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1.
Providing fault tolerance in wireless access networks 总被引:2,自引:0,他引:2
Research and development on network survivability has largely focused on public switched telecommunications networks and high-speed data networks with little attention on the survivability of wireless access networks supporting cellular and PCS communications. This article discusses the effects of failures and survivability issues in PCS networks with emphasis on the unique difficulties presented by user mobility and the wireless channel environment. A simulation model to study a variety of failure scenarios on a PCS network is described, and the results show that user mobility significantly worsens network performance after failures, as disconnected users move among adjacent cells and attempt to reconnect to the network. Thus, survivability strategies must be designed to contend with spatial as well as temporal network behavior. A multilayer framework for the study of PCS network survivability is presented. Metrics for quantifying network survivability are identified at each layer. Possible survivability strategies and restoration techniques for each layer in the framework are also discussed 相似文献
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This paper formulates a general framework that includes and extends the existing definitions for network survivability. Based on this framework, network survivability is characterized by a survivability function rather than a single-value survivability measure, and various quantities of interest can be derived from the function. Examples are the expected survivability, the worst-case survivability, the r-percentile survivability, and the probability of zero survivability. The survivability function is especially useful for the study of large-scale disasters. For illustration, the authors derive the survivability function in closed form for a simple ring network under link failures. They also discuss the general procedure for finding survivability functions for complex networks, and show that the survivability function reveals useful information about a network. This framework provides a unified and practical approach to analyzing and designing highly survivable communications networks 相似文献
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Andriolli N. Giorgetti A. Valcarenghi L. Castoldi P. 《Lightwave Technology, Journal of》2007,25(5):1152-1162
Optical networks carrying traffic belonging to different survivability classes must ensure not only the proper survivability differentiation but also the efficient network resource utilization. Current approaches improve network resource utilization by carrying low-class preemptable traffic along high-class spare resources, which are idle (i.e., unutilized) during failure-free conditions. In this paper, the proposed idle protection capacity reuse (IR) framework generalizes the practice of reutilizing idle spare resources to both failure-free and failure conditions. The IR framework is based on the idea of exploiting idle high-class lightpath protection resources not only for routing low-class lightpaths during the provisioning phase (i.e., provisioning-phase IR, P-IR) but also for dynamically restoring low-class lightpaths during the recovery phase (i.e., recovery-phase IR, R-IR). Both P-IR and R-IR have the potential to improve network utilization while providing multiclass lightpaths with the required survivability differentiation. The numerical evaluation shows that the utilization of R-IR in dynamic restoration results in an improved low-class lightpath survivability with respect to the utilization of stub release. Moreover, if P-IR and R-IR are alternatively exploited, then the former improves the provisioning performance, while the latter guarantees a higher survivability. In the end, if P-IR and R-IR are concurrently employed in the provisioning and in the dynamic restoration of two different low classes of lightpaths, respectively, an inherent survivability differentiation is achieved 相似文献
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Manijeh Keshtgary A. H. Jahangir Fahad A. Al-Zahrani Anura P. Jayasumana 《Photonic Network Communications》2006,11(1):15-27
Network Survivability is defined as the ability of a network to support the committed Quality of Services (QoS) continuously
in the presence of different failure scenarios. Both availability and performance degradation of a system in presence of failure
are integral components of survivability evaluation. Therefore, a composite model is presented for network survivability that
includes system availability analysis to find out the cost due to system downtime, and system failure impact analysis to find
out the transient performance degradation when failure occurs. A new analytical technique is presented to evaluate the excess
loss due to failure (ELF) as the transient performance degradation when the system is operating in gracefully degraded states.
Single and multiple link failures as well as node failures are considered. An algorithm is proposed to carry out the steady
state availability analysis of a network even when the available paths between a pair of nodes are non-disjoint. A recursive
generalized form of the availability algorithm when there are multiple paths available between a pair of nodes is presented.
