A manner of providing an energy-efficient two-stage PON using a multistage-PON repeater to forward data traffic and other communications between the first stage and the second stage. The multistage-PON repeater receives BI-PON transmission frames from and OLT and decimates them, forwarding data intended for end devices of the second stage. The multistage-PON repeater rate adapts the transmissions so that faster speeds may be associated with PON first stage communications and slower speeds are associated with PON second stage communications. Many though not all of the multistage-PON components are configured to operate at the slower clock speed, conserving energy. Upstream transmissions from the end devices of the second stage are buffered in the multistage-PON repeater and forwarded to the OLT according to an allocation schedule received from the OLT in a BI-PON frame.