NGN的IP承载方案

NGN是完全基于数据网络、特别是分组网络（IP网络）的IP承载网来实现语音业务及其他增值业务的开放平台.分析了NGN基于IP的承载方案：NGN对承载网的要求、NGN的承载方式、QoS保证及国内的著名应用介绍等.     

IMS中的承载控制和计费控制

自3GPP研究并制定IP多媒体子域(IMS)的标准以来,已经有包括ETSI和ITU-T等在内的区域性或国际性标准组织,将其选择作为下一代网络(NGN)的业务控制子系统之一。IMS工作在NGN的“业务层”,独立于接入技术和承载技术,因此如何通过对IMS对承载层进行控制,以及实现基于IMS的业务计费,是IMS/NGN面临的主要问题之一。北电网络(中国)有限公司的《IMS中的承载控制和计费控制》一文对IP承载管理器方案以及基于FBC的实时计费方案介绍的比较详细,值得业界借鉴。     

WSON关键技术和解决方案

纵观IP与光网络的发展与融合过程,IP over WDM光链路解决了IP业务对带宽的渴求。目前,3G、NGN、IPTV均可通过基于IP的路由型多业务平台实现综合承载。电信网络IP化的趋势越来越明显。此时的IP网络与几年前IP网络扮演的角色、承担的责任已大不相同。随着信息业务IP化、电信业务承载IP化,IP网络不但要承载日益增加的Internet上网业务,     

构建新一代运营商级VoIP业务网的探索与实践

VoIP 将是NGN 的最大应用之一。如何将现有VoIP 网络的QoS 提升到“运营商级”,同时又保持IP 业务的低成本,是每一个电信运营商正在思考和探索的课题。上海联通基于UniOne(统一业务)和MISN( 城域综合业务网) 等新的技术运营理念,在对NGN 的软交换、MPLS/VPN 以及IPv6 等相关技术的深入研究基础上,经过近两年的实践,走出了一条提高IP 承载网QoS 和运用软交换技术实现集中业务管理和控制的有效途径。     

NGN网络测试仪H.264合成模块的研究与实现

以下一代网络(NGN)网络测试仪的研制为背景,在基于对H.264协议的深入理解基础上,通过软件方法将H.264协议数据从IP包、实时传送协议,实时传送控制协议(RTP/RTCP)消息中分离出来,然后对H.264协议的数据按帧进行解码处理,通过软件实现其数据合成,最后在NGN网络测试仪中成功建立基于H.264的视频合成模块.     

基于NGN商用试验网的组网模式及其具体技术研究

文章针对当前基于电路交换的语音网络(PSTN/iSDN)和基于包或信元交换的数据通信网络的现状及存在的问题,以IP承载网所采用的技术为例,就NGN试验网中互通方案、网管模式、业务提供设备、承载网络组织等方面进行NGN商用试验网的技术可行性论证。     

语音与增值业务在NGN网络运营中的地位分析

要涉及到NGN网络的运营,首先应该了解一些NGN网络的基本知识和NGN网络的特点,然后才能就语音业务和增值业务的地位进行分析和理解。 NGN是以电路交换为主的传统电信网络逐渐迈向以分组交换为主的新电信网络,它承载了原有电路交换网络的所有业务,同时把大量的数据业务传输旁路到IP网络中以减轻电路交换网络的负荷,又以IP技术的新特性增加和增强了许多新老业务。从这个意义上讲,NGN是基于TDM的语音网络和基于IP/ATM的分组网络融合的产物,它使得在新一代网络上     

IP承载网“全民转型”铺垫3G应用

中国网通历经两年时间建设的一张覆盖全国300多个城市、成为全球覆盖范围最广的NGN／3G承载网络之一的IP承载网，即将建成并投入使用。该网络可承载的业多争包括NGM、视频、IPTV以及未来的3G等增值业务。两年前的10月，华为与中国网通签约，独家承建网通NGN IP承载网和大客户NGN业务网，其设备也大规模应用到了网通NGN长途网中。     

基于NGN网络语音质量测量的探讨

基于IP承载网络和软交换技术的下一代网络（NGN）有着很大的发展趋势，NGN网络的基本业务是语音业务，影响语音质量的因素是由多个方面决定的，主要包括时延、丢包、抖动等。语音质量的好坏直接影响用户对运营商的选择，因此对NGN网络语音服务质量进行有效的分析和测量是十分重要的。     

中国联通下一代网络的实践与思考

文章介绍了中国联通的多业务统一网络平台,包括多业务服务质量(QoS)保障的融合的承载平台、融合的软交换核心控制架构、多业务QoS保障的城域综合业务网络和基于IPv6的网络承载技术.依据中国联通在下一代网络(NGN)方面的实践,文章对多业务统一网络平台的先进性、效果与效益进行了总结,并指出了存在的问题.文章指出:由于未来NGN技术将向基于IP多媒体子系统(IMS)的NGN方向继续演进,同时网络承载层技术将逐步从IPv4过渡到IPv6,因此中国联通将积极探索基于IMS的NGN网络架构与组网模式,努力开展面向IPv6的应用实验与推广工作,特别是移动IPv6业务的开发和推进.     