The availability model and the performance model are combined to construct a hierarchical model to evaluate the network survivability
performance. Simulation results are used to validate the proposed model. A WDM network with wavelength conversion is considered
as an example for this evaluation. 相似文献
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Integrity of public telecommunications networks 总被引:1,自引:0,他引:1
Tsong-Ho Wu McDonald J.C. Flanagan T.P. Ken-Ichi Sato 《Selected Areas in Communications, IEEE Journal on》1994,12(1):1-4
Provides an overview of the special issue of the IEEE Journal of Communications, Volume 12, Number 1 (January 1994) which addresses open questions in network integrity, reliability and survivability. Current progress in this area is discussed. The questions addressed include user survivability perspectives on standards, planning, and deployment; the analysis and quantification of network disasters; survivable and fault-tolerant network architectures and associated economic analyses; and techniques to handle network restoration as a result of physical damage or failures in software and control systems. Special interests are devoted to the survivability of broadband networks employing the new transport/switching techniques based on the synchronous optical network (SONET) and asynchronous transfer mode (ATM) standards due to their emerging role in future B-ISDN. Network integrity due to failures of common channel signaling (CCS) systems is also very critical. The present special issue includes 22 papers and is organized into the following sections: user perspectives and planning, software quality and reliability, network survivability characterization and standards, network restoration for SONET networks, network restoration for ATM networks, traffic effect and performance enhancement for computer networks, and survivable network design methods. Network restoration methods for SONET, ATM, and computer networks correspond to those for the physical layer (SONET), ATM layer, and the network layer, defined in the CCITT broadband ISDN layer structure 相似文献
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提出了基于管理技术的ATM网络抗毁性组织结构概念,指出了在网络规划设计与维护管理阶段进行层次化技术处理的重要性。ATM网络抗毁性组织结构要求在网络规划设计阶段、运用各种规划算法和仿真技术进行抗毁性设计与验证;在网络管理维护阶段,从网络各个层次,运用各种管理算法或机制维护网络抗毁性。在网络实际运行过程当中,该组织结构强调联合应用网络各层次上的抗毁性管理技术,充分发挥各个层次上的抗毁性,以提高整个网络抗毁性能。 相似文献
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可生存网络系统的形式化定义 总被引:8,自引:0,他引:8
随着大规模、分布式网络系统对信息安全需求的进一步提高,其安全问题的研究重点已转移为网络系统的可生存性研究.那么,首要问题是建立统一、规范的网络系统的可生存性定义.文中从网络系统的可生存需求出发,借鉴了近年来国内外的可生存研究成果,提出了规范化的网络系统的可生存性定义,并给出其形式化的描述及其实现模型,为下一阶段的系统可生存性的定量分析提供统一、规范的可生存性定义. 相似文献
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The development of robust, survivable wireless access networks requires that the performance of network architectures and protocols be studied under normal as well as faulty conditions where consideration is given to faults occurring within the network as well as within the physical environment. User location, mobility, and usage patterns and the quality of the received radio signal are impacted by terrain, man-made structures, population distribution, and the existing transportation system. The work presented herein has two thrusts. One, we propose the use of overlapping coverage areas and dynamic load balancing as a means to increase network survivability by providing mobiles with multiple access points to the fixed infrastructure. Two, we describe our simulation approach to survivability analysis which combines empirical spatial information, network models, and fault models for more realistic analysis of real service areas. We use our simulation approach to compare the survivability of our load balancing protocols to a reference scheme within two diverse geographic regions. We view survivability as a cost-performance tradeoff using handover activity as a cost metric and blocking probabilities as performance metrics. Our results illustrate this tradeoff for the protocols studied and demonstrate the extent to which the physical environment and faults therein affect the conclusions that are drawn. 相似文献
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As an important part of future 5G wireless networks,a vehicular network demands safety,reliability and connectivity.In this context,networking survivability is usually considered an important metric to evaluate network performance.In this paper,we propose a survivability model for vehicle communication networking based on dual cluster heads,wherein a backup cluster head(CH)will be activated if the primary CH fails,thereby effectively enhancing the network lifetime.Additionally,we introduce a software rejuvenation strategy for the prime CH to further improve the survivability of the entire network.Using the Probabilistic Symbolic Model Checker(PRISM),we verify and discuss the proposed survivability model via numerical simulations.The results show that network survivability can be effectively improved by introducing an additional CH and further enhanced by adopting the software rejuvenation technique. 相似文献
