If a rogue ONU exists on a PON port of the OLT and has gone...

A rogue ONU that transmits out of schedule or at abnormal optical levels can disrupt upstream time-slotting on the PON, causing collision and interference. This can force other ONUs on the same PON to deregister or flap frequently. Huawei OLTs provide rogue ONU detection/isolation to protect the PON.