一种改进的EPON网络拓扑保护机制

本文分析了目前常用的几种EPON网络保护机制存在的问题,探讨了一种改进的EPON保护机制:分支环网+全光纤保护机制。通过Matlab仿真分析证明,这种保护机制比现行各种保护机制有更好的生存性。     

SDH网络保护机制组合应用问题研究

首先介绍了几种常用的SDH保护机制,然后针对常见的多复用段保护组合、复用段保护和SNCP(子网连接保护)组合以及不同等级SNCP保护组合三种方式进行了分析和讨论,指出保护机制组合应用时存在的问题和出现这些问题的原因,最后在此基础上提出了相应的解决建议.     

光传送网的保护策略

本根据ITU-TG.872(11/2001)建议，分析了光传送网的几种保护机制的工作原理，并对实用性较强的路径保护和共享保护环给出了具体实例。     

光传送网的保护策略

本文根据ITU-TG.872(11/2001)建议,分析了光传送网的几种保护机制的工作原理,并对实用性较强的路径保护和共享保护环给出了具体实例。     

RPR的网络保护及其与SDH保护方式的互通

RPR是由顺时针、逆时针两个传输方向光环组成的,这种组网方式赋予RPR的健壮性。RPR的保护倒换机制主要有两种:采用定向保护机制和采用回绕保护机制。首先概述了RPR网络保护协议,然后分析了RPR的保护倒换机制及RPR的网络保护与SDH保护方式的互通。     

一种应用于EPON的新型保护环和分区保护子环结构

以太无源光网络(EPON)是下一代宽带接入网的一种可行方案,为了增强网络的生存性,ITU-T G.983.1定义了几种无源光网络(PON)保护结构.在此基础上,文章提出了一种应用于EPON的新型保护环结构和分区保护子环结构,研究了其保护机制,分析了倒换时间,估计保护时间小于14ms.     

SDH自愈环的跨距和环路保护转换分析

叙述了提高网络,尤其是SDH自愈环的可用性和生存性的措施和方法.介绍了SDH自愈环的结构及其保护机制、保护转换的指令与协议.最后分析比较了几种常见的SDH自愈环.     

三种基于环分解的网状网保护结构比较

在电信传输网中,环网的优良生存特性为人们所熟知。同时,网状网在生存性方面也很有优势。为此,人们开发了几种网状网的生存方案,其中有现在的研究热点--智能化的动态保护,另一种即是网状网的环分解。本文就针对环分解方案,分析对比它的几种保护机制。     

弹性分组环的两种保护方式研究

弹性分组环(RPR)是由顺时针、逆时针两个传输方向的光环组成的．其保护倒换机制主要有两种：采用源路由保护机制和采用回绕保护机制．文章将分析RPR的保护倒换机制．     

浅谈PTN保护技术在烽火设备的具体实现

PTN是一种以承载分组业务为主、兼容传统TDM业务、ATM业务的新一代多业务统一传送技术,是传送网、IP、以太网三种技术相结合的产物。PTN技术具有面向连接的数据转发机制、丰富的OAM、严格的QoS机制以及50ms的网络保护等技术特征,适用于承载电信运营商的无线回传网络、以太网专线以及IPTV等高品质的多媒体数据业务。网络安全性是各大运营商最为关心的技术,是衡量一个网络质量是否优良的最重要的指标之一。文章重点介绍了PTN的几种保护技术,并对各种保护技术在传输设备的实现做了详细分析。     

A multi-period design model for survivable network architectureselection for SONET interoffice networks

The authors propose a multi-period design model to select a best mix of SONET survivable network architectures. These include: (1) point-to-point/hubbing architectures with diverse protection and (2) ring architectures. The algorithm can be used to study growth strategies, for networks incorporating the ring architecture, that minimize the network evolution cost. Numerical examples show that the algorithm can generate a good solution quickly, using a VAX 6000-420 computer for most practical applications. A case study suggests that a particular well accepted engineering rule can work well. This engineering rule is: use direct point-to-point systems in conjunction with self-heating rings and hubbing/diverse protection architectures only when a few demand pairs have appreciably higher demand requirements than other demand pairs. When demand is fairly even, then use self-healing rings or hubbing/diverse protection without direct point-to-point systems     

