IT用语小词典

IT(Information Technology)信息技术。是对计算机软硬件、因特网、通信等领域技术的通称。 IP(Internet Protocol)因特网协议。VoIP为Voice over Internet Protocol,是在网络上实现话音及传真信号传输的一门全新数据网络技术。计算机之间可以通过因特网打IP电话。电信公司也提供IP电     

基于VxWorks的PIM-SM协议的改进设计

简要介绍了互联网组管理协议（Internet Group Management Protocol,IGMP）和协议无关组播的稀疏模式（Protocol Independent Multicast-Dense Mode,PIM-SM）协议的基本原理。结合移动无线自组网的需求和VxWorks 6.9操作系统的特点,对IGMP协议和PIM-SM协议进行了适配和改进。首先,给出了IGMP协议的查询器选举和Query消息的接收者的改进方法;其次,扩展了PIM-SM协议在单接口和路由表项不写入内核等情况下的应用场景,设计了一套多任务处理方案,通过轮询实现了内核信令的触发（如“IGMPMSG＿NOCACHE”类型的信令）和组播数据转发调度的功能;最后,通过搭建两对“主机-电台”的实测环境,实现了消息交互功能,验证了该方案的可行性。     

SIP在3G通信网络中的应用研究

在高速移动的条件下方便快捷而又经济地通信,是市场的迫切需求.会话初始化协议(SIP)是能够在第3代移动通信系统(3G)中传输IP(Internet Protocol)多媒体业务的信令协议.它能够融合Internet和移动蜂窝系统.文中简要介绍和分析了SIP,并给出了一种基于该协议的在3G通信网络中的应用方案.     

移动IP路由优化性能分析及仿真

因特网技术的普及,使得人们实现了网际通信和信息共享,但基于有线方式的Internet受到空间和时间的限制,无法满足用户随时随地能够接入因特网的要求,这成为研究移动主机路由协议的驱动力.移动IP是一种简单、可扩展的全球IP移动性的解决方案,但三角路由问题的存在带来了网络花费问题和性能问题.路由优化移动IP协议是解决移动IP相关问题的侯选协议之一.本文对两种协议进行了理论分析和仿真.结果表明,是否采用路由优化协议,不能一概而论,要根据网络及业务到达特征决定.另外,两种协议都不能很好地支持将来的微小区带来的频繁切换,而解决该问题就是我们下一步的研究方向.     

城域网中的网络地址

目前,国内众多有线电视台利用冗余光纤网络建立了城域网,从事网络信息服务,为广大企事业单位提供宽带、高速数据传输业务。在所建设的网络中,采用的网络传输协议多是TCP/IP(Transmission Control Protocol传输控制协议/Internet Protocol因特网协议)协议。Internet之所以能将广阔范围内各种各样网络系统的计算机互联起来,主要是因为应用了“一统天下”的TCP/IP协议。在应用TCP/IP协议的网络环境中,为了唯一地确定一台主机的位置,必须为TCP/IP     

移动IP及其改进技术

为了在移动通信网络中运用IP协议，因特网工程任务组(Internet Engineering Task Force,IETF)制定了Mobile IP协议。Mobile IP是一种简单可扩展的全球Internet移动解决方案，使节点在切换链路时仍可保持正在进行的通信。传统的Mobile IP中要求移动节点移动到异地网络时获得转交地址，数据通过隧道经由家乡代理转发给移动节点。然而当移动节点在微移动条件下频繁移动时，传统的Mobile IP存在着许多不足。本详细介绍了移动IP的工作原理以及移动IP机制中的路由优化策略，并且针对微移动问题，从切换质量、路由更新、位置更新等方面比较了Mobile和Cellular IP、HAWAⅡ、TeleMIP等几种改进方法的性能。     

