LACP Extension for Bi-directional Link Liveness Detection
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Solution Overview
Problem
The Link Aggregation Control Protocol (LACP) lacks full liveness detection and bi-directional link detection, leading to delayed identification of defective links, resulting in potential network packet loss due to its rudimentary checks and non-configurable timers.
Innovation Solution
An extension to LACP is introduced that supports bi-directional link detection and configurable timers, enabling faster detection of defective links by using a subtype within the 802.3ad standard, allowing for incremental deployment and ensuring link operability in both transmission directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LACP protocol is used for link aggregation management, then link bundling capability is provided, but liveness detection capability is insufficient leading to delayed defective link identification
Solution Approach 1:
The patent combines LACP protocol functionality with BFD (Bidirectional Forwarding Detection) liveness detection capabilities into a unified system. The LACP state machine is enhanced to include BFD state machine operations, allowing simultaneous link aggregation management and rapid liveness detection. This merging enables the system to detect defective links faster while maintaining link bundling functionality.
Solution Approach 2:
The enhanced LACP protocol is designed to perform multiple functions: traditional link aggregation management plus comprehensive liveness detection. The state machine can operate in multiple modes (LACP-only, BFD-only, or combined) and supports various packet types (LACP packets, BFD packets, or both). This multi-functionality allows a single protocol to address both link management and health detection needs.
2Adaptability or versatility
If standard LACP protocol is used, then compatibility with existing systems is maintained, but bi-directional link detection capability is lacking
Solution Approach 1:
The patent implements a dynamic state machine that can adapt its operational mode based on peer device capabilities. The system can dynamically switch between LACP-only mode, BFD-only mode, or combined mode depending on whether the peer device supports BFD. This dynamic behavior maintains backward compatibility with legacy devices while enabling enhanced bi-directional detection when peers support the extended protocol.
Solution Approach 2:
The protocol extends LACP by introducing new packet types and state machine parameters without fundamentally changing the existing LACP framework. The state machine parameters include packet type indicators that can be set to LACP packets, BFD packets, or both. This parameter-based extension allows the protocol to change its detection capabilities while maintaining compatibility with standard LACP implementations.
3Ease of operation
If LACP protocol is used, then link aggregation management is provided, but timer configurability is limited resulting in slower detection
Solution Approach 1:
The system performs preliminary configuration of detection parameters including timer values and packet intervals. The state machine is pre-configured with configurable timers that can be set to appropriate values for the desired detection speed. This preliminary setup allows the system to operate with optimized detection timing without requiring complex runtime adjustments, maintaining operational simplicity while achieving faster detection.
Data Source
AI summary
An extension is provided to a Link Aggregation Control Protocol (LACP) that can use the LACP protocol transport and provides Link Aggregation Group (LAG) management while also functioning as a full liveness detection protocol. Bi-directional link detection is supported and timers are configurable to any number. The extension can be backwards compatible with standard LACP and can use a subtype that is specified as unused. The extension can start up using standard LACP packet rates and include additional information in the unused subtype. If a LACP speaker does not support the extension, then the protocol conforms to standard LACP. A state machine of the extension is used if it detects conforming information from a peer speaker. The state machine can allow faster detection should a link error occur.