An approach to support IP multicasting in networks with mobile hosts

It is an efficient way for a mobile host to obtain multicast service via a local multicast router on the visited network.However,there is a possibility for a temporary disruption of multicast service due to the join latency and other issues in handoff procedure.This paper proposes a scheme to solve such a problem. A smooth handoff mechanism is introduced to avoid unnecessary data loss.Besides,any mobility agent capable of multicast can be appointed to provide service to mobile hosts,which makes it possible to deploy the protocol widely.Discrete-event simulations were conducted to survey the performance of the proposed scheme.The simulation results show that the scheme has better performance than the compared approaches.     

基于主从样式的移动代理安全模型的研究与实现

In the ages of current network technology, as a new technology, the emergence of mobile agent shows us a wider and wider application prospect in the fields of network technology, such as Network Management,Intelligence Information Retrieval and Electronic Commence and so on. The security is the essence of mobile agent technology. In this paper we analyze the security issues and survey some representative approaches to solve the problem in mobile agent systems. We focus on the issues about the agent's security and propose a master-slave designpattern based security model for mobile agent called SMAP(Secure Mobile Agent Platform). In the end we give anapplication example to show how to use these.     

Dynamic retransmission control for reliable mobile multicast

Most existing multicast protocols adopt a static retransmission scheme(unicast or multicast) to retransmit lost packets.In the mobile multicast environment,static multicast retransmission mode may lead to congestion in the receivers‘ wireless interfaces,while static unicast mode may result in great network load.Both static unicast and multicast retransmission modes will cause a performance loss.This paper logically divides the mobile multicast network into fixed and mobile parts,and focuses on the mobile part.Then this paper analyzes the retransmission costs when multicast or unicast mode is chosen.Two main parameters are used to compare their efficiencies:the average air-interface utilization of each receiver and the average network load.Based on the results of analysis,two new algorithms,called NLPA(Network Load Priority Algorithm)and AUPA(Air-interface Utilization Priority Algorithm)are presented.Finally,simulation results conclude that,with proper parameters,both NLPA and AUPA can dynamically alternate between unicast and multicast retransmission modes acording to the conditions of network and receiver,and avoid congestion in receivers‘ wireless interfaces as well as great network load,with a better use of network and terminal resources.     

A New Protocol for the Detection of Node Replication Attacks in Mobile Wireless Sensor Networks

Wireless sensor networks (WSNs) are often deployed in harsh environments.Thus adversaries can capture some nodes,replicate them and deploy those replicas back into the strategic positions in the network to launch a variety of attacks.These are referred to as node replication attacks.Some methods of defending against node replication attacks have been proposed,yet they are not very suitable for the mobile wireless sensor networks.In this paper,we propose a new protocol to detect the replicas in mobile WSNs.In this protocol,polynomial-based pair-wise key pre-distribution scheme and Counting Bloom Filters are used to guarantee that the replicas can never lie about their real identifiers and collect the number of pair-wise keys established by each sensor node.Replicas are detected by looking at whether the number of pair-wise keys established by them exceeds the threshold.We also derive accurate closed form expression for the expected number of pair-wise keys established by each node,under commonly used random waypoint model.Analyses and simulations verify that the protocol accurately detects the replicas in the mobile WSNs and supports their removal.     

基于时序逻辑的移动计算的形式方法分析

At present,mobile computing is widely considered as a new computing paradigm supported by advanced computational technologies.One of main characteristics of this paradigm is the ability to dynamically change the binding for hardware and/or software components,that is mobility. Although there are many languages appeared to announce supporting mobile computing,the requirements and features of this paradigm are still scarcely recognized.So a lot of research is being expanded on formal models and methods for mobile computing. In this paper,we analyze a temporal logic based formalism for mobile computing——Mobile Unity. At first,we summarize the features of mobile computing,and generalize that mobile systems should be decoupled,strongly-autonomous,context-dependent and owning new requirements for location-transparency.Then we introduce Mobile Unity,its extensions for U NITY from syntax to computational semantics,specially analyze the correspondence between the language structures of Mobile Unity and the abstraction of mobile features,such as location,mobility,transient interactions etc.At the end,we conclude its some deficiency for supporting mobile computing.     

基于JavaCard的移动代理系统安全性研究

With wide and increasing range applications of mobile agent technology, the security problem has gotten more and more focus. This paper discusses the security problems that the mobile agent system faces with at presentand the existing protesting schemes for it. Then a solving method based on JavaCard is proposed to protect mobile a-gents. And a feasible solving method is also provided to solve the security problems of JavaCard itself.     

Triangle Routing Problem in Mobile IP

Mobile Internet Protocol is a recommended Internet protocol designed to support the mobility of a user （host）. Host mobility is becoming important because of the recent blossoming of laptop computers and the high desire to have continuous network connectivity anywhere the host happens to be. The development of Mobile IP makes this possible. The traditional Mobile IP specification forces all packets forwarded to the MN （mobile node）, to be routed via HA （home agent）, which often leads to Triangular routing, which in turn causes data transmission delay and wastes network resources. This paper discusses means of resolving the triangle routing problem, it introduces some of the recent route optimization schemes that have been used to solve that problem.     

