[ NETINFO:TP4-MEMO.TXT ]                                 [ 8/86, FP ]


The following memo from the DoD Interoperability and Standards office
addresses the DoD plans for eventual transition to international
standards, in particular, the ISO TP-4 protocol.

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                         M E M O R A N D U M

From:      DoD Interoperability and Standards Office

Date:      18 August 1986

Subject:   DoD Transition to ISO TP-4

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DoD policy concerning a transition to ISO TP-4 was specified in a 3
April 1985 Memorandum from Mr. Donald C. Latham, Assistant Secretary
of Defense, Command, Control, Communications and Intelligence.
"Whenever international standards are available and can be used to
support military requirements, they will be implemented as rapidly as
possible to obtain maximum economic and interoperability benefits.
However, TP as a proven commercial offering is not available at this
time.  The progress of TP will be monitored carefully, and once
commercially available, TP will be tested and evaluated for use in
military applications."  Further study by DoD has indicated that a one
layer transition from TCP to TP-4 is not viable.  Any transition
should happen on an "all layers" basis to preclude multiple
transitions and modifications of layer interfaces.  Full seven-layer
implementations of ISO protocols are only just now being announced.
(Note that DoD is already essentially ISO conformant/compatible at
layer 3 and below.)

The ISO protocols can be characterized as having many optional
features.  In the DoD environment, to ensure maximum interoperability
and often to meet specific military requirements, the options must be
more narrowly specified.  DoD Military Specification Supplements for
each of the ISO protocols are under development.  Tests for
conformance to these MIL-Spec-Supplements are also planned.  It must
be emphasized that the objective is not to create DoD unique versions
of commercial protocol products, but to define an options set.
Possible modification of an ISO protocol is not ruled out, however, if
it is determined that the ISO protocol does not satisfy specific
military requirements.

The National Research Council report "Transport Protocols for
Department of Defense Data Networks," (RFC:RFC942.TXT) recommended
that a method for ISO protocols to interoperate with current DoD
protocols should be developed.  This is underway with the development
of an "Application Layer Translating Gateway" for both file transfer
and mail service for the two protocol suites.  When this work is
complete and the Supplement specifications and tests are available,
DoD expects to announce Co-Standard status for the ISO protocols.
This is expected within 18 months.  A date that new networks will be
required to use ISO protocols has not yet been determined.  In the
case of existing DoD networks with no need to interoperate with
others, the current DoD protocols may not be phased out through the
lifetime of that network.