移动组播的多家乡代理实现机制

针对移动组播中存在的家乡代理单点失效问题,提出一种多家乡代理实现机制,解决多家乡代理中移动节点的家乡注册问题,引入新的应用层任播算法,可以从多个家乡代理中为移动组播接收者选择“最近”的家乡代理。分析结果表明,该任播算法不仅可以有效解决家乡代理单点失效问题,还能为移动节点提供高质量的任播解析服务。     

无线传感器网络中的鲁棒性分段组播路由算法

在无线传感器网络(Wireless Sensor Network,WSN)组播路由算法的各类研究中,无状态组播可扩展性差,而分级及分支组播又存在单点失效问题.为权衡可扩展性及鲁棒性,提出一种鲁棒性分段组播路由算法(Robust Segmented Multicast Routing Algorithm,RSMR),将组播树分割成多个组播子树,并将这些组播子树的拓扑信息分布式地存储在一部分分支节点上,从而在控制分组头长度的同时减少了整个组播结构单点失效的概率.另外,还提出一种组播树存储节点的更新算法,在原存储节点剩余能量过小时,从附近选取一个新的存储节点,从而进一步提升整个组播结构的鲁棒性.仿真结果表明,RSMR能获得可扩展性及鲁棒性综合性能的提升,且在密集部署的大规模WSN中提升尤为显著.     

基于区域代理选择的移动组播算法

针对移动组播接入点切换造成的组播树频繁重建问题,本文提出了基于移动频率的区域代理选择方法。整个无线网络被划分为不同的区域,在某一区域内,选择移动频率最小的节点作为该区域的组播代理,为移动网络内该区域的节点提供组播服务。实验证明,该方法有效减少了因节点移动而造成的组播树重构频率。     

基于动态组播代理的移动组播协议

根据动态组播代理的移动组播算法原理,提出一种移动组播协议,采用新的快速组播切换机制,以时间量度和距离量度为依据,动态选择组播代理。仿真结果表明,该协议避免组播转发树的频繁重构,降低组播切换延迟,具有次优的组播传输路径,可以与现有网络协议相融合。     

移动IPv6协议中两个组播机制的实现

移动组播是移动IP的重要服务,不仅要处理组播中动态的组成员关系,而且要处理移动节点位置的动态改变。该文简单介绍移动IPv6协议中远程签署和家乡签署两种组播机制,重点说明在Linux系统上对这两种算法的实现。     

移动IPv6网络家乡代理容错方法研究

移动IPv6基于家乡代理的转发,实现节点移动过程中的可寻址性.提出主动检测和迁移的家乡代理容错方法,通过在家乡代理之间设计环状检测和备份链,使家乡代理之间相互检测失效情况的发生;所有注册信息在家乡链路上仅备份一次;检测到失效后,有效家乡代理自动地暂时接管失效家乡代理的工作,并主动通告给相关移动节点;移动节点收到家乡代理失效信息后,主动启动恢复过程.给出了实现该方法的数据结构和容错算法,描述了具体的容错处理过程.通过理论分析证明了该方法比协议标准中的方法具有更小的容错时间和信令开销,特别是在移动节点的移动频率较慢的情况下更是如此.     

基于区域不相交策略的无线传感器网络任播路由算法

任播技术应用在无线传感器网络(WSN)中可以均衡数据流和能耗。以往算法在寻找任播路径时多采用路径或节点不相交路由策略,该策略无法解决因隐终端问题造成的传递碰撞问题,导致额外的大量重传能耗。针对以上问题,提出一种基于区域不相交策略的WSN任播路由算法(ZDAR),该算法根据各路径的邻居节点影响因子(邻居节点参与其他任播路径的度)依次选择无传递碰撞问题的任播路径,相比较最短路径优先选择策略,ZDAR算法能够寻找到更多数量的区域不相交任播路径。仿真结果表明证明相比较节点不相交路由策略和最短路径优先区域不相交路由策略,ZDAR算法的系统能耗和能耗均衡的综合指标具有较好的性能优势,从而提高网络生存期。     

