WOLF Advanced Technology’s technical whitepaper, PCIe Switches and Lane-Rate Conversion, explains how PCIe switches support lane-rate conversion, enabling data received on one port at a specific PCIe generation and lane width to be transmitted through another port operating at a different rate.
This capability is a built-in feature of modern PCIe switches and does not require manual configuration. The process allows devices with different link speeds and widths to be connected within the same system.
The paper outlines key PCIe fundamentals, including link training, during which each port independently negotiates its lane width and operating speed based on the capabilities of the connected devices. It also describes the PCIe packet structure, where Transaction Layer Packets (TLPs) are created by the transmitting device and remain unchanged across the data path, while Data Link Layer (DLL) and Physical Layer information are removed and regenerated at each hop. This structure allows the switch to retransmit data across links with different speeds and widths.
Further technical detail is provided on how the Physical Layer manages encoding and lane striping, which affect throughput. The paper also explains that PCIe switches buffer incoming packets, remove the incoming DLL and Physical Layer information, and retransmit the TLP with newly generated link-level information appropriate for the outgoing port. TLP sizes are not modified during this process, and PCIe switches cannot split TLPs into smaller packets.
To find out more information on PCIe switches and lane-rate conversion, visit WOLF Advanced Technology.
