Constant-time dynamic ATM bandwidth scheduling for guaranteed and best effort services with overbooking

摘要

We present an analysis of an existing rate-based ABR scheduling algorithm described by Kline (see ATM-Forum Contribution 94-0849), and propose an enhanced rate-based round robin (RBR) scheduling algorithm for ATM switches and end systems. One of the novel aspects of RBR is that the scheduler supports available bit rate (ABR) traffic as well as guaranteed bandwidth reservations. In addition, bandwidth overbooking is allowed by the scheduler for ABR services to improve the link efficiency as recommended by most flow control schemes. Under competition, the scheduler distributes the bandwidth in a max-min fair way. Any unused reservations for guaranteed services are reallocated to ABR services. Finally, the operations performed during each scheduling cycle are constant, independent of the number of connections. Simulation results are also presented and analyzed.