A Real-Time Measurement Algorithm for Available Bandwidth

Available bandwidth estimation is useful for route selection in overlay networks, QoS, and traffic engineer-ing. Many measurement algorithms, such as Pathload, Pathchar, and Packet Transmission Rate (PTR) method, etc. have been proposed. PTR method sends a sequence of packet trains to characterize the interac-tion between probing packets and the competing traffic, and uses the average rate of the packet train as an estimate of the available bandwidth. However, this PTR algorithm does not fully consider the situation that the detection packets lost themselves. This paper improves the original PTR algorithm which considers the specialty of the burst of the network background flow. The improved PTR algorithm uses the method to match the initial gap value and gap step value to solve the problem about the burst of background flow, and the improved PTR algorithm record and control the number of packets with source and destination to solve the lost of some packets. Finally, theory and experiments, verified by the improved algorithm of PTR, can reflect the changes of the network stably and timely under the circumstance of the network fluctuates fre-quently. It improves the accuracy of a network measurement and makes the measurement results, which can reflect the changes of the network more clearly