtual topology layer. Since different definitions of blocking probability may lead to different objectives, we define two kinds of blocking probability, mean blocking probability of requests (MBPR) and mean blocking probability of users (MBPU). According to the two definitions of blocking probability, we propose two multicast multi-granular grooming heuristic algorithms, Heuristic Algorithm with minimizing MBPR and Heuristic Algorithm with minimizing MBPU based on IAGG. Simulation results show that the two proposed algorithms are both efficient and have better performances than traditional multicast grooming algorithm.     

Improved Shuffled Frog-Leaping Algorithm Based QoS Constrained Multicast Routing for Vanets

Prompt and reliable communication between vehicular nodes are essential as its limited coverage and dynamic mobility rate introduces frequent change of network topology. The key feature of vehicular communication that establishes direct connectivity or Road Side Unit-based data transfer among vehicular nodes is responsible for sharing emergency information during critical situations. Multicast routing data dissemination among vehicular nodes is considered to be the potential method of parallel data transfer as they facilitate the option of determining an optimal multicast tree from feasible number of multicast trees established between the source and destinations. This estimation of optimal multicast tree using meta-heuristic techniques is confirmed to improve the throughput and reliability of the network when QoS-based constraints are imposed during multicast routing. An Improved Shuffled Frog-Leaping Algorithm-Based QoS Constrained Multicast Routing (ISFLABMR) is proposed for estimating an optimal multicast tree that confirms effective multi-constrained applied multicast routing between vehicular nodes. ISFLABMR minimizes the cost of transmission to 22% by reducing the number of multicast clusters formed during multicasting through the utilization of local and global-based optimizations. The simulation results of ISFLABMR proveits predominant reduction rate of 24% and 21% in average packet latency and energy consumptions incurred under multicast routing.     

基于双向共享树的MPLS多播流聚合算法

可扩展性是影响多播在MPLS网络大规模使用的主要问题,为解决该问题提出了一种基于双向共享树的多播流聚合算法.它根据节点之间的关系计算多播流的可聚合度,然后将标记边缘路由器聚类生成共享树的叶子节点集,并由树管理服务器计算双向共享树的拓扑结构,最后将可聚合度大于指定阈值的多播流汇聚到树中.实验结果表明,该算法可以大幅缩小MPLS标记的占用,简化中间节点的处理过程,减少路由器的转发状态,大大提高了MPLS多播的可扩展性.     

Stateless overlay multicast with in-packet bloom filters

Due to the difficulty of deploying Internet protocol (IP) multicast on the Internet on a large scale, overlay multicast has been considered as a promising alternative to develop the multicast communication in recent years. However, the existing overlay multicast solutions suffer from high costs to maintain the state information of nodes in the multicast forwarding tree. A stateless overlay multicast scheme is proposed, in which the multicast routing information is encoded by a bloom filter (BF) and encapsulated into the packet header without any need for maintaining the multicast forwarding tree. Our scheme leverages the node heterogeneity and proximity information in the physical topology and hierarchically constructs the transit-stub overlay topology by assigning geometric coordinates to all overlay nodes. More importantly, the scheme uses BF technology to identify the nodes and links of the multicast forwarding tree, which improves the forwarding efficiency and decreases the false-positive forwarding loop. The analytical and simulation results show that the proposal can achieve high forwarding efficiency and good scalability.