Abstract: A method of measuring jitter of a packet flow includes identifying the data packet flow at each of a first and second network locations by analyzing the data fields of each of the packets in the flow. The method associates a transmit time code with each packet transmitted from the first location, and associates a receive time code with each packet received at the second location. The method calculates inter-arrival times for consecutive pairs of packets by (i) subtracting the transmit time code of the first packet from the transmit time code of the second packet, (ii) subtracting the receive time code associated with the first packet from the receive time code associated with the second packet, and (iii) subtracting the results. The method includes calculating a jitter value as a smoothed version of two or more inter-arrival times, smoothed over a predetermined number of pairs of consecutive packets.

Abstract: A system for time-stamping a data packet associated with a data network allows software applications, running on non-deterministic systems, to determine the precise time that packets were transmitted to or received from a physical network interface. The system includes a network media interface device for transferring a data packet to or from a network medium, and a time source for generating and maintaining a time code. The system further includes a time-stamping circuit for sampling a time code from the time source when the interface device transfers the data packet to or from the network medium, and for associating the time code with the receive data packet so as to form a time-stamped packet.

Abstract: A method of measuring jitter of a packet flow includes identifying the data packet flow at each of a first and second network locations by analyzing the data fields of each of the packets in the flow. The method associates a transmit time code with each packet transmitted from the first location, and associates a receive time code with each packet received at the second location. The method calculates inter-arrival times for consecutive pairs of packets by (i) subtracting the transmit time code of the first packet from the transmit time code of the second packet, (ii) subtracting the receive time code associated with the first packet from the receive time code associated with the second packet, and (iii) subtracting the results. The method includes calculating a jitter value as a smoothed version of two or more inter-arrival times, smoothed over a predetermined number of pairs of consecutive packets.

Abstract: A system for time-stamping a data packet associated with a data network allows software applications, running on non-deterministic systems, to determine the precise time that packets were transmitted to or received from a physical network interface. The system includes a network media interface device for transferring a data packet to or from a network medium, and a time source for generating and maintaining a time code. The system further includes a time-stamping circuit for sampling a time code from the time source when the interface device transfers the data packet to or from the network medium, and for associating the time code with the receive data packet so as to form a time-stamped packet.

Abstract: A system for time-stamping a data packet associated with a data network includes a network media interface device for transferring a data packet to a network medium, and a time source for generating and maintaining a time code. The system further includes a time-stamping circuit for sampling the time code from the time source when the data packet is available to be transferred to the network medium so as to acquire an outgoing time code. The time-stamping circuit also embeds the outgoing time code into a predetermined field in the data packet. The time-stamping circuit also provides the data packet with the embedded outgoing time code to the interface device, and the interface device subsequently transfers the data packet to the network medium.

Abstract: A method of characterizing a propagation delay of a data element propagating from a software source to a physical medium destination includes associating, in software, a first time code with the data element when the software source dispatches the data element to the physical medium destination. The method further includes associating, via a time-stamping circuit, a second time code with the data element when the data element reaches the physical medium destination. The method also includes subtracting the first time code from the second time code so as to calculate the propagation delay. In a similar manner, the method may also be used to characterize the propagation delay of the data element in the reverse direction, i.e., from the physical medium to the software source.