Abstract: The available bandwidth is the residual bandwidth of a network link or path.This metric is important for traffic engineering and rate sensitive applications.Current estimation methodologies are generally based on single-hop topology or fluid cross traffic model，and are not robust against bursty traffic model and multi-hop paths.This paper presents a novel probing technique called Self-Loading Decreasing Rate Train（SLDRT）.Simulations based on NS-2 show that SLDRT gives more accurate estimation than pathChirp under multi-hop topology and non-fluid cross traffic model，with mean measurement time less than 30 ms，which proves it to be a fast and accurate probing scheme.