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The OSI Deprogrammer

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Re: The OSI Deprogrammer

#61

Post by kiitos »

Almondsetat wrote: post #39
yjftsjthsd-h wrote: post #21

> People today can’t comprehend the original model because they have no experience with terminals and mainframes. This makes them treat OSI as a deep mystery. In fairness, I have come to think that we should teach computer science by plopping students in front of a PDP-11 and teletype (probably actually a PiDP-11 under the hood, but the students don't need to know how we realized the machine), running v6 unix, take t…

Computer science is about computers just as much as physics is about telescopes. Computer scientists should think of computers in terms of logic, computability and complexity theory. We don’t expect physicists to learn how the first telescopes worked in detail because it’s useless. A physicist should learn optics and then understand why telescopes were build that way. The history of something can help put it in conte…

This is a fun way to describe the academic domain of CS theory, but practice demands an enormous amount of mechanical sympathy.

Re: The OSI Deprogrammer

#62

Post by ogurechny »

It is good to remind yourself once in a while that “networks” don't exist, they are an illusion based on processing of independent packets based on magical numbers in them. In theory, there is nothing strange in a system that decides to hold all IP addresses higher than a certain number, or offer some service on all even ports at once. It only needs a different mathematical operation on those numbers to be performed.

Also, in theory, we can have internet-wide broadcasts (in a multicast-like or some other graph traversal manner). Then, say, ALL p2p file sharing can be reduced to a single standard request "WHO-HAS The.Matrix.DivX.l33tR1pZ.avi". Then one starts to think why it is not possible in practice.

Re: The OSI Deprogrammer

#63

Post by KirillPanov »

robertgraham wrote: post #53
tptacek wrote: post #6

Earlier quoted context omitted.

Ethernet, IPv4, TCP, and HTTP; what functions do each provide, how is each coupled to its neighbor, and what are the viable alternatives in the design spaces of each? Part of the OSI layering model was I think meant to get people's brains wrapped around the dynamics of packet switching networks, which were once a novelty and are now just part of the air we breathe. Then, read: https://web.mit.edu/Saltzer/www/publicat…

It's wrong to think of them as different functions of the same network. Instead, they are differnet networks. Ethernet and the Internet both provide the function of forwarding packets through a network to the target destination address. The MAC protocol and IP protocol provide the same theoretical function. Where they differ is that Ethernet was designed to a be a local network, whereas the Internet is designed to be…

> Where they differ is that Ethernet was designed to a be a local network, whereas the Internet is designed to be an internetwork.

Then your criticism of the first three OSI layers is merely that they should be named "point-to-point", "local", and "inter".

I can agree with that criticism. But I can't agree with needing 239 pages to convey it.

Re: The OSI Deprogrammer

#64

Post by corethree »

kiitos wrote: post #52
corethree wrote: post #35

Earlier quoted context omitted.

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 co…

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.

Re: The OSI Deprogrammer

#65

Post by IshKebab »

onetimeuse92304 wrote: post #15
mannyv wrote: post #14

I always thought this model was pretty worthless. I remember when they tried to apply it to the internet. It didn't quite fit, but they needed a model because intellectuals.

It depends on when it was. Back in 1999 it fit pretty well. Even if not perfect it still was a good teaching tool to explain "how it all works" on some level. Then you got to know the hairy details. Nowadays "Internet" is mostly HTTP 2 for most people and then this model doesn't even remotely explain the structure of it.

It didn't fit any better in 1999 than it does now and it wasn't a good teaching tool because it didn't match reality at all but was presented as if it did. Definitely caused more confusion than learning.

Re: The OSI Deprogrammer

#66

Post by KirillPanov »

thayne wrote: post #42
tptacek wrote: post #6

Earlier quoted context omitted.

Ethernet, IPv4, TCP, and HTTP; what functions do each provide, how is each coupled to its neighbor, and what are the viable alternatives in the design spaces of each? Part of the OSI layering model was I think meant to get people's brains wrapped around the dynamics of packet switching networks, which were once a novelty and are now just part of the air we breathe. Then, read: https://web.mit.edu/Saltzer/www/publicat…

I would probably add TLS in thereas an optional layer between TCP and HTTP. But http/3 and quic complicates things because it kind of blends the tcp, tls, and http layers together.

Layer 4 is the lowest layer of the OSI model that isn't packet-based (i.e. can handle messages of arbitrary size).

IMHO that's the highest layer of the OSI model that is useful. After that it's various ways of tunnelling streams inside of streams.

Re: The OSI Deprogrammer

#67

Post by mpweiher »

Almondsetat wrote: post #39
yjftsjthsd-h wrote: post #21

> People today can’t comprehend the original model because they have no experience with terminals and mainframes. This makes them treat OSI as a deep mystery. In fairness, I have come to think that we should teach computer science by plopping students in front of a PDP-11 and teletype (probably actually a PiDP-11 under the hood, but the students don't need to know how we realized the machine), running v6 unix, take t…

Computer science is about computers just as much as physics is about telescopes. Computer scientists should think of computers in terms of logic, computability and complexity theory. We don’t expect physicists to learn how the first telescopes worked in detail because it’s useless. A physicist should learn optics and then understand why telescopes were build that way. The history of something can help put it in conte…

> Computer science is about computers just as much as physics is about telescopes.

I too am a sucker for a pithy quote.

Alas it couldn’t be more wrong.

Computer science is about computers and how to program them. It is an engineering discipline, not a science.

Re: The OSI Deprogrammer

#68

Post by ahoka »

yjftsjthsd-h wrote: post #21

> People today can’t comprehend the original model because they have no experience with terminals and mainframes. This makes them treat OSI as a deep mystery. In fairness, I have come to think that we should teach computer science by plopping students in front of a PDP-11 and teletype (probably actually a PiDP-11 under the hood, but the students don't need to know how we realized the machine), running v6 unix, take t…

Most curriculums suffer from teaching outdated concepts in CS, how would this help? Universities' purpose is not to satisfy someones retrocomputing history interest, but to supply state of the art understanding of a group of subjects.

Re: The OSI Deprogrammer

#69

Post by [deleted] »

thayne wrote: post #42
tptacek wrote: post #6

Earlier quoted context omitted.

Ethernet, IPv4, TCP, and HTTP; what functions do each provide, how is each coupled to its neighbor, and what are the viable alternatives in the design spaces of each? Part of the OSI layering model was I think meant to get people's brains wrapped around the dynamics of packet switching networks, which were once a novelty and are now just part of the air we breathe. Then, read: https://web.mit.edu/Saltzer/www/publicat…

I would probably add TLS in thereas an optional layer between TCP and HTTP. But http/3 and quic complicates things because it kind of blends the tcp, tls, and http layers together.

[deleted]

Re: The OSI Deprogrammer

#70

Post by technion »

culopatin wrote: post #2

This is hilarious. I happen to be preparing for a test centered around the OSI model and I don’t get why it’s set this way. Every few paragraphs the text says something like “remember that nowadays things a bit fuzzier and don’t fit within one layer” well then why are we even using this model?

Yep, for every person who says they haven't touched osi in a decade, there's someone studying the topic either at a school or for a vendor certification.

And for every "the bottom layers are worthwhile", there's a network engineer applying for a job with some leetcode like tool asking them about layer 5.

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