rfc939.txt

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         4.   Specific applications that use the above protocols for
              their particular purpose.

      Accordingly, if a network is developed using one transport
      protocol, it would generally not be able to interoperate
      functionally with other networks using the same transport protocol
      unless both networks were also using the higher-level utility and
      application protocols.  In evaluating whether or not to convert to
      TP-4 and in developing a transition plan, the following factors
      must be considered:

         The DOD contains numerous communities of interest whose
         principal need is to interoperate within their own members,


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RFC 939                                                    February 1985
Executive Summary of the NRC Report Transport on Protocols


         independently. Such communities generally have a specific,
         well-defined mission. The DOD Intelligence Information System
         (DODIIS) and the World Wide Military Command and Control System
         (WWMCCS) are examples. Interoperability is needed primarily
         between the higher layer applications programs initially unique
         to each community of interest.

         There are many different kinds of operations needed between
         communities of interest.  Examples of such operations are
         headquarters' need for access to several subordinate
         communities and the communities' need for some minimum
         functional interoperability with each other (such as mail
         exchange).

         The need for functional interoperability can arise,
         unexpectedly and urgently, at a time of crisis or when improved
         management opportunities are discovered.  Widespread
         standardization of TP-4 and higher-level protocols can readily
         help to achieve these needs.  Often, special development of
         additional applications that cost time and money will be
         necessary.

         The DOD needs functional interoperability with many important
         external agencies that are committed to ISO standards:  The
         North Atlantic Treaty Organization (NATO), some intelligence
         and security agencies, and other parts of the federal
         government.

         The same objectives that have prompted the use of standardized
         protocols at higher-level headquarters will lead to their use
         by tactical groups in the field.

   SOME COMPARISONS

      A detailed comparison of the DOD Transmission Control Protocol and
      the ISO Transport Protocol indicates they are functionally
      equivalent and provide essentially similar services.  Because it
      is clear that a great deal of care and experience in protocol
      development have gone into generating the specifications for TP-4,
      the committee is confident that TP-4 will meet military
      requirements.

      Although there are differences between the two protocols, they do
      not compromise DOD requirements.  And, although in several areas,
      including the data transfer interface, flow control, connection
      establishment, and out-of-band, services are provided in different
      ways by the two protocols, neither seems intrinsically superior.


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RFC 939                                                    February 1985
Executive Summary of the NRC Report Transport on Protocols


      Thus, while existing applications may need to be modified somewhat
      if moved from TCP to TP-4, new applications can be written to use
      either protocol with a similar level of effort.

      The TCP and TP-4 protocols are sufficiently equivalent in their
      security-related properties in that there are no significant
      technical points favoring the use of one over the other.

      While TCP currently has the edge in maturity of implementation,
      TP-4 is gaining rapidly due to the worldwide support for and
      acceptance of the Open System Interconnection (OSI) international
      standards.  Experimental TCP implementations were completed in
      1974 at Stanford University and BBN Communications Corporation.
      Between 1974 and 1982 a large number of implementations were
      produced.  The Defense Advanced Research Projects Agency (ARPA)
      network switched to a complete use of TCP in January 1983.
      Operations have been satisfactory and its use is growing.  A
      number of TCP implementations are also in commercial use in
      various private networks.

      In contrast, TP-4 has not yet been implemented in any large
      operational system.  It has been tested experimentally, however,
      and has received endorsement by many commercial vendors worldwide.
      In addition, substantial portions of TP-4 have been demonstrated
      at the National Computer Conference in July 1984.

      The Internet Protocol (IP) part of the standards is not believed
      to be a problem.  The ISO IP is not as far along as TP-4, but it
      is much less complex.  The ISO IP, based very strongly on the DOD
      IP, became a draft international standard in April 1984.

      The rapidity of the progress in ISO and the results achieved over
      the past two years have surprised even the supporters of
      international standards. The reasons for this progress are
      twofold:  strong market demands stemming from the growing
      integration of communications and data processing and the progress
      in networking technology over the past years as the result of ARPA
      and commercial developments.

      Although the DOD networks have been a model upon which the ISO
      transport standards have been built, the rest of the world is
      adopting TP-4. Because the DOD represents a small fraction of the
      market and because the United States supports the ISO standard, it
      is not realistic to hope that TP-4 can be altered to conform with
      TCP.  This raises the question as to what action should be taken
      by the DOD with respect to the ISO standard.



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RFC 939                                                    February 1985
Executive Summary of the NRC Report Transport on Protocols


   SOME ECONOMIC CONSIDERATIONS

      The DOD has a large and growing commitment in operational TCP
      networks, and this will increase by 50 to 100 percent in the next
      eighteen months.  This rate of investment will probably continue
      for the next five years for new systems and the upgrading of
      current ones.  The current Military Network (MILNET) and Movement
      Information Network (MINET) systems are expanding and will shortly
      be combined.  The Strategic Air Command Digital Information
      Network (SACDIN) and DODIIS are undergoing major upgrading.  When
      these changes are completed, there are plans to upgrade the WWMCCS
      Intercomputer Network (WIN) and to add separate SECRET and TOP
      SECRET networks.  There are plans to combine these six networks in
      the late 1980s, and they will become interoperable and multilevel
      secure using an advanced technology now under development.  If
      these plans are implemented on schedule, a delay of several years
      in moving to TP-4 would mean that the DOD networks in the late
      1980s would be virtually all TCP-based. Subsequent conversion to
      international standards would be very expensive if hastily
      attempted in order to maintain established DOD interoperability
      and gain interoperability with a large body of users.

