Re: Idle chatter about reference models


tcp-ip-RELAY%SRI-NIC.ARPA (@MIT-Multics.ARPA,@UBC.MAILNET,@SFU,@UM.CC.UMICH.EDU:tcp-ip-RELAY@SRI-NIC.ARPA)
Tue, 24 Nov 87 09:47:40 PST


Sorry to have kept you waiting; I have been off form as it happens, and
off to the Left Coast to boot.

Rather than succumb to the temptation of trying to see how many epicycles
the ISORM has these days (though I must confess I had been convinced at
one point in time that the party line was that each layer could/did have
a management sublayer--but never found out if that also applied to each
sublayer, so wasn't sure if L3 was four or six epicycles deep), let's
go back to the initiating question. As I recall, it was something like
where things like GGP, EGP, and HMP went in the layering. Although I
have a great deal of sympathy for those who didn't bite and in essence
placed such things orthogonal to the layering, I would like to observe
that there's an alternative for those who find that view unsatisfying:
If you believe that the layers are Applications/Process, Host-Host, and
Network (Interface)--i.e., the old simple as I, II, III ARM I've always
espoused--then the answer ought to be easy to derive for any of the
three (or other, like protocols). If they have to do with doing things
in common for the users' processes to get the bits to go from Host to
Host, then they're L II is one approach. If they're clearly not part
of the interface to the proximate comm subnet processor and also fairly
clearly not directly germane to the Applications/Process Layer, then
they're L II is the other approach. (Note to the original question-
raiser: you're of course welcome to use my Form, but it works better
if you use my Content too.) (Note to John Laws: as you well know, my
main problem with the ISORMites is that they seem to me to be attempting
to substitute Form for Content almost all the time.)

Hope that's not too characteristically cryptic; if it is, I'll cop
a plea based on an imminent cold on top of the jetlag.

   cheers, map
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