Patent ID: 7080160
Filing Date: 2006-07-18
Classification: H04J,H04L

Abstract:
1. A method for creating accurate time-stamped frames sent between computers via a network, comprising the steps of: receiving a universal coordinated time reference signal; synchronizing clocks electronically connected to universal coordinated time reference signal receivers and associated with sending and receiving computers, but operating independently of operating system clocks of the sending or receiving computers, with the universal coordinated time reference signal by initializing the clocks with the received universal coordinated time reference signal; using the clocks to create sub-microsecond time values corresponding to a fractionalized universal coordinated time reference signal; over time, adjusting the clock into synchronization with the universal coordinated time reference signal; creating a test frame including a tag having reserved fields for transmit and receive time stamps representing the universal coordinated time reference signal and the sub-microsecond time values; inserting a transmit time stamp into the reserved transmit time stamp field corresponding to the time on the synchronized clock of the sending computer at the instant the test frame is sent onto the network without intervention of the sending computer's central processing unit; and receiving the test frame having the transmit time stamp and inserting a receive time stamp into the reserved receive time stamp field corresponding to the time on the synchronized clock of the receiving computer when the test frame was received by the receiving computer.