Patent ID: 6769029
Filing Date: 2004-07-27
Classification: H04L

Abstract:
A transmission delay measuring method which is used in a packet network and which comprises the steps of:detecting by the use of first and second clocks, for each of first direction-data packets transmitted from a first terminal to a second terminal through said packet network, input and output time instants when each of said first direction-data packets enters and leaves said packet network, respectively; recording the input and the output time instants for said first direction-data packets as recorded input and recorded output time instants for said first direction-data packets; detecting by the use of said second and said first clocks, for each of second direction-data packets transmitted from said second terminal to said first terminal through said packet network, input and output time instants when each of said second direction-data packets enters and leaves said packet network, respectively; recording the input and the output time instants for said second direction-data packets as recorded input and recorded output time instants for said second direction-data packets; calculating, for each of said first direction-data packets, a first-direction provisional delay which is a first difference given by subtracting, for each of said first direction-data packets, said recorded input time instant from said recorded output time instant; calculating, for each of said second direction-data packets, a second-direction provisional delay which is a second difference given by subtracting, for each of said second direction-data packets, said recorded input time instant from said recorded output time instant; and deriving a time difference between said first and said second clocks from a first minimum value of said first-direction provisional delays and a second minimum value of said second-direction provisional delays.