Adaptive PDU Transmission for Link Aggregation Stress
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Solution Overview
Problem
Current link aggregation techniques poorly cope with stress conditions, leading to continuous flapping and failure in forming and maintaining link aggregation groups, especially in configurations with hundreds, thousands, or tens of thousands of groups, due to system reloads, control plane congestion, and other stressors.
Innovation Solution
The period between periodic transmissions of protocol data units (PDUs) is dynamically adjusted through an adaptive control loop, initially set to a low fixed value, increased via slow linear and then rapid exponential growth in response to detected stress, and decreased back to the fixed value when stress subsides, to minimize link aggregation flapping and failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the period between PDU transmissions is kept low to enable fast link aggregation formation, then link aggregation formation speed is improved, but system stress increases under congestion conditions causing flapping and failure
Solution Approach 1:
The patent implements dynamic adjustment of the PDU transmission period based on real-time stress detection. The system transitions from a static low fixed period to a dynamic period that adapts to system conditions, using slow linear growth followed by rapid exponential growth when stress is detected, and controlled decrease when stress subsides. This resolves the contradiction by making the transmission period flexible rather than fixed.
Solution Approach 2:
The patent changes the transmission period parameter from a constant low value to a variable value that responds to stress conditions. By monitoring stress indicators and adjusting the period parameter accordingly (increasing during stress, decreasing when stress subsides), the system maintains fast formation under normal conditions while ensuring stability under stress, thus resolving the contradiction between speed and reliability.
2Productivity
If PDUs are transmitted rapidly to form link aggregation groups quickly, then productivity is improved, but control plane congestion worsens causing excessive PDU loss and stress
Solution Approach 1:
The patent implements a feedback mechanism where the system monitors stress conditions resulting from rapid PDU transmissions and adjusts the transmission rate accordingly. When control plane congestion is detected through stress indicators, the system increases the transmission period to reduce PDU loss. This feedback loop resolves the contradiction by allowing high productivity when the control plane can handle it, while preventing congestion when capacity is exceeded.
Solution Approach 2:
The patent applies preliminary anti-action by detecting stress conditions before they lead to severe PDU loss and flapping. By monitoring stress indicators and proactively increasing the transmission period when stress is detected, the system prevents the harmful effects of control plane congestion before they compound, thus maintaining productivity while avoiding the harmful factors of excessive congestion.
3Reliability
If the transmission period is increased to reduce stress during congestion, then system reliability is improved, but link aggregation formation time increases
Solution Approach 1:
The patent uses dynamic adjustment of the transmission period rather than a static high period. The system starts with a low fixed period for fast formation, then transitions to increased periods only when stress is detected. This dynamic approach resolves the contradiction by maintaining fast formation (low period) during normal operation while switching to slower, more reliable transmission only when necessary under stress conditions.
Solution Approach 2:
The patent implements periodic monitoring of stress conditions and periodic adjustment of the transmission period. Rather than continuously increasing the period, the system uses periodic stress detection and responds with controlled period increases (slow linear then rapid exponential growth) followed by controlled decreases when stress subsides. This periodic action resolves the contradiction by temporarily sacrificing formation speed only when reliability is threatened, then restoring fast formation when conditions improve.
Data Source
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AI summary
In one embodiment, a period between periodic transmissions of protocol data units (PDUs) used to form or maintain a link aggregation group is initially set to a fixed value. When a stress condition is detected, the period between periodic transmissions of PDUs is increased from the initial value. When the stress condition is determined to have eased, the period between periodic transmissions of PDUs is reduced back toward the fixed value.