The Research Of Network Performance Analysis And Measurement

As lnternet expands, how to better manage and utilize Internet has caused extensive concern. To achieve this purpose, it is necessary to measure theperformance of Internet. There are a 1ot of factors influencing the wholeperformance of Internet, and bandwidth is one of the most important factors. bandwidth directly influences user Perceived Performance,To accurate1y measure and estimate avai1ab1e bandwidth is an essential issuein traffic engineering.Currently bandwidth measurement mainly use end-to-end activemeasurement technique, Available bandwidth measurement is one important part of network measuremen. In this paper ,first Introducing the method of end-to-end path available bandwidth. These methods can be divlded into two categories: one based on self-congestion and the other based on mathematical model. Then the problem of bandwidth measurement(testing speed,bandwidth estimating,background stream) and a policy of selecting the length of measurement packets are discussed. we proposed that 800 bytes is the preferred measuerment packet length in network performance measurement. Also, the simulate tool NS2 is introduced.In this paper,Researching on the Pathload Algorithm based on the bandwidth estimation metrics,knowing that Pathload measure end-to-end path available bandwidth by self-loading periodic streams technique, it judged whether the sending rate of the periodic stream is greater than end-to-end path available bandwidth or not, by detecting whether the one-way delay of the periodic stream packet show increasing trend or not. Then Pathload bring the periodic stream rate close to end-to-end path available bandwidth following an iterative algorithm similar to binary search. But the convergent rate of Pathload is slow, and its overhead is too large. a modified available bandwidth measurement algorithm was proposed, adopting destination end velocity of the cycle stream replacing the velocity of cycle stream, it was found that the proposed algorithm of measurement could measure the network available bandwidth more promptly and exactly, also the overhead of measurement is reduced. The results of simulation on NS-2 show the method is valid and efficient.