网络数据重传机制中平均站距的计算方法

A Method for Calculating the Expectation of the Number of the Stations D uring the Process of Data Re-sending

数据在网络中传输时,由于传输线路和接口信息处理机(InterfaceMessageProcessor简称:IMP)等多种因素会造成数据的丢失,这样发送端将要重新发送消息,直到目的主机收到消息为止,从源主机到目的主机有可能存在多条路径,最佳路径不仅与所经过的IMP的数目有关,而且与IMP的可靠性有关。因此,得到每条路径的平均站距对于路由选择来说十分重要。该文给出了一种理想模型情况下,数据经过两个IMP,平均传输站距和平均传输次数的计算方法,并讨论了经过n台IMP机,数据传输平均站距的计算方法。进而给出了更为一般情况下的结果。

Wh en Data is transmitted from one host to another across a network,it might be l ost due to the poor reliability of transmission medium,Interface Message Proces sor or multi-factors.Then the source host will re-send the same data until t he destination host receives it.There may be many routes between the source and the destination.The best route is determined not only by the number of IMPs b ut also by the reliability of IMPs.So,it's important to calculate the averag e number of stations for each route.This paper presents an ideal model which co nsists of a source host,a destination host and two IMPs ,and the author gives a method for calculating the expectation of the number of stations and the send ing frequency for such an ideal model,and also gives a result for a more genera l model which consists of n IMPs.