The OLT restarts {TAIL ~ communication} with {HEAD ~ the ONU} over the optical line upon receipt of data traffic for the ONU 
The OLT restarts { TAIL ~ communication } with { HEAD ~ the ONU } over the optical line upon receipt of data traffic for the ONU
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH