Clock Synchronization Packet Filtering via IP Information
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Solution Overview
Problem
Clock synchronization between master and slave devices in computer networks is compromised by unexpected delays in Precision Time Protocol (PTP) packets due to route diversion attacks or network failures, leading to inaccurate synchronization and potential desynchronization.
Innovation Solution
Incorporating Internet Protocol (IP) information into clock-synchronization packets to identify and discard packets that experience delays exceeding a predetermined threshold, ensuring accurate synchronization by filtering out unreliable packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PTP packets are transmitted through a network that may be subject to route diversion attacks, then clock synchronization can be achieved, but the synchronization accuracy deteriorates due to unexpected delays in diverted packets
Solution Approach 1:
The patent applies preliminary action by embedding IP information (such as TTL values or route identifiers) into PTP packets before transmission. This allows the slave device to later identify and filter out packets that have been diverted through unauthorized routes, preventing them from corrupting the synchronization calculation.
Solution Approach 2:
The patent uses IP information as an intermediary mechanism to track packet routes. By incorporating fields like TTL (Time To Live) or route identifiers into the PTP packets, the system can indirectly determine whether packets traversed authorized networks, enabling filtering of compromised packets without directly monitoring network traffic.
2Duration of action of stationary object
If all received PTP packets are used for synchronization, then synchronization can be maintained, but inaccuracy increases due to inclusion of delayed packets from diverted routes
Solution Approach 1:
The patent applies local quality by treating different PTP packets differently based on their IP information characteristics. Packets with valid IP information indicating authorized routes are accepted for synchronization, while packets showing signs of diversion (such as abnormal TTL values or unrecognized route identifiers) are rejected, creating a selective filtering mechanism.
Solution Approach 2:
The patent changes the parameter of packet selection by introducing IP information-based filtering criteria. The slave device examines IP fields in received PTP packets and uses these parameters to determine which packets are suitable for synchronization, dynamically adjusting the set of usable packets based on route verification.
3Measurement precision
If IP information is added to PTP packets to identify diverted packets, then synchronization accuracy improves, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent extracts only the essential IP information elements needed for route verification, such as TTL values or specific route identifier fields, from the complete IP packet structure. This selective extraction minimizes the processing burden while maintaining the ability to identify diverted packets, reducing complexity compared to analyzing entire IP packets.
Data Source
AI summary
A computer-implemented method for improving clock synchronization between master and slave devices may include receiving at least one clock-synchronization packet transferred from a master device to a slave device via a network that supports an IP. The method may also include identifying at least one item of IP information added to the clock-synchronization packet during the transfer from the master device to the slave device. The method may further include determining that the clock-synchronization packet experienced a delay that exceeds a predetermined threshold during the transfer based at least in part on the item of IP information. Finally, the method may include discarding the clock-synchronization packet from a set of clock-synchronization packets used to synchronize the slave device with the master device in response to the determination. Various other methods, systems, and computer-readable media are also disclosed.