Fiber Link Detection for PTP Time Synchronization
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Solution Overview
Problem
The Precision Time Protocol (PTP) used for time synchronization in telecommunications networks is not effective due to the presence of devices on fiber links that do not support PTP, which affects the precision of time synchronization.
Innovation Solution
A method and apparatus for detecting the presence of non-PTP supporting devices on fiber links by measuring forward and reverse delay values and comparing them to thresholds, using timestamp differences and optical power analysis to determine if a third network device is present, allowing for improved time synchronization precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PTP protocol is used for time synchronization between network devices, then time synchronization can be achieved, but time synchronization precision deteriorates when non-PTP supporting devices are present on the fiber link
Solution Approach 1:
The patent applies preliminary action by detecting the presence of non-PTP supporting devices on the fiber link before performing time synchronization. The master device sends detection packets through the fiber link and measures round-trip delays to identify whether third network devices are present. This preliminary detection allows the system to determine if PTP-based time synchronization should be performed or if alternative methods should be used, thereby preventing precision degradation from the outset.
2Adaptability or versatility
If non-PTP supporting devices are present on the fiber link, then device connectivity is maintained, but time synchronization precision deteriorates
Solution Approach 1:
The patent uses PTP detection packets as an intermediary mechanism to bridge the gap between PTP-supporting and non-PTP supporting devices. By sending specially marked detection packets through the fiber link and analyzing round-trip delays, the system can identify the presence of intermediate devices that do not support PTP. This intermediary detection approach allows the network to maintain connectivity through diverse devices while still achieving accurate time synchronization by adjusting methods based on detection results.
3Adaptability or versatility
If fiber link includes third network device, then network topology flexibility is improved, but time synchronization precision deteriorates
Solution Approach 1:
The system performs preliminary detection of the fiber link topology by analyzing round-trip delays of detection packets before initiating time synchronization. This preliminary action reveals the presence of third network devices in the topology, allowing the system to adapt its synchronization approach accordingly - using direct PTP synchronization when the link is clear or alternative methods when intermediate devices are detected, thus maintaining precision despite topology flexibility.
Solution Approach 2:
The patent implements feedback by continuously monitoring round-trip delay measurements of detection packets sent through the fiber link. When the measured delay exceeds expected thresholds or shows anomalous patterns indicating third devices, the system receives feedback about the degraded link quality and adjusts its time synchronization strategy accordingly, preventing precision loss in complex topologies.
Data Source
AI summary
A fiber link detection method is implemented by a first network device of an optical communications network. The fiber link detection method includes obtaining a forward delay value indicating a forward delay of transmitting a first Precision Time Protocol (PTP) packet by a second interface of a second network device to a first interface of the first network device over a fiber link. A reverse delay value indicating a reverse delay of transmitting a second PTP packet by the first interface to the second interface over the fiber link is obtained, and a determination is made, based on the forward delay value, the reverse delay value, and a first threshold, that the fiber link comprises a third network device, where the first network device and the second network device support a PTP, and where the third network device does not support the PTP.