VOQ Scheduling Weights for Fair Bandwidth Under Oversubscription
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Solution Overview
Problem
Conventional virtual output queue (VOQ) scheduling techniques fail to provide proportionally fair scheduling due to varying port speeds and traffic arrival rates, leading to unfair bandwidth distribution and resource wastage, impacting network device performance and customer satisfaction.
Innovation Solution
A network device calculates arrival and departure rates for VOQs, determines oversubscription factors, and adjusts scheduling weights based on scale factors to achieve rate differential weighted fair output queue scheduling, ensuring consistent congestion levels across VOQs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple round robin scheduling is used for VOQs, then device complexity is reduced, but bandwidth distribution fairness deteriorates due to varying port speeds and traffic arrival rates
Solution Approach 1:
The patent implements dynamic scheduling weights that adapt to changing traffic conditions. The scheduler continuously monitors packet arrival rates at each VOQ and adjusts weights dynamically to maintain proportional fairness, transitioning from static round-robin to adaptive weight-based scheduling.
Solution Approach 2:
The patent changes the scheduling parameter from fixed turn-based selection to variable weight-based selection. By modifying the weight parameter according to measured arrival rates and target oversubscription factors, the system achieves proportional bandwidth sharing while maintaining manageable complexity through mathematical formulations.
2Ease of operation
If conventional VOQ scheduling is used, then ease of operation is maintained, but resource wastage increases due to unfair bandwidth distribution and packet drops
Solution Approach 1:
The patent implements a feedback mechanism where the scheduler measures actual packet arrival rates at each VOQ, compares them to target oversubscription factors, and adjusts scheduling weights accordingly. This closed-loop feedback eliminates resource wastage by ensuring fair bandwidth distribution and preventing unnecessary packet drops.
Solution Approach 2:
The scheduling system performs self-adjustment by automatically measuring traffic conditions and modifying its own weights without external intervention. The scheduler serves itself by continuously optimizing based on observed packet arrival patterns, eliminating the need for manual configuration while preventing resource wastage.
3Device complexity
If fixed scheduling weights are used, then device complexity is minimized, but adaptability to varying traffic conditions deteriorates
Solution Approach 1:
The patent transforms fixed scheduling weights into dynamic variables that respond to real-time traffic conditions. The weight adjustment mechanism incorporates measured arrival rates and target oversubscription factors, enabling the system to adapt to varying traffic patterns while maintaining configuration simplicity through automated calculations.
Data Source
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AI summary
A network device may receive packets and may calculate, during a time interval, an arrival rate and a departure rate, of the packets, at one of multiple virtual output queues. The network device may calculate a current oversubscription factor based on the arrival rate and the departure rate, and may calculate a target oversubscription factor based on an average of previous oversubscription factors associated with the multiple virtual output queues. The network device may determine whether a difference exists between the target oversubscription factor and the current oversubscription factor and may calculate, when the difference exists, a scale factor based on the current oversubscription factor and the target oversubscription factor. The network device may calculate new scheduling weights based on prior scheduling weights and the scale factor, and may process packets received by the multiple virtual output queues based on the new scheduling weights.