Techniques, apparatus and systems are described for an optical line terminal (OLT) operable in a passive optical network (PON) system to isolate and mitigate the behavior of a rogue optical network unit (ONU) that transmits optical power up the optical distribution network (ODN). In one aspect, a method of mitigating the behavior of rogue ONUs can include detecting the presence of a rogue ONU on the PON system, and transmitting, based on the detection, a message addressed exclusively to the ONUs that have not yet been discovered or identified by the OLT.