Abstract: Based on the ATM network model with multiple bottlenecks, an explicit rate controller for ABR traffic is designed to solve the congestion problems due to such networks. The sufficient condition for the stability of the closed-loop system is presented, and an algorithm for changeable number of ABR users is given to the real-time estimate of the number of controllable ABR users. The numerical simulation done on different network conditions showed that the proposed algorithm is able to not only overcome the adverse effect caused by multiple round-trip propagation delays but estimate the number of controllable ABR users exactly with high robustness.