Dynamics of TCP flow control over high-speed ATM networks

TCP performance over high-speed ATM networks is evaluated. In TCP over UBR (unspecified bit rate), packet losses caused by congestion deteriorates throughput and fairness. Even if early packet discard (EPD) is added, fairness still remains as a problem as long as cell loss occurs. TCP over ABR(ER) (available bit rate-explicit rate) can provide high performance by suppressing cell loss, as long as ABR rate control does not interact with TCP flow control. Coarse timer granularity and large window size can avoid the interaction. When end-to end ABR is not available, further enhancement of TCP control using implicit or explicit congestion notification is needed for performance improvement.