Patent ID: 7127508

Claim:
A method of measuring latency in a network comprising for each source, first network element, second network element, destination, service level parameter permutation for which latency is to be measured: at a first network element, receiving a first stream of packets from a source, the first stream of packets having at least one associated service level parameter; at the first network element, on an ongoing basis and independently of said source inserting into the first stream of packets a probe packet to produce a first probe packetized stream of packets, each probe packet containing a respective source transmit time which represents first network element time at a time of insertion of the probe packet; the first network element processing and forwarding each packet of the first probe packetized stream of packets in accordance with the at least one associated service level parameter; at a second network element, receiving the first probe packetized stream of packets; the second network element extracting each probe packet and adding to each probe packet a respective destination receive time which represents second network element time at a time of extraction of the probe packet; the second network element receiving a second stream of packets from the destination, the second stream of packets having at least one associated service level parameter; the second network element independently of the destination inserting into the second stream of packets each extracted probe packet to produce a second probe packetized stream of packets after adding to each extracted probe packet a respective destination transmit time which represents second network element time at a time of insertion of the probe packet; the second network element processing and forwarding each packet of the second probe packetized stream of packets in accordance with the at least one associated service level parameter; the first network element receiving the second probe packetized stream of packets; the first network element extracting each probe packet from the second probe packetized stream of packets and adding to each probe packet a respective source receive time which represents first network element time at a time of extraction of the probe packet; and the first network element using the source transmit network time, the destination receive time, the destination transmit time, and the source receive time to compute a latency for each probe packet.