共查询到19条相似文献,搜索用时 156 毫秒
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基于共享有限波长和参量波长转换器的冲突解决方案 总被引:1,自引:0,他引:1
研究了一种共享有限波长转换器(LRWC)和参量波长转换器(PWC)相结合的解决全光分组波长资源竞争的方案,并提出了PWC优先算法作为光分组交换中的波长竞争解决方案。仿真结果表明:本文结构与共享LRWC节点结构相比,减少了波长转换器的数目,并且能够明显降低光分组交换节点的分组丢包率(PLP),提高波长转换器的利用率。研究还发现,不同波长转换器配置方案对系统性能有影响。 相似文献
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提出了一种基于业务负载选择的光分组交换(OPS)网络的光缓存结构,根据业务负载大小灵活选择缓存方式。输出缓存光纤延迟线(FDL)采用分段式共享机制配置,输出/反馈共享缓存模块采用简并式配置,以提高有限数目FDL的利用率。分析和仿真表明,这种可选择的缓存结构可以有效降低丢包率和OPS节点需求的FDL数目。 相似文献
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共享有限范围多波长和全单波长转换器的光组播冲突解决方案 总被引:4,自引:4,他引:0
研究了一种有限范围多波长转换器(LMWC)反馈共享连接和全单波长转换器(FRWC)输出共享连接相结合的解决全光组播波长资源竞争的解决方案,并提出有限范围多波长转换器优先的波长变换调度算法,以最大双向匹配最小边长权重方法选择多波长转换器解决冲突光组播波长变换。仿真结果表明:所提的结构与输出共享全多波长转换器(FMWC)节点结构或输出共享FRWC节点结构相比,都能够明显降低光组播节点的分组丢包率(PLP),减少系统需求LM-WC多波长转换器的数目,提高多波长转换器的利用率;LMWC具有不同波长转换范围对光分组冲突解决性能也有影响。 相似文献
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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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设计了基于业务优先级的光突发交换核心节点模型,采用多级光纤延迟线的光缓存来提高交换网络的性能.交换节点在4个端口8条波长(4×8核心交换结构)的情况下,当光纤延迟线基本延迟单元为50μs、级数为8,负载为0.8时,丢包率小于0.01;为了满足不同业务服务质量的要求,将数据包按优先级划分,采用基于优先级的插空算法(VFPP),在相同缓存配置条件下使高优先级数据的丢包率降低到以下,在高负载下平均时延小于不区分优先级的情况. 相似文献
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Jianming Liu Lee T.T. Xiaohong Jiang Horiguchi S. 《Lightwave Technology, Journal of》2009,27(8):955-966
Buffers are essential components of any packet switch for resolving contentions among arriving packets. Currently, optical buffers are composed of fiber delay lines (FDL), whose blocking and delay behavior differ drastically from that of conventional RAM at least two-fold: 1) only multiples of discrete time delays can be offered to arriving packets; 2) a packet must be dropped if the maximum delay provided by optical buffer is not sufficient to avoid contention, this property is called balking. As a result, optical buffers only have finite time resolution, which may lead to excess load and prolong the packet delay. In this paper, a novel queueing model of optical buffer is proposed, and the closed-form expressions of blocking probability and mean delay are derived to explore the tradeoff between buffer performance and system parameters, such as the length of the optical buffer, the time granularity of FDLs, and to evaluate the overall impact of packet length distribution on the buffer performance. 相似文献
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Signal loss and noise accumulation can cause fading in optical buffers implemented by fiber delay lines (FDLs). Optical packets that excessively recirculate through FDLs are easily dropped from their routing paths. Therefore, analytical models and packet scheduling schemes require additional considerations for FDL buffers. This work proposes an analytical model for all-optical packet switching networks with finite FDL buffers and a general class of scheduling schemes including many basic scheduling schemes. We intend to minimize the packet loss probability by ranking packets to achieve an optimal balance between latency and residual lifetime in the general class of scheduling schemes. The analytical model is based on a non-homogeneous Markovian analysis to study the effects of various scheduling schemes on packet loss probability and average latency. Analytical results show how various network parameters affect the optimal balance, and illustrate how properly balancing latency and residual distance can significantly improve network performance. 相似文献
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提出了一种采用时隙处理光分组竞争冲突的基于光纤延迟线的光分组交换缓存算法——时隙可变长分组缓存调度算法SVPB(slotted variable-length-packet-capable buffer)。该算法根据先到先服务的排队原则,通过对到来的光分组进行时间轴分段处理,解决了FDLs作为缓存器的不足。从仿真结果得到,在网络负载较高时所提出的调度算法SVPB比已有的调度算法分组丢失率有明显的降低。 相似文献
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Optical buffers implemented by fiber delay lines (FDLs) have a volatile nature due to signal loss and noise accumulation.
Packets suffer from excessive recirculation through FDLs, and they may be dropped eventually in their routing paths. Because
of this, packet scheduling becomes more difficult in FDL buffers than in RAM buffers, and requires additional design considerations
for reducing packet loss. We propose a latency-aware scheduling scheme and an analytical model for all-optical packet switching
networks with FDL buffers. The latency-aware scheduling scheme is intended to minimize the packet loss rate of the networks
by ranking packets in the optimal balance between latency and residual distance. The analytical model is based on non-homogeneous
Markovian analysis to study the effect of the proposed scheduling scheme on packet loss rate and average delay. Furthermore,
our numerical results show how various network parameters affect the optimal balance. We demonstrate quantitatively how to
achieve the proper balance between latency and residual distance so that the network performance can be improved significantly.
For instance, we find that under a given latency limit and light traffic load our scheduling scheme achieves a packet loss
rate 71% lower than a scheduling scheme that ranks packets simply based on latency. 相似文献
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In this paper, a novel optical packet switch is proposed, which uses a set of shared fiber delay lines (FDLs) and a set of
shared tunable wavelength converters (TWCs) to resolve optical packet contentions. In addition, two control algorithms, i.e.,
Fiber-First (FF) and Wavelength-First (WF), are proposed to schedule optical packets. Performance of the novel switch is evaluated
by means of simulation experiments. Simulation results show that based on either of these two control algorithms, the switch
can achieve super performance without employing a lot of FDLs and TWCs. Moreover, the performance of FF and WF is compared.
Detail analyses are also given in this paper. 相似文献