Techniques are described for managing traffic flow to an optical network terminal (ONT) on a passive optical network (PON) to prevent an individual ONT from being overrun. Specifically, the techniques involve reducing a transmission rate of a unique traffic flow and selectively denying access to a common traffic flow. By reducing the transmission rate of the unique traffic flow, sufficient bandwidth may be released to receive the unique traffic flow and the common traffic flow without overflowing the ONT. For example, the ONT or, alternatively, the OLT may send the requested common traffic flow without reducing the transmission rate of the unique traffic flow when sufficient bandwidth is available, send the common traffic flow but reduce the transmission rate of unique traffic flow by an appropriate amount, or deny access to the common traffic flow altogether without reducing the transmission rate of the unique traffic flow.