长距离光纤接入网络优化通信研究与仿真

在光纤接入网络通信优化的研究中,光纤接入网络交换机和终端设备不能适应长距离通信需求,一旦距离过长,光信号强度会大规模衰减,直至网络数据无法传输.传统的解决办法只能依靠增加中继放大设备,不断对衰减信号进行补偿,实现长距离通信,但补偿过程仅仅通过距离判断,能耗高,补偿过程不细致,效果不佳.提出一种光纤接入网络优化编码的方法优化通信过程,利用优化编码构建多个虚拟专网机制,用虚拟专网替代硬件设备,使网络数据实现在任何一个虚拟专网中都完整准确地传递,实现数据在光接入网络中的长距离传输.在仿真中引入了数据吞吐量增益做为测试的标准,来检验数据在每一个虚拟专网和多个虚拟专网中传输的完整性,结果表明,利用优化编码方法构建虚拟网络,数据在每个专网和多个虚拟专网中都能完整的传输.     

以太无源光网络及其在综合业务接入中的应用

正处于高速发展阶段的以太无源光网络(EPON)是以太网技术和无源光技术相结合的产物,是一种全新的接入网技术,被业界看成是ATM无源光网络(APON)的替代者。文章讨论了以太无源光网络的发展现状、网络结构、工作原理及其优势,进而阐述了它在接入网络中的应用前景。它可以同时支持语音、数据、视频的传输,以一套在综合业务接入中的成功方案显示了它的优越性。     

以太无源光网络及其在综合业务接入中的应用

正处于高速发展阶段的以太无源光网络 (EPON) 是以太网技术和无源光技术相结合的产物,是一种全新的接入网技术,被业界看成是ATM无源光网络(APON)的替代者.文章讨论了以太无源光网络的发展现状、网络结构、工作原理及其优势,进而阐述了它在接入网络中的应用前景.它可以同时支持语音、数据、视频的传输,以一套在综合业务接入中的成功方案显示了它的优越性.     

VPN虚拟专网的实施方案探究

文章根据不同学校VPN虚拟专用网络组网的实际出发，对VPN虚拟专用网络规划及实施过程遇到的问题进行了分析，为各学校、公司之间VPN虚拟专用网络的构建提供参考。     

浅析广电数字双向网络改造中的EPON技术应用

以太无源先网络是一个专门应用于接入网的技术.采用点到多点的网络拓扑结构,在一芯光纤上利用上下行两个波传输数据,下行数据采用广播方式的时分复用方式,上行数据采用时分多址接入的方式,达到利用光纤实现数据、语音和视频多种业务接入的目的.     

网络编码在无源光网络中的应用研究

介绍无源光网络接入网技术及网络编码的基本理论,将网络编码应用到无源光网络体系结构中,重点阐述系统中数据交换过程,理论分析证明在不改变硬件设备的条件下,可以提高无源光网络系统的下行吞吐量,提高网络的带宽利用率。最后,结合缓冲策略给出了可以进一步实现的软件框架模型和基本算法。     

VPN虚拟专网技术在供电所网络建设中的应用

VPN虚拟专网是在互联网公用网络上建立私有的专用网络。它利用加密技术对经过隧道传输的数据进行加密,从而保证了数据的私有性和安全性。它具有运行成本低、扩充灵活、网络移动性强等特点。供电公司下属的供电所点多面广,租用2M数据专网运行费用昂贵。就某个供电公司采用VPN技术建立供电所与支公司之间的网络,作了详细的介绍。     

新一代业务光网络技术研究

文章在对新一代业务光网络演进发展趋势进行分析的基础上,以业务为核心对业务光网络的功能分层进行了明确,提出了业务光网络参考模型,构建了业务光网络功能框架,给出了基于智能光网络的业务管理思路。     

Linux中配置虚拟专网

本单位有着丰富的内网资源,比如内网的文件服务器、财务工资查询、人事查询,这些服务都只能在本单位内部的电脑上才能访问。同时,本单位的官网管理入口,出于安全的考虑,开启的是8081端口和8082端口,这些在公网上也是禁止访问的,因此当有紧急事件,需要在家或者出差的异地访问本单位的内网服务时,就需要一台提供虚拟专用网络接入的服务器,简称VPN服务器。本文介绍利用Linux操作系统和x12tpd开源软件配置自己的虚拟专用网络服务器的方法。     

“光进铜退”背后的两种接入方案

到目前为止,光纤到户技术（Fiber To The Home——FTTH）在日本和美国已得到广泛应用,但在我国还处于明芽阶段。现有的FTTH技术主要包括无源光网络（Passive Optical Network——PON）接入技术和小区有源交换光网络（Active Optical Network——AON）接入技术,它们各有优势,适用于不同的应用环境。     

A Web-based monitor and management system architecture for enterprise virtual private network

Virtual private network (VPN) not only possesses the low cost, inexpensive fees, and excellent support advantages of the Internet, it also has the benefit of the security as the leased line. How to properly manage the VPN is an issue in which the enterprise IT engineers have to take seriously.

This research is based on the new network management technologies such as policy-based network management, mobile agent, etc., to design a VPN monitor and management system architecture that contains high level management with low network traffic load. This system architecture integrates both VPN devices and general network devices, such the feature can integrate the monitor and manage the VPN and Intranet at the same time.

