Half-Duplex Ethernet Monitoring for PLCA Mode Recovery

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Solution Overview

Problem

Half-duplex Ethernet networks, such as 10BASE-T1S and 100BASE-T1S, experience a significant decrease in performance when switching to a degraded CSMA/CD mode due to the absence of a synchronization signal, making them non-deterministic and unsuitable for critical applications like avionics.

Innovation Solution

A method for monitoring Ethernet Half Duplex networks that includes nodes with PLCA and CSMA/CD modes, involving each node to retrieve and transmit its internal state, analyze external states, and reconfigure as necessary to maintain or restore PLCA mode, using identifier shifts and validation techniques to ensure deterministic operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the network switches to CSMA/CD operating mode due to absence of synchronization signal, then the network can continue operating in degraded mode, but network performance decreases significantly and determinism is lost

Engineering Contradiction:
Improvenetwork continuityVSAvoidnetwork performance
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent implements a feedback mechanism where each node monitors the presence of synchronization signals and the operational states of other nodes. When a node detects that the master node is absent or the network has switched to CSMA/CD mode, it triggers a reconfiguration process. Nodes exchange state information through monitored frames and automatically elect a new master node to restore PLCA mode, ensuring the network returns to its high-performance deterministic state rather than remaining in degraded mode.

Inventive Principle:
Principle #23Feedback

2Productivity

If the network operates in PLCA mode with master node sending synchronization signals, then deterministic operation is maintained, but the system becomes vulnerable to master node failure

Engineering Contradiction:
Improvenetwork determinismVSAvoidmaster node dependency
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent prepares for master node failure by implementing a standby mechanism where slave nodes continuously monitor for the absence of synchronization signals. When the master node fails, the monitoring nodes detect the absence of expected frames and automatically initiate master node election and reconfiguration. This beforehand preparation ensures seamless transition without network collapse, cushioning against the vulnerability of master node dependency.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The network implements self-healing capability where nodes automatically detect master node failure, elect a new master, and reconfigure themselves without external intervention. Each node contributes to monitoring, detection, and recovery processes, allowing the network to self-correct and restore deterministic PLCA operation autonomously.

Inventive Principle:
Principle #25Self-service

3Reliability

If identifier shifting is implemented during reconfiguration, then PLCA mode can be restored after master node failure, but additional communication overhead is required

Engineering Contradiction:
Improvemode restorationVSAvoidreconfiguration time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary actions by having slave nodes pre-calculate their new identifiers and prepare reconfiguration data before actual master node failure occurs. When failure is detected, nodes already have their reconfiguration parameters ready, allowing immediate execution of identifier shifting and mode restoration without extensive real-time computation, thus minimizing reconfiguration time.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4576682B1Method for monitoring an ethernet half-duplex network and associated ethernet half-duplex network
Publication Date: 2025.11.19 THALES SA
  • EP4576682B1 patent drawingFigure 1
  • EP4576682B1 patent drawingFigure 2
  • EP4576682B1 patent drawingFigure 3

AI summary

The present invention relates to a method for monitoring a Half Duplex Ethernet network comprising a plurality of nodes and having a PLCA operating mode and a CSMA/CD operating mode, each node being defined by an identifier. The method comprises the following steps implemented by each node: - retrieving (110) an internal state of the node describing the operating mode of the network; - transmitting (120) the internal state to all the other nodes; - analyzing (130) the external states received corresponding to the internal states transmitted by other nodes; - based on this analysis, reconfiguring (140) the node or maintaining its current configuration.