Switching Device Cell Scheduling for Bandwidth Utilization
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Solution Overview
Problem
Current data switching technologies face challenges in efficiently selecting and scheduling data packets for forwarding, particularly in managing varying link rates and minimizing cost while ensuring high bandwidth utilization and minimal data loss, which is complicated by the need for fair resource allocation and scalability.
Innovation Solution
A switching device that determines the optimal times for forwarding cells of a data packet based on the characteristics of the egress port, using a scheduling mechanism that allows for inter-cell dependencies and independent arbitration and scheduling for each ingress port, enabling efficient data packet transmission even across different link rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data packets are buffered in FIFO queues, then data loss is minimized, but bandwidth utilization and throughput are reduced
Solution Approach 1:
The patent segments data packets into fixed-size cells for transmission through the switch core. This segmentation allows the buffering mechanism to operate at the cell level rather than packet level, enabling more granular control and better utilization of buffer resources while maintaining data integrity
Solution Approach 2:
The patent performs preliminary scheduling of cells before they are transmitted through the switch core. By determining the transmission time for each cell in advance and storing this scheduling information in a pipeline, the system optimizes bandwidth utilization while preventing data loss through proactive resource allocation
2Device complexity
If arbitration and scheduling are combined in a single operation, then device complexity is reduced, but productivity and efficiency are limited
Solution Approach 1:
The patent divides the switching control function into two independent stages: arbitration (selecting which data packets to forward) and scheduling (determining when to forward the selected packets). This segmentation allows each stage to be optimized independently, improving overall efficiency while maintaining manageable complexity
Solution Approach 2:
The patent performs arbitration first to select candidate data packets, then performs scheduling to determine the optimal transmission time for each selected packet. This preliminary arbitration followed by scheduling allows the system to make informed decisions about both selection and timing, maximizing throughput
3Adaptability or versatility
If the switch supports varying link rates between ingress and egress ports, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent uses parameter changes to handle varying link rates. The scheduling mechanism adjusts the transmission time parameters for cells based on the specific link rates of ingress and egress ports. By dynamically changing the timing parameters rather than the fundamental switching architecture, the system achieves adaptability while controlling complexity
Data Source
AI summary
A switching device comprising a plurality of ingress ports and a plurality of egress ports. The switching device is arranged to receive data packets through said ingress ports and to forward received data packets to respective ones of said egress ports. The switching device is further arranged to: determine a first time at which a first cell of a selected data packet is to forwarded to one of said egress ports, determine a further time at which a respective further cell of the selected data packet is to be forwarded to said one of said egress ports, store data indicating that said respective further cell is to be forwarded at said determined further time, forward said first cell at said first time, and forward said further cell of said selected data packet at said determined further time.