Multi-Stage Switch Fabric Arbitration for Algorithm Complexity

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Solution Overview

Problem

Existing switch fabric systems face complexity and area challenges due to complex algorithms and increased buffer requirements, making it difficult to implement efficiently, especially with a large number of input and output ports, leading to low performance.

Innovation Solution

A switch fabric system utilizing two arbiters for scheduling data between crossbar units, reducing algorithm complexity and area requirements by breaking down the N×N scheduling into two lower complexity algorithms, O(L×N) and O(M×1), and implementing a multi-stage buffered crossbar structure with cascaded CU units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a bufferless crossbar structure is used, then the area is reduced, but the algorithm complexity increases

Engineering Contradiction:
Improvecrossbar areaVSAvoidalgorithm complexity
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent divides the N×N crossbar into multiple smaller crossbar units (CUs), each handling a subset of input/output ports. This segmentation reduces the algorithm complexity from O(N²) for a single large crossbar to O(M×N) for multiple smaller CUs, while also reducing the area required for each individual crossbar unit.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If a buffered crossbar structure is used, then the algorithm complexity is reduced, but the buffer area increases

Engineering Contradiction:
Improvealgorithm complexityVSAvoidbuffer area
Core Design Contradiction:
Device complexityVSArea of stationary object

Solution Approach 1:

The patent distributes buffers across multiple smaller crossbar units rather than using a single large buffer. Each CU has its own buffer, reducing the peak buffer area requirement at any single location while maintaining the buffering functionality needed for low algorithm complexity.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If the number of input and output ports increases, then the switching capability is improved, but the implementation difficulty increases

Engineering Contradiction:
Improveswitching capabilityVSAvoidimplementation difficulty
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent implements a modular architecture where the large N×N switching fabric is divided into multiple smaller crossbar units. This modular approach makes implementation more manageable by breaking down the complex task of implementing a large switch into smaller, more tractable units that can be designed and manufactured separately.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-level N×N crossbar to a multi-level hierarchical structure with multiple stages of crossbar units. This dimensional change from a flat single-layer architecture to a multi-layer hierarchical architecture reduces the complexity of individual units while maintaining overall switching capability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

4Device complexity

If the number of arbiters is reduced, then the device complexity is reduced, but the scheduling capability deteriorates

Engineering Contradiction:
Improvenumber of arbitersVSAvoidscheduling capability
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent distributes arbitration functions across multiple smaller arbiters, each responsible for a subset of ports, rather than using a single complex N×N arbiter. This segmentation reduces the complexity of each individual arbiter while collectively maintaining the scheduling capability needed for the entire switching fabric.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3306880B1A switch fabric system and a data switching method
Publication Date: 2022.03.30 HUAWEI TECH CO LTD
  • EP3306880B1 patent drawingFigure 1
  • EP3306880B1 patent drawingFigure 2
  • EP3306880B1 patent drawingFigure 3~4

AI summary

Embodiments of the present invention provide a switch fabric system and a data switching method. The switch fabric system of the present invention includes: M first crossbar units CUs and N second CUs, where each first CU includes: L first input ports, a first arbiter, a first crossbar, and N first output ports, each second CU includes: M second input ports, a second arbiter, a second crossbar, and one second output port, and M×N first output ports of the M first CUs are respectively coupled to N×M second input ports of the N second CUs, where N first output ports of each first CU are respectively coupled to and in a one-to-one correspondence with one second input port of each second CU in the N second CUs, N = M × L, and M, N, and L are all positive integers. The embodiments of the present invention reduce complexity of an algorithm and an area of a crossbar, and can reduce difficulty in implementing an SF system and improve performance when there is a relatively large quantity of input ports and output ports.