We introduce an alternative approach to congestion avoidance and control, which has the potential to increase efficiency and fairness in multiplexed channels. Our approach, bimodal congestion avoidance and control, is based on the principles of TCP's additive increase multiplicative decrease. It is designed to better exploit the system properties during equilibrium, without trading off responsiveness for smoothness. In addition, it is capable of achieving convergence to fairness in only two congestion cycles. As a result, both efficiency and fairness are improved, responsiveness is not degraded, and smoothness is significantly improved when the system is in equilibrium. We provide a theoretical analysis and we discuss the potential of our approach for packet networks. Our experiments confirm that bimodal congestion avoidance and control as a component of the transmission control protocol outperforms the traditional scheme.