The result of this research provides enterprises with a VPN architecture for monitoring and managing the enterprises, as well as to establish a prototype for the enterprise VPN monitor and management system. Such system architecture can effectively assist the semiconductor companies to monitor and manage their enterprise VPN in order to utilize the Internet resources, and to reduce the possible operation off time. The prototype system could proof the feasibility of the systematic architecture, it can automatically detect and activate the backup mechanism according to the preset management policy, and to achieve the effective and fast solution for the enterprise network problems.     

基于分布式安全代理提升VPN系统安全接入性能研究

分析了传统的VPN系统安全接入实现机制及存在的问题，提出了采用基于“分布式安全代理”技术的一种VPN系统安全接入模式。进而介绍了分布式安全代理的原理及关键安全代理模块。最后，通过并发接入性能对比测试验证了采用分布式安全代理技术对于VPN系统并发安全接入性能提升的作用，说明了该技术在实际应用中的意义。     

Topology-transparent reservation time division multiple access in multihop ad hoc networks

In this paper, an optimal topology-transparent reservation time division multiple access (OTTR-TDMA) protocol is proposed for multihop ad hoc networks. Our MAC protocol is based on a slotted TDMA architecture in which every slot is divided into reservation phase and data transmission phase. Every node not only transmits data in its assigned slots that are computed by Chlamtac’s algorithm, but it also utilizes free slots among its non-assigned slots through reservation. Through theoretical analysis, we derive the proper parameter for the best performance. We compare our protocol with other TDMA protocols and find that it gives better performance. Simulation results show that they are consistent with our analytical results.     

无线体域网中基于属性加密的数据访问控制方案

作为一种新的电子医疗技术,无线体域网(wireless body area networks,WBANs)将在病情监测中发挥重要作用,安全性及隐私性保护是无线体域网的重要内容.针对WBANs数据访问控制提出一种细粒度的数据访问方法,该方法采用基于属性的数据加密方法,加密者将数据访问结构作为访问策略,当解密者所具有的属性满足该结构时,即可访问该数据,否则,拒绝用户访问.分别从正确性、安全性及能量消耗三方面对方案进行分析.仿真实验结果表明,本方案相对其他方案能量消耗较小.     

A new forwarding address for next generation networks

The forwarding address plays an important role in constructing a communication network.In this paper,a new forwarding address suitable for next generation networks named the vector address(VA) is proposed which is different from the forwarding address coding methods of current networks.The characteristics of the VA are analyzed.Complex network theory and a theoretical analysis method are introduced to study the average address length of the VA when used to construct a global network.Simulation experiments in a practical network topology model are carried out to validate the results.The results show that not only can the VA construct a simpler,more secure,and more scalable network,but it also can accommodate many more users than an Internet Protocol(IP) network with the same address length.     

Inter-domain service management of broadband virtual private networks

The emergence of an open market for telecommunication services provides a wide range of opportunities for the provision of value-added services by providers other than public network operators. One service already available today is a Virtual Private Network (VPN) that provides dispersed corporate sites with wide-area data communication capabilities using public network services. The introduction of Broadband ISDN allows for the provision of VPN services in a more integrated fashion. However, any effective VPN service must be able to deal with the technological and organizational heterogeneities that are present when providing a high level of service functionality over an arbitrary number of administrative and technological domains. This paper presents a management service for a VPN service that addresses some multi-domain and network heterogeneity issues. It outlines how a design based on the ITU-T's Telecommunications Management Network (TMN) Recommendation was developed and how working prototypes were implemented over real broadband networks.     

A user-centric approach to service creation and delivery over next generation networks

Next Generation Networks (NGN) provide Telecommunications operators with the possibility to share their resources and infrastructure, facilitate the interoperability with other networks, and simplify and unify the management, operation and maintenance of service offerings, thus enabling the fast and cost-effective creation of new personal, broadband ubiquitous services. Unfortunately, service creation over NGN is far from the success of service creation in the Web, especially when it comes to Web 2.0. This paper presents a novel approach to service creation and delivery, with a platform that opens to non-technically skilled users the possibility to create, manage and share their own convergent (NGN-based and Web-based) services. To this end, the business approach to user-generated services is analyzed and the technological bases supporting the proposal are explained.     

一种集成的可伸缩的网络安全系统

常用的网络安全技术有防火墙、VPN(virtual private network)和NAT(network address translation)等,它们的作用各异.但现有的一些网络安全系统未能将上述技术有机地加以结合,不能很好地兼顾系统执行效率,对系统内部缺乏细粒度的安全管理.针对上述问题,提出了一种集成的可伸缩的网络安全系统--NEUSec(NEUsoft security system),它在Linux环境下将包过滤防火墙、VPN和NAT技术有机地融合在一起,结合NAT和代理服务技术组成了可伸缩的虚拟代理服务器,提出了基于改进型Radix树的安全策略查找机制,采用RBAC(role-based access control)技术解决了系统内部安全管理的问题.与其他安全系统相比,NEUSec是一个较为全面的、可伸缩的、兼顾效率的网络安全系统,在实际应用中取得了较好的效果.     

一种基于网格虚拟组织的跨域访问控制算法*

在网格中,主机存在于不同的信任域中,在主机间建立互信是实现资源共享、协同工作的前提,为资源的访问建立规则是实现资源安全的基础。网格中的访问控制算法旨在解决上述两个问题。结合安全数据库的访问控制策略,融入基于身份和基于行为的访问控制思想,实现了以任务发起者为中心的网格虚拟组织的跨域访问控制,并对其中建立互信的核心算法进行了BAN逻辑推理。