Switch Port Management for PCIe Enumeration in Looped Topologies
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Solution Overview
Problem
The standard PCIe topology discovery process is inapplicable to non-tree topology structures due to the formation of loops, which limits the computing performance of high-performance computing systems with multi-chip interconnection.
Innovation Solution
A device management method that involves a switching device obtaining information about connected devices, determining response ports to receive management packets, and processing non-response ports to suppress loops, allowing the use of a standard PCIe topology discovery process in non-tree topology structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a non-tree topology structure is used for multi-chip interconnection, then data transmission bandwidth and delay performance are improved, but loops are formed making the standard PCIe topology discovery process inapplicable
Solution Approach 1:
The patent segments the non-tree topology into multiple spanning trees by introducing root switches and configuring multiple root ports. Each spanning tree is independently managed, allowing the system to maintain non-tree physical connectivity while creating logical tree structures that are compatible with standard PCIe discovery processes. This segmentation resolves the contradiction by dividing the complex non-tree topology into manageable tree segments.
Solution Approach 2:
The patent introduces root switches as intermediary devices between end devices and the management system. These root switches act as mediators that perform device enumeration and topology discovery, translating the complex non-tree topology into standardized tree-based information that can be processed by existing PCIe management tools. This intermediary approach enables compatibility without sacrificing the performance benefits of non-tree topology.
2Adaptability or versatility
If multiple ports are connected to the same device in non-tree topology, then routing flexibility and bandwidth are improved, but multiple response ports create management complexity and potential loops
Solution Approach 1:
The patent performs preliminary device enumeration and response port determination during system initialization, before normal operation begins. The root switch identifies all devices connected to multiple ports and pre-determines which ports will serve as response ports for each device. This preliminary action eliminates management complexity during runtime while preserving multiple physical connections for routing flexibility.
Solution Approach 2:
The patent applies different roles to different ports of the same switching device. For each device connected to multiple ports, one port is designated as the response port with specific management functions, while other ports serve as non-response ports with different characteristics. This local differentiation simplifies management by creating clear functional distinctions while maintaining the flexibility of multiple connections.
Data Source
AI summary
A switching device is provided obtains information about devices connected to a plurality of ports of the switching device and determines response ports of the switching device based on the information about the devices connected to the plurality of ports. Different response ports of the switching device are connected to different devices, and each response port is configured to receive a management packet or a response to the management packet that is sent by a device connected to each response port in a device enumeration process.