OTV Edge Device Synchronization for Loop-Free AED Elections

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional Overlay Transport Virtualization (OTV) systems face convergence delays and loop prevention issues due to uncoordinated authoritative edge device (AED) elections, misconfigurations, and inability to handle arbitrary VLAN partitions and merges optimally.

Innovation Solution

Implementing a synchronization mechanism among edge devices before AED elections, using interlocks with Layer-2 access protocols and exchanging Root Bridge IDs to ensure deterministic and loop-free transitions, allowing for robust handling of site partitions and merges, and supporting non-congruent site topologies and failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If uncoordinated AED election is used among multiple edge devices, then device complexity is reduced, but convergence delay increases and network stability deteriorates

Engineering Contradiction:

ImproveAED election mechanism complexityVSAvoidconvergence delay

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The patent implements preliminary actions by having edge devices exchange synchronization information and perform coordinated AED elections before actual VLAN traffic forwarding begins. This ensures that the new AED is fully synchronized and ready to forward traffic immediately, eliminating convergence delays while maintaining manageable system complexity through structured pre-coordination protocols.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If uncoordinated AED election is used, then ease of operation is improved, but network reliability deteriorates due to loop prevention issues

Engineering Contradiction:

ImproveAED election operationVSAvoidloop prevention

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent implements feedback mechanisms where edge devices continuously exchange synchronization information, Root Bridge IDs, and AED status with each other. This feedback loop ensures that all devices have consistent view of the network state, enabling reliable loop prevention through coordinated AED elections while maintaining ease of operation through automated feedback-driven decision making.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces synchronization protocols and control plane messages as intermediaries between edge devices during AED elections. These intermediaries carry essential information such as Root Bridge IDs and synchronization status, mediating the election process to ensure loop-free operation while keeping the overall system easy to operate through standardized communication protocols.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If conventional AED election is used, then adaptability to simple topologies is maintained, but ability to handle arbitrary VLAN partitions and merges deteriorates

Engineering Contradiction:

Improvetopology handling capabilityVSAvoidVLAN partition handling

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements dynamic AED election mechanisms that can adapt to changing network conditions including arbitrary VLAN partitions and merges. Edge devices continuously exchange synchronization information and can dynamically re-elect AEDs based on current network state, enabling the system to handle complex dynamic scenarios while maintaining reliability through coordinated transition protocols that prevent loops during reconfiguration.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9521073B2Enhanced fine-grained overlay transport virtualization multi-homing using per-network authoritative edge device synchronization

Publication Date: 2016.12.13 CISCO TECHNOLOGY INC

AI summary

In some embodiments, edge devices associated with a network segment are identified. One of the devices is elected as an authoritative device and any previous authoritative devices are instructed to halt forwarding network traffic to an overlay network.