一种基于分区的移动IPv6组播算法

提出的基于分区的移动组播算法旨在解决移动节点远离本地网络且持续快速运动情况下的组播重构开销过大的问题,通过将网络划分成不同的区域并指定一个区域代表,降低了组播树重构频率。仿真结果表明,此算法较之FHSR算法在网络利用率及组播重构开销方面有更好的性能。     

基于时延敏感无线传感器网络的最优任播算法

任播技术应用在基于休眠唤醒机制的无线传感器网络(WSN)中可以改善其时延较长的问题,但以往技术是针对每一跳候选节点的休眠时延进行优化的,该策略在端对端时延上往往并不最优甚至有时效果很差。针对端对端时延问题提出基于时延敏感WSN的最优任播算法。协议中基站采用AODV多路径路由协议获取任播路径信息,采用遗传算法进行最优化计算,并将所得各节点至任播组最优任播路径的信息返回给各节点。该算法具有自适应调节任播路径和全局优化的特点。实验数据表明,与以往算法相比,该算法可以更有效地降低端对端时延。     

大型视频组播系统整体效用层次化建模与求解

为了有效地分析和评价大型视频组播系统的自适应方法与技术,文中首先抽象描述了大型视频组播系统整体效用最大化问题,针对该问题集中式求解存在的单点失效、反馈内爆和自适应控制延迟大等缺陷,该文提出了基于瓶颈链路的层次化分解方法,建立了大型视频组播系统整体效用层次化模型,给出了一个基于层次化代理的分布优化求解方法OptUtility算法,可获得大型分层视频组播系统中通过各个层次代理的各个会话的优化带宽、优化的分层数量和各层次优化的发送速率.通过对该算法的计算复杂度的分析与对比实验,证明该算法对于解决大型视频组播系统整体效用优化问题具有较低的计算时间复杂度,容易实现,且实时性能好.     

Fault tolerance for home agents in mobile IP

In the conventional IP protocol, whenever a mobile device moves to a different network, it must change its IP address to communicate with other nodes in the Internet. Mobile IP protocol keeps mobile nodes online without changing their IP addresses while changing the attachment points. The packets destined to mobile nodes (MN) are relayed by their home agents (HA). However, once the only one HA fails, all MNs managed by the HA will not receive packets normally. In the paper, we propose a novel protocol with multiple mobile agents (MA) where only double mobility bindings are maintained in the whole system. When an HA is failed, its backup HA can take over it in a short time without fetching the bindings from other places. Besides, we also consider the load balancing between these HAs during HA takeover and recovery. Through the simulation and analyses, we found that our method has less registration overheads, better MN-scalability, less sensitivity on MN mobility, more fault-tolerance robustness, and less takeover time than others.     

fP2P–HN: A P2P-based route optimization architecture for mobile IP-based community networks

Wireless technologies are rapidly evolving and the users are demanding the possibility of changing their point of attachment to the Internet (i.e. Access Routers) without breaking the IP communications. This can be achieved by using Mobile IP or NEMO. However, mobile clients must forward their data packets through its Home Agent (HA) to communicate with its peers. This sub-optimal route (lack of route optimization) considerably reduces the communications performance, increases the delay and the infrastructure load. In this paper, we present fP2P–HN, a Peer-to-Peer-based architecture that allows deploying several HAs throughout the Internet. With this architecture, a Mobile Node (MN) or a Mobile Community Network (i.e. a NEMO) can select a closer HA to its topological position in order to reduce the delay of the paths towards its peers. fP2P–HN uses a Peer-to-Peer network to signal the location of the different HAs. Additionally, it uses flexible HAs that significantly reduce the amount of packets processed by the HA itself. The main advantages of the fP2P–HN over the existing ones are that it is scalable, it reduces the communications delay and the load at the HAs. Since one of the main concerns in mobility is security, our solution provides authentication between the HAs and the MNs. We evaluate the performance of the fP2P–HN by simulation. Our results show that the fP2P–HN is scalable since the amount of signalling messages per HA does not increase, even if the number of deployed HAs increases. We also show that the average reduction of the communication’s delay compared to Mobile IP/NEMO is 23% (with a minimum deployment) and the reduction of the load at the HA is at least 54%.     

