共查询到16条相似文献,搜索用时 93 毫秒
1.
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
2.
3.
4.
5.
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
6.
光纤延迟线应用研究动态 总被引:3,自引:0,他引:3
对目前正成为研究热点的光纤延迟线(FDL)进行了原理和结构特点的分析,总结了光纤延迟线的分类,对光纤延迟线的3个重要应用领域作了详细的跟踪研究.在光纤传感与光学测量领域,分析了激光器线宽测试系统、晶体双折射参数测量系统、光相干层析成像(OCT)测镀系统及光相关光谱术(OCS)测量系统,指出了光纤延迟线在这些系统中的丰要作用及参数设置;存光纤通信领域,从原理和系统结构上莺点分析了高速脉冲串发生器、光缓存器及光编/解码器,指出了目前存在的问题;在微波光子学领域,详细分析了多频光振荡器、微波光纤延迟线、光A/D转换器及光信号相关处理器.指出了关于光纤延迟线技术的最新研究方向主要足提高延时精度、实现连续可调、减小插入损耗和提高工程可靠性.解决这些问题是光纤延迟线实用化的关键所在. 相似文献
7.
8.
9.
10.
将一种新的光缓存技术--慢光可变延时缓存器,与可调波长转换器结合,构成光分组交换模型.简要分析了慢光缓存器的时延特性,并对其解决信息网络交换拥塞进行了应用设计与仿真,分析结果表明,慢光缓存器与光纤延迟线缓存相比较,不仅能更有效地降低丢包率,而且还可以简化光分组交换的结构,其体积更小,使用更灵活. 相似文献
11.
Zheng Liang Shilin Xiao 《Lightwave Technology, Journal of》2007,25(8):1978-1985
The fiber delay line (FDL) buffer is widely used in optical packet switching networks for contention solution. In this paper, a quantized delay buffer model is proposed to analyze the performance of the single-wavelength FDL buffer. Considering the delay quantization in the FDLs, the delay time and the waiting time of the packet are discussed. Without specific assumptions of the packet arrival process and length distribution, the model presents a generic approach to study the delay time distribution and modify the integral equation for the waiting time distribution. Analytic and exact results of the two aforementioned distributions can be obtained without any approximation. The accuracy of the model is validated through simulation. 相似文献
12.
13.
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
14.
Scheduling algorithms for shared fiber-delay-line optical packet Switches-part I: the single-stage case 总被引:1,自引:0,他引:1
In all-optical packet switching, packets may arrive at an optical switch in an uncoordinated fashion. When contention occurs, fiber delay lines (FDLs) are needed to delay (buffer) the packets that have lost the contention to some future time slots for the desired output ports. There have been several optical-buffered switch architectures and FDL assignment algorithms proposed in the literature. However, most of them either have high implementation complexity or fail to schedule in advance departure time for the delayed packets. This paper studies the packet scheduling algorithms for the single-stage shared-FDL optical packet switch. Three new FDL assignment algorithms are proposed, namely sequential FDL assignment (SEFA), multicell FDL assignment (MUFA), and parallel iterative FDL assignment (PIFA) algorithms for the switch. The proposed algorithms can make FDLs and output-port reservation so as to schedule departure time for packets. Owing to FDL and/or output-port conflicts, the packets that fail to be scheduled are discarded before entering the switch so that they do not occupy any FDL resources. It is shown by simulation that with these algorithms, the optical-buffered switch can achieve a loss rate of /spl sim/10/sup -7/ even at the load of 0.9. These algorithms are extended to the three-stage Clos-Network optical packet switches in the companion paper. 相似文献
15.
Scheduling Algorithms for a Slotted Packet Switch with either Fixed or Variable Length Packets 总被引:3,自引:2,他引:1
Callegati F. Cerroni W. Corazza G. Develder C. Pickavet M. Demeester P. 《Photonic Network Communications》2004,8(2):163-176
We address the problem of congestion resolution in optical packet switching (OPS). We consider a fairly generic all-optical packet switch architecture with a feedback optical buffer constituted of fiber delay lines (FDL). Two alternatives of switching granularity are addressed for a switch operating in a slotted transfer mode: switching at the slot level (i.e., fixed length packets of a single slot) or at the burst level (variable length packets that are integer multiples of the slot length). For both cases, we show that in spite of the limited queuing resources, acceptable performance in terms of packet loss can be achieved for reasonable hardware resources with an appropriate design of the time/wavelength scheduling algorithms. Depending on the switching units (slots or bursts), an adapted scheduling algorithm needs to be deployed to exploit the bandwidth and buffer resources most efficiently. 相似文献