多媒体业务NAT／防火墙穿越

计算机网络、电信网络和有线电视网．这三网正在走向融合的基于IP技术的下一代网络(NGN)．导致了对IP地址资源需求的迅速增加．超出了最初预期和设计的32bit(IPv4地址长度)。解决地址资源短缺的思路大致有两类：(1)“开源”，即使用地址长度更大的下一代IP协议——IPv6。(2)节流．即尽量提高对现有IPv4地址资源的利用率．比如动态分配IP地址．使用网络地址翻译(NAT)技术等。     

IPv6协议下的多播DNS解析方式

IPv6是“Internet Protocol Version 6”的缩写，也被称作下一代互联网协议，它是由IETF设计的用来替代现行的IPv4协议的一种新的IP协议。它的提出最初是因为随着互联网的迅速发展，IPv4定义的有限地址空间将被耗尽，地址空间的不足必将妨碍互联网的进一步发展。IPv4采用32位地址长度，只有大约43亿个地址，那么按照现在网络的发展速度IP将会在五到十年内被分配完毕，而IPv6采用128位地址长度，几乎可以不受限制的提供地址空间。     

IPv6导致网络应用不畅

目前使用的IP协议,其学名为IPv4,地址长度32位。互联网的快速发展,使得IP地址日益枯竭,从而催生了下一代IP协议IPv6。IPv6地址长度是128位,可有效解决IP地址短缺和网络安全等问题。近几年推出的操作系统,基本都支持IPv4和IPv6。     

IP地址、子网掩码与IP v6

因特网的迅速发展也带出了一个术语“IP”。本文将针对IP地址，着重讨论一下子网掩码（SubnetMask）和下一代IP协议—IPv6。一般而言，不同的物理网络技术有不同的编址方式，因而也有不同的物理网络地址。作为统一不同物理网络技术的IP协议，其首先要解决的就是不同地址的统一问题，而解决方案即是已推出的32位IP地址（IPv4版），它能用米屏蔽物理网络地址的差异。32位IP地址分为4部分，每部分编号从0到255，这4部分以点号连接，即每8位值被一点号分开，如192．1680．129。它同时又是一种层次型地址，可划分为网络号（netid）和主机…     

下一代互联网新协议——IPv6

互联网的迅猛发展导致了IP地址资源的紧张，为了扩大下一代互联网络的地址资源，拟通过IPv6重新定义地址空间．本文介绍了IPv6的技术原理、技术优势、IPv4到IPv6的过渡以及主要的IPv6业务模式。     

从宽带运营需求看IPv6带来的机遇

我国IPv4地址不足的问题长期以来一直存在,虽然已经采用了一些节约使用IPv4公网地址的技术(如为用户分配“临时地址”、“内部地址”等),以延缓地址的消耗速度。但这些技术对IP业务的发展带来不良影响,也不能从根本上解决地址不足的问题。因此,我国IPv4地址资源即将枯竭的问题仍然无法回避。而构建基于IPv6的新的网络业务运营模式逐渐浮出水面。相比IPv4网络技术,IPv6集成了海量地址空间、简洁的移动互联技术、嵌入的安全技术、易于快速处理的流标签技术等优势。而这些技术优势有利于转变现有IP网络的业务模式,即由单一的IP传送业务模式转变为以服务为中心,网络为纽带的全业务网络。也就是说,IPv6能够满足各个电信网络对未来业务发展的要求。华为技术有限公司陈保江所撰《从宽带运营需求看IPv6带来的机遇》一文,对IPv4在当前宽带业务运营环境下面临的问题进行了探讨,并进一步分析了IPv6的部署给运营模式带来的新机遇,从而为运营管理者提供一些新的思路。     

IPV6协议将沦为“鸡肋”？

近些年，随着网络用户数量逐年增加，IPv4地址几近枯竭，增加Pv4地址工程已势不可挡。虽然IPv6工程目前已有突破进展，但在耗费大量人力、物力以及财力的同时，其规模商用前景还是未知数。如何解决IPv4地址匮乏问题成为业界关注的焦点。优恩艾斯通播网技术（北京）有限公司CEO汪涛先生在2000年提出了通播网理论，并称该理论下的超级IP协议已成为解决IP地址匮乏问题的“另一条路”。究竟超级IP协议有何过人本领？它能否肩负引领网络发展的重任？通信世界网带着这些问题对汪涛先生进行了专访。     

