In this dissertation, we present performance prediction models for rate-based and window¡Vbased flow control mechanisms. For rate-based flow control, such as in ATM network, we derive two analytical models to predict the ACR rates for congestion-free and congestion networks, respectively. To coordinate the cooperative problems of TCP over ATM networks, we propose a new algorithm to monitor the states of ATM switches and adjust TCP congestion window size based on RM cells. For window-based flow control mechanisms, such as in TCP-Reno and TCP-SACK, we respectively present analytical models to systematically capture the characteristics of multiple consecutive packet losses in TCP windows. Through fast retransmission, the lost packets may or may not be recovered. Thus, we present upper bound analyses for slow start and congestion avoidance phases to study the effects of multiple packet losses on TCP performance. Above the proposed upper bounds, the lost packets may not be successfully recovered through fast retransmission. Finally, we develop a model to study the TCP performance in terms of throughput degradation resulted from multiple consecutive packet losses. The analytical results from the throughput degradation model are validated through OPNET simulation.