Duplicate Frame Detection in Redundant Network Ports

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Solution Overview

Problem

Existing communication protocols like PRP and HSR struggle to efficiently detect and discard duplicate frames in redundant communications, leading to increased network load and potential operational issues in upper layer protocols.

Innovation Solution

A method and apparatus for detecting duplicate frames using a data structure that associates a source address with the newest sequence number and a memory pointer to reception information within a window of frames, allowing for efficient duplicate detection across redundant paths with different travel times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If duplicate frames are discarded using traditional methods, then network load is reduced, but duplicate detection accuracy deteriorates due to inability to handle different travel times on redundant paths

Engineering Contradiction:
Improvenetwork loadVSAvoidduplicate detection accuracy
Core Design Contradiction:
Loss of energyVSMeasurement precision

Solution Approach 1:

The patent segments the duplicate detection process by creating separate window structures for each redundant path (ring A and ring B). Each path maintains its own sequence number window, allowing independent tracking of frames received through different paths. This segmentation enables accurate duplicate detection despite different travel times on each path.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary action by pre-defining acceptance windows for sequence numbers before frames arrive. When a frame is received, its sequence number is checked against the pre-established window for that path. This preliminary window setup allows rapid duplicate detection without complex real-time comparisons, maintaining both accuracy and efficiency.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If sequence numbers are tracked for every frame, then duplicate detection precision is improved, but device complexity increases

Engineering Contradiction:
Improveduplicate detection precisionVSAvoiddata structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the essential elements needed for duplicate detection: sequence numbers and path identifiers. Rather than tracking complete frame data, it maintains minimal window structures containing only sequence number ranges for each path. This extraction reduces device complexity while preserving duplicate detection precision.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the parameter representation from tracking individual frame details to tracking sequence number ranges (windows). By representing acceptance criteria as parameter ranges rather than discrete frame records, the system achieves precise duplicate detection with reduced data structure complexity.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If frames from redundant paths are accepted with different travel times, then reliability is improved, but duplicate frame identification becomes more difficult

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidduplicate frame identification difficulty
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces path-specific sequence number windows as intermediaries between the redundant paths and the duplicate detection logic. Each path (ring A or ring B) has its own window mediator that tracks expected sequence numbers independently. This intermediary structure simplifies duplicate identification by providing a clear reference point for each path, even when travel times differ.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2920924B1Relaying frames
Publication Date: 2018.10.03 TTTECH FLEXIBILIS OY
  • EP2920924B1 patent drawingFigure 1a~1b
  • EP2920924B1 patent drawingFigure 2a~3c
  • EP2920924B1 patent drawingFigure 4

AI summary

Frames received at a redundant port connecting a node to a communications network are identified by the frames including a sequence number associated with a source. A frame is received at the redundant port from a source. A newest sequence number of frames received from the source at the node is determined. A window of frames from the source is determined by corresponding sequence numbers, said window comprising sequence numbers preceding the newest sequence number and associated with reception information of a corresponding frame at the node. The node relays the frame, when a sequence number of the received frame is within the window and the reception information indicates a first reception of the frame at the node.