可靠组播拥塞控制最新研究进展

Congestion control,which is one of the important research points of reliable multicast protocol,has become a active field in the computer network and communication areas.In the paper the principal problems of congestion control for reliable multicast are analyzed first,and then merits and limitaition of methods for addressing these problems are demonstrated detailedly.At lats the future work is pointed out.     

DRMR: Dynamic-ring-based multicast routing protocol for Ad hoc networks

Recently a number of multicast routing protocols for ad hoc networks have been proposed, however,most of them do not provide proper tradeoffs between effectiveness, efficiency and scalability. In this paper, a novel multicast routing protocol is presented for ad hoc networks. The protocol, termed as dynamic-ring-base dmulticast routing protocol (DRMR), uses the concept of dynamic ring whose radius can be adjusted dynamically and DRMR configures this type of ring for all group member nodes. According to the principle of zone routing,two nodes whose rings overlap can create route to each other, thus, when the ring graph composed of all rings is connected, each member node has one or more routes to others. DRMR uses the method of expanding ring search (ERS) to maintain the connected ring graph, and also can decrease the radius of the ring to reduce the overhead. The performances of DRMR were simulated and evaluated with NS2, and results show that DRMR has a high data packet delivery ratio, low control overhead and good scalability.     

自适应移动组播算法

在分析用户移动模式的基础上，提出一种基于用户移动模式的自适应移动组播算法。移动主机根据移动模式和当前移动状态自适应地选择双向隧道机制或者远程加入机制完成组播切换。该算法的优点是，当移动速率较小时，以较小的组播树重构代价实现组播数据的优化传输，而移动速率较大时，可以避免频繁的组播切换，减小组播树重构代价。     

一种基于范围的可靠移动组播算法

移动IP[1]提出了双向隧道和远程签署两种移动组播算法,各自有明显的优缺点.在以双向隧道为基础的改进算法RBMoM[4]中引入了服务范围的概念.提出移动组播算法在远程签署的基础上结合服务范围概念,寻求最优转发路径和最小组播树管理开销之间的折衷,并在节点移动时采用在移动代理间建立隧道的方式补充数据包,提高组播可靠性.对模拟结果的分析和比较显示该算法具有更好的综合性能.     

一种基于层次结构的移动组播算法

移动IPv6协议给出了支持主机移动的远程签署和家乡签署两种组播方法,它们具有互补的优缺点.提出的移动组播算法综合了这两种基本方法,同时采用区域的层次型结构的路由思想,减少因主机移动而重构组播树的频率,并对模拟结果进行了分析和比较.     

分层移动IPv6方法在移动IPv6组播中的应用

提出的移动组播算法综合了远程加入和双向隧道两种基本方法,根据层次型结构的路由思想,采用先MAP后远程加入方法,最后分析了其算法的优缺点。     

一种多QoS约束的可靠移动组播路由协议

针对复杂多变的移动组播环境，从整体上提出了一种基于优先级的报文管理机制(PDMM)。对不同类型的报文赋以不同的优先级别，提出了一种基于层次结构的自适应移动组播路由协议(AMMPH)，在子网内采用隧道机制、子网间采用远程签署和隧道机制相结合的组播路由协议，保证了报文的可靠高效传输，并在寻求最短转发路径和减少组播树重构开销间取得了较好的平衡。     

支持主机移动的组播协议的性能评价

使用移动IP协议可以使主机移动到Internet的任何区域都能够保持与其它节点之间的通信。IP组播能够高效传输大量数据到一组接收者,可有效利用网络带宽。随着大量移动设备接入Internet,支持主机移动的组播协议已成为人们研究的问题之一。文章首先给出评价支持主机移动的组播协议性能的标准,然后详细介绍了目前已经提出的主要移动组播协议,并进行了性能分析和对比,最后探讨了移动组播的研究方向和发展趋势。     

基于DMSP共享的移动多播方案

RBMoM是一种综合了IETF的移动IP协议中远程加入和双向隧道两种基本方法、综合性能较优的移动多播协议。文中通过分析RBMoM移动多播协议中存在的问题,提出了DMSP共享机制,基于此机制实现了一个高效的移动多播方案。该方案有效地减少了网络中的多播通信量并降低了多播树的维护代价,却没有给多播数据传输带来太大的延迟。     

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。     

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Internet中的IP组播研究综述

随着组播应用的不断增加以及参与者的增多,组播领域的研究一直受到人们的广泛关注.而另一方面,近年来,移动设备迅速得到了普及,并且无线网络技术也得到了飞速的发展,因此,如何为移动主机提供更好的支持引起了人们的普遍关注.由于组播应用所具有的可扩展性强、高效等特点在移动这种资源受限的环境中显得尤为突出和重要,因此,移动环境中的组播应用引起了人们越来越多的重视,在该领域展开了大量的研究.详细地介绍了现有的主要移动组播算法和协议,讨论了每种算法或协议的适应范围以及优点,比较深入地剖析了其中存在的缺陷和问题,并且对这些移动组播算法和协议进行了综合对比.同时,特别针对移动环境可靠性较差的特点,对移动环境中进行可靠组播所面临的新问题以及相关研究现状进行了讨论.希望通过这些说明和对比,能够帮助研究者为其特定的需求选择适当的移动组播算法或协议.最后,讨论了移动环境中IP组播未来的研究方向.