向IPv6时代演进的核心网络路由器

互联网的迅猛发展．使得IP地址资源非常紧张．而下一代语音、数据、视频融合的通信网络对安全、质量和移动性都提出了更高的要求。在发展下一代网络过程中，IPv6是一个重要的方面。未来的网络是基于IP的，而目前IP网络的基本协议是IPv4。IPv4在地址空间、端到     

IPv6网络域名系统综述

随着IPv4地址的枯竭,IPv6技术以其充足的地址空间,良好的网络层次划分等技术优势,成为了下一代互联网的核心。作为联系其互联网内两大基础性资源——域名及IP地址的纽带,域名系统在互联网由IPv4向IPv6网络演进的过程中,将继续发挥其重要作用。本文对于域名系统为适应IPv6网络所做出的改变进行了详细的总结与分析．并针对IPv4向IPv6过渡阶段域名系统所面临的问题,提出域名系统的过渡解决方案。     

IPv6网络平滑演进研究

英特网传统IP地址资源的枯竭,是英特网发展面临的全球性问题。IPv6(互联网通信协定第6版)早在1998年12月被IETF(互联网工作小组)通过公布互联网标准规范的方式定义出台。IPv6提供了足够多的非传统IP地址资源,但是在彻底替换传统IPv4(互联网通信协定第4版)地址之前,涉及大量网络和应用软件改造。本文从运营商的角度探讨了一个趋于平滑的,对传统应用软件无需改造的技术方案,作为IPv6演进的一种可供选择的方式。     

下一代IP协议

INTERNET的高速发展验证了TCP/IP协议的生命力 ,同时也使IPv4协议天生的地址空间不足、层次结构不合理、安全性不够、没有QoS保证等问题暴露无遗 ,较之IPv4协议IPv6地址长度为 1 2 8位 ,地址空间更大、高效的层次寻址及路由结构、全状态和无状态地址配置、内置安全设施和更好的QoS支持彻底地解决了IP网不能作为电信基础网的难题     

大规模IPv4/IPv6演进环境下的地址管理关键技术与应用

分析了校园有线网和无线网大规模IPv4/IPv6演进环境下的基本地址管理需求,对IPv6地址管理技术进行了阐述,并对适用于这种大规模演进环境的地址管理服务关键运行技术进行了探索性讨论。最后通过实际部署案例,给出了地址管理服务在大规模IPv4/IPv6双栈演进环境中的具体应用,为基于IPv6的下一代校园有线网和无线网统一地址管理和演进积累了经验。     

广电网络IPv6规划与实践

目前,各种IPv6过渡技术都存在不足,如何合理地使用这些技术实现过渡到下一代互联网,是目前一大难题。本文从广东广电网络双向业务IP地址不足这一急迫诉求入手,针对广电双向业务平台、网络、终端等各环节向IPv6过渡的问题进行了分析,制定了广电网络运营商IPv6演进路线。     

ad hoc网络地址自动配置技术研究

针对ad hoc网络的地址自动配置问题,介绍了该领域研究现状和最新进展,以及有代表性的配置机制的配置思想和实施方法,比较了各配置机制的相关性能,在此基础上给出了结论.     

