a data determination unit determining, on {HEAD ~ the basis} of {TAIL ~ all LINK IDs} present in the data of at least one of the optical network units among the aforementioned optical network units, the data requiring storage from among all data sent to the optical network unit 
of
a data determination unit determining , on { HEAD ~ the basis } of { TAIL ~ all LINK IDs } present in the data of at least one of the optical network units among the aforementioned optical network units , the data requiring storage from among all data sent to the optical network unit
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH