I'm not a network engineer but learnt OSI back in 1997. It may not be perfect, and other stacks exist, but it's probably a rare case of an exceptional core fou

I'm not a network engineer but learnt OSI back in 1997. It may not be perfect, and other stacks exist, but it's probably a rare case of an exceptional core foundation model, e.g. ppp, Kermit, some obscure inter-bank pre TCP stacks using EBDIC instead of ASCII are all I can remember of non OSI model protocols from back in the day, and have no idea how they interacted below the software config for baud rate etc. But I remember OSI.