What is PCIe SW

Peripheral Component Interconnect express (PCIe), you may have seen this name on motherboards. Do you know PCIe Switch that uses this standard?

PCIe SW was originally a standard for accessing memory from the CPU, but now it is often used for servers and storage. In addition, even within the industry, which has not shown interest in high-speed communication, attention is now focused on high-speed communication as the amount of data increases with the advent of high-precision cameras and 5G. In this article, we will explain in order while focusing on the basic functions and features of PCIe SW.

PCIe transactions

In Part 5, we will explain the contents of PCIe transactions in a little more detail.

PCIe data exchange is done in units called transactions. As discussed in Part 2, there are four types of transactions: memory, I/O, configuration, and messages. These transactions are classified as either Posted or Non-Posted.

I will explain non-posted / posted transactions. For non-posted transactions, when the requester sends a request TLP (Transaction Layer Packet) to the completer, the completer returns a notification called completion to the requester as a completion report of receipt. A posted transaction does not return a completion when the requester sends the request TLR to the completer.

Thus, non-posted is intended for more accurate communication, while posted is for more performance-oriented communication.

In Part 5, I briefly explained PCIe transactions. In the 6th article, I will continue to explain the basic knowledge related to PCIeSW.

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