[aklug] Re: Seemingly random OSI-related questions

On Tue, 8 Feb 2011, Christopher Howard wrote:

> A few seemingly random questions relating to the OSI model:
>
> 1) Is it pure coincidence that the OSI model happened to be developed by
> the ISO? (Reverse acronym.)

OSI was developed under the auspices of ISO, but they're not exactly GNU,
I'm sure the irony of their choice of acronyms was lost on them.

> 2) Could someone explain a bit more clearly what exactly the
> presentation layer is for? Do we use it today?

Presentation is really an extension of the application protocol layer. It's
the programmer's responsibility (if we're to assume cross-platform
support for binary data, for example) to encode and decode data from network
order bytes (which is really just big-endian) to the native order
(little-endian for the majority of this list's participants), or to
filter all communications through an encryption layer like SSL. So, yes, we
do use it.

> 3) Let's say I rip out all the Ethernet cables in my apartment and
> replace them with a wireless router. Which layers of the model (in my
> network) will be affected by that decision? Just the physical? If the
> data link as well, which sub-layers? (MAC, LLC?)

Layer 1 & 2 are affected, including sublayers.

         --Arthur Corliss
           Live Free or Die
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Received on Tue Feb 8 09:09:48 2011