Adaptive Ethernet Pause Flow Control for Buffer Management
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Solution Overview
Problem
Existing Ethernet flow control methods face limitations in link distance, latency variation, and inefficiency, particularly with XON/XOFF and periodic quanta methods, which result in buffer overflow and underflow issues and reduced throughput, especially for small frames.
Innovation Solution
An adaptive quantized Ethernet pause flow control system that dynamically adjusts pause quanta values based on buffer fill levels and container rates, using optimal quanta values for small and large frame sizes, and accounting for packing efficiency and round trip delay to prevent buffer overruns and underflows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If XON/XOFF flow control is used to avoid buffer overflow and underflow, then buffer management is improved, but link distance is limited and latency variation increases
Solution Approach 1:
The patent implements dynamic flow control by transitioning from static XON/XOFF to adaptive periodic quanta. The system continuously monitors buffer fill levels and dynamically adjusts pause frame transmission timing and quanta values, enabling the flow control mechanism to adapt to varying network conditions and overcome link distance limitations while maintaining buffer management effectiveness.
Solution Approach 2:
The patent changes the fundamental parameters of flow control by introducing periodic quanta-based pause frames instead of binary XON/XOFF states. By varying pause quanta values and transmission periods based on buffer conditions, the system achieves both reliable buffer management and extended link distance capability, resolving the contradiction between these two parameters.
2Reliability
If XON/XOFF flow control is used to avoid buffer overflow and underflow, then buffer management is improved, but latency variation increases
Solution Approach 1:
The patent employs periodic action by transmitting pause frames at regular intervals based on monitored buffer conditions. This periodic quanta approach replaces the event-driven XON/XOFF mechanism, creating predictable, rhythmically spaced flow control actions that reduce latency variation while maintaining effective buffer management through systematic monitoring and response.
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring buffer fill levels and using this information to dynamically adjust pause frame transmission. The feedback loop ensures that flow control actions are taken at optimal moments, preventing both buffer overflow and excessive latency, thereby resolving the contradiction between reliable buffer management and minimal latency variation.
3Length of moving object
If periodic quanta is used to overcome link distance limitation, then link distance is improved, but throughput efficiency decreases especially for small frames
Solution Approach 1:
The patent makes the periodic quanta system dynamic by adjusting pause quanta values and transmission periods based on real-time buffer monitoring. This dynamic adaptation allows the system to optimize throughput efficiency for different frame sizes and network conditions while maintaining the extended link distance capability that static periodic quanta provided, thereby resolving the contradiction between link distance and throughput efficiency.
Solution Approach 2:
The patent changes pause quanta parameters adaptively based on buffer conditions and frame characteristics. By varying these parameters rather than using fixed values, the system achieves both long link distance support and high throughput efficiency, including optimized performance for small frames, thus resolving the contradiction between these two performance parameters.
4Length of moving object
If larger buffer is used to support long link distance with XON/XOFF, then link distance is improved, but device complexity and resource requirements increase
Solution Approach 1:
The patent reduces device complexity by implementing dynamic flow control that adapts to actual buffer conditions. Instead of provisioning excessively large buffers to support long link distances under worst-case static XON/XOFF operation, the dynamic periodic quanta system with active monitoring achieves long distance support with smaller, more efficiently utilized buffers, thereby resolving the contradiction between link distance and device complexity.
Data Source
AI summary
A network element implemented method includes receiving an Ethernet connection at a first rate, transmitting the Ethernet connection at a second rate, monitoring a buffer fill associated with the Ethernet connection, and periodically transmitting pause frames to a device associated with the Ethernet connection, wherein the pause frames include a determined optimal pause quanta value based on the first rate, the second rate, and the buffer fill. A network element includes a first port receiving an Ethernet connection at a first rate, a second port transmitting the Ethernet connection at a second rate, and monitor circuitry configured to monitor a buffer fill associated with the Ethernet connection and cause the first port to periodically transmit pause frames, wherein the pause frames include a determined optimal pause quanta value based on the first rate, the second rate, and the buffer fill.