The admission control and bandwidth allocation for ATM (asynchronous transfer mode) networks are studied. A dynamic bandwidth allocation algorithm is proposed and shown to improve the bandwidth equitable accessibility and the overall throughput. The algorithm is evaluated and compared with other allocation algorithms using blocking rate and cell throughput as evaluation criteria. An on-going study of the user-controlled bandwidth variation is also briefly described. It is shown that as more calls intend to crossover from a lower bandwidth destination to a higher one, the network suffers from a higher connection blocking. >