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软件定义光网络(SDON)作为智能光网络中最新一代网络架构,其控制平面承载着诸多核心功能,其中控制平面的生存性、控制冗余和控制时延等因素对网络整体性能起到至关重要的作用。该文提出一种以生存性条件为约束的软件定义光网络(SCD)控制器部署算法,在保证用户对网络生存性需求的前提下,利用最短路径和极小支配集等数学原理来降低控制时延和减少控制器部署个数,降低控制冗余,并利用联合判决条件选择管控中心部署节点,协调控制器间的工作。实验表明:首先,所提算法可以百分之百保证用户对网络的生存性要求;其次,所提算法相对于C-MPC算法至少降低了15%的网络故障告警概率,提高了网络生存性;同时,相对于以时延为约束的部署算法减少了约40%的控制器部署个数。特别是在生存性要求较高的场景中,所提算法表现出良好的适应性。此外,管控中心的部署算法在复杂的大规模网络中,可以动态地满足用户对网络生存性不同程度的需求。 相似文献
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针对通信网网络优化设计提出了一种在网络抗毁性指标和网络最小费用之间进行均衡、折衷的优化设计方法。分析了通信网络的特点和设计要素,在此基础上提出了将通信网络进行模型化的方法,根据模型化后的图求出最小费用的连通网络结构,在尽量减少费用的前提下进行抗毁设计的修改。通信网络优化设计的最终设计目标是具有一定抗毁性指标且费用最少的网络拓扑结构。 相似文献
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多域光网络的生存性作为衡量网络性能优劣的关键指标,与实际网络应用的关系最为密切,是当前迫切需要解决的关键问题;聚焦高速化、多业务化驱动的多域光网络环境下的生存性技术.基于光网络的多业务、分布式控制的特性,分析了多域光网络生存性机制的研究现状及面临的挑战;给出了一种针对多域光网络生存性问题的分类方法;结合多域光网络对生存性的需求,对相关关键技术进行了归类和研究,并指明了进一步研究的方向和重点. 相似文献
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Performance evaluation of the survivability schemes in WOBAN: a quality of recovery (QoR) method 下载免费PDF全文
Minglei Fu Maolin He Zichun Le Weiwen Wang Bisheng Quan 《International Journal of Communication Systems》2015,28(5):818-841
The hybrid wireless optical broadband access network (WOBAN) is a combination of an optical backhaul and a wireless front‐end, which combine the huge amount of available bandwidth of optical networks and the ubiquity and mobility of wireless access networks with the objective of reducing their cost and complexity. Survivability is one of the most important issues in WOBAN. In this paper, the survivability schemes in WOBAN are addressed from a particular point of view of the quality of recovery (QoR) method. The QoR is a comprehensive measure to evaluate the survivability schemes in terms of availability, recovery time, redundancy, and bandwidth of backup path. The specific procedures to set up the analytical models for the survivability schemes in WOBAN are given based on the QoR concept, including abstract, normalization, and application. Besides, the weights assignment is provided to calculate the QoR value for the operators, home users, or business users with different requirements, which in turn offers the user‐perceptive quality of service. To verify the performance of the survivability schemes by the QoR method, extensive simulations are made under different WOBAN configurations. Numerical results show that for the intra‐domain survivability schemes, the wireless and optical mixed protection scheme is the best choice for failure recovery in WOBAN. The wireless scheme is the second choice for the solution, which emphasizes cost control, while for the solution that emphasizes the network performance, the 1:1 scheme is the second choice. The 1:N scheme obtains the worst QoR value as the splitter ratios increase. For the inter‐domain survivability schemes, optimizing backup optical networking units selection and backup fibers deployment scheme outperforms maximum protection with minimum cost scheme from the point of view of QoR. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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一种信息系统生存性的量化分析框架 总被引:10,自引:0,他引:10
生存性是信息系统在安全性之上必需考虑的问题,对其量化分析可对系统生存性做出更为准确的评价以改进系统。基于有限状态机描述信息系统,利用系统状态转移图来定义生存性分析过程,而系统状态的层次化结构避免了Markov链模型中的列举系统状态问题。在SNA方法的基础上,提出一种便于计算机实现的生存性量化分析框架:通过系统定义、系统生存性测试和生存性计算,最后给出分析报告。其中基于事件分类分级建立的事件库使得测试方案的生成自动化和客观化,系统的生存性通过层次化的方式从可抵抗性、可识别性和可恢复性3个方面进行了量化计算。 相似文献
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The evolution of transport network survivability 总被引:12,自引:0,他引:12
The bandwidth explosion ushered in by the popularity of the Internet has spurred the acceleration in the development and deployment of equipment supporting packet-based services. This-coupled with the widespread deployment of dense wavelength-division multiplexed systems in the core transport network to satisfy the corresponding increase in capacity demand-has led network planners to reconsider traditional approaches to network survivability. Existing architectures for transport network survivability were developed based on a ubiquitous circuit-switched/TDM network paradigm. As tariffed services increasingly migrate from circuit-switched/TDM to packet-switched/DWDM networks, survivability architectures must also evolve to meet the service requirements of this “new” packet-switched/DWDM network paradigm. We begin with an overview of existing strategies for providing transport network survivability, followed by an analysis of how the architectures for network survivability may evolve to satisfy the requirements of emerging networks 相似文献