Output Queue Flow Control for Network Switches
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Solution Overview
Problem
The existing 3-level switching systems in network communication face challenges in managing cell scheduling and flow control, particularly in ensuring efficient buffer management and preventing buffer overflow, as conventional back pressure control methods are not flexible enough to adapt to varying cell priorities and source chip capacities.
Innovation Solution
A queue-based flow control method and apparatus that count cells based on priority, output port, and source chip number to generate back pressure information, allowing for dynamic control of cell transmission and prevention of buffer overflow by adjusting back pressure levels according to actual requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional back pressure control methods are used, then flow control can be implemented, but the system lacks flexibility to adapt to varying cell priorities and source chip capacities
Solution Approach 1:
The patent segments the back pressure control mechanism into multiple independent components: (1) cell counting units for each input queue, (2) threshold comparison units, and (3) back pressure signal generation units. Each segment operates independently based on local queue conditions, enabling flexible adaptation to different cell priorities without requiring a monolithic complex control system.
Solution Approach 2:
The patent implements dynamic back pressure control by continuously monitoring queue lengths and dynamically adjusting back pressure signals based on real-time conditions. The system dynamically adapts to varying cell priorities by applying back pressure selectively to specific input queues based on their current load and priority level, rather than using static control rules.
2Reliability
If back pressure control is implemented to prevent buffer overflow, then buffer management is improved, but the control mechanism becomes less flexible
Solution Approach 1:
The patent applies local quality by implementing back pressure control at the individual queue level rather than system-wide. Each input queue has its own back pressure control mechanism that operates independently based on local buffer conditions. This allows the system to prevent buffer overflow in specific queues while maintaining flexibility in other queues with different traffic patterns and priority requirements.
Solution Approach 2:
The patent employs feedback mechanisms where back pressure signals are generated based on real-time buffer status and fed back to the input queues. The feedback loop continuously monitors queue length and dynamically adjusts back pressure application, enabling the system to reliably prevent buffer overflow while adapting to changing traffic conditions and priority requirements.
3Productivity
If cell transmission is controlled uniformly, then simplicity is maintained, but efficiency in managing different cell priorities is reduced
Solution Approach 1:
The patent segments the cell transmission control into priority-specific channels, with separate back pressure control mechanisms for each priority level. This segmentation enables efficient handling of different cell priorities by applying appropriate back pressure control to each priority channel independently, improving overall transmission efficiency without requiring a single complex unified control system.
Solution Approach 2:
The patent changes the control parameter from uniform back pressure to priority-dependent back pressure. By introducing priority as a variable parameter, the system can adjust back pressure application based on cell priority levels, thereby improving transmission efficiency for high-priority cells while maintaining simpler control logic through standardized priority-based rules.
Data Source
AI summary
A method and apparatus for implementing output queue-based flow control is provided. The method includes: implementing queue scheduling and flow control by using an output port-based cell queue and by counting the number of cells from different angles. In this system, the flow control and queue management are performed separately. The queue management is directly applied to the cell scheduling. The flow control does not directly depend on the cell statistical results in the queue management. Instead, it is implemented on the basis of the cell statistical results that are obtained according to the cell priority, output port and source chip number of the cells. Therefore, the provided method and apparatus may reduce and simplify the number of queues to be scheduled and implement fine and flexible back pressure control.