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From: jbn@wdl1.UUCP (jbn )
Newsgroups: net.lan
Subject: Re: IP variants
Message-ID: <469@wdl1.UUCP>
Date: Fri, 12-Oct-84 21:22:24 EDT
Article-I.D.: wdl1.469
Posted: Fri Oct 12 21:22:24 1984
Date-Received: Sun, 14-Oct-84 08:16:54 EDT
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Nf-ID: #R:ariel:-75700:wdl1:8900006:000:1703
Nf-From: wdl1!jbn    Oct 12 18:14:00 1984


     ISO IP and DoD IP are not the same protocol.  ISO IP allows for longer
addresses, among other things; the consensus is that 32 bits is not enough for 
a worldwide address space.  It is supposedly possible to run TCP on top of
ISO IP.  There is also an ISO Transport Protocol, which is quite different
from TCP but like TCP provides a byte-oriented virtual circuit.  It is based
on the National Bureau of Standards Transport Protocol, but there are 
significant differences.  ISO Transport is very much a compromise, like 
X.25, and there are lots of optional operating modes to placate the datagram
and virtual-circuit factions.  ISO Transport was used at the big GM-sponsored
demo at the National Computer Conference last month.  The present spec for
this protocol is not very tightly drawn as yet; there is talk of using a
formal technique to specify the protocol.
     Incidentally, the official DoD definitions of IP and TCP are not the
RFCs, but MIL-STD-1777 (IP) and MIL-STD-1778.  The MIL-STD versions are
written in an Ada-like psuedocode.  A revision of MIL-STD-1778 is underway
with the objective of tightening up the spec to the point that compliance
insures interoperability.  The object is not to change anything, but to
bind certain important decisions left unspecified in the present document.
In other words, if A can't talk to B, then we should be able to tell 
whether A is wrong or B is wrong.  If we can't, the spec is wrong.
The person formally in charge of the revision is Mike Corrigan (Corrigan
@DDN1) of the Defense Data Network program office.

				John Nagle
				Ford Aerospace and Communications Corp.

ps: Please do not ask me for copies of the MIL-STDs; contact NTIS.