Passive Time Device for Network Clock Synchronization
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Solution Overview
Problem
Existing time synchronization methods, such as the Precision Time Protocol (PTP), require each device to implement the full protocol and exchange messages with a master device, leading to increased network traffic and potentially lower quality time precision.
Innovation Solution
A passive time device taps the link between a time protocol master and slave to intercept and timestamp time protocol messages, allowing calculation of the clock offset without requiring full protocol implementation on all devices, using timestamps from sync and delay messages to adjust clock frequencies for synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full protocol implementation is required on all devices for time synchronization, then time synchronization can be achieved, but device complexity and protocol implementation burden increase
Solution Approach 1:
The patent extracts the time synchronization measurement function from the full PTP protocol implementation. A passive time device taps into existing PTP traffic between master and slave devices, extracting only the necessary timestamp information from protocol messages without requiring the passive device to implement the complete PTP protocol stack. This separates the measurement function from the protocol implementation burden.
Solution Approach 2:
The passive time device acts as an intermediary that observes and measures time offsets by tapping into the communication link between master and slave devices. It intercepts PTP messages, records timestamps, and calculates offsets without participating in the protocol exchange itself, thereby mediating the synchronization measurement without requiring full protocol implementation.
2Reliability
If time protocol messages are exchanged between master and slave devices, then clock synchronization can be achieved, but network traffic increases
Solution Approach 1:
The passive time device creates copies of PTP protocol messages by tapping into the communication link between master and slave devices. Instead of requiring additional message exchanges, it captures and analyzes copies of the existing traffic, thereby obtaining synchronization data without generating additional network traffic.
3Device complexity
If passive time device taps into the link to intercept messages, then protocol implementation burden is reduced, but measurement precision may be affected
Solution Approach 1:
The passive time device performs preliminary timestamping of intercepted PTP messages at the point of interception. By recording timestamps immediately when messages pass through the tap point, it captures accurate transmission timing information before any processing delays, ensuring high measurement precision despite the passive interception approach.
Data Source
AI summary
Techniques described herein may be used for determining an offset between clocks in a network. Such techniques may include obtaining, by a passive time device, a first timestamp pair corresponding to a first time protocol message; obtaining, by the passive time device, a second timestamp pair corresponding to a second time protocol message; and calculating, by the passive time device, a clock offset between a time protocol master and the passive time device using the first timestamp pair, the second timestamp pair, and a pre-determined time delay constant corresponding to a network tap.