共查询到17条相似文献,搜索用时 140 毫秒
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光分组在核心节点处的冲突解决问题是实现全光 组播分组交换的关键。本文提出了一种新型的解决光组播冲突的节 点结构,用于冲突解决的部分包括输出共享的网络编码模块和光纤延迟线(FDL)环 形反馈共享缓存(FDL-LSFB)模块。网络编码 模块将异或网络编码作为冲突解决方式,利用全光异或门将冲突组播进行网络编码并且改变 编码后分组波长,从而避免波长 冲突。而FDL-LSFB模块由子交换矩阵和FDL缓存组连接成环状,且冲突组 播可从任意子交换矩阵进出缓存模块, 使用少数的FDL可以提供大容量的光缓存、提高FDL利用率。针对FDL-LSFB模块冲突组播调 度问题,为减小缓存时延,设计了最小缓存长度级联控制算法(MLCBST),进而提出冲突光 组播的总调度策略。仿真结果表明,本文提出的组播节点结构和调度策略在降低丢包率(PLP)和减小缓存时延方面具有明显的效果。 相似文献
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双环结构级联型全光缓存器 总被引:1,自引:0,他引:1
提出了一种基于平行排列3×3耦合器的双环结构全光缓存器(DLOB)的级联方案,分析了单级和级联结构的缓存原理及读写方式,通过分析半导体光放大器(SOA)的噪声性能,得到光缓存器输出性能丰要由读写操作阶段注入的控制光功率及SOA的工作电流决定的结论,提出了在反馈式光缓存器中实现单级多圈和多级缓存的可能性,并搭建了一个两级的缓存系统,实验验证两级级联各缓存9圈时,输出信号光的功率几乎没有减少,信噪比(SNR)下降不到4 dB.理论分析和实验都表明,级联型光缓存器能够实现从纳秒级到毫秒级的缓存.可以满足未来光包交换(OPS)发展的需要. 相似文献
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研究了FDL和有限长波长转换器(LRWC)相结合的方法来解决异步变长的分组交换网中的冲突问题,对这种冲突解决方案建立了数学模型并进行了理论分析,提出了一个用于修正最佳延迟单元的公式,即在负载较大的情况下,我们要求延迟单元较小,这样可显著的降低在此交换网中的分组丢失率;对系统丢包率与负载、FDL数目和最佳延迟单元的关系进行了研究和讨论,结果表明:在同样的输入负载情况下,有限长波长转换器(LRWC)的引入可以降低缓存的数量;对延迟单元的修正可以大大降低丢包率,同时系统的性能较之单独使用FDL时有较大的改善。 相似文献
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Packet contention is a major issue in an optical packet switching network. It is not a trivial task to resolve contention
due to lack of optical RAM technology. This article proposes a two-stage shared fiber delay line (FDL) optical packet switch
for contention resolution. In this article, shared FDLs are used to buffer optical packets, in which a pool of buffer memory
is shared among all switch output ports. Most of the existing optical buffering schemes are output-based which require a huge
number of FDLs as well as a larger switch size that incur extra implementation cost. However, a shared buffering approach
is considered in this article in order to reduce implementation cost. In this article, FDLs are implemented in two stages
using an extremely simple auxiliary switch. The proposed switch architecture leads to more efficient use of buffer space.
The superiority of the proposed switch architecture has been established by means of extensive simulations. The performance
of the proposed switch is investigated under bursty traffic. Simulation result shows that the proposed switch can achieve
satisfactory performance at the price of a reasonable amount of FDLs. Moreover, the significance of the proposed switch is
confirmed by simulation. 相似文献
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This paper addresses the problem of dimensioning buffers realized by means of fiber delay lines in optical routers able to switch packets that have variable length and are sent asynchronously on the optical links. The optical buffer is analyzed focusing on the different behavior of a delay buffer and an electronic memory. The role of the time unit of the fiber delay lines is discussed, showing that it is a crucial parameter to determine the queuing performance. The paper presents two approximate analytical models that can be used both for analysis and engineering of the optical buffer and in particular to dimension the buffer time unit in an way that is optimal with respect to packet loss probability. The first model is based on an infinite queuing approximation. It is not very accurate and is valid for a limited set of values of the traffic load, but is extremely simple. The second model is based on a finite queuing approximation. It is more complex but more accurate and is valid for any value of traffic load. The accuracy of the models is compared with simulation and their range of applicability purposes is discussed. 相似文献
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Wu Dapeng Wang Ruyan Huang Sheng Zhang Jie Long Keping 《Photonic Network Communications》2011,22(1):73-78
A novel buffer architecture for Optical Packet Switching Networks is proposed. The utilization of fiber delay lines and corresponding
switch component can be improved obviously; moreover, service differentiating can be achieved effectively. Results and analysis
show that the packet delivery ratio is enhanced and the average packet delay is decreased; comparing to the output buffer
architecture, the number of optical fiber delay lines of our proposed buffer architecture is reduced, and the complexity is
relatively lower. 相似文献
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在光突发交换(OBS)网络中,突发竞争是影响网络性能的一个重要因素,因此如何有效地解决它,成了OBS网络非常重要的问题.在分析当前文献中的解决方案的优缺点后,提出了一种突发竞争解决方案的系统实现.该实现将光纤延迟线(FDL)时城缓存与波长转换器(TWC)波长变换、空城技术结合在一起,构造了一个基于前向转发缓存和反馈循环缓存的两级交换结构.最后从多方面对该系统实现的竞争解决有效性进行了性能分析和计算机仿真,结果表明:它在适当的业务强度(小于0.6)下,能有效改善突发丢失率和突发延迟;同时能降低系统所需的光器件数目. 相似文献
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R. Geldenhuys Y. Liu M. T. Hill G. D. Khoe F. W. Leuschner H. J. S. Dorren 《Photonic Network Communications》2006,11(1):65-75
This paper considers the performance of an all-optical packet-switched cross-connect. All-optical header processing and all-optical
routing are implemented in the cross-connect architectures. The main metric considered to measure the performance is the packet
loss ratio for the buffering. This is influenced primarily by three factors. The first is the cross-connect architecture:
feedback or feed-forward buffering, incorporating wavelength domain contention resolution. The second is the selection of
the fibre delay line distribution: degenerate or non-degenerate distributions. And the third is the traffic load together
with the traffic model used for the performance analysis: a Poisson distribution or a self-similar model. It is shown that
the optimal implementation of a feedback buffer requires a technique such as overflow buffering as well as the superior performance
of an all-optical switch in order to maintain signal quality through multiple recirculations. 相似文献