Network Node Coordinator Mode Counter Synchronization
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Solution Overview
Problem
In control networks, especially those without a reliable source of time, synchronizing clocks across nodes is challenging, leading to issues with message replay attacks, as existing solutions rely on a single-point-of-failure coordinator node, which is undesirable and prone to failures.
Innovation Solution
A network node with normal and coordinator modes, where the counter manager increments a counter at regular intervals and switches to coordinator mode if synchronization messages are not received, ensuring synchronization and preventing message replay by periodically sending counter synchronization messages, thus eliminating the single-point-of-failure and addressing network delays and inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a synchronized clock and timestamp mechanism is implemented to prevent message replay, then message authentication security is improved, but system complexity and reliability requirements worsen due to the need for reliable time synchronization across nodes
Solution Approach 1:
The patent extracts the time synchronization function from a centralized clock source and implements it through distributed counter values stored at each network node. Each node maintains its own counter that is updated independently, eliminating the need for complex centralized time synchronization while still enabling replay attack prevention through counter-based authentication.
Solution Approach 2:
Each network node independently maintains and updates its own counter value without requiring coordination with other nodes or an external time source. The counter is automatically incremented by the incrementing unit, and nodes use their local counter values for authentication, making the system self-sufficient and eliminating external time synchronization dependencies.
2Device complexity
If a single coordinator node is used to manage counter synchronization, then counter synchronization is simplified, but system reliability worsens due to single-point-of-failure
Solution Approach 1:
The patent segments the counter synchronization function by eliminating the need for a dedicated coordinator node. Instead, any network node can temporarily assume the coordinator role by sending synchronization messages when needed, and the function is distributed across all nodes. This segmentation removes the single-point-of-failure while maintaining synchronization capability.
Solution Approach 2:
The system dynamically assigns coordinator functionality based on operational needs rather than having a fixed coordinator. When a node needs to send counter synchronization messages, it temporarily takes on the coordinator role, and this role can be assumed by any node in the network. This dynamic allocation ensures system continuity even if a particular node fails.
3Measurement precision
If counter synchronization messages are sent frequently to maintain synchronization, then synchronization accuracy is improved, but network traffic and energy consumption increase
Solution Approach 1:
The patent implements periodic counter synchronization where nodes send synchronization messages at regular intervals rather than continuously. The incrementing unit updates counters at defined periods, and nodes send synchronization messages periodically to propagate these updates. This periodic action maintains synchronization accuracy while significantly reducing network traffic and energy consumption compared to continuous synchronization.
Data Source
Figure 1a~1b
Figure 2
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AI summary
A network node (110) is provided having a normal mode and a coordinator mode. The network node comprises a counter (130) and an incrementing unit (132), the incrementing unit being arranged to increment the counter at regular time intervals. If the network node does not receive counter synchronization messages it switches to coordinator mode.