NTP Time Correction Using Extension Fields
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Solution Overview
Problem
Current clock synchronization protocols, such as NTP, lack a dedicated field for time correction information, making it difficult to accurately synchronize clocks across networks with multiple intermediate nodes, as they rely on general-purpose extension fields for this purpose.
Innovation Solution
Incorporating time correction values into general-purpose extension fields of protocol packets, allowing intermediate nodes to add or update time correction fields to account for residence times, enabling accurate clock synchronization by adjusting the slave clock based on these values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If NTP protocol is used without dedicated time correction field, then protocol simplicity is maintained, but time synchronization accuracy deteriorates
Solution Approach 1:
The patent reuses the existing extension field in NTP packets, which was originally designed for optional functionality, to carry time correction information. This allows the general-purpose extension field to serve a specific time synchronization function without adding dedicated fields, thereby maintaining protocol simplicity while enabling accurate time correction across intermediate nodes
2Measurement precision
If dedicated time correction field is added to NTP packets, then time synchronization accuracy is improved, but protocol complexity increases
Solution Approach 1:
Instead of creating a dedicated time correction field, the patent utilizes the existing extension field structure in NTP packets. The extension field type indicator is set to specify time correction information, allowing the same field to serve multiple purposes depending on its configuration. This avoids increasing protocol complexity while enabling accurate time synchronization
3Measurement precision
If time correction information is collected from multiple intermediate nodes, then synchronization accuracy is improved, but information processing complexity increases
Solution Approach 1:
The patent segments the time correction information from different intermediate nodes into separate extension fields within the NTP packet. Each intermediate node that supports time correction adds its own correction value in the extension field format. The slave clock device then processes these segmented correction values individually and combines them to calculate the total time offset, simplifying the processing architecture
Solution Approach 2:
The extension field acts as an intermediary structure that standardizes the format of time correction information from multiple intermediate nodes. By using a统一的 extension field format with type indicators, the patent enables seamless collection and processing of time correction data without requiring complex node-specific processing logic
Data Source
AI summary
A network device receives a packet that conforms to a protocol that i) defines a time stamp field, ii) does not define a dedicated field for time correction information, and iii) defines a plurality of general purpose extension fields. The packet includes (i) a time stamp generated by a source node in the time stamp field, and (ii) a time correction value corresponding to multiple ones of the plurality of intermediate nodes, the time correction value being located in one of the general purpose extension fields. The network device identifies (i) a time specified by the time stamp, and (ii) time correction information specified in the one general purpose extension field, and uses the time correction information and the time specified by the time stamp to synchronize a clock maintained by the network device to a clock maintained by the source node.