Subj : Re: Notice that...
To   : Andre
From : tenser
Date : Wed Feb 16 2022 11:13:38

On 15 Feb 2022 at 03:38p, Andre pondered and said...
 
 An>  te> You're describing applications of the Internet, not the Internet
 An>  te> itself.
 An> 
 An> Correct. The internet is not something you just dump something on, it's
 An> not a big truck. It's a series of tubes. And if you don't understand,
 An> those tubes can be filled, and if they're filled, when you put your
 An> message in, it gets in line. It's going to be delayed by anyone that
 An> puts into that tube enormous amounts of material.

Well, no, that's not quite right either. The pipe analogy is not
bad, but is only part of it; in packet-switched systems, large
amounts of "material" are broken up into smaller packets that are
sent separately.  On top of that, we layer protocols like TCP,
that provide for reliable, sequenced delivery.  So while large
data transfers do compete with smaller data transfers, it's not
like the Internet is _blocked_ waiting for a lot of data to move
somewhere before small amount of data gets moved.

A faintly ridiculous analogy might be imagine a large network
of pneumatic tubes: to move a book from one place to another,
one might imagine taking all of the pages, putting each in a
pneumatic carrier labeled with the destination, and dropping
it into a tube that  you _think_ will get it closer to the
wherever you'd like it to go.  An operator at the other end of
that tube (which may not be the final destination) will look
at the label on the carrier, and send it on to where they think
will get it closer to the final destination, and so on.  If
some node along the way can't send the message on, they may
send a message back to the origin saying so.  Eventually, we
presume that all of the pages arrive at the destination, but
they may not be in order; it's up to the recipient to put the
pages back together in the original order to get the original
book back (but the pagers are numbered, so that's ok).

Anyway, the point is, that the waystations along the way don't
necessarily care what's in the carriers; that's a bit of an
oversimplification, but to a first order approximation it's
not too bad.  Given that, moving lots of data just competes
for the bandwidth of forwarding, but doesn't necessarily block
any other traffic until completion.  On a host, the OS
presumably multiplexes the network adapter between different
applications (pretty much every TCP stack out there does this,
except for very old ones for anemic systems like DOS).

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