Loop Prevention in Vertical Stack Networks via Designated Source CB

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Solution Overview

Problem

In a two-level vertical stack network, non-unicast packets can form loops when forwarded among Core Backbone (CB) devices, leading to inefficiencies and potential network disruptions.

Innovation Solution

A method is implemented where each Port Extender (PE) device is bundled with a designated CB device, and non-unicast packets are forwarded through a specified optimized path to prevent loops, ensuring that only the designated CB device acts as the source within the stack system, and other CB devices redirect packets along the shortest path to this designated device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If non-unicast packets are forwarded among CB devices in a ring topology, then network connectivity and redundancy are improved, but loops are formed causing network inefficiency and disruptions

Engineering Contradiction:
Improvenetwork connectivityVSAvoidpacket forwarding efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent introduces a loop detection mechanism as an intermediary that monitors packet forwarding paths among CB devices. When a loop is detected, the mechanism selectively blocks specific forwarding paths while maintaining overall network connectivity, thus preventing the harmful effect of loops without completely disrupting the ring topology's redundancy benefits.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements dynamic path selection where CB devices can adaptively adjust packet forwarding paths based on real-time network conditions and loop detection results. This allows the network to maintain optimal forwarding efficiency while preserving connectivity through alternative paths when loops are present.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If multiple CB devices can act as sources for non-unicast packets, then network flexibility and load distribution are improved, but loop formation risk increases

Engineering Contradiction:
Improvenetwork flexibilityVSAvoidloop prevention
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies local quality by designating specific CB devices as source devices for non-unicast packets based on their position and role in the ring topology. Instead of allowing all CB devices to act as sources, the system selectively enables source functionality at specific locations, thereby maintaining network flexibility while reducing loop formation risk through localized control.

Inventive Principle:
Principle #3Local quality

3Device complexity

If standard packet forwarding is used without optimization, then device complexity is reduced, but network performance and stability deteriorate due to loops

Engineering Contradiction:
Improveforwarding logicVSAvoidnetwork stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where CB devices monitor packet forwarding paths and detect loops in real-time. Based on this feedback, the system dynamically adjusts forwarding decisions to prevent loops, thereby maintaining network stability without requiring overly complex pre-configured forwarding logic at each device.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP2992651B1Preventing a loop in a vertical stack network
Publication Date: 2017.10.04 HEWLETT PACKARD ENTERPRISE DEV LP
  • EP2992651B1 patent drawingFigure 1~2
  • EP2992651B1 patent drawingFigure 3
  • EP2992651B1 patent drawingFigure 4~5

AI summary

According to an example, a Port Extender (PE) device is bundled with a Core Backbone (CB) device to prevent a loop in a vertical stack network including the PE device and the CD device.