PCIe Switch Demultiplexer for Endpoint Aggregation

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Solution Overview

Problem

General purpose PCIe switches are complex, consume high operational power, and are costly due to their feature-rich designs, which include full crossbar routing and support for various PCIe functions, making them inefficient for connecting multiple endpoint devices to a root complex.

Innovation Solution

A PCIe switch apparatus with a root port and endpoint ports, each associated with a function number, utilizing downstream and upstream buffers to queue and direct transaction layer packets, and a demultiplexer to selectively route packets to appropriate endpoint ports, reducing complexity and power consumption by limiting functionality to only what is necessary for each endpoint device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a general purpose PCIe switch includes all advanced functions and full crossbar routing, then the switch can support various PCIe functions and endpoint devices, but the device complexity, operational power consumption, and cost increase

Engineering Contradiction:

Improvesupport for PCIe functionsVSAvoidswitch complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the PCIe switch functionality by separating the root complex interface from individual endpoint device interfaces. Each endpoint device has a dedicated simplified switch instance that handles only communication with the root complex, eliminating the need for complex crossbar routing and inter-endpoint communication capabilities in each switch instance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts and removes unnecessary advanced PCIe functions from the switch design, keeping only the essential functionality required for connecting endpoint devices to the root complex. This includes removing support for NTB units, frame switching, multicasting, and variable lane configurations that are not needed for the specific application.

Inventive Principle:

Principle #2Taking out (Extraction)

2Adaptability or versatility

If a general purpose PCIe switch includes all advanced functions and full crossbar routing, then the switch can support various PCIe functions and endpoint devices, but the operational power consumption increases

Engineering Contradiction:

Improvesupport for PCIe functionsVSAvoidoperational power consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If a general purpose PCIe switch includes all advanced functions and full crossbar routing, then the switch can support various PCIe functions and endpoint devices, but the cost increases

Engineering Contradiction:

Improvesupport for PCIe functionsVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #2Taking out (Extraction)

4Quantity of substance

If the number of PCIe ports in the switch increases, then more endpoint devices can be connected, but the complexity, power consumption, and cost increase further

Engineering Contradiction:

Improvenumber of endpoint devicesVSAvoidswitch complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the architectural dimension from a centralized multi-port switch to a distributed hierarchy of simplified switches. Each endpoint device connects to its own dedicated switch instance, which in turn connects to the root complex, effectively adding a hierarchical dimension to the connection topology.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS10872053B2PCIe switch for aggregating a large number of endpoint devices

Publication Date: 2020.12.22 LENOVO GLOBAL TECHNOLOGIES SWITZERLAND INTERNATIONAL GMBH

AI summary

An apparatus includes a root port for coupling to a root complex, and a plurality of endpoint ports for coupling to endpoint devices, wherein each endpoint port is associated with a function number. A downstream buffer queues transaction layer packets (TLPs) received from the root port, wherein each TLP in the downstream buffer is directed to an endpoint port associated with the identified function number. An upstream buffer queues TLPs received from each endpoint port, and directs the queued TLPs to the root port. A method includes associating a function number with each endpoint port of a switch, wherein each endpoint port is adapted for coupling to an endpoint device. The method further includes receiving a first TLP from a root complex, identifying a function number within the first TLP, and directing the first TLP to an endpoint device through the endpoint port associated with the identified function number.