A system and method for determining end-to-end available bandwidth of a path in a packet-switched communication network. A multi-rate packet chirp injector injects probe traffic packets at different probing rates, u, into the network utilizing a probe chirp. A receiver samples time separation of the probe traffic packets to generate time-separation samples, which are used to calculate relative inter-packet separation strain, ε, samples at different probing rates. An Expectation-Maximization, EM, analyzer utilizes an EM algorithm to identify useful strain ε samples and to estimate parameters of a line l2 representing a direct linear relationship between the probing rate and the inter-packet separation strain ε at probing rates greater than a break point. A filter such as, for example, a Kalman filter then determines the available bandwidth of the network path based on the estimated parameters of the line l2.