Abstract: A method and apparatus for data flow control of a transmission port includes processing that begins by obtaining, for the transmission port over time, input data rate of at least one data transport type and output data rate of the at least one data transport type. The data type transport type is one of available bit rate (ABR), variable bit rate (VBR), constant bit rate (CBR), and unspecified bit rate (UBR). The data flow control continues by deriving a difference term from the input data rate and the output data rate and using the difference term and a previous generic explicit rate to generate a current generic explicit rate. The current generic explicit rate may further be generated from the previous generic explicit rate, the difference term, and an error term, where the error term is derived from a current queue value and a target queue value.