Dynamic hierarchical mobility management strategy for mobile IP networks

One of the major challenges for the wireless network design is the efficient mobility management, which can be addressed globally (macromobility) and locally (micromobility). Mobile Internet protocol (IP) is a commonly accepted standard to address global mobility of mobile hosts (MHs). It requires the MHs to register with the home agents (HAs) whenever their care-of addresses change. However, such registrations may cause excessive signaling traffic and long service delay. To solve this problem, the hierarchical mobile IP (HMIP) protocol was proposed to employ the hierarchy of foreign agents (FAs) and the gateway FAs (GFAs) to localize registration operations. However, the system performance is critically affected by the selection of GFAs and their reliability. In this paper, we introduce a novel dynamic hierarchical mobility management strategy for mobile IP networks, in which different hierarchies are dynamically set up for different users and the signaling burden is evenly distributed among the network. To justify the effectiveness of our proposed scheme, we develop an analytical model to evaluate the signaling cost. Our performance analysis shows that the proposed dynamic hierarchical mobility management strategy can significantly reduce the system signaling cost under various scenarios and the system robustness is greatly enhanced. Our analysis also shows that the new scheme can outperform the Internet Engineering Task Force mobile IP hierarchical registration scheme in terms of the overall signaling cost. The more important contribution is the novel analytical approach in evaluating the performance of mobile IP networks.     

IP网络性能指标体系的研究

网络性能指标是网络测评的基础。本文从网络测评的不同角度对IP网络的性能指标进行了综合分析，指出了一种能系统反映IP网络性能的指标体系，并给出了IP网络性能指标体系的形式描述。在此基础上引入了泛化指标和确定性指标的概念，探讨了确定性指标的内容有及描述框架。该研究突破了目前IP网络性能指标体系研究的简单性、局限性，对IP网络测试和性能评价具有指导意义。     

Privacy-Preserving Data Packet Filtering Protocol with Source IP Authentication

Packet filtering allows a network gateway to control the network traffic flows and protect the computer system. Most of the recent research works on the filtering systems mainly concern the performance, reliability and defence against common network attacks. However, since the gateway might be controlled by red an untrusted attacker, who might try to infer the identity privacy of the sender host and mount IP tracking to its data packets. IP spoofing is another problem. To avoid data packets to be filtered in the packet filtering system, the malicious sender host might use a spoofed source IP address. Therefore, to preserve the source IP privacy and provide source IP authentication simultaneously in the filtering system is an interesting and challenging problem. To deal with the problem, we construct a data packet filtering scheme, which is formally proved to be semantic secure against the chosen IP attack and IP guessing attack. Based on this filtering scheme, we propose the first privacy-preserving packet filtering system, where the data packets whose source IP addresses are at risk are filtered, the privacy of the source IP is protected and its correctness can be verified by the recipient host. The analysis shows that our protocol can fulfil the objectives of a data packet filtering system. The performance evaluation demonstrates its applicability in the current network systems. We also presented a packet filtering scheme, where the data packets from one subnet can be filtered with only one filter policy.     

一种IP网络性能测量和评价系统的设计

IP网络性能测量和评价是从事网络理论研究、网络管理和网络工程开发的重要手段。首先概述了国内外IP网络测量技术的研究现状和发展动态,然后给出了一种可扩展的分布式IP网络性能测量和评价系统的设计方案,包括系统层次结构、体系结构和功能结构,描述了系统的关键组件和可以开展的应用。     

Signaling cost and performance of SIGMA: A seamless handover scheme for data networks

Mobile IP has been developed to handle mobility of Internet hosts at the network layer. Mobile IP (MIP), however, suffers from a number of drawbacks such as requirement of infrastructure change, high handover latency, high packet loss rate, and conflict with network security solutions. In this paper, we describe and evaluate the performance of SIGMA, a Seamless IP diversity‐based Generalized Mobility Architecture. SIGMA utilizes multihoming to achieve seamless handover of mobile hosts, and is designed to solve many of the drawbacks of MIP, including requirement for changes in infrastructure. We first evaluate the signaling cost of SIGMA and compare with that of hierarchical Mobile IPv6 (an enhancement of Mobile IP) by analytical modeling, followed by comparison of handover performance of SIGMA and Mobile IPv6 enhancements. Criteria for performance evaluation include handover latency, packet loss, throughput, and network friendliness. Our results indicate that in most cases SIGMA has a lower signaling cost than Hierarchical Mobile IPv6. Moreover, for a typical network configuration, SIGMA has a higher handover performance over Mobile IP. Copyright © 2005 John Wiley & Sons, Ltd.     

