Aggregated Non-Transparent Requester ID Translation for PCIe Switches
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Solution Overview
Problem
The existing PCIe systems with multiple root complexes require large requester ID lookup tables for non-transparent bridging, leading to significant memory storage needs, which is undesirable and pushes the limits of ASIC technology, especially in applications involving solid state drives and cascaded topologies.
Innovation Solution
The implementation of an aggregated non-transparent requester ID translation method in a PCIe switch, which reduces the number of table entries by using an aggregated downstream port to translate requester IDs with a captured bus number and an aggregated switch number, thereby minimizing memory requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If each PCIe switch stores requester ID entries for all endpoints in the hierarchy, then routing between multiple root complexes is enabled, but the lookup table size increases significantly
Solution Approach 1:
The patent divides the lookup table into two separate tables: a first lookup table storing requester ID entries for locally connected endpoints, and a second lookup table storing requester ID entries for remotely connected endpoints. This segmentation allows each switch to store only necessary entries rather than all possible endpoint IDs in the hierarchy, significantly reducing memory requirements while maintaining routing capability.
Solution Approach 2:
The patent introduces a new dimension to the routing architecture by adding a second lookup table that handles remote endpoint routing separately from the first lookup table that handles local endpoints. This dimensional separation enables the system to scale to multiple root complexes without proportionally increasing the size of individual switch lookup tables.
2Adaptability or versatility
If cascaded PCIe switches are used to accommodate multiple solid state drives, then system scalability is improved, but the required storage for the lookup table increases
Solution Approach 1:
By segmenting the routing functionality into two separate lookup tables (local and remote endpoints), the patent enables cascaded switches to scale the system to accommodate multiple solid state drives without each switch needing to store complete endpoint ID mappings for the entire hierarchy, thus controlling memory storage requirements.
3Adaptability or versatility
If a large lookup table is implemented to support multiple root complexes, then non-transparent bridging functionality is achieved, but integrated circuit embedded memory requirements increase
Solution Approach 1:
The patent implements non-transparent bridging capability by segmenting the endpoint ID storage into two separate lookup tables rather than requiring a single large table, thereby achieving the necessary routing functionality while reducing the volume of embedded memory required in each PCIe switch.
Solution Approach 2:
The patent adds a dimensional separation between local and remote endpoint routing tables, enabling non-transparent bridging across multiple root complexes without requiring each switch to allocate large contiguous memory blocks, thus optimizing embedded memory utilization.
Data Source
AI summary
A system and method are disclosed for aggregated non-transparent requester ID translation in a PCIe switch. The system may include a first switch that is enabled to receive a request from a non-transparent port of a second switch at an aggregated downstream port of the first switch and translating the requester ID of the request at the first switch using the aggregated switch number and the captured bus number of the requester ID. The method may include receiving a request from a non-transparent port of a second switch at an aggregated downstream port of a first switch and translating the requester ID of the request at the first switch using the aggregated switch number and the captured bus number of the requester ID.