The Research Of End-To-End Bandwidth Measurement

Bandwidth is one of the important network resources. Bandwidth measurement can apply to Throughput analysis, Overlay network routing, Internet traffic engineering, quality of service (QoS) and verification, and so on. In addition, bandwidth directly affects the web experience of common users. Bandwidth includes Link bandwidth and available bandwidth. End-to-end available bandwidth for a certain period of time in a given path to send data on the maximum bandwidth available, will change dynamically with the cross traffic in the path. This makes it difficult to measure end-to-end available bandwidth efficiently,so the measurement of end-to-end available bandwidth has become a researching focus.Based on a large number of domestic and international articles on end-to-end bandwidth measurement, this thesis analyzes the relationship of the probing rate, available bandwidth and the one-way delays. And then, a method based on polynomial fitting called PFAB (polynomial fitting for available bandwidth) is presented to measure end-to-end available bandwidth. This thesis mostly accomplishes the following works:(1) Present improved SLoPS(Self-Loading Periodic Streams) methodAim to the problem that has a long time to measure and interference in network in the existing measurement method SLoPS, An improved method is proposed, which will send decreasing the probing rate to measure available bandwidth instead of probes at the fixed rate. Through analysis and simulation, this thesis arrive at a function relationship between probe rate, available bandwidth and one-way delay. This could effectively reduce the measurement time.(2) Present PFAB to measure available bandwidth using polynomial fittingIn order to determine the function relationship between probe rate, available bandwidth and one-way delay, by the change of one-way delay to send the frequency, In the situations, the discrete probe is viewed as a continuous stream of data. According to the change of probe rate and one-way delay, using the axiom that polynomial function can be approximated with continuous functions, this thesis use Least-squares method to find out a function which is the relationship of delivery time and one-way delay. Then Derivative of the function gets a delivery time corresponding to the maximum one-way delay. The delivery time corresponding to probe rate is the available bandwidth.(3) Measurement tools and simulationsThe method of PFAB is achieved in this thesis, and this thesis uses the above tools to measure available bandwidth in the campus network environment. Then make use of the NS-2 to simulate experiment, the results show that the method can reduce the number of probe bytes, the time of probing and network interference. As a result of polynomial fitting method, it can find out extreme point with lowing measurement errors when probing rate has a big change.