QoS Provisioning in Wireless IP Networks

This paper deals with quality of service (QoS) provision in wireless IP networks. QoS provision is particularly challenging in wireless networks, where network resources are generally limited, variable over time and shared. In the design of possible measures to assure QoS one should consider that standardization is well established for the network layer Internet Protocol and for many underlying technologies of frequent use (e.g. IEEE 802.11, BLUETOOTH or HIPERLAN II). Therefore, as far as research on QoS is concerned, there is little room in both the IP and the link-layers for improved IP over wireless interfaces. In this paper we illustrate a solution in which an intermediate Wireless Adaptation Layer (WAL) is transparently interposed between the IP layer and specific link-layer technologies as a solution to provide QoS. The WAL addresses two main issues: (i) compensation for channel impairments in different platforms in order to enhance wireless channel reliability and (ii) implementation of traffic control and packet scheduling mechanisms to satisfy bandwidth and delay requirements, as well as to enforce a general principle of fairness among the IP associations contending for network resources and achieve optimal exploitation of transmission capacity. The WAL consists of a set of modules, each one in charge of a specific task, which can be enabled or disabled depending on the specific network environment. The novelty of the WAL approach is its capability of adapting itself to different wireless interfaces selecting performance enhancing modules for specific networks. This requires to modify the standard TCP/IP protocol stack by introducing an intermediate layer between the IP layer and the Data Link layer, with performance enhancement purposes. This paper focuses on two modules in particular, namely a traffic control module, which is in charge of performing congestion control and channel state dependent scheduling (CSD) packet scheduling, and a forward error correction (FEC) module, which compensates for channel impairments. This paper presents the proposed architecture provided with these modules and reports some measurements and simulations highlighting benefits resulting from the use of such modules.     

Transparent bridging support for Bluetooth–IP service interworking

A PC‐based transparent gateway for interconnecting Bluetooth Piconets and IP local area networks (LAN) was designed in our research. The essential function of this designed Bluetooth‐IP gateway is to achieve a seamless integration among home appliances, networking elements and multi‐systems using the address resolution protocol (ARP) and connection management scheme. The key techniques developed, as well as the performance analysis in terms of queue length, loss rate, throughput and transmission delay are explored in this research. The results allow us to determine the value of the optimal command and infer the maximum queue length requirements such that the service quality is kept at an acceptance level. Copyright © 2002 John Wiley & Sons, Ltd.     

IPv6的安全机制及其对现有网络安全体系的影响

IPv6不但解决了当今IP地址匮乏的问题,并且由于它引入了加密和认证机制,实现了基于网络层的身份认证,确保了数据包的完整性和机密性,因此,可以说IPv6实现了网络层安全。但是,这种安全不是绝对的。并且由于IPv6的安全机制,给当前的网络安全体系带来了新的挑战,致使许多在现有的网络中对保护网络安全中起着重要作用的工具受到巨大的冲击,急需安全专家进一步研究和积累经验,尽快找出合适的解决方法。     

MPLS and traffic engineering in IP networks

Rapid growth and increasing requirements for service quality, reliability, and efficiency have made traffic engineering an essential consideration in the design and operation of large public Internet backbone networks. Internet traffic engineering addresses the issue of performance optimization of operational networks. A paramount objective of Internet traffic engineering is to facilitate the transport of IP traffic through a given network in the most efficient, reliable, and expeditious manner possible. Historically, traffic engineering in the Internet has been hampered by the limited functional capabilities of conventional IP technologies. Recent developments in multiprotocol label switching (MPLS) and differentiated services have opened up new possibilities to address some of the limitations of the conventional technologies. This article discusses the applications of MPLS to traffic engineering in IP networks     

Advances in Wireless Video Delivery

This paper reviews practical video delivery technologies, examining existing mobile networks, commercialized or standardized transport, and coding technologies. Compression efficiency, power dissipation, and error control are intrinsic issues in wireless video delivery. Among these issues, error control technologies are evaluated at four layers: 1) layer-1/2 transport; 2) end-to-end transport layer such as TCP/IP or RTP/UDP/IP; 3) error-resilience tool and network adaptation layer) and 4) source coder layer. Layer-1/2 transport tends to provide two distinct conditions: one quasi-error-free, in which upper layer error control technologies show a limited improvement, and one with a burst of errors during the fading period, in which the adaptability of error control is essential. Emerging mobile network quality of service will have a large variation of bandwidth and delay. Thus, adaptive rate control and error recovery are identified as more crucial issues for future research.     

IP connectivity for gateway GPRS support node

In the Universal Mobile Telecommunications System, the gateway GPRS support node (GGSN) provides IP connection between the mobile telecommunications network and external packet data networks (e.g., the Internet). Specifically, the GGSN exercises session management to transfer user packets between mobile stations and external data networks. In this article we focus on the GGSN functions for IP connection including access point name processing, IP address allocation, tunneling technologies, and QoS management. Based on our experience as a mobile operator, we give several examples to show how these functions can actually be implemented in a commercial mobile network.