Patent ID: 6985499

Claim:
A method for improving time precision in a network including a first clock and a second clock using a packet based network time protocol that is transmitted and received in accordance with a data packet transmission protocol that also includes an error checking code for use in detecting transmission errors in the received data packets, comprising: determining a scheduled time of transmission when each packet containing network timing information is to be released for transmission from a respective first or second physical interface to the network; writing the scheduled time of transmission and the associated error checking code in each outgoing information packet; releasing each outgoing information packet at the respective physical interface when the first or second clock associated with that interface indicates that the current time is equal, within a predetermined precision, to the respective said scheduled time of transmission; using the respective other clock to determine, within the predetermined precision, a time of reception when each released information packet is received at the other physical interface to said network; storing said time of reception in an auxiliary timestamp external to the information packet in a manner that is transparent to said transmission protocol without any updating of said error checking code; associating each auxiliary time stamp with the respective incoming information packet; and using the time of reception data in the auxiliary timestamps and the scheduled time of transmission data in the information packets to synchronize the first clock to the second clock, wherein said network time protocol is an existing time protocol and said transmission protocol is an existing transmission protocol, wherein the arriving packets are sent to a receive buffer after the auxiliary timestamp has been stored and wherein no changes are made to physical layer drivers or to any of ISO rules for packet structure, at all network layers.