Patent ID: 7742415

Claim:
A method for determining latency in IP networks, the method comprising: sensing a packet header on a first physical layer interface (e.g., int 0); determining a sensed packet status; in the case of a sensed packet, creating a hashed record of said packet header and the local clock time corresponding to sensing said packet; determining if said packet represents an acknowledgement (ACK) to a previously sensed TCP packet; in the case of said packet representing an ACK to a previously sensed packet, calculating a time delay between the previous sensing of said packet and said ACK; receiving sensed packet data from a second physical layer interface (e.g., int 1); identifying if said sensed packet data from said second physical layer interface corresponds to a packet in said hashed record of said first physical interface layer (e.g., int 0); and identifying a time difference between sensing said packet at said first physical interface layer and said second physical interface layer to determine the One-Way Flight Time between said first physical interface layer and said second physical interface layer.