While referring to optical transceiver modules say 400G-DR4 optical modules, where there are 4 electrical lanes for 4 optical fibers - the data sheets report 53.125GBd symbol rate. I used to think of 400G PAM4 as 4 lanes each with 50GBaud and each symbol has 2 bits altogether making to 400Gbits/sec. But I wonder if there is a reasoning behind why we have .125 floating decimals instead of 50GBaud. Does anyone have insight into if this is a DAC/SERDES/filter related thing that has been standardized over the years?
Optik alıcı ve vericilerde sinyalleme hızını optik kaynağın gücü, liflerin sayısı,dayanıklılığı, uzunluğu ve aralarındaki mesafe,ağın etkili olduğu alana bağlı olarak değişir. Ağın etkileşimi ise veri merkezine bağlı olarak şekillenir. Bunlar da fotonik ve optik kaynağa bağlı olarak değişir.
Some explanations are here https://www.reddit.com/r/networking/comments/fcfyu1/why_does_25_gbe_exist/ basically it is hierarhy of baud rate build to accomodate some number of lower rate channles ... i ssupect it all starts with first voice phone digital lines digitizing at 64kbit /sec
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