MLAG Forwarding Database Switching for Fast Link Failure Recovery

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Solution Overview

Problem

Existing MLAG link failure switching methods in multi-chassis link aggregation systems suffer from prolonged downtime due to the need for CPU processing and MAC address re-learning, which interrupts traffic and prolongs the switching time.

Innovation Solution

An MLAG link switching method that updates an active-standby switching flag in a forwarding database to redirect traffic through a peer-link, utilizing multiple forwarding databases to minimize database entry modifications and reduce switching time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If link failure detection methods such as BFD or VRRP are used, then link failure detection speed is improved, but system complexity and resource consumption increase

Engineering Contradiction:
Improvelink failure detection speedVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the link failure detection function from complex protocols like BFD and VRRP, and implements a simplified detection mechanism within the routing device itself. The routing device directly monitors link status through local interface detection, eliminating the need for separate detection protocols and reducing system complexity while maintaining fast detection capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The routing device performs self-detection of link failures through built-in monitoring mechanisms. The device automatically detects link status changes on its own interfaces and triggers local policy-based routing switches without requiring external detection protocols or additional devices, thereby reducing overall system complexity while achieving rapid failure detection.

Inventive Principle:
Principle #25Self-service

2Speed

If local policy-based routing is used for fast switching, then switching speed is improved, but control precision and security are reduced

Engineering Contradiction:
Improveswitching speedVSAvoidcontrol precision
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent pre-configures multiple routing policies with different priorities and conditions before link failures occur. When a link failure is detected, the system immediately switches to a pre-prepared alternative routing policy, achieving fast switching while maintaining precise control through pre-planned routing decisions that were carefully configured in advance with proper security and control parameters.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors link status and provides feedback to the routing decision mechanism. When link status changes are detected, the feedback triggers automatic switching between routing policies while maintaining control precision through configurable policy rules that ensure secure and controlled routing decisions. The feedback mechanism allows the system to adapt routing decisions based on real-time link conditions while preserving administrative control.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4207646B1MLAG link failure switching method and apparatus
Publication Date: 2026.05.20 HUAWEI TECH CO LTD
  • EP4207646B1 patent drawingFigure 1
  • EP4207646B1 patent drawingFigure 2
  • EP4207646B1 patent drawingFigure 3

AI summary

This application discloses an MLAG link failure switching apparatus and method. The apparatus includes a chip. The chip is configured to: generate a forwarding database, and forward a packet based on the forwarding database, where the forwarding database includes a first forwarding database, a second forwarding database, and a third forwarding database. The apparatus switches a faulty MLAG link by modifying a value of an active-standby switching flag corresponding to the faulty link in the first forwarding database, thereby reducing a link switching time and improving link switching efficiency.