Multi-plane cell switch fabric division loss
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Solution Overview
Problem
The effective switching capacity of multi-plane cell switch fabric systems decreases due to division loss of the switch and packet loss when handling variable-length packets, as existing methods fail to efficiently synchronize and reassemble packets across multiple switching units, leading to reduced throughput and increased latency.
Innovation Solution
A multi-plane cell switch fabric system with distribution units that divide variable-length packets into fixed-length cell payloads with a cell header containing destination information, source ID, sequential number, and packet head-tail information, and reordering units that classify and reassemble packets by source ID and sequential number, ensuring efficient data switching and reassembly across asynchronously operating switching units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If variable-length packets are divided into fixed-length cell payloads for parallel switching, then switching capacity is increased, but division loss occurs reducing effective switching capacity
Solution Approach 1:
The patent segments packets into fixed-length cell payloads for parallel processing across multiple switching units. Each packet is divided into cells with standardized structure (header + payload), enabling systematic distribution and processing. This segmentation allows the system to achieve high parallel switching capacity while managing division loss through structured reassembly at output units.
2Productivity
If packets are divided into sub-data blocks to match the number of ATM switches, then switching capacity utilization improves, but packet loss increases due to padding requirements
Solution Approach 1:
The patent changes the parameter of cell payload length to be variable rather than fixed, allowing cell payloads to exactly match the packet size without padding. This is achieved by having distribution units dynamically determine cell payload length based on packet characteristics, and reordering units reconstructing packets using the actual payload lengths stored in headers, thereby eliminating packet loss while maintaining switching capacity utilization.
3Productivity
If synchronous operation of all switching units is required, then switching capacity is maximized, but processing of small grain size packets becomes difficult
Solution Approach 1:
The patent introduces dynamic operation where switching units can process cells asynchronously rather than requiring strict synchronous operation. The system uses sequence numbers and reordering buffers to handle cells arriving at different times from different switching units. This dynamic approach allows the system to maintain high switching capacity while effectively processing packets of any size, including small grain size packets, without synchronization constraints.
4Productivity
If cells are distributed to all switching units, then load balancing is achieved, but reassembly complexity increases
Solution Approach 1:
The patent introduces output reordering units as intermediary components between switching units and final destinations. These reordering units receive cells from multiple switching units, use sequence numbers and buffering to reorder cells into correct packet sequence, and then forward reassembled packets to output ports. This intermediary approach simplifies the overall system by centralizing the complex reassembly logic in dedicated units rather than requiring each switching unit to handle reassembly, thereby achieving load balancing while managing reassembly complexity efficiently.
Data Source
AI summary
A multi-plane cell switch fabric system prevents a decrease of the effective switching capacity when switching the variable-length packets. Distribution units classify input variable-length packets for each address, arranges the packets by a first division length unit, divides the packets into fixed-length cell payloads by a second division length unit that is an integer multiple being twice or more as large as the first division length unit, and forms a fixed-length cell by providing destination information, a source ID, a sequential number, and packet head tail information to each of the cell payloads. The cells are distributed to all the switching units one by one whenever the cells are collected to be the same number as the plural switching units. The reordering units classify the cells, reorder the sequential number in an original order, and reassemble the packets by the packet head tail information of the cell.