PTP Boundary Clock Time Correction Mechanism
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Solution Overview
Problem
Time synchronization systems using the Precision Time Protocol (PTP) face challenges when dealing with switch devices from different manufacturers and owners, which can result in varying levels of time synchronization accuracy. This leads to significant time errors when correcting times independently across different devices.
Innovation Solution
A time synchronization device that connects to a time retaining device using the PTP standard, and includes a synchronization information transmitter, a request information receiver, a response information transmitter, and a time corrector. The device calculates the propagation delay time relative to the time retaining device during a specific period and executes time correction based on this calculation, preventing errors that occur when timings are determined independently across different devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If time correction is executed independently at each switch device based on its own synchronization timing, then each device can operate autonomously, but significant time errors occur in the corrected time relative to the reference time
Solution Approach 1:
The boundary clock executes time correction in advance before transmitting synchronization information to other boundary clocks. This preliminary time correction ensures that the synchronization information itself carries accurate time data, which is then used by other boundary clocks for their time correction, creating a cascading effect of accurate synchronization throughout the network.
Solution Approach 2:
The boundary clock acts as an intermediary between the grandmaster clock and other boundary clocks. It receives synchronization information from the grandmaster, corrects its time based on this information, and then transmits the corrected synchronization information to other boundary clocks. This intermediary role ensures that all boundary clocks receive consistent and accurate time reference data.
2Adaptability or versatility
If multiple types of switch devices with different synchronization accuracies are used in the network, then device versatility and adaptability are improved, but time synchronization accuracy deteriorates due to independent timing determination
Solution Approach 1:
The invention implements a homogeneous time correction approach where all boundary clocks follow the same correction procedure: receive synchronization information, execute time correction based on this information, and then transmit corrected synchronization information to other boundary clocks. This uniform approach ensures consistent time synchronization accuracy across diverse device types with different native synchronization capabilities.
Data Source
AI summary
A first slave device (300) is connected between a master device (200) retaining a reference time and a second slave device (400) and executes time synchronization with the master device (200) in accordance with the PTP, together with the second slave device (400). A first synchronization information transmitter (332) transmits Sync and Follow_Up messages to the second slave device (400), a first request information receiver (313) receives a Delay_Req message from the second slave device (400), and a first response information transmitter (333) transmits a Delay_Resp message to the second slave device (400). A first time corrector (320) executes time correction based on a propagation delay time relative to the master device (200), calculated from times identified through transmission and reception of messages to and from the master device (200), during a period different from the period from transmission of the Sync message until reception of the Delay_Req message.