Abstract-This paper proposes an adaptive bandwidth control algorithm that efficiently provides aggregate loss guarantee to resolve the problem of inefficient bandwidth allocation due to incomplete, inaccurate traffic descriptors supplied by users. Because the control attempts to allocate the bandwidth only just enough to meet the QoS requirement, the amount of bandwidth saving compared to static allocation can be substantial. Another distinct advantage of our control algorithm is that no a priori information on the traffic characteristics of the aggregate is required. From the simulation study, the proposed control can maintain the packet loss QoS while attaining very high utilization, and is robust against different system configurations. Symposium: High-Speed Networks