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