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本文依据一个有关传输工程建设的案例,即某运营商对某地区进行的关于保护倒换时间的测试,对SDH自动保护倒换进行了简单的分析及思考.本文根据SDH自动保护倒换机制、ITU-T和国家通信标准,在理论上对该地区自动保护倒换时间进行了计算,并将其与实际相比较,依据各方面的论述得出该地区保护倒换时间满足规范化要求的结论. 相似文献
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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。 相似文献
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本文依据一个有关传输工程建设的案例,即某运营商对某地区进行的关于保护倒换时间的测试,对SDH自动保护倒换进行了简单的分析及思考。本文根据SDH自动保护倒换机制、ITU-T和国家通信标准,在理论上对该地区自动保护倒换时间进行了计算,并将其与实际相比较,依据各方面的论述得出该地区保护倒换时间满足规范化要求的结论。 相似文献
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从组网设计的角度,介绍了SDH自愈环时钟同步与保护倒换的策略及实现机制,并以深圳某公司的产品CGCS-1000为例,说明了通道保护倒换环时钟软件的设计原理,并给出了软件的设计步骤。 相似文献
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对电信网上广泛应用的SDH光传输环保护系统的保护倒换时间这一重要指标,针对实际条件,提出了用HP37717B监测高附通道字节的办法来计算倒换时间的一种可行的测试方案。 相似文献
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1概述N G N承载网接入层的可靠性不能仅依赖设备的可靠性,还必须通过网络的可靠性来保证。毫秒级的倒换时间是N G N可靠性保护的目标。但是目前I P网络通用的保护技术的倒换时间往往都在秒级,无法满足N G N承载网对于毫秒级倒换的要求。在N G N的核心网汇聚层面,由于是一个单纯 相似文献
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随着光传输网络规模的不断扩大,对光纤通道的保护显得尤为重要。智能化光纤保护系统正是为了满足这一时代需求应运而生,它不但可以提供性价比合理的光保护系统,而且还具备强大的局端网管功能和快速自动控制倒换功能。文章简要介绍了光通信网络中独立式光路切换保护的一种方式以及它与传统环路及链路保护方式的区别,对关键性技术进行了分析与探讨。 相似文献
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Xu Shao Xiaofei Cheng Yong Kee Yeo Luying Zhou Yixin Wang Yuebin Bai 《Photonic Network Communications》2010,20(1):1-9
With the increase of size and number of shared risk link groups (SRLGs) in WDM networks, path protection tends to have longer working paths and backup paths due to SRLG-disjoint constraints, which makes physical impairment a major concern in working path and backup path provisioning, particularly in large-sized all optical networks. As a simple and efficient algorithm, the working path first algorithm is often used for path protection against SRLG failures, where the working path is calculated first by using the shortest-path algorithm on the graph, followed by using the SRLG-disjoint shortest path as backup path. Compared with the working path, the backup path calculated after the working path in the working path first algorithm is more vulnerable to physical impairment, since it may be much longer than the working path. As a result, if we reject those connections that cannot meet the physical impairment requirement, with SRLGs the blocking probability of path protection will be much higher. We argue that impairment must be taken into account together with capacity efficiency in a comprehensive way during SRLG-disjoint working path and backup path selection. To solve this problem, we motivate the needs to study physical impairment-aware shared-path protection by considering two policies. Policy I uses two SRLG-disjoint least impairment paths as working path and backup path, respectively, and Policy II tries to benefit from both the shortest path and the least impairment path by choosing them intelligently. Analytical and simulation results show: (1) compared with impairment-unawareness, impairment-aware SRLG failure protection performs much better in terms of blocking probability especially with strong physical impairment constraints; (2) impairment-aware SRLG failure protection can significantly reduce physical-layer blocking probability; and (3) the algorithm based on Policy II achieves a good balance between capacity efficiency and physical impairment requirement. 相似文献
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In this article a framework for end-to-end service-guaranteed shared protection in dynamic wavelength division multiplexing (WDM) mesh networks, called short leap shared protection (SLSP), is introduced. The idea of SLSP is to divide each working path into several overlapped protection domains, each of which contains a working and protection path pair. In addition to a guaranteed restoration service, SLSP is designed to satisfy the future requirements of wavelength-routed optical mesh networks in scalability, class of service, and capacity efficiency. Tutorial-like discussions are given in the architecture design and signaling mechanisms for implementing the SLSP framework in a dynamic network environment with examples and illustrations. To show that SLSP can improve capacity efficiency, simulations are conducted using four networks (22-, 30-, 79-, 100-node) for a comparative study between ordinary shared protection schemes and SLSP 相似文献
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Distributed quality-of-service routing in ad hoc networks 总被引:10,自引:0,他引:10
