Network Interface Card Timestamp Synchronization
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Solution Overview
Problem
Existing time-of-day synchronization methods between computer servers in a networked system are inaccurate due to delays and varying transmission times, leading to significant time differences between clocks, especially when systems are operating at maximum processing capacity.
Innovation Solution
The method involves generating and transmitting messages with time difference and timestamp values from network interface cards on both computers to accurately calculate and synchronize time-of-day clocks, using equations to determine and adjust for clock discrepancies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time stamps are exchanged between computers to synchronize time-of-day clocks, then time synchronization is achieved, but transmission delays and processing capacity limitations cause significant time differences between clocks
Solution Approach 1:
The patent introduces an intermediary timestamp mechanism that records the exact time when a message is transmitted from the network interface card, rather than relying on the application-layer time stamp. This intermediary timestamp serves as a more accurate reference point that eliminates the uncertainty introduced by processing delays and variable transmission times, directly resolving the contradiction between achieving synchronization and suffering from transmission delays
Solution Approach 2:
The patent applies preliminary action by having the network interface card generate and include its internal timestamp in the transmitted message before the message undergoes processing and transmission delays. This preliminary timestamp captures the true transmission time, allowing the receiving system to compensate for subsequent delays and maintain accurate time synchronization
2Measurement precision
If messages are transmitted between computers for time synchronization, then clock synchronization is achieved, but the transmission time period varies causing relatively large time differences
Solution Approach 1:
The patent implements feedback by having each computer send its network interface card timestamp to the other computer, and each system uses the received timestamp along with its own local timestamp to calculate the time difference. This feedback loop allows continuous measurement and adjustment of time synchronization, achieving high precision without requiring complex centralized control mechanisms
3Productivity
If software programs access time-of-day clock values during maximum processing capacity operations, then system productivity is maintained, but time stamp generation is delayed reducing synchronization accuracy
Solution Approach 1:
The patent extracts the time stamping function from the software application layer and places it at the network interface card hardware level. By taking out the timestamp generation from the software processing path, the system can maintain maximum processing capacity for productivity-critical operations while the hardware-level timestamp continues to provide accurate time records independent of software delays
Data Source
AI summary
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.