The latest Gen-Z white paper, recently posted on our website, expands upon the earlier white paper, “Highly Resilient 25G PHY.” The previous white paper presented a case for high-resilience fabric performance while avoiding Forward Error Correction (FEC). The new white paper discusses the performance that can be achieved at 50GT/s by limiting channel characteristics, such as insertion/reflections losses and crosstalk.
The Gen-Z Physical Layer Specification does not normatively specify channel frequency masks – to ensure interoperability, Gen-Z instead specifies an industry-adopted method for validating channel compliance, known as channel operating margin (COM).
The white paper also addresses Gen-Z Phit FEC. Gen-Z 50G PAM4 local and fabric use a 288-bit Physical Digit, or Phit, which contains the FEC code word. Phits differ from traditional Flow Control Digits, or Flits, in that Phits do not involve in flow control. The use of Phits allows FEC to be handled completely by the Physical Layer. This allows the Link Layer to support a multitude of Physical Layers with or without FEC.
Download the latest white paper, “50G Gen-Z PHY and Channel Design,” along with many other educational resources on our website.