The Actual OSI Model
Agreed. To take it further, the OS APIs suck for protocol selection too. And router technologies. And basically everything.E.g. in theory your router should work with level 3 and below. This includes the firewall. However, try to implement a new Level 4 protocol and all of a sudden your packets won't route.This was the whole point of this separation - that while UDP and TCP are useful in general cases, there are much better and novel ways to frame packets for e.g. cust infrastructure with different properties and different requirements.But it simply doesn't work.This stuff has driven me nuts for decades. OSI has rarely been helpful aside from just general communication of ideas. It shouldn't be used as any authoritative reference, ESPECIALLY not in classrooms.