多模移动终端的移动IP功能设计与实现

当前主流移动IP系统的移动台(MN)端均通过优先级策略选定当前代理,即以代理管理为中心实现移动IP协议。这些方案既难以提高多模移动终端所需要的跨媒体垂直切换能力,也不利于移动IP协议本身在Windows平台下的实现。给出了Windows平台下一种以链路管理为中心的移动IP客户端的设计与实现方案。     

IP电话——全球通信的热点

飞速发展的信息社会需要便捷的通信,然而高昂的通信费用却使人们只能“望价兴叹”。近年出现的IP电话给大家带来了福音:它以价廉的优势挑战传统电话业务,它将成为目前全球通信业的热点。IP电话(Internet Protocol Phone,简称IP Phone)是因特网协议电话的简称,它是利用Internet实现双方语音传输的工具,因此又称互联网电话或网络电话。由于IP电话是在Internet网上实现的话     

TRIP在软交换中的应用研究

介绍了因特网工程部特别工作组(IETF)提出的基于IP的电话路由协议(TRIP：Telephone Routing over Internet Protocol)的路由机制及特点，讨论了TRIP进行软交换路由的应用进程。     

一种基于中心代理的移动Ad—Hoc网络接入方法

本文针对已有接入方法所存在的缺点,提出一种以移动节点间相互竞争出现的中心节点作为移动代理,利用移动IP协议实现MANET接入Internet的新方法,并对中心代理节点的选取、MANET整体移动接入等问题进行了探讨。该方法具有开销小、接入灵活、不需对移动IP做大的改动等优点。     

基于C/S模型的视频信息传输系统研究

讨论了IP网络与C／S模型，并对多媒体网络的传输协议作了分析，借助RTP／RTCP协议来确保视频信息传输的质量，采用C／S模型，在Windows2000环境下，设计了一个支持IP组播的视频信息传输系统，用它能够实现IP网络上的实时视频信息传输。     

多跳蜂窝网互连性研究

将Ad Hoc网络与蜂窝网融合首要解决的问题是Ad Hoc如何接入蜂窝网,多数方案使用的是移动IP。提出了一种基于扩展Ad Hoc路由协议的多跳转发网络方案。Ad Hoc多种路由协议中可以实现Ad Hoc网络与蜂窝网互连的只有DSDV,但在移动场景中的低性能限制了它的发展。AODV是Ad Hoc路由协议中最有前途的协议,但它并不支持Ad Hoc节点接入基站的路由搜索。研究对AODV协议进行改进,以使它能支持移动节点到固定基站以及有线网络的寻路。     

基于身份的移动IP注册协议研究

针对移动IP注册协议中家乡和移动节点过多且复杂的计算问题,提出了一个新的基于身份的密钥分发方案,并在此基础上设计了一种高效的移动IP注册协议。该协议实现了移动IP各个节点间相互认证,其中移动节点与家乡代理之间具有双重认证的特点。双线性对和秘密随机数的选取保证了消息的安全性,消息认证码Mac和数字签名Sig保障了消息的完整性。该协议从整体上减少了计算量,降低了注册延迟率,同时也有效地保证了安全性。安全性分析表明,该方案满足移动IP的安全要求。     

IIPP: integrated IP paging protocol with a power save mechanism

The advent of advanced mobile/wireless systems has been facilitating the battery‐powered mobile computing devices (nodes) to remain always connected to the internet. However, until now, the power‐drain rate of mobile nodes is very high in comparison with the available power of portable batteries. To reduce the energy consumption of mobile nodes, we present an integrated IP paging protocol (IIPP) by integrating the IP‐layer paging protocol based on Mobile IPv4 regional registration (MIPRR) with a power save mechanism. IIPP reduces the frequency of signaling messages between mobile nodes and networks. When not sending or receiving data for a certain time, mobile nodes enter power save mode (PSM), and consume very low power. We formulate analytical models and carry out simulations to evaluate the proposed IIPP. The results show that, compared to MIPRR, IIPP significantly reduces the average power consumption of the mobile node and signaling overheads in the network. Copyright © 2006 John Wiley & Sons, Ltd.     

