Egress Timestamp Generation Using Correction Factors
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Solution Overview
Problem
Current time synchronization techniques in distributed networks face challenges in achieving high accuracy and complexity in generating egress timestamps, which are crucial for precise clock synchronization and network quality of service measurements.
Innovation Solution
A two-operation timestamp protocol is implemented, using a semi-autonomous, non-packet stateful, virtualization-friendly software model that generates an initial semi-accurate timestamp near the last controllable point of the egress pipeline and adjusts it with a correction factor based on historical data to produce an accurate egress timestamp, eliminating the need for packet buffering and reducing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional time synchronization techniques are used to generate egress timestamps, then clock synchronization can be achieved, but the accuracy is insufficient and the process becomes complex
Solution Approach 1:
The timestamp generation process is segmented into two distinct operations: (1) generating a semi-accurate timestamp at a controllable point in the egress pipeline, and (2) applying a correction factor to achieve high accuracy. This segmentation allows each operation to be optimized independently, improving overall timestamp accuracy while maintaining manageable complexity
Solution Approach 2:
A preliminary semi-accurate timestamp is generated at a known controllable point in the egress pipeline before the actual packet transmission. This preliminary timestamp serves as a baseline that is then refined using a correction factor, allowing the system to prepare timing information in advance rather than attempting to measure the entire transmission process at once
2Measurement precision
If packet buffering is implemented to capture accurate egress timestamps, then timestamp accuracy improves, but operational complexity increases
Solution Approach 1:
The invention extracts the timestamp capture function from the packet data path by capturing timing information at a specific controllable point in the egress pipeline. This extraction eliminates the need to buffer packets solely for timestamp purposes, as the timing information is captured independently at the point where it is most useful for synchronization calculations
Solution Approach 2:
A correction factor acts as an intermediary between the semi-accurate timestamp captured at the controllable point and the final high-accuracy egress timestamp. This intermediary element bridges the gap without requiring complex packet buffering mechanisms, simplifying the overall operation while maintaining accuracy
Data Source
AI summary
Methods, apparatus, systems, and articles of manufacture to generate a timestamp are disclosed. Examples disclosed herein generate a correction factor based on a first timestamp and a second timestamp, the first timestamp generated before a first data packet is obtained by ethernet physical coding sublayer (PCS), the second timestamp generated before the first data packet is obtained by a physical ethernet port coupled to the ethernet PCS; and generate a third timestamp for a second data packet based on the correction factor and a fourth timestamp, the fourth timestamp generated by network interface circuitry for the second data packet.