In an ad hoc network, all communication is done over wireless media, typically by radio through the air, without the help of wired base stations. Since direct communication is allowed only between adjacent nodes, distant nodes communicate over multiple hops. The quality-of-service (QoS) routing in an ad hoc network is difficult because the network topology may change constantly, and the available state information for routing is inherently imprecise. In this paper, we propose a distributed QoS routing scheme that selects a network path with sufficient resources to satisfy a certain delay (or bandwidth) requirement in a dynamic multihop mobile environment. The proposed algorithms work with imprecise state information. Multiple paths are searched in parallel to find the most qualified one. Fault-tolerance techniques are brought in for the maintenance of the routing paths when the nodes move, join, or leave the network. Our algorithms consider not only the QoS requirement, but also the cost optimality of the routing path to improve the overall network performance. Extensive simulations show that high call admission ratio and low-cost paths are achieved with modest routing overhead. The algorithms can tolerate a high degree of information imprecision 相似文献
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Dynamic Survivability in WDM Mesh Networks Under Dynamic Traffic 总被引:3,自引:0,他引:3
Network survivability is a crucial requirement in WDM mesh networks. In this paper, we systematically consider the problem of dynamic survivability with dynamic single link failure in WDM networks under dynamic traffic demands. Specifically, we investigate various protection schemes, such as dedicated path protection (DPP), shared path protection (SPP), dedicated link protection (DLP), shared link protection (SLP), and two restoration schemes, path restoration (PR) and link restoration (LR). Moreover, two new shared protection methods are proposed, i.e., SRLG-based shared link protection (SRLG-SLP) and SRLG-based shared path protection (SRLG-SPP). The SRLG (shared risk link group) constraint defines the availability of protection resources to a working path, which requires that any two working paths sharing the same risk of failure (or in the same SRLG) cannot share the same protection resources. Furthermore, in our study, we consider a more practical dynamic single-link failure model, in which the link-failure-interarrival time and link-failure-holding time are considered as two independent parameters. Based on this link-failure model, extensive simulations are done to analyze and compare the dynamic survivable performance of various protection and restoration schemes. Resource utilization, protection efficiency, restoration efficiency, and service disruption ratio are employed as survivable performance metrics versus traffic load, link-failure frequency, and link-failure reparation time to evaluate the survivable performance. Many meaningful results are given. In addition, we show that the developed SRLG-SLP and SRLG-SPP protection schemes perform very well in terms of protection efficiency and service disruption ratio, while sacrificing some performance in terms of resource utilization. 相似文献
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A Study of Path Protection in Large-Scale Optical Networks 总被引:1,自引:1,他引:0
We consider the problem of designing a network of optical cross-connects (OXCs) which provides end-to-end lightpath services to large numbers of client nodes, under the requirement that the network will survive any single-link failure. Our main objective is to quantify the additional resource requirements of implementing path protection schemes over a network with no survivability properties. To this end, we present heuristic routing and wavelength assignment algorithms for dedicated path protection and two variants of shared path protection, and integrate them into the physical and logical topology design framework we developed in an earlier study. We apply our heuristics to networks with up to 1000 client nodes, with a number of lightpaths that is an order of magnitude greater than the number of clients, and for a wide range of values for system parameters such as the number of wavelengths per fiber, the number of optical transceivers per client node, and the number of ports per OXC. Our results provide insight into the relative resource requirements of dedicated and shared path protection schemes. We also find that, using shared path protection schemes, it is possible to build cost-effective survivable networks that provide rich connectivity among client nodes with only a modest additional amount of resources over a network with no survivability properties. 相似文献