Ethernet Redundancy via Physical Layer Failover

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Solution Overview

Problem

Existing Ethernet network redundancy systems are complex and costly to implement, especially in high-reliability applications, due to the need for network layer protocols and lengthy convergence times when replacing faulty links, which is not acceptable for low-criticality networks.

Innovation Solution

Implementing a communication method at the physical layer to determine and control operational Ethernet networks, using dedicated frames to assess network functionality and switch between redundant networks transparently to upper protocol layers, reducing the need for expensive routers and complex processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If network layer routing protocols are used to achieve redundancy, then reliability is improved, but device complexity and cost increase

Engineering Contradiction:
Improvenetwork reliabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the redundancy management function from the network layer to the physical layer. Each physical interface independently monitors link status and manages its own failover, eliminating the need for complex network layer routing protocols. This segmentation allows simple switches to provide redundancy without requiring intelligent routing devices.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements self-service by enabling each physical interface to autonomously detect link failures and switch to backup interfaces without external control. The system automatically monitors link status, detects failures, and performs failover locally at each interface, eliminating the need for complex centralized routing protocol management.

Inventive Principle:
Principle #25Self-service

2Reliability

If network layer routing protocols are used for link replacement, then reliability is improved, but convergence time increases

Engineering Contradiction:
Improvenetwork reliabilityVSAvoidconvergence time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-configuring backup physical interfaces and establishing standby link paths before failures occur. When a link failure is detected, the system immediately activates the pre-prepared backup interface, eliminating the time-consuming route recalculation required by network layer protocols. This advance preparation enables instantaneous failover.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent inverts the traditional approach by implementing redundancy management at the physical layer instead of the network layer. This inversion allows failover to occur at the hardware level with microsecond response time, compared to the second-scale convergence time of network layer protocols. The backup interface is activated by simply changing the active physical interface at the data link layer.

Inventive Principle:
Principle #13The other way round (Inversion)

3Reliability

If routers are used to implement redundancy, then reliability is improved, but cost increases

Engineering Contradiction:
Improvenetwork redundancyVSAvoidimplementation cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive intelligent routers with simple, inexpensive switches that lack routing capabilities. By moving redundancy management to the physical layer, the system can use basic switching hardware instead of costly routing devices. The switches perform only simple frame forwarding based on MAC addresses, significantly reducing equipment cost while maintaining redundancy functionality through physical interface failover.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Data Source

PatentEP2238717B1Method for communicating data between terminal devices from a plurality of ethernet networks of a redundancy system
Publication Date: 2018.08.08 SAFRAN ELECTRONICS & DEFENSE (FR)
  • EP2238717B1 patent drawingFigure 1~2
  • EP2238717B1 patent drawingFigure 3~4
  • EP2238717B1 patent drawingFigure 5

AI summary

The invention relates to a method for communicating data between at least two terminal devices from a plurality of Ethernet networks that are independent from each other and each allow the communication of data between said at least two terminal devices. The invention comprises implementing at the layer physically closest to the link, i.e. at the link management module, such a communication method in order to determine a first network of the redundancy system that will be used for the communications between the terminal devices, to control the operation of the network during the entire length of the communications, and to determine a new network of the redundancy system in case of failure of the network used hitherto.