Evaluation And Improvement Of Algorithms For Available Bandwidth Measure

With the rapid development of the Internet and network services, quality of network service has become increasingly demanding.Network measurement technology is the key to obtain network performance indicators effectively. Available bandwidth is one of the most important technical parameters for network performance measurement.At present, many researches on available bandwidth measurement have been done, however, the algorithms of available bandwidth estimation are lack of systematic and in-depth assessment, existing algorithms have many deficiencies in application and measurement accuracy. This thesis analyzes the the above problems deeply.The major contributions are outlined as follows:1,Based on end-end path characterization as well as input and output analysis of probing, the thesis designs an evaluation model of algorithms for available bandwidth estimation.Different from the existing level of assessment methods based on indicators, the model not only provides systematic and effective evaluation methods based on algorithm principle and error analysis, but also proposes related solutions.Based on theoretical derivation and simulation testing, the thesis verifies the correctness and validity of the model.2,Based on the evaluation model, the thesis analyzes and evaluates typical algorithms for available bandwidth measurement. The above work not only points out the problems related to algorithms and proposes some solutions, but also provides strong theoretical support to algorithm design, improvement and analysis of experimental data.3,Based on the non-size-equal packet-pair probing theory, the thesis presents the improved algorithm E-IGI and E-Spruce.The above algorithms not only solve the problem cased by interference from traffic on "nontight" links, but also achieve single-ended measurement easier. Simulation results show that compared with the pre-improvements.E-IGI and E-Spruce have stronger anti-interference and high precision.4,The thesis presents a hybrid model and develops an available bandwidth measure method HM-ABM based on this model.Unlike the current available bandwidth measurement methods, HM-ABM blends of a variety of probing techniques and uses layers and a phased implementation approach to take advantages of each probing technology. This thesis verifies the validity and applicability of HM-ABM by carry out HM-ABM in different network environments.