An approach to congestion control based on open-loop regulation of the input is investigated. The input rate regulation schemes are studied from the viewpoint of their smoothing and regulating effects on the incoming traffic. The smoothing effect is characterized by the variance of the interdeparture time of the packet departure process from the input rate regulation mechanism. Under the assumption of Poisson arrivals the characteristics of this departure process are explicitly derived in terms of the particular scheme's parameters, and the tradeoff between the smoothness of the departure process and packet waiting time is studied. Results for both finite- and infinite-buffer pool sizes are presented.>