SONET ring applications for survivable fiber loop networks

Synchronous optical network (SONET) self-healing rings (SHR) are studied in the loop environment. SONET SHR architectures for loop feeder networks are discussed, focusing on three possible dual central office (CO) architectures for fiber loop networks, using SONET SHRs to reduce network costs and provide network service survivability. These architectures reflect an integrated planning concept for SONET networks that eliminates the boundary between the access network and the inter-office network. It is shown that the use of SONET SHRs makes it easy to evolve to a protected dual CO access architecture. Economic and survivability studies are discussed. The economic studies show that using the ring approach yields significant advantages over the traditional diverse protection approach in terms of cost and survivability, especially for the dual CO architectures     

Cost vs. reliability performance study of fiber access network architectures

Fiber to the home is the future-proof technology for broadband access networks. Several fiber access network architectures have been developed (e.g., point-to-point, active optical network, and passive optical network). PON is considered the most promising solution due to the relatively low deployment cost and high resource efficiency. Meanwhile, because of the growing demand for reliable service delivery, fault management is becoming more significant in all parts of communications networks. However, there is a trade-off between the cost of protection and the level of service reliability. Since economical aspects are most critical in the access part of networks, improving reliability performance by duplication of network resources (and capital expenditures) could be too expensive. Therefore, recent work has focused on PON protection schemes with reduced CAPEX. The future trend will probably migrate toward minimizing operational expenditures during the access network lifetime. The main contributions of this article include providing a general method for CAPEX and OPEX analysis that can be applied to any type of fiber access network with consideration of changed component cost in time and variable take rates, and comparing the total cost (i.e., sum of CAPEX and OPEX) for the selected representative architectures with and without protection for business and residential users in relation to reliability performance. The aim is to give a guideline for the design of the most cost-effective protection schemes, while maintaining acceptable service reliability.     

EPON系统环网保护组网方式

提出可以实现EPON系统业务保护和故障恢复的快速环网方式。在OLT上通过快速以太网环网,在PON口采用主干光纤保护或全保护,在ONU侧通过手拉手保护组网方式,实现整个EPON系统的冗余保护。此保护方式达到了保护时间小于50 ms的电信级要求,而且具有算法简单、拓扑收敛速度快,业务恢复时间快等显著优势。EPON系统网络拓扑,采用此种组网方式能有效地提高以太网环网的可靠性和稳定性,实现较好的业务保护效果。     

移动互联网安全接入机制研究

文中关注移动互联网网络接入安全性,介绍移动互联网面临的安全威胁,研究移动互联网的网络结构和接口协议,提出跨网系的统一认证与授权管理技术,阐述网络接入安全需求,针对EAPSIM和EAP-AKA两种安全机制,分析网络接入鉴权与密钥协商流程,以及演进分组核心网络各网元设备功能,实现用户和网络之间的认证性、机密性和完整性的安全防护,为移动互联网网络安全体制建设提供理论依据与技术支撑。     

Emerging technologies for fiber network survivability

Reducing network protection costs, while maintaining an acceptable level of survivability, has become an important challenge for network planners and engineers. This article will review technology and architectures that may be used to implement cost effective survivable fiber networks for each transport layer, and discuss the interworking system between survivability mechanisms across different layers and associated open issues. Standards development, product availability and the current status of deployment will also be reviewed. The first section reviews a class of survivable fiber network architectures that has been deployed or is scheduled to be deployed. Next is a review of emerging technologies for these survivable architecture implementations. These emerging technologies include SONET, ATM, and passive optical technology. Finally the issue of multiple layer interworking on SONET/ATM networks is discussed     

