Checksum Trailer for Timing Protocol Packet Integrity
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Solution Overview
Problem
In communication packets, modifying timestamps can invalidate checksums, causing receiving devices to ignore the checksum value and fail to verify packet integrity, especially when intermediate nodes add or modify timestamps without efficiently updating the checksum.
Innovation Solution
A method and apparatus for processing data packets in timing protocols that involve modifying timestamps and determining a checksum trailer value to maintain checksum correctness by setting a portion of the extension or padding field to this value, ensuring integrity verification even when checksums are modified.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an intermediate node modifies the timestamp in a communication packet, then the timing accuracy is improved, but the checksum becomes invalid and packet integrity verification fails
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the original checksum value in the packet before it reaches the intermediate node. When the timestamp is modified, the intermediate node uses this pre-stored checksum along with the checksum trailer determination to maintain verification capability, thus preserving reliability while enabling timing modifications.
Solution Approach 2:
The patent introduces a checksum trailer field as an intermediary element that mediates between the timestamp modification and checksum verification. This additional field carries information that allows the receiving node to verify packet integrity even after the intermediate node has modified the timestamp, thus resolving the contradiction between timing accuracy and verification reliability.
2Reliability
If the checksum is updated after timestamp modification, then packet integrity verification is maintained, but the processing complexity increases
Solution Approach 1:
The patent segments the checksum verification function into multiple parts: the original checksum field, the checksum trailer field, and the timestamp field. This segmentation allows the intermediate node to modify the timestamp independently while the receiving node can verify integrity using the segmented checksum components, reducing processing complexity compared to recalculating the entire checksum.
Solution Approach 2:
The patent enables self-service by having the intermediate node automatically determine and set the checksum trailer value based on the modified timestamp and original checksum. This automated process maintains packet integrity verification without requiring complex manual intervention or extensive processing, thus reducing overall system complexity.
3Adaptability or versatility
If the checksum value is set to zero to indicate modification, then the receiving device ignores the checksum, but the ability to verify packet integrity is lost
Solution Approach 1:
The patent adds another dimension to the checksum system by introducing the checksum trailer field alongside the traditional checksum field. This dimensional expansion allows the system to maintain checksum verification capability even when the timestamp is modified, rather than simply setting the checksum to zero and losing verification ability. The receiving node can now verify integrity across multiple fields including the checksum trailer.
Data Source
AI summary
A data packet is received, wherein the data packet includes i) a checksum and ii) a timestamp. The timestamp is modified to generate a modified timestamp. A checksum trailer value to maintain correctness of the checksum in the data packet having the modified timestamp is determined. At least a portion of i) an extension field of the data packet and/or ii) a padding field of the data packet is set to the checksum trailer value.