A passive optical network (PON) processor comprises a packet processor for processing packets belonging to a certain flow through a plurality of processing stages of a programmable data-path; a microprocessor-data for performing one or more user-defined functions in the programmable data-path on designated packets belonging to the certain flow, wherein packets of respective flows to be processed by the microprocessor-data are designated in a flow table; a microprocessor-control for managing connections handled by the PON processor; a data-path bus for connecting the packet processor and the microprocessor-data, wherein the designated packets are transferred between the packet processor and the microprocessor-data on the data-path bus; and a control-path bus for connecting the packet processor and the microprocessor-control.