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Comment by kiitos | Hacker News Reader

> [OSI's] negatives far outweigh its positives. OSI is not theory, it’s not a framework, it’s not helpful, it’s not a standard, it’s not anything those who use it claim it to be. Anything you teach with the OSI Model can better be taught without it.

This is a naive understanding of the OSI model, whose primary virtue is not any specific detail it expresses, but instead its ubiquity.

The only way to successfully replace a (clearly entrenched) status quo is to make the positive case for the new thing, which has to be just obviously and significantly better. Pointing out the flaws in the current thing is never convincing, and never a winning strategy.

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It's far from ubiquitous though. It breaks down as soon as you enter the real world. It's simultaneously too vague to be useful for talking about specifics and too inaccurate to be useful for talking about generalities.

It's absolutely ubiquitous as a model. It's taught in every CS curriculum in every university in the world.

It also doesn't break down in the real world, unless you're being extremely pedantic. Many bits of software don't map cleanly to the defined layers, but we can still talk about the distinction between the network layer vs. the session layer, for example, and get value out of that discussion.

> It also doesn't break down in the real world, unless you're being extremely pedantic.

It breaks down if you're trying to do anything at all with it. There are basically two layer boundaries that are useful to talk about in the real world - between Ethernet and TCP/IP, and between TCP/IP and application protocols. The OSI model has 6 layer boundaries but a) neither of them maps cleanly to either of those two real-world buondaries b) no-one knows what the other 4 are (you can kinda-sorta say that the boundary between TCP and IP is one of them, but that isn't the distinction that the OSI says it is either). Depending who you ask you can sort of retrofit it and say that the boundary between Ethernet and TCP/IP is between OSI layer 2 and 3 or 3 and 4, and the boundary between TCP/IP and application protocols is somewhere between layers 4 and 7, which is sort of ok because no-one knows WTF layers 5 and 6 are meant to be. But you're really not getting any value from using the OSI model at that point; it's not telling you anything useful and it's actively getting in the way of understanding what's going on.

> we can still talk about the distinction between the network layer vs. the session layer, for example, and get value out of that discussion.

Like what?

You can't. Nobody knows what the session layer does. Most falsely believe that layer handles sessions.

Ubiquity isn't a necessarily good thing.

It depends on the type of person you are for this analogy to work but...

Religion is ubiquitous and it is largely just inaccurate made up fantasy stories posing as truth. It's generally not good from this perspective.

OSI is religion. And like religion, it is ubiquitous. Is that a good thing? I'm not sure.

OSI is just a model. Like all models, it's wrong. But its ubiquity, and the fact that it's survived the test of time, clearly signal that it is a useful model. And that's as good as models get.

Not all models are truly wrong. But I get your point. I think though the author isn't just arguing that the OSI is like your typical "wrong" model. I think he's saying it's a shitty model. It's crap. It's like using Hippocrates four humors to model human health.

Yeah that model is wrong just like every model. But unlike every model it's a garbage model.

Religion has ALSO survived the test of time, but Jesus Christ coming back from the dead and walking on water is still utter bullshit. Not to get into a religious argument here, but if you're Christian let me know and I'll have to look harder for another analogy.

Anyway my point is: Surviving the test of time, Does not mean shit.

Look, just tautologically, if it was so shitty, we wouldn't be talking about it, because nobody would be using it.

You're free to use a definition of "shitty" that doesn't take into account usage or longevity, but that definition is not really relevant except at the theory level.

So why are we talking about moses putting 2 of every animal on the face of the earth on an ark? Why is it being taught to tons of good Christians all over the world?

Let's face it. The story of moses, in terms of the actuality of what happened? Utter bullshit. Just because everyone teaches it and talks about it, doesn't make it not bullshit.

You know what I mean by shitty or bullshit. You just disagree. You're just saying, in your opinion, it's not bullshit, but you absolutely know what I mean here.

Your opinion is valid.

I'm just saying that ubiquity does not prevent something from being bullshit.

Something that is being talked about everywhere and all the time does not prevent that something from being bullshit.

So you may believe that OSI is NOT bullshit. But your reasoning would be invalid if the two above points are the starting axioms of your logic.

And this specific model is very wrong. It is not useful; it survived mostly because it's useless: slapping an "OSI level X" label on something affects pretty much nothing so sure, you can keep doing that and keep teaching it to people.

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