For educational purposes, let us assume we have a network based on the
ISO model with its 7 layers... and with level 2 sub-divided per the

OK, I have some data in my computer I want to send across the network
to another computer...

The data is on my disk or in RAM... no matter whether it is a saved
file or an email or a chat connection or what... the data is going to
be on disk, RAM or some other storage medium... unless it is created
in real time... but then it still probably goes to disk or ram before
being sent over the network.

From a hardware point of view... the data goes from disk or ram via
the processor or dma or whatever to the network card... probably
transferred there as parallel bytes, words or whatever... but it could
even go to the network card from a sio (serial input/output)
device/chip... no matter... the data gets to the network card.

Now the data is pumped out bit by bit over the internet... in serial
fashion... each little section... call it a data load... has its own
header... and maybe so protocol data at the end... (trailer maybe?)

Now some of the level's are created in the local computer... but
others may be created by switch's, routers, the telecom/phone company
who has handling the data at each point along the way...

So, in trying to relate all of this to real world software and

For each of the 7 layers/levels... what piece of hardware and/or
software creates... bundles & unbundles... each layer/level?

A lot of systems people tell me... don't worry about it... it doesn't
matter... just memorize it... but that doesn't do it for me as I have
designed hardware and written software at both the assembly language
level and using higher level languages... but I've never worked on
networking... now I'm trying to relate this to the real world... some
piece of software... be it the networking part of Windows, Linux,
Unix, Apple, or whatever... or be it the driver for the network
card... or be it the t-1 mux at the Telco or the switch or whatever...
understanding who's job is who's is important in a practical sense...
as well as from a theoretical point of view.

Thanks in advance for any comments and help on this.