Dual-Card Redundancy Switching Across Chassis

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Solution Overview

Problem

Current network protocols, such as G.8031, primarily focus on rapid switching between working and protect paths within the same network card or node, lacking an efficient method for rapid switching between separate networking devices, especially across different chassis, which is essential for providing redundant network connections over large geographical areas.

Innovation Solution

The implementation of a dual-card redundancy system using separate cards in the same or different chassis, with a state machine and card logic that rapidly switches between working and protect paths based on failure conditions, utilizing field programmable gate arrays (FPGAs) and software to manage traffic and ensure only one path is active at a time, without requiring higher protocol layers or software involvement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If G.8031 protocol is used for rapid switching between working and protect paths within the same network card, then switching speed is improved, but the system cannot provide redundant connections across different chassis

Engineering Contradiction:

Improveswitching speedVSAvoidgeographical coverage

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The system segments the redundancy function into separate network cards that can be distributed across different chassis. Each card independently implements protection switching logic, allowing geographical distribution while maintaining fast switching capability through localized decision-making at each card level.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A synchronization mechanism acts as an intermediary between separate network cards in different chassis, coordinating their switching states without requiring higher protocol layer involvement. This enables cross-chassis redundancy while preserving the speed benefits of lower-layer switching.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If separate network cards in different chassis are used for redundancy, then geographical coverage is improved, but switching complexity increases

Engineering Contradiction:

Improvegeographical coverageVSAvoidswitching complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Each network card independently monitors its own path status and autonomously executes switching decisions based on local failure detection. This self-service approach eliminates the need for complex centralized control logic, reducing overall system complexity while enabling cross-chassis redundancy.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent merges the protection switching functionality into the data link layer implementation on each card, combining monitoring and switching operations into a unified low-layer process. This integration simplifies the system architecture by eliminating separate higher-layer control mechanisms.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If higher protocol layers are involved in path switching, then control flexibility is improved, but switching response time increases

Engineering Contradiction:

Improvecontrol flexibilityVSAvoidswitching response time

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent replaces the mechanical hierarchy of protocol layers with a distributed state-machine model implemented at the data link layer. This substitution allows switching decisions to be made locally and immediately based on path status, eliminating the time delays inherent in hierarchical protocol processing while maintaining control flexibility through state-machine logic.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9960985B2System and method for providing redundant Ethernet network connections

Publication Date: 2018.05.01 CIENA CORP

AI summary

A primary and secondary card are coupled to protect and working paths, respectively providing a redundant connection to a node. The primary and secondary cards implement an inter-card path that is a working path for the primary card and a protect path for the secondary card. Responsive to a fault in the working path, the secondary card generates a simulated error condition on the inter-card path, causing the primary card to make the protect path the active path. When the protect path is the active path and goes down, the primary card generates a simulated error condition on the inter-card path, causing the secondary card to make the working path the active path. Switching of packets to the active and protect paths on the primary and secondary cards and is performed by an FPGA that maintains its own state machine subject to instructions from software executed by the cards.