一种反馈FDL结构竞争解决丢包率的研究

对反馈FDL结构的光分组交换竞争解决方案建立了数学模型并进行了理论分析，推导出了在反馈FDL输入分组比输入光纤输入分组具有更高输出优先级时的系统丢包率公式，对系统丢包率与负载、输入光纤端口数和FDL数目的关系进行了数值计算和讨论.结果表明：由于FDL缓存分组的概率与输入分组负载的非线性关系导致了反馈FDL结构在低负载时对丢包率的改善非常明显，对高负载的改善却十分有限.随着FDL数目的增加，对系统丢包率的改善不会趋于一个极限值，这是与使用波长转换器进行竞争解决的不同之处，因此使用反馈FDL结构可以降低波长转换器的丢包率极限.

Theoretical Analysis of Packet Loss Probability in Contention Resolution Based on Feedback Fiber Delay Lines

The mathematical model of optical packet switching architecture based on feedback FDL contention resolution is stablished and analyzed.The priority of the packets from FDLs is higher than those from input fibers in this model.The formulation of packet loss probability is deduced through neglecting the degradation of optical signal and the crosstalk in optical switch matrix.The packet loss probability is lower in low load than in high load.This is due to the nonlinear distribution of the probability of arriving packet from feedback FDL vs the load.With the increment of the load,the probability of arriving packet increases very slowly in low load and very fastly in high load.There exists no limit in packet loss probability by adding the number of FDL to improve the performance.The characteristic is different from the contention resoluton based on wavelength conversion that exits a limit.It will be very useful to comine wavelength conversion and FDL to break through the limit.