PRP Frame Pair Comparison for Early Network Path Fault Detection
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Solution Overview
Problem
Commercially available Parallel Redundancy Protocol (PRP) packages do not provide path fault diagnostics, leading to communication path fault detection only after multiple faults occur, which is too late for time-sensitive systems like process control systems.
Innovation Solution
Incorporating a redundancy manager in electronic devices with PRP-based communication networks to detect path faults by transmitting frame pairs over multiple lanes and implementing a receive processing flow that compares frame parameters to identify and alert on path faults, providing early warning and enabling timely corrective action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PRP is used without additional fault detection mechanisms, then device complexity is minimized, but path fault detection capability is lost until multiple faults occur
Solution Approach 1:
The PRP system performs self-diagnosis by using its own redundant frame transmission mechanism to detect path faults. The receiver compares sequence numbers of received frames to automatically identify when a path fault occurs, without requiring external monitoring systems. This allows the system to detect faults at the first occurrence while maintaining minimal additional complexity.
Solution Approach 2:
The system implements feedback by having the receiver monitor the sequence numbers of received frames and generate fault notifications when discrepancies are detected. This feedback mechanism enables the system to detect and report path faults immediately, allowing for timely corrective action before multiple faults occur.
2Reliability
If PRP transmits duplicate frames over multiple lanes, then communication reliability is improved, but the ability to detect single path faults is lost
Solution Approach 1:
The system segments the fault detection function by separately tracking sequence numbers for each lane. The receiver maintains independent sequence number counters for frames received on different lanes, allowing it to identify which specific lane experienced a fault. This segmentation enables fault detection while preserving the redundant transmission capability.
Solution Approach 2:
The system uses sequence numbers as identifiers (analogous to color changes) to track frames from different lanes. By incrementing sequence numbers for each transmitted frame and comparing received sequence numbers against expected values, the system can detect when a lane fails to deliver frames, thereby identifying path faults without compromising communication reliability.
3Loss of time
If no path fault detection is implemented, then system overhead is minimized, but timely corrective action cannot be taken in time-sensitive systems
Solution Approach 1:
The system performs preliminary fault detection by continuously monitoring sequence numbers of incoming frames. The redundancy manager is pre-configured to compare received sequence numbers against expected values and immediately identify path faults. This preliminary detection capability ensures that faults are detected at the first occurrence, providing sufficient time for corrective action in time-sensitive systems.
Solution Approach 2:
The redundancy manager implements self-service fault detection by autonomously comparing sequence numbers and generating fault notifications without requiring external intervention. This self-monitoring capability minimizes the additional complexity required while enabling timely detection and response to path faults in process control systems.
Data Source
AI summary
An electronic device and other electronic device include a first and second port that utilizes a parallel redundancy protocol in a communications network including a first and second lane. The devices include a processing circuit, a PRP handler, a protocol stack, a memory, permanent storage accessible by the processing circuit, and transmit and receive circuitry for transmitting and receiving packets. A redundancy manager is for identifying path faults in the network. The processing circuit implements a method of detecting network path fault, including the other electronic device transmitting a frame pair over the first lane and second lane. The electronic device receives the frame pair and implements a receive processing flow, when the first frame or the second frame is identified to be a redundant frame, removes the redundant frame, and compares a first frame parameter to a second frame parameter to determine when the path fault is present.