A method for optimizing data transmission in a data transfer system is provided where the data transfer system includes a transmitting device that transmits data to a receiving device through a switch. The method includes monitoring data transfer congestion in a buffer of the switch. The monitoring includes marking the data when data transfer congestion is detected. If data transfer congestion is detected, the method includes marking an acknowledgement (ACK) data after the marked data is received by the receiving device. The method further includes transmitting the ACK data from the receiving device to the transmitting device. The method also includes adjusting a data transfer rate between the transmitting device and the receiving device based on data transfer congestion. Monitoring data transfer congestion includes marking the data according to a probability corresponding to a percentage of time that the buffer is full.