Network design sensitivity studies for use of digital cross-connectsystems in survivable network architectures

Provides the results of an economic study on the use of SONET digital cross-connect systems (DCS) to provide survivable transmission network architectures in local exchange networks. Three fundamental survivable transmission technologies are considered: (1) a SONET self-healing ring, (2) a SONET point-to-point fiber system with 1:1 automatic protection switching and diverse routing of protection facilities, and (3) a DCS mesh with automatic DCS restoration (rerouting) protection. These three technologies are used in various combinations to form six survivable network alternatives for evaluation. Two local exchange carrier (LEC) networks are used (a 15 node network and a 53 node network) and demand, network connectivity, and unit equipment cost sensitivities are evaluated on these alternatives. In addition, the survivability of each alternative in the event of a major node failure is calculated. The motivation for the study is to determine the viability of DCS-based survivable network architectures and, in particular, the viability of SONET DCS with integrated optical terminations. The study has two objectives: (1) given a specific survivable network technology, under what conditions is it economical to place a broadband DCS (B-DCS) in a central office as opposed add-drop multiplexers (ADM); and (2) which survivable technologies with B-DCS are economical, and under what conditions. The authors conclude that the most cost-effective networks consist of “hybrids” of SONET point-to-point, ring, and mesh technologies, and that the B-DCS is economically viable for interconnection between these technologies     

A passive protected self-healing mesh network architecture andapplications

The self-healing mesh network architecture using digital cross-connect systems (DCSs) is a crucial part of an integrated network restoration system. The conventional DCS self-healing networks using logical channel protection may require a large amount of spare capacity for network components (such as DCSs) and may not restore services fast enough (e.g., within 2 s). The authors propose a passive protected DCS self-healing network (PPDSHN) architecture using a passive protection cross-connect network for network protection. For the PPDSHN architecture, network restoration is performed in the optical domain and is controlled by electronic working DCS systems. Some case studies have suggested that the proposed PPDSHN architecture may restore services within a two-second objective with less equipment cost than the conventional DCS self-healing network architecture in high-demand metropolitan areas for local exchange carrier networks. The proposed PPDSHN architecture may apply to not only the centralized and distributed control DCS network architectures, but also asynchronous, SONET and ATM DCS networks. Transparency of line rates and transmission formats makes the PPDSHN network even more attractive when network evolution is a key concern of network planning     

Evaluation of throughput and protection in optically switched metropolitan network architectures

In this study, we investigate the performance of optical packet/burst switched (OPS/OBS) architectures connected as mesh and as ring topologies for future optical metropolitan networks. Network throughput and protection to link failure under uniform traffic distribution for all nodes are investigated to evaluate the sensitivity of OPS/OBSN performance. Our data are based on analytic results and computer simulations that include a comparison between various mesh and ring topologies. We also consider detailed traffic distributions over the network links and the impact caused by failure of more or less loaded links, thus providing a method to select links that require protection, which can be very useful in network planning.     

The Genesis Kernel: a programming system for spawning networkarchitectures

Currently, the design, deployment, and refinement of new network architectures is a manual, ad hoc, and time-consuming process. We present the design, implementation, and evaluation of the Genesis Kernel, a programming system that automates the life cycle process for the creation, deployment, management, and architecting of network architectures. We discuss our experiences in building a spawning network that is capable of creating distinct virtual network architectures on-demand. The Genesis Kernel is based on a methodology that allows a child virtual network to operate on top of a subset of its parent's network resources and in isolation from other spawned virtual networks. We show through experimentation how a number of diverse network architectures can be spawned and architecturally refined. These spawned network architectures include a parent network that supports IP forwarding, and interior and exterior routing. We discuss how two child networks based on Cellular IP and Mobiware architectures can be spawned on the parent network to support wireless access to data and continuous media services, respectively