Patent ID: 8913549

Claim:
A method in an Optical Line Terminal (OLT) system comprising a plurality of physical OLT Passive Optical Network (PON) ports, wherein each physical OLT PON port is for communicating with at least one Optical Network Unit (ONU), and wherein each physical OLT PON port has a respective enforced maximum upstream bandwidth; the OLT system further including an uplink port through which data received from each physical OLT PON port are transmitted; the method comprising: preventing or alleviating congestion of said data at the uplink port of the OLT system by reducing an enforced maximum upstream bandwidth for at least one physical OLT PON port; wherein said reducing the enforced maximum upstream bandwidth for the at least one physical OLT PON port includes the steps of: obtaining parameters relating to each physical OLT PON port and reducing the enforced maximum upstream bandwidth for the at least one physical OLT PON by an amount dependent upon the parameters; obtaining an indication of whether there is congestion of said data in a buffer of the OLT system, the buffer storing said data prior to transmission through the uplink port of the OLT system, and said data comprising data of different classes; and reducing the enforced maximum upstream bandwidth for the at least one physical OLT PON if there is congestion of said data in the buffer; wherein said reducing the enforced maximum upstream bandwidth for the at least one physical OLT PON port causes the at least one physical OLT PON port to perform at least one of: (i) reducing a number of transmission windows granted to at least one ONU connected to the at least one physical OLT PON port, and (ii) reducing a duration of one or more transmission windows granted to at least one ONU connected to the at least one physical OLT PON port.