A method and apparatus for reducing data congestion in Clos networks is disclosed. A congestion detector is provided at an output port of a first layer of the Clos network. A pause timer is provided at an input port of a second layer of the Clos network. The congestion detector generates a feedback message indicating a data congestion level of the output port, and the pause timer determines a pause duration based on the feedback message. For example, the pause duration may be proportional to the congestion level of the output port of the first layer. A pause signal generator may also be provided at the input port to generate a first pause signal based on the pause duration. The pause signal generator may further output the pause signal to a transmitting device to suspend a transmission of data for the pause duration.