If an ONU does not wish to use its entire allocated time slot, it may inform the OLT about this. The OLT may then decide to reallocate the remaining time slot to another ONU which does not have an SLA.
If an ONU does not intend to utilize its entire allocated time frame, it may notify the OLT about this. The OLT can then decide to redistribute the remaining time slot to another ONU that lacks a Service Level Agreement (SLA).