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From: louden@MITRE-GATEWAY.ARPA.UUCP
Newsgroups: mod.protocols.tcp-ip
Subject: Re: RFC986 questions
Message-ID: <8606121253.AA11410@ucbvax.Berkeley.EDU>
Date: Thu, 12-Jun-86 08:10:17 EDT
Article-I.D.: ucbvax.8606121253.AA11410
Posted: Thu Jun 12 08:10:17 1986
Date-Received: Thu, 12-Jun-86 19:28:18 EDT
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Organization: The ARPA Internet
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Approved: tcp-ip@sri-nic.arpa


If the goal is to allow both ISO and DoD on the ARPANET, why not use
the same link level and different net levels?

This would be compatable with both protocols since X.25 is in both.
Connecting the two worlds can then be done at the applications level
by application gateways that understand what is needed, such as X.400 to SMTP.

The issue of gateways can be handled by implementing both DoD and ISO
net level protocols and selecting the one that makes sense for a packet, such
as checking version number is correct.

This method works in a well defined way (all the protocols are spec.ed)
and does not require the large development effort to be wasted on a tempory
patch until a complete transition is made.

Note that changing to ISO net layer requires all hosts to modify their software
even if they will be replaced before the network converts fully to ISO.
Dual mode operation would only require gateways connection dual mode networks
to be modified.  This sounds cheeper to me.

To my knowledge there are at least 3 organizations working on this solution.
The largest and best funded is the NBS effort to develop a standard application
gateway.  This has been discussed at the NBS ISO workshops.

...
Sorry I cannot reply directly to you because we are using a BBN C70 with the
standard release software.  This does not support domain addresses other
than .ARPA.  BBN says they will fix as soon as they can but it is an
example of the problems in requiring a conversion in existing protocols.
It sometimes takes more time and money than you have.