1、Experimental and Analytical Evaluation of Available Bandwidth Estimation Tools,Cesar D. Guerrero and Miguel A. LabradorDepartment of Computer Science & Engineering University of South Florida,Outline,Motivation Problem Testbed Description Analytical Model Target Tools Performance Evaluation Conclusi
2、ons,Motivation Why to evaluate available bandwidth tools?,Available bandwidth to improve network applications performance. Applications different time, accuracy, and overhead from estimators. Evaluation determine whether a tool is suitable for an application.,Problem What issues do we want to solve?
3、,Evaluate tools over the same variable network conditions Analytical model to have a theoretical value to compare with,Topology Link capacities Packet loss rate Delay,Testbed Description Architecture,Client and server hosting bandwidth estimation tools Intermediate nodes hosting a packet shaper and
4、a traffic generator Phython applications running in all the machines to automatically perform experiments. Internet connected,Low cost,Analytical Model Jackson Network,Eight M/M/1 queues model input and output packet flows. The Jackson model gives the average arrival rate to a node j = j + iij The a
5、vailable bandwidth is the minimum non utilized capacity of the queues associated to the links: A = mini=1,3,5,7 (Ai) = mini=1,3,5,7 (1-i),Client,Server,1,2,3,4,5,6,7,8,Target Tools Estimation Approaches,Probe Rate Model,Pathload. TOPP Pathchirp PTR,Target Tools Pathload,Fleet of probing streams are
6、sent to fill the available bandwidth. The one-way delay increases when the rate of the probing traffic is higher that the available bandwidth. In the gray region, the tool reports the available bandwidth,Figure copied from the paper “Pathload: A Measurement Tool for End-to-end Available Bandwidth” b
7、y M. Jain and C. Dovrolis,Target Tools IGI,Estimates the cross traffic as a function of the amount of traffic inserted between a packet pair. Available bandwidth is given by the average rate of the packet train when the initial packet gap is equal to the output gap.,Figure copied from the paper “Eva
8、luation and Characterization of Available Bandwidth Probing Techniques” by N. Hu and P. Steenkiste,Target Tools Spruce,Probing packets are sent with an intra-pair gap (in) equal to the narrow link transmission time of a 1500B packet (to guarantee that the pair will be in the queue at the same time)
9、Cross traffic is measured using the dispersion of the probing packets (out) calculated at the receiver. It requires a previous calculation of the tight link capacity (C),Performance Evaluation Experiments,Metrics: accuracy, time, overhead 28 network scenarios: link capacities from 1 to 10 Mbps and f
10、rom 10 to 100 Mbps Each scenario with four cross traffic loads: 0%, 25%, 50%, and 75% of the capacity Every estimation was performed 35 times Accuracy plots have a 95% confidence interval,11760 experiments,Performance Evaluation Accuracy with 75% of the capacity as cross traffic,Estimated available
11、bandwidth / total bandwidth (capacity),Pathload,IGI,Spruce,Performance Evaluation Relative Error,Pathload,IGI,Spruce,Performance Evaluation Convergence Time,Pathload,IGI,Spruce,Performance Evaluation Overhead,Pathload,IGI,Spruce,Probing traffic / total bandwidth (capacity) in the tight link,Conclusi
12、ons,Main contributions: Low cost and flexible testbed to evaluate estimation tools in a controlled network. Analytical model to fairly compare the tools accuracy with a theoretical value. Regarding to the tools evaluation: Pathload is the most accurate tool but the slowest to converge IGI is the fas
13、test tool but the least accurate Spruce is the least intrusive tool with intermediate accuracy and convergence time.,Experimental and Analytical Evaluation of Available Bandwidth Estimation Tools,Cesar D. Guerrero cguerrercse.usf.edu Miguel A. Labrador labradorcse.usf.eduDepartment of Computer Science & Engineering University of South Florida,
