Re: Does TCP/IP "comform" to ISO/OSI?


Michael Padlipsky (PADLIPSKY@A.ISI.EDU)
Wed 31 Aug 88 14:24:24-EDT


Kent England:

Just for the record, it seems to ME that there's no connection whatsoever
between my observation that TCP/UDP-IP is philosophically closer to the
"Reference Model" than X.25-X.75 and "this argument of 'OSI implies X.25
and X.75'" you mention. If anything, the observation is more reasonably
misconstruable as a suggestion that OSI precludes X.25-X.75 than that it
implies 'em, although it doesn't say that either.

Of more interest, however, is whether you'll actually be able to satisfy
your stated expectation that you won't "have to run OSI protocols over
virtual circuit networks " "[i]n the US": As long as DDN and GOSIP mandate
X.25, neither ARPA nor ISO IP users will be able to avoid paying (in one or
more senses) for unasked-for subnet functionality, in the long haul, as it
were. Are you, perhaps, counting on ISDN to save the day? (For that
matter, does anybody out there know for sure whether ISDN, unlike X.25, WILL
offer datagram service, and, unlike X.75, dynamic/"real" alternate routing?)
If so, you'd be better advised to argue with the proprietors of DDN and
the propounders of GOSIP about the non-OSIness of X.25, not with me, since
the bold-face line in the middle of p.154 of _The Elements of Networking
Style_ (Prentice-Hall, 1985) proves that I haven't lumped OSI and X.25 for
several years--even if I'll never forgive the panacea pedlars who had
tricked me into lumping them previously.

   cheers, map
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