可变长光分组交换的短包优先调度

为了解决因可变长光分组交换的输出队头阻塞问题造成分组的平均排队时延增加，分析了可变长分组的长度分布特点，提出了基于抢占方式的短包优先调度（PSPF）算法，以减少分组在输入排队中的平均等待时间。在PSPF算法中，短包可以抢占长包的传输时间而获得优先服务。分析和仿真结果表明：当到达业务负载较低或中等程度时，采用PSPF算法可使短包的平均排队时延接近0，所有分组的平均等待时延减小，还保证了实时性TCP业务较低的平均等待时延。

Short packet first scheduling for variable length optical packet switching

In order to solve the problem of the average queue delay increase caused by the packets block of the output queue header in the variable length optical packet switching, the characteristics of variable length packet is analyzed and the preemptive short packets first (PSPF) algorithm for reducing the total packet waiting time in the input queue is proposed. In PSPF algorithm, the short packet can preempt the transmission time of the long packet and be served first. The analysis and the simulation show that the PSPF algorithm can reduce the average waiting time of the short packet to zero and decrease the total packet average waiting time largely. In addition, PSPF algorithm can guarantee the low average waiting delay for the real time TCP traffic implementation.