OTN保护方式及多重保护协同方案

目前OTN是业务承载的主要方式,为提高网络的安全性,网络中采用OLP/OMSP、ODUk SNCP 1+1、OCP 1+1等多种保护措施.同时,业务层自身也有保护,多重保护嵌套后,如何实现各种保护的协调,保证故障时不会出现多保护同时倒换,避免倒换震荡和业务闪断是需要在网络开通时需要关注的问题.本文通过分析不同保护方式倒...     

光传输网中复用段保护倒换失败的处理方法

在SDH传输系统的网络保护方式中，双纤双向复用段保护环由于节省传输带宽、配置简单等优点被广泛应用。但是，网络规模的增长和传输业务种类的增多，对保护倒换的成功率提出了更高的要求。因为复用段保护倒换采用APS（Automatic Protection Switching，自动保护开关）协议，所以各网元的协议处理和保护通路的正常是保护倒换成功的先决条件。也就是说，环网上的任何一个网元不正常都能导致倒换失败，以致当出现线路故障时无法有效地保护业务。     

SDH倒换故障处理实例

基于各种不同保护机理的SDH自愈环大大提高了网络的生存能力,使之在出现故障的情况下,无需人为干预,就能在极短的时间内从失效的故障状态自动恢复传输所携带的业务,使网络具备一种可替代的传输路由.但是自愈网络也有失去保护的时候,当保护倒换协议出现异常,传输业务就会中断.本文就SDH网络MSP(复用段保护)环倒换失败进行原因分析和处理.     

接入网设计施工体会

我局于１９９７年开始实施光纤接入网工程 ,目前市县区大部分中心区域已实现光纤到路边（ＦＴＴＣ）或光纤到大楼（ＦＴＴＢ） ,并大量采用了接入网设备 ,传输电路越来越多地采用有自愈功能、安全可靠的光纤环形网。１自愈环网中保护功能的原理自愈环网指能在网络中出现意外故障时自动保护信息倒换并恢复业务的网络。目前 ,自愈环有如下２种结构和４种倒换方式 :通道倒换２纤单向通道倒换环２纤单向复用段倒换环复用段倒换４纤双向复用段倒换环２纤双向复用段倒换环（１）在通道倒换中 ,业务信息的保护是以每个通道为基础的 ,根据环内每个通…     

光传送网络的保护时间下限模型

本文首先分析了光传送网络业务在故障情况下的保护操作过程,并据此创建了光网络保护/倒换时间的下限模型.仿真结果表明,网络业务的保护时间与保护倒换协议有重要关系,而光开关的动作时间对保护倒换时间的影响与网络规模没有关系.     

基于TCP连接修复的高可靠性主备倒换研究

为满足网络的高可用性,尤其是体现在当设备主备倒换时能够不中断业务的继续转发,文中提出了一种新型的技术:TCP连接修复技术(TCP CONNECTION REPAIR)。区别于传统的主备倒换流程,在设备正常工作时,便将网络的链路状态和数据等信息从主控制盘拷贝到备用控制盘,实现实时同步,以便设备在发生故障时进行主备倒换后能自行完成链路状态的修复和转发表项的重新生成。一方面,实时备份保证了数据状态的精准性。另一方面,该方法分离了数据同步和链路切换,大大缩短了主备倒换的时间,实现了无缝连接。     

PON系统中的PON保护倒换技术研究

经过近几年的发展,PON技术日益成熟,要保障工程应用中业务的稳定性,应对各种通信中断故障,就需要实现PON保护倒换技术。分析设计了1种PON保护倒换机制和流程,可以满足A、B类保护业务中断时间小于150 ms,C类保护业务中断时间小于50 ms,实现安全、准确、快速PON保护倒换。     

SDH环网保护倒换对客户业务的影响分析

简述了环网保护倒换的原理以及网络保护倒换时间测试说明,通过实际网络割接测试案例,分析并探讨环网保护倒换对大客户专线业务的影响,并依此结论应用于网络割接的客户通知工作,有效提升了客户感知。     

SDH网络时钟保护倒换的原理

１实现时钟保护倒换的重要性和必要条件１郾１实现时钟保护倒换的必要性SDH环网的一个优点就是其可以提供自愈保护功能，即当光缆发生故障时，SDH环网可以利用通道或复用段的保护功能，使得在电路上开放的业务不会因光缆的故障而被中断。但是如果网络中没有采取时钟保护倒换，此时由于环上各网元的时钟不同步，将可能造成传输性能的劣化。例如，在图１所示的网络中，当电路正常时，假设全网同步于A网元的本振时钟，即网元A采用本振时钟，网元B跟踪网元A的时钟，网元C跟踪网元B的时钟，网元D跟踪网元C的时钟。当网元B、C间的光缆中断…     

S16光板处理倒换K字节异常导致业务中断的故障分析

SDH2.5G光板—S16光板在处理光路和业务方面正常,但处理倒换K字节异常,影响了复用段环的正常倒换,造成复用段环上的业务中断。由于K字节只有在倒换时才发送,无法提前通过告警等发现异常,正因为S16光板本身无告警,给故障处理带来了一定的难度。     

Optimal synthesis problems for Markovian queueing systems with several given characteristics

For an M/M/1/r queueing system and an M/M/1 system with threshold switching of service modes at the instant of the change in the number of customers as well as for the same system with threshold blocking of the flow of customers, the monotonic dependence of stationary characteristics (the mean number of serviced customers per unit time, the mean service cost per unit time, the probability of system downtime, and the mean waiting time of a customer in the queue) on the system parameters (the buffer size, the system usage, and the threshold of switching between the service modes) is used to solve the optimal synthesis problems for systems with several given stationary characteristics. The solution of a particular optimal synthesis problem is the optimum value of one of the above parameters.     

