Method and apparatus for traffic flow control in data switches are
disclosed. Emission and loss priorities of cells to be switched are
translated into a single discard priority, referred to as a bandwidth
priority, which has consistent meaning across different emission
priorities. This translation allows simultaneous consideration of loss and
emission priority in determining which cells to discard when a switch
becomes congested with cell traffic. Such consideration alleviates
problems that can arise if cell discard decisions are based solely on
either loss priority or emission priority. The invention is particularly
useful for Asynchronous Transfer Mode (ATM) switches.