基于HMIPv6的民用航空移动网络设计及实现

当一个移动节点(MN)或移动路由器(MR)移动到另一个移动网络,并通过另一个MR提供接入时,这样的情况称为嵌套移动网络,这样的嵌套可以有很多层。一个典型的例子是携带笔记本电脑的乘客登上一架通过MR提供移动网络服务的航班,并通过该MR访问互联网或公司的内部网络。在这种情况下,移动节点和通信节点之间的数据包的传送路径将到达每个节点的HA(家乡代理)处,因此其路径将比基本的MIP(移动IP)长得多,现有路由优化方法不能解决这个问题,因为可以旁路MN的HA,但是却无法跳过MR的HA。本文通过在民航移动网络的设计中应用HMIP(层次移动IP)思想,并对其进行一定的改进来解决上面的这些问题,提高网络的运行效率。     

IP anycast point-to-(any) point communication

The Internet supports three communication paradigms. The first, unicast, is the point-to-point flow of packets between a single source (client) and destination (server) host. Web browsing and file Me transfer are unicast applications. The next, multicast, is the point-to-multipoint flow of packets between a single source host and one or more destination hosts. Broadcast-style videoconferencing, for example, employs IP multicast. Anycast is the point-to-point flow of packets between a single client and the "nearest" destination server identified by an anycast address. The idea behind anycast is that a client wants to send packets to any one of several possible servers offering a particular service or application but does not really care which one. Any number of servers can be assigned a single anycast address within an anycast group. A client sends packets to an anycast server by placing the anycast address in the packet header. Routers then attempt to deliver the packet to a server with the matching anycast address     

基于Anycast RP的组播源发现协议在单一PIM域中的研究与实现

分析当前大型单一PIM-SM(协议无关组播路由稀疏模式Protocol Independence Multicast Sparse Mode)域组播网络传输机制中存在的缺陷:多个接收者同时访问组播网络中某个组播组时,导致该组播组汇聚点RP(Rendezvous Point)的负载加重,影响整个组播网络的性能。一种新的任意播RP技术,将PIM-SM域间的组播源发现协议MSDP(Multicast Source Discovery Protocol)引入到大型单一PIM域组播网络中,解决网络中RP负载不均衡问题,同时又实现网络中RP"就近原则",减少转发时延。同时,实现RP间的冗余备份,提高网络性能。实际组网测试证明,单一PIM-SM域组播网络中利用任意播RP技术,缩短传输时延2～3倍,RP路由器CPU占用率降低10%。     

Design and implementation of light-weight mobile multicast for fast MIPv6

Mobile multicast is a research hotspot and can provide many applications. Some mobile multicast schemes have been proposed, but most of them introduce new entities and study construction algorithms of the dynamic multicast delivery structure which is heavyweight for wireless devices. In this paper, we propose a light-weight mobile multicast (LMM) scheme for Fast Mobile IPv6 which reduces the redundant operational overhead by simplifying multicast listener discovery (MLD) proxying. The LMM scheme implements simplified MLD proxying function on home agent to reduce the complicated multicast routing protocol and modifies MLD host part function on mobile node to reduce the multicast membership messages interaction. In order to solve the tunnel convergence problem, LMM also introduces a multicast tunnel combination and reconstruction algorithm. We set up a test-bed to evaluate the performance of LMM, and compare it with other mobile multicast schemes. The experimental results show that LMM reduces the multicast disruption time at handover. Based on the experimental results, we analyze the cost of LMM, and the results show that it has lower protocol cost than other schemes.     

基于遗传算法的多约束QoS多播路由优化算法

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约束的多播路由问题成为越来越重要，它吸引了许多爱好者．本文讨论了多约束QoS多播路由问题，主要包含延迟、延迟抖动、带宽和分组丢失率等QoS约束，文中描述了一种在动态网络环境及不确定参数下适应于研究QoS多播路由的网络模型．提出了一种在网络规模、可行性方面为Imernet、移动网络和高性能网络下基于遗传算法的多约束QoS多播路由优化算法（MQMRGA）．仿真结果表明该算法收敛速度快、可靠性高．MQMRGA为QoS多播路由提供了一种新的有效途径．     

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.