An optical line terminal, OLT, comprising: an optical module (41, 61), a clock and data recovery module (42, 62, 64), a media access control chip (43, 63, 65) and a control module, wherein: said optical module (41, 61) is configured to: receive upstream data sent by optical network units, ONUs, with different transmission rates and send said upstream data to said clock and data recovery module (42, 62, 64); said clock and data recovery module (42, 62, 64) is configured to: receive said upstream data with different transmission rates, recover a clock signal according to said upstream data, and send said upstream data and said clock signal corresponding to said upstream data to said media access control chip (43, 63, 65); said media access control, MAC, chip (43, 63, 65) is configured to: save said upstream data and said clock signal corresponding to said upstream data; said control module is configured to: acquire an upstream rate of said upstream data according to said clock signal corresponding to said upstream data, and allocate an upstream bandwidth to said ONU according to said upstream rate; characterized in that, the number of the clock and recovery module is m, m is a positive integer; when the number of the clock and data recovery module comprised by the OLT is m=1, said clock and data recovery module is configured to recover said clock signal, and send said upstream data and said clock signal corresponding to said upstream data to said MAC chip by: recovering n channels of clock signals according to the number n of said ONUs with different transmission rates and said upstream data, and sending said upstream data and said n clock signals corresponding to said upstream data to said MAC chip; or, recovering one channel of clock signal according to the number n of said ONUs with different transmission rates and said upstream data, and sending said upstream data and said one channel of clock signal to said MAC chip; wherein, said n is a positive integer greater than 1. said optical module (41, 61) is configured to: receive upstream data sent by optical network units, ONUs, with different transmission rates and send said upstream data to said clock and data recovery module (42, 62, 64); said clock and data recovery module (42, 62, 64) is configured to: receive said upstream data with different transmission rates, recover a clock signal according to said upstream data, and send said upstream data and said clock signal corresponding to said upstream data to said media access control chip (43, 63, 65); said media access control, MAC, chip (43, 63, 65) is configured to: save said upstream data and said clock signal corresponding to said upstream data; said control module is configured to: acquire an upstream rate of said upstream data according to said clock signal corresponding to said upstream data, and allocate an upstream bandwidth to said ONU according to said upstream rate; characterized in that, the number of the clock and recovery module is m, m is a positive integer; when the number of the clock and data recovery module comprised by the OLT is m=1, said clock and data recovery module is configured to recover said clock signal, and send said upstream data and said clock signal corresponding to said upstream data to said MAC chip by: recovering n channels of clock signals according to the number n of said ONUs with different transmission rates and said upstream data, and sending said upstream data and said n clock signals corresponding to said upstream data to said MAC chip; or, recovering one channel of clock signal according to the number n of said ONUs with different transmission rates and said upstream data, and sending said upstream data and said one channel of clock signal to said MAC chip; wherein, said n is a positive integer greater than 1.