Re: Does TCP/IP "comform" to ISO/OSI?


Phil R. Karn (thumper!karn@faline.bellcore.com)
30 Aug 88 21:16:56 GMT


> Does OSI conform to ARM?
>
> No.

And, of course, one might ask the question: "Do the 'OSI Protocols'
conform to TCP/IP?" The answer again, sadly, is also no.

But even if you limit the discussion to reference models, the "OSI
Model" is hopelessly out of date. By the time you delete the unnecessary
layers (e.g., Session), combine distinct layers that really shouldn't be
separate (e.g., Application and Presentation), create the sublayers
required by modern concepts like internetworking (the Internet and
Subnet Layer) and multiple access networks (e.g., the Media Access
Layer), about the only morsel you'd still have left from the original
OSI model is that "Layering is often a useful tool in building
networks".

Then when you add Postel and Cohen's paper showing how a fixed number of
layers is simply unworkable in the real world, what you finally end up
with looks remarkably like the ARPANET Reference Model (ARM).

But does ISO ever revise its preconceived ideas and admit its mistakes?
Of course not. It just covers them over with even more paper and ad
hype.

"No Need for XYZ, Just TCP!" --Seen on a British billboard

Phil



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