A smart probing technique for monitoring end-to-end available bandwidth on the Internet is described, which uses a pair of probe trains of different probing rates. The technique makes full use of a limited set of measurement results with a few probing packets, yielding short measurement time and small amount of probing bits, while keeping measurement error minimum under a set of optimized measurement parameters specified in this paper. Simulation results in a single-hop network show the technique achieves fast and accurate performance. It is also discussed that some active measurement techniques of available bandwidth look like an impulse response measurement for measuring bandwidth of analogue circuits. Such an analogical point of view gives help for us to design the proposed probing technique.