Demand assigned capacity management (DACM) in IP over optical (IPO) networks

The demand assigned capacity management (DACM) problem in IP over optical (IPO) network aims at devising efficient bandwidth replenishment schedules from the optical domain conditioned upon traffic evolution processes in the IP domain. A replenishment schedule specifies the location, sizing, and sequencing of link capacity expansions to support the growth of Internet traffic demand in the IP network subject to economic considerations. A major distinction in the approach presented in this paper is the focus of attention on the economics of "excess bandwidth" in the IP domain, which can be viewed as an inventory system that is endowed with fixed and variable costs and depletes with increase in IP traffic demand requiring replenishment from the optical domain. We develop mathematical models to address the DACM problem in IPO networks based on a class of inventory management replenishment methods. We apply the technique to IPO networks that implement capacity adaptive routing in the IP domain and networks without capacity adaptive routing. We analyze the performance characteristics under both scenarios, in terms of minimizing cumulative replenishment cost over an interval of time. For the non-capacity adaptive routing scenario, we consider a shortest path approach in the IP domain, specifically OSPF. For the capacity adaptive scenario, we use an online constraint-based routing scheme. This study represents an application of integrated traffic engineering which concerns collaborative decision making targeted towards network performance improvement that takes into consideration traffic demands, control capabilities, and network assets at different levels in the network hierarchy.     

大型IP网络时延的主成分分析

网络时延是评估网络性能的关键指标之一。主成分分析(PCA)是数据挖掘领域常用的一种多变量分析和降维算法。通过对大型IP网络时延进行PCA分析,旨在挖掘网络时延的深层原因及网络各节点间的相互依赖关系,并搭建一个科学合理的网络时延评价体系,最终得到IP网络建设、优化改造的有效建议。对历史网络时延进行离线分析只是主成分分析方法的一种初步应用,今后可结合网络拓扑结构、现网流量流向、路由、距离等相关因素,将主成分分析方法应用到针对网络流量、网络时延、网络丢包等网络性能的实时在线监测分析中,进一步提升网络运营的效率和质量。     

基于协议栈芯片的嵌入式WEB服务器低成本实现方法

现在所存在的WEB服务器设计大多采用向微处理器上移植TCP／IP协议栈的方法，这些实现一般对微控制器的处理能力要求比较高，而且成本比较高，虽然数据传输速度较快，但在有些情况下这并不必要。本文介绍了一种利用集成了TCP／IP协议栈的接口芯片S7600以及MODEM模块接入Interact来构成WEB服务器的方式，这种方式对处理器性能要求不高，成本低，结构简单，性能稳定，在小规模的应用场合非常合适。     

SMS-MIPv6: An End-to-End Mechanism for IPv6 Mobility Management in Mobile Networks

As IP has been extended from core networks to access networks, a mobile network can be considered as an overlay of a traditional cellular network and an IP network. SMS-MIPv6 attempts to integrate mobility management of these two kinds of networks. The basic idea behind SMS-MIPv6 is to exploit existing mobility management in the cellular network (i.e. in the form of well-defined short messages) to locate a Mobile Terminal (MT) in the IPv6 network. We should emphasize that the motivation of SMS-MIPv6 is not to replace or optimize existing mature mobility management schemes. On the contrary, as an entirely end-to-end mechanism for IPv6 mobility management, it provides an alternative mechanism for free peer-to-peer applications such as Voice over IP (VoIP) without support from mobile network operators. We describe the implementation of SMS-MIPv6 in detail and analyze its performance. The evaluation results show that SMS-MIPv6 achieves acceptable performance so that it can be deployed in most current mobile networks. It performs best in terms of signaling cost, data traffic overhead compared with Mobile IPv6 (MIPv6) and Proxy MIPv6 (PMIPv6). Moreover, SMS-MIPv6 can reduce the handover latency significantly, although it is considered as a mobility management scheme for global mobility. However, it increases the session initialization latency due to hybrid binding through the cellular network.     

基于嵌入式LINUX的GPRS数据传输系统

简要分析了嵌入式Linux操作系统和GPRS传输原理，并结合嵌入式Linux技术和GPRS网络，提出基于嵌入式Linux操作系统的GPRS数据传输系统设计方法。目前，中国移动的GPRS网络运行稳定且支持TCP／IP协议，Linux内核也支持此协议栈，这样以很少的投入就可以开发出满足不同需要的GPRS数据传输应用。