Fast Duplicate Address Detection for Seamless Inter-Domain Handoff in All-IPv6 Mobile Networks

In All-IP networks, each computer or communication equipment needs an IP address. To supply enough IP addresses, the new Internet protocol IPv6 will be used in next generation mobile communication. Although IPv6 improves the existing Internet protocol (IPv4), Duplicate Address Detection (DAD) mechanism may consume resources and suffer from long delay. DAD is used to make sure whether the IP address is unique or not. When a mobile node performs an inter-domain handoff, it will first generate a new IP and perform a DAD procedure. The DAD procedure not only wastes time but also increases the signaling load on Internet. In this paper, we propose a new DAD mechanism to speed up the DAD procedure. We create a DAD table in access or mobility routers in All-IP networks and record all IP addresses of the area. When a new IP address needs to perform DAD, it can just search in the DAD table to confirm the uniqueness of the address. Furthermore, we propose a new method, Fast Duplicate Address Detection (Fast DAD), to reduce data search time. Simulation results show that our method outperforms the existing DAD methods.     

Integrated Mobility Management Methods for Mobile IP and SIP in IP based Wireless Data Networks

With developments in voice over IP (VoIP), IP-based wireless data networks and their application services have received increased attention. While multimedia applications of mobile nodes are served by Session Initiation Protocol (SIP) as a signaling protocol, the mobility of mobile nodes may be supported via Mobile IP protocol. For a mobile node that uses both Mobile IP and SIP, there is a severe redundant registration overhead because the mobile node has to make location registration separately to a home agent for Mobile IP and to a home registrar for SIP, respectively. Therefore, we propose two new schemes that integrate mobility management functionality in Mobile IP and SIP. We show performance comparisons among the previous method, which makes separate registration for Mobile IP and SIP without integration, and our two integrated methods. Numerical results show that the proposed methods efficiently reduce the amount of signaling messages and delay time related to the idle handoff and the active handoff.     

Mobility management for VoIP in 3G systems: evaluation of low-latency handoff schemes

The introduction of IP-based real-time services in next-generation mobile systems requires coupling mobility with quality of service. The mobility of the node can disrupt or even intermittently disconnect an ongoing real-time session. The duration of such an interruption is called disruption time or handover latency, and can heavily affect user satisfaction. Therefore, this delay needs to be minimized to provide good quality of VoIP services. In this article, we focus on network-layer mobility and mobile IP since it is a natural candidate for providing such mobility. We evaluate different low-latency schemes based on mobile IP and compare their performances in terms of disruption time for VoIP services. Low-latency handoffs are performed by anticipating and/or postponing the mobile IP registration process. With these methods, disruption time is reduced to 200 ms in most considered cases.     

IDSDDIP: a secure distributed dynamic IP configuration scheme for mobile ad hoc networks

In IP‐based networks, IP address uniqueness is one of the most important requirements since a node has to participate in unicast communications and routing. Often nodes are assumed to have unique IP addresses configured a priori. However, this is not the case and cannot be achieved easily in mobile ad hoc networks (MANETs). Most of the existing dynamic address allocation schemes of MANET rely on network‐wide flooding for address solicitation and/or duplicate address detection. As a result, several types of security threats can be seen at the time of address allocation. In this paper, we present an ID‐based distributed dynamic IP configuration scheme that securely allocates IP addresses to the authorized nodes without flooding the entire network. Here each node acquires capability of generating unique IP addresses from its own IP address and can assign those addresses to the new nodes. The proposed scheme provides security against the associated threats with dynamic IP allocation protocol without the help of a trusted third party. It also efficiently handles the network partitioning and merging and reduces the chance of address conflicts. Performance analysis and simulation results are present to show that the proposed addressing scheme has low communication overhead and fairly low addressing latency with added security mechanisms compared to the similar existing dynamic address allocation schemes. Copyright © 2013 John Wiley & Sons, Ltd.