[ih] Hourglass model question

[Jack Haverty]

On 7/3/19 11:20 AM, Joe Touch wrote:

> I think there was at least some terminology borrowing; not sure who came
> up with what first, e.g., link, net, transport, etc.

IMHO it's important when looking at history to remember that computer
networking did not start with OSI, or the Internet, or even the ARPANET.  

Before those existed, there were lots of people sitting in front of lots
of terminals using the telephone network to interact with their
mainframes.   Protocols like BISYNC (circa 1967) and others were used,
along with "multidrop lines" that enabled lots of terminals to use the
same telephone line.

IIRC, much of the "networking" terminology was borrowed from that
environment - terms like "link" and "transport" for example.  I suspect
you'd find a lot of "our" terms in early IBM documents.

My impression of the 7-layer model has always been that it came from
that kind of early 60s "network" world - lots of human users sitting at
a slightly smart terminal (e.g., IBM 2260 or later 3270) interacting
with some application running on a remote mainframe over a virtual
circuit carried by modems and telephone lines.  The seven layers match
reasonably well to that technology.

The problem we had back in the early 80s with forcing the Internet into
that model was a result of the multiple endpoints involved in virtually
every scenario.   Users were still at terminals, but only the TIP/TAC
scenario (remote login) fit into the 7-layer model. 

Most scenarios were more complex, and the communications over the
ARPANET and later Internet were largely computers interacting with other
computers.  When a human user was involved he or she was likely using a
"client" program on a local computer (e.g., Telnet or FTP from ISIA,
BBNE, MIT-DM (where I hung out)...) and that local computer was
interacting with a computer at the "other end" as well as with computers
"in the middle", e.g., information exchanges with gateways (routers),
with servers such as DNS or NTP, etc.

There were lots of other scenarios with no human user in sight, e.g,.
mail servers talking amongst themselves, DNS servers getting
synchronized and updated, etc.

It was really hard to put the round ARPA Networking block into the
square OSI hole....

Today, if you look at a single web-page, you'd likely see dozens of
interactions going on between lots of network sites as all of the page
content is pulled or constructed from all over the Internet to get the
ads, cryptominer malware, teasers for other sites, et al onto the
screen.  Sure seems far away from that 7-layer model....

/Jack

PS - a factoid you might find amusing.  In the Internet, routers used to
be called "gateways".  When I was at BBN in the 80s, we sporadically
tried to sell gateways to our X.25 network customers.   No one would
touch a "gateway".   We finally learned that the term "gateway" in
IBM-land referred to something which had a reputation of being
expensive, hard to install, and very unreliable.   So we started calling
them "routers" instead...