PBB-TE分段保护的关键技术

运营商骨干桥流量工程(PBB-TE)采用端到端的保护技术。随着PBB-TE网络规模的扩大,端到端的保护技术在流量切换效率、多点故障、点到多点路径等保护等方面存在不足,难以满足分组传送网的越来越精细的保护倒换要求。PBB-TE的分段保护技术由此应运而生。文章通过对PBB-TE分段保护技术及其数据业务切换、M:1关键技术的分析阐述,为提高长距离分组传送网可靠性问题提出了解决方案。     

关于充换电设施检修运维公司的生产运营模式优化研究

在电动汽车行业迅猛发展的推动下,充换电设施建设得到了快速的发展,一些城市的充换电设施服务网络目前已初具规模.本文对充换电设施检修运维公司的三种主要生产运营模式进行了一定介绍,并提出了一些充换电设施检修运维公司生产运营模式的优化对策.     

Sojourn times in different modes in the queueing system with batch Poisson arrivals,general service times,and hysteretic policy

Consideration is given to the model of the SIP server modelled as a single-server queueing system with finite capacity R and two batch Poisson flows (priority and non-priority), general service times, and bi-level hysteretic control of arrival rates, which is defined by two numbers: L and H (0 < L < H < R). The hysteretic policy under consideration implies that, at each instant, the system can be in one of the three operation modes: normal, overload, and blocking. The system accepts customers from both flows when it is in normal mode, accepts only priority flow when is it overloaded, and rejects all new customers in the discard modes. It is assumed that the switching between operation modes can occur only at the instant of service completion. The analytical method for computing the distributions (in terms of Laplace–Stieltjes transforms) of system’s sojourn times in each operation mode and return times to the normal mode is proposed. Illustative examples are presented.     

SLALOM: semiconductor laser amplifier in a loop mirror

The processing of optical signals in the optical domain is an important issue resulting from the desire to take advantage of the full bandwidth of the optical fiber. In this paper, we present detailed investigations on a device, which utilizes a semiconductor laser amplifier in a loop mirror configuration (SLALOM). Different modes of operation are reported like nonlinear single pulse switching and two-pulse switching at different operation speeds (1-100 Gb/s). Furthermore, a number of applications of the SLALOM in photonic systems, like pulse shaping, decoding, retiming and time-division demultiplexing, are presented. In addition, the SLALOM can be used for an estimate of the linewidth enhancement factor α and the carrier lifetime τ _e in an SLA     

弹性分组环保护倒换策略的研究

保护倒换是弹性分组环中的一项关键技术,目前IEEE802.17草案中的保护倒换策略只能够提供小于50ms 的保护倒换时间,但却无法在保护倒换发生后保证实时业务的服务质量。为解决此问题,针对RPR MAC层的两种结构模式单队列和双队列模式,我们制定了两种不同的保护倒换策略并对它们进行了性能分析。仿真结果表明, 这些策略能在保护倒换发生后很好地确保实时业务的服务质量。     

Analysis of a two-unit standby system with three modes and imperfect switching device

In this paper we study the effect of imperfect switching on a two-unit cold standby system in which each unit works in three different modes—normal, partial failure and total failure. Failure time distributions of units are negative exponential whereas repair time distributions of units and switch are general. The switch is available at the time of need with probability p(= 1?q). Using the regeneration point technique reliability characteristics of interest to system designers as well as operation managers have been evaluated.     

Designing a green optical network unit using ARMA-based traffic prediction for quality of service-aware traffic

The optical access networks (OANs) provide an attractive solution to the bandwidth bottleneck problem of the last mile. However, it has been proved (Baliga et al. in J Lightwave Technol 27(13):2391–2403, 2009; Baliga et al. in IEEE Commun Mag 49(6):70–77, 2011) that the OAN consumes a significant ratio of the total energy consumed in an optical networking scenario. This has provided incentive for inspection of energy-efficient schemes for OANs. It has been demonstrated in the literature that energy consumption figures of an OAN can be improved by either designing efficient hardware or employing better media access control (MAC) protocols. In this paper, we design a MAC protocol for OANs to ensure energy-efficiency in the presence of quality of service (QoS)-aware traffic. The proposed scheme incorporates traffic prediction-based selection of different sleep (energy-efficient) modes of operation, of the optical network units—ONUs (OAN end units). It also implements switching between different sleep modes to maintain high QoS with significant energy-efficiency figures. The discussed scheme requires processing at the ONU only and can work independent of the entire OAN (ONU assisted). Thus, our proposal is an attractive solution for the already deployed networks or even in green field deployment.     

Quality of service based protection in optical networks using diversity constraint

In this paper, we present a simple approach towards providing quality of service based partial protection in optical networks. We use a diversity based protection mechanism to ensure that in the event of link/node failures, a fraction of demand is always survived. To determine routing of optical paths while honoring restrictions such as wavelength continuity and exclusivity restriction, switching capability of OXCs, etc., we present a mixed-integer linear program formulation. Due to large size of the formulation, we develop an accompanied solution approach based on Lagrangian relaxation and sub-gradient optimization. We then present numerical results towards impact of diversity constraint upon the survivability, switch size, and number of carried wavelengths. Using them, we also show that optical networks based on sparse graphs might require higher number of wavelengths per fiber and the switching capacity of the OXCs to ensure higher values of fraction of accepted demands.