Multi-Domain PTP Time Synchronization Using Stored Delay Offsets
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Solution Overview
Problem
Existing Precision Time Protocol (PTP) standards, such as 802.1AS-2011 (gPTP), lack specifications for synchronizing multiple time domains, leading to increased costs and resource consumption when physically reconfiguring networks for time synchronization across different time zones.
Innovation Solution
A method and apparatus for PTP-based time synchronization across multiple time domains, involving a slave node calculating and storing propagation delays, and using offsets to synchronize hardware clocks with a master node, enabling synchronization across various time domains without additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical reconfiguration of the network with separate hardware devices is used for time synchronization across multiple time domains, then time synchronization capability is improved, but cost and resource consumption increase
Solution Approach 1:
The existing PTP infrastructure is made multi-functional by enabling it to handle both single time domain and multiple time domain synchronization scenarios. The slave node calculates and stores propagation delays for different time domains and applies appropriate offsets to obtain times in respective time domains, allowing the same hardware to serve multiple time synchronization purposes without additional dedicated hardware devices.
Solution Approach 2:
The invention changes the operational parameters of the existing PTP system by introducing time domain identifiers and offset calculations. Instead of requiring separate hardware for each time domain, the system modifies the time calculation parameters (adding offset values based on stored propagation delays) to enable multiple time domain support within the same hardware infrastructure.
2Measurement precision
If physical reconfiguration with separate hardware devices is implemented for multiple time domain synchronization, then synchronization accuracy is improved, but device complexity increases
Solution Approach 1:
The time synchronization function is segmented into distinct time domains, with each time domain having its own offset value stored in the slave node. The slave node selectively applies the appropriate offset based on the target time domain, allowing accurate synchronization across multiple time domains while maintaining a unified hardware structure rather than requiring complex physical reconfiguration.
3Device complexity
If existing PTP infrastructure is used without modifications for multiple time domains, then device simplicity is maintained, but adaptability to multiple time domains deteriorates
Solution Approach 1:
The PTP system is made dynamic by enabling the slave node to adaptively select and apply different propagation delay offsets based on the target time domain. The system transitions from a static single-time-domain configuration to a dynamic multi-time-domain configuration where the offset application is determined by the specific time domain synchronization requirement, enhancing adaptability without hardware changes.
Data Source
AI summary
A slave node calculates and stores a propagation delay generated when exchanging a message with a master node. The master node transmits a reference time indicated by a hardware clock of the master node, and the slave node synchronizes a hardware clock of the slave node to the reference time indicated by the hardware clock of the master node. The master node transmits a time value in a first time domain to the slave node, where the time value is calculated by the master node by adding an offset of the first time domain to the reference time. The slave node calculates the offset using the time value and the stored propagation delay, and obtains a time in the first time domain by applying the calculated offset to a reference time indicated by the hardware clock of the slave node.