According to the 64 splitting ratio, each GPON port
can serve a total of 4 FATs as each FAT contain 1:16 splitter,
then 48 GPON ports are required to serve the 185 FATs.
Another bunch of redundant 48 GPON ports is used to
provide type-B protection. The total number of OLT GPON
cards used by the design will be 12, with 6 cards in each
direction. 6 FDTs are used to hold level-1 splitters with each
FDT hold 8 splitters. As a result each FDT will be connected
to one OLT card using 8 Fibers from one direction and to the
backup card using 8 fibers from the other direction as shown
in Figure 6