A request-permit procedure based bandwidth allocation algorithm for non-real time stream is presented

which suits for SuperPON with large round-trip-delay and multi-customer.It requests slot switches dynamically between fixed allocation and random access

which adapts to the load situations.The delay performance is investigated with the help of the computer simulations

which prove that the algorithm assures low delay at light load and high throughput at heavy load

and then improves the performance of best effort services.