PCIe Lane Aggregation via Optical PAM for Long-Distance Data Center Links

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Solution Overview

Problem

Current data communication systems in data centers face challenges in efficiently aggregating and transporting high-speed I/O components over long distances due to cable limitations and inadequate bandwidth, leading to increased costs and complexity.

Innovation Solution

A computer network system utilizing a spine-leaf architecture with logical PCIe aggregators, including downstream and upstream aggregator modules, that aggregate multiple serial lanes into high-speed lanes for reliable long-distance transmission, employing pulse amplitude modulation (PAM) for optical communication links to enhance bandwidth and reduce cabling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If multiple PCI-Express lanes are aggregated into fewer high-speed lanes, then the number of cables and wires is reduced, but the transmission distance and reliability requirements increase

Engineering Contradiction:

Improvenumber of cablesVSAvoidtransmission reliability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The PCI-Express interface is segmented into multiple serial lanes that are independently transmitted over the optical link. Each lane is encoded and transmitted separately, then reassembled at the receiving end, allowing reliable long-distance transmission while reducing cable count through aggregation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An optical intermediary device is introduced to convert electrical PCI-Express signals into optical signals for transmission. This intermediary enables extended transmission distances beyond copper cable limitations while maintaining signal integrity through optical transmission properties

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If I/O components are moved out of server boxes into central I/O appliances, then serviceability improves and TCO reduces, but the distance for cable connections increases

Engineering Contradiction:

ImproveserviceabilityVSAvoidcable length

Core Design Contradiction:

Ease of manufactureVSLength of stationary object

Solution Approach 1:

The electrical cable transmission system is replaced with an optical transmission system. Optical fibers substitute for copper cables, enabling much longer transmission distances without signal degradation, thus allowing I/O components to be centrally located while maintaining connection quality

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If copper cabling is used for PCI-Express connections, then installation is simple, but distance limitations are imposed

Engineering Contradiction:

Improveinstallation simplicityVSAvoidcable distance

Core Design Contradiction:

Ease of manufactureVSLength of stationary object

Solution Approach 1:

The transmission medium parameter is changed from electrical (copper) to optical (fiber). This parameter change fundamentally extends the achievable transmission distance while maintaining installation simplicity through standardized optical connectors and interfaces

Inventive Principle:

Principle #35Parameter changes

4Productivity

If disaggregated I/O components are implemented, then resource utilization improves and costs reduce, but bandwidth requirements increase

Engineering Contradiction:

Improveresource utilizationVSAvoidbandwidth requirement

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

Multiple PCI-Express lanes are merged into a unified optical transmission channel. By aggregating multiple serial lanes and transmitting them over a single optical fiber interface, the system achieves high total bandwidth while reducing the number of physical connections required

Inventive Principle:

Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables better resource utilization, independent scaling of memory capacity, and efficient data sharing among servers, reducing total cost of ownership and power consumption while maintaining high-speed data transfer reliability over extended distances.

Implementation Method 1

employing pulse amplitude modulation (PAM) for optical communication links to enhance bandwidth and reduce cabling

Methodology Applied

Scientific EffectPulse amplitude modulation: Phase Modulation

Data Source

PatentUS10929325B2PCIE lane aggregation over a high speed link

Publication Date: 2021.02.23 MARVELL ASIA PTE LTD

AI summary

A method of operating a computer network system configured with disaggregated inputs/outputs. This system can be configured in a leaf-spine architecture and include a router coupled to a network source, a plurality of core switches coupled to the router, a plurality of aggregator switches coupled to each of the plurality of core switches, and a plurality of rack modules coupled to each of the plurality of aggregator switches. Each of rack modules can include an I/O appliance with a downstream aggregator module, a plurality of server devices each with PCIe interfaces, and an upstream aggregator module that aggregates each of the PCIe interfaces. A high-speed link can be configured between the downstream and upstream aggregator modules via aggregation of many serial lanes to provide reliable high speed bit stream transport over long distances, which allows for better utilization of resources and scalability of memory capacity independent of the server count.