Re: ISO8473 vs. IP


Michael Padlipsky (PADLIPSKY@A.ISI.EDU)
10 Sep 1987 11:31:41 EDT


My initial impulse was to respond to the call for a hose to hose
protocol with a private message saying "Nozzle yourself, Vinton: you
really shouldn't faucet like that." Then I made the mistake of thinking
a bit about what hose to hose protocols would actually be like, and I
realized that there's a fairly powerful metaphor lurking there. Think
about it: if you have two garden hoses, all you need is a suitably
threaded (presumably "female-female") adaptor, even if the threads on
each of the hoses "aren't standard". The worst that would happen is that
you'd discover nobody made appropriate adaptors and it would be cheaper
to buy a longer hose (which, with any luck at all, was thread compatible
with the faucet) than to have someone fabricate the special widget.
(Please recall I've always spoken well of physical standards, b/t/w.)
But if you want to couple a fire hose and a garden hose, you'd need to
call in a fluid dynamicist to calculate how long the taper had to be so
as not to lead to bursting the garden hose and then go in for some
serious metalwork to get the adaptor built. (Not a job for the
village smithy [they shoe horses, don't they?], I'd imagine.)
And if you wanted to go beyond the conventional Gateway problem,
consider the Translating/Mapping Gateway analogue, where some of
the time what you need is to couple a hose designed for carrying
liquid oxygen with a hose designed for carrying water to your
lawn: by the time you put enough heat into the adaptor so the
garden hose doesn't shatter from the cold, you've probably lost
sight of the fact that your lawn doesn't really need oxygen in
the first place.

Other permutations on the theme are doubtless available, and even
relevant, but can safely be left as an exercise....

cheers, map

P.S. At the risk of violating tradition and linking this back up
to the question which started it all, one way of viewing the
difference between ISO IP and ARPANET IP is that each is supposed
to be threaded to a different faucet. But, then, another way of
viewing the difference is to think about the news item I heard
over the weekend, where some builder in one of the cities the Pope
is visiting had donated several of his houses for the lodging
of the papal entourage, since he believed they'd be worth more later
because he had heard that the Pope blessed every house he entered
(not clear that the Pope would enter every house, of course,
but then I've never claimed to be up on ad man logic):
so to change the metaphor from the lawn to the house, they do
have slightly different floor plans, they both serve the same
fundamental purpose of being boxes to stay out of the weather
in, they're in the same neighborhood and all, but this one's
gonna cost ya $25,000 more because It's Been Papally Blessed!

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