GPON
acronymISP & telecom
Gigabit Passive Optical Network: one fiber from the OLT is split passively among up to 64 or 128 subscribers, sharing 2.5 Gbps down and 1.25 up.
The dominant FTTH standard of the 2010s; XGS-PON is its symmetrical 10-gigabit successor.
GPON is a passive optical network: one fibre leaves the exchange, a passive splitter divides it among subscribers, and no powered equipment sits between the two ends. That passivity is the economic argument, because the outside plant needs no power, no cooling and almost no maintenance.
The consequence is that capacity is shared. The line rate is divided among everyone on the splitter, downstream by broadcast with each subscriber decrypting only its own traffic, upstream by time slots the OLT grants. Contention is therefore a design parameter rather than a fault, and a subscriber's experience depends on how many others share the split and what they are doing, which is why advertised and delivered rates diverge at busy hours.