System, method, and article of manufacture for synchronizing time of day clocks on first and second computers
First Claim
1. A method for synchronizing first and second time-of-day clocks on first and second computers, respectively, the first computer having a third clock on a first network interface card, the second computer having a fourth clock on a second network interface card, the first and second network interface cards communicating with one another via a communication network, the method comprising:
- generating a first message having a first time difference value and a second time stamp value and transmitting the first message from the first network interface card, the first time difference value corresponding to a time difference between the first time-of-day clock and the third clock, the second time stamp value corresponding to a time determined by the third clock on the first network interface card when the first message is transmitted from the first network interface card;
receiving from the second network interface card a second message having the first time difference value, the second time stamp value, a third time stamp value, a fourth time difference value, and a fifth time stamp value, the third time stamp value corresponding to a time determined by the fourth clock on the second network interface card when the first message is received by the second network interface card, the fourth time difference value corresponding to a time difference between the second time-of day clock and the fourth clock, the fifth time stamp value corresponding to a time determined by the fourth clock when the second message is transmitted from the second network interface card;
determining a sixth time stamp value associated with the second message, the sixth time stamp value corresponding to a time determined by the third clock when the second message is received by the first network interface card; and
determining a seventh time difference value corresponding to a time difference between the first and second time-of-day clocks based on the first time difference value, the second time stamp value, the third time stamp value, the fourth time difference value, the fifth time stamp value, and the sixth time stamp value.
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Accused Products
Abstract
A system, method, and article of manufacture for synchronizing first and second time-of-day clocks on first and second computers, respectively, are provided. The first and second computers have first and second network interface cards with third and fourth clocks, respectively, thereon. The system utilizes time stamp values generated by the third and fourth clocks to synchronize the first and second time-of-day clocks.
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Citations
12 Claims
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1. A method for synchronizing first and second time-of-day clocks on first and second computers, respectively, the first computer having a third clock on a first network interface card, the second computer having a fourth clock on a second network interface card, the first and second network interface cards communicating with one another via a communication network, the method comprising:
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generating a first message having a first time difference value and a second time stamp value and transmitting the first message from the first network interface card, the first time difference value corresponding to a time difference between the first time-of-day clock and the third clock, the second time stamp value corresponding to a time determined by the third clock on the first network interface card when the first message is transmitted from the first network interface card; receiving from the second network interface card a second message having the first time difference value, the second time stamp value, a third time stamp value, a fourth time difference value, and a fifth time stamp value, the third time stamp value corresponding to a time determined by the fourth clock on the second network interface card when the first message is received by the second network interface card, the fourth time difference value corresponding to a time difference between the second time-of day clock and the fourth clock, the fifth time stamp value corresponding to a time determined by the fourth clock when the second message is transmitted from the second network interface card; determining a sixth time stamp value associated with the second message, the sixth time stamp value corresponding to a time determined by the third clock when the second message is received by the first network interface card; and determining a seventh time difference value corresponding to a time difference between the first and second time-of-day clocks based on the first time difference value, the second time stamp value, the third time stamp value, the fourth time difference value, the fifth time stamp value, and the sixth time stamp value. - View Dependent Claims (2, 3, 4)
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5. A networked system, comprising:
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a first computer having a first network interface card and a first time-of-day clock and a second computer having a second network interface card and a second time-of-day clock, the first network interface card having a third clock, the second network interface card having a fourth clock; the first computer configured to generate a first message having a first time difference value and a second time stamp value and to transmit the first message from the first network interface card, the first time difference value corresponding to a time difference between the first time-of-day clock and the third clock, the second time stamp value corresponding to a time determined by the third clock on the first network interface card when the first message is transmitted from the first network interface card; the first computer further configured to receive from the second network interface card a second message responsive to the first message, the second message having the first time difference value, the second time stamp value, a third time stamp value, a fourth time difference value, and a fifth time stamp value, the third time stamp value corresponding to a time determined by the fourth clock on the second network interface card when the first message is received by the second network interface card, the fourth time difference value corresponding to a time difference between the second time-of day clock and the fourth clock, the fifth time stamp value corresponding to a time determined by the fourth clock when the second message is transmitted from the second network interface card; and the first computer further configured to determine a sixth time stamp value associated with the second message, the sixth time stamp value corresponding to a time determined by the third clock when the second message is received by the first network interface card, the first computer further configured to determine a seventh time difference value corresponding to a time difference between the first and second time-of-day clocks based on the first time difference value, the second time stamp value, the third time stamp value, the fourth time difference value, the fifth time stamp value, and the sixth time stamp value. - View Dependent Claims (6, 7, 8)
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9. An article of manufacture, comprising:
a computer storage medium having a computer program encoded therein for synchronizing first and second time-of-day clocks on first and second computers, respectively, the first computer having a third clock on a first network interface card, the second computer having a fourth clock on a second network interface card, the first and second network interface cards communicating with one another via a communication network, the computer storage medium comprising; code for generating a first message having a first time difference value and a second time stamp value and transmitting the first message from the first network interface card, the first time difference value corresponding to a time difference between the first time-of-day clock and the third clock, the second time stamp value corresponding to a time determined by the third clock on the first network interface card when the first message is transmitted from the first network interface card; code for receiving from the second network interface card a second message having the first time difference value, the second time stamp value, a third time stamp value, a fourth time difference value, and a fifth time stamp value, the third time stamp value corresponding to a time determined by the fourth clock on the second network interface card when the first message is received by the second network interface card, the fourth time difference value corresponding to a time difference between the second time-of day clock and the fourth clock, the fifth time stamp value corresponding to a time determined by the fourth clock when the second message is transmitted from the second network interface card; code for determining a sixth time stamp value associated with the second message, the sixth time stamp value corresponding to a time determined by the third clock when the second message is received by the first network interface card; and code for determining a seventh time difference value corresponding to a time difference between the first and second time-of-day clocks based on the first time difference value, the second time stamp value, the third time stamp value, the fourth time difference value, the fifth time stamp value, and the sixth time stamp value. - View Dependent Claims (10, 11, 12)
Specification