In a data packet transmission network a stream of packets of data sent by a first terminal passes in transit through at least one network equipment with which there is associated a stream measurement unit; wherein said first terminal and said measurement unit are connected to a collection unit. The measurement method comprises the following steps the first terminal generates a stream of packets, comprising a first and a second session status control packets the measurement unit analyzes said first and/or second packet of said stream, in transit through the network equipment the first terminal sends the collection unit a sent packet stream description comprising at least the number of packets sent the stream measurement unit sends the collection unit a stream description comprising at least one information item indicating the number of analyzed packets; and the collection unit identifies each analyzed packet of the stream as a function of the stream description to correlate said stream description and said sent packet stream description packet by packet.