A method for performing a time measurement on a data flow transmitted from a transmitter to a receiver of a communication network is provided. The method comprises: at the transmitter, dividing the data flow in first and second time alternating blocks of data units, transmitting them, increasing a transmission counter while the first blocks are transmitted and setting a transmission timestamp to a current time when a predetermined data unit of each first block is transmitted; at the receiver, receiving the first and second blocks, increasing a reception counter while the first blocks are received and setting a reception timestamp to a further current time when the predetermined data unit of each first block is received; and at a management server, periodically detecting values of the transmission counter, the reception counter, the transmission timestamp and the reception timestamp, and using them for performing the time measurement.