Methods, systems, and computer program products for managing memory of a passive optical network (PON) are provided herein. The method includes the steps of receiving a plurality of data packets from a stream of packets. A plurality of packet descriptors associated with each data packet is stored in a configurable first queue. The first queue includes a plurality of cache slots and is managed in an internal memory. A state of the first queue is identified. In response to the state of the first queue meeting a predetermined threshold, packet descriptors from a tail cache slot of the first queue are transferred to a second queue. The second queue is managed in an external memory.