      As the Department of Defense policy recognizes, there are
      significant advantages in using commercial vendor products if they
      meet the department's operational needs.  The major advantages are
      as follows:

         Costs to the DOD for development, production, and maintenance
         are significantly lower because (1) vendors spread the cost
         over a much larger user base, (2) commercial vendors are
         generally more efficient in their operations, and (3) vendors
         look for ways to improve their product to meet competition.

         The department generally gets more effective products because
         vendors integrate the protocol functions into their entire
         software and hardware product line.  Thus the DOD may be able
         eventually to use commercial software products that are built
         on top of, and thereby take advantage of, the transport
         protocols.

         By depending on industry to manage the development and
         maintenance of products, the department can use its scarce
         management and technical resources on activities unique to its
         mission.

      Because the costs of transport and internet protocol development
      and maintenance are so intertwined with other factors, it is


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RFC 939                                                    February 1985
Executive Summary of the NRC Report Transport on Protocols


      impossible to give a precise estimate of the savings that would be
      achieved by using commercial products.  Savings will vary in
      individual cases.  The marginal savings should range from 30 to 80
      percent.

   RECOMMENDATIONS

      The ISO protocols are now well specified but will not generally be
      commercially available for many months.  Nevertheless, this
      committee believes that the principles on which they are based are
      well-established, and the protocols can be made to satisfy fully
      DOD's needs.  The committee recommends that the DOD move toward
      adoption of TP-4 as costandard with TCP and toward exclusive use
      of TP-4.

      Transition to the use of the ISO standards, however, must be
      managed in a manner that will maintain DOD's operational
      capabilities and minimize risks.  The timing of the transition is,
      therefore, a major concern.

      Descriptions of two options that take this requirement into
      account follow.  A majority of the committee recommends the first
      option, while a minority favors the second.  A third option--to
      defer action--is also described but not recommended.

      Option 1

         The first option is for the DOD to immediately modify its
         current transport policy statement to specify TP-4 as a
         costandard along with TCP.  In addition, the DOD would develop
         a military specification for TP-4 that would also cover DOD
         requirements for discretionary options allowed under the NBS
         protocol specifications.  Requests for proposals (RFPs) for new
         networks or major upgrades of existing networks would specify
         TP-4 as the preferred protocol.  Contracts for TP-4 systems
         would be awarded only to contractors providing commercial
         products, except for unique cases.

         Existing networks that use TCP and new networks firmly
         committed to the use of TCP-based systems could continue to
         acquire implementations of TCP.  The DOD should carefully
         review each case, however, to see whether it would be
         advantageous to delay or modify some of these acquisitions in
         order to use commercial TP-4 products.  For each community of
         users it should be decided when it is operationally or




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RFC 939                                                    February 1985
Executive Summary of the NRC Report Transport on Protocols


         economically most advantageous to replace its current or
         planned systems in order to conform to ISO standards without
         excessively compromising continued operations.

         United States government test facilities would be developed to
         enable validation of TP-4 products (4).  The Department of
         Defense would either require that products be validated using
         these test facilities or that they be certified by the vendor.
         The test facilities could also be used to isolate multivendor
         protocol compatibility problems.  The existing NBS validation
         tools should be used as the base for the DOD test facilities.

         Because under this option networks based on both TCP and TP-4
         would coexist for some time, several capabilities that
         facilitate interoperability among networks would need to be
         developed.  The Department of Defense generally will not find
         them commercially available.  Examples are gateways among
         networks or specialized hosts that provide services such as
         electronic mail.  The department would need to initiate or
         modify development programs to provide these capabilities, and
         a test and demonstration network would be required.

      Option 2

         Under Option 2 the Department of Defense would immediately
         announce its intention to adopt TP-4 as a transport protocol
         costandard with TCP after a satisfactory demonstration of its
         suitability for use in military networks.  A final commitment
         would be deferred until the demonstration has been evaluated
         and TP-4 is commercially available.

         The demonstration should take at most eighteen months and
         should involve development of TP-4 implementations and their
         installation.  This option differs from Option 1 primarily in
         postponing the adoption of a TP-4 standard and, consequently,
         the issuance of RFPs based on TP-4 until successful completion
         of a demonstration.  The department, however, should proceed
         with those provisions of Option 1 that may be completed in
         parallel with the demonstration.  Early issuance of a TP-4
         military specification, development of validation procedures,
         and implementation of means for interoperability would be
         particularly important in this regard.







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RFC 939                                                    February 1985
Executive Summary of the NRC Report Transport on Protocols


      Option 3

         Under the third option the DOD would continue using TCP as the
         accepted transport standard and defer any decision on the use
         of TP-4 indefinitely.  The department would be expected to stay
         well informed on the development and use of the new protocol in
         the commercial and international arena and, with the National
         Bureau of Standards, work on means to transfer data between the
         two protocol systems.  Testing and evaluation of TP-4 standards
         by NBS would continue.  The DOD might eventually accommodate
         both protocol systems in an evolutionary conversion to TP-4.

      Comparison of Options

         The committee believes that all three options equally satisfy
         the functional objectives of the DOD, including matters of
         security.  It believes the two protocols are sufficiently
         similar and no significant differences in performance are to be
         expected if the chosen protocol implementation is of equal
         quality and is optimized for the given environment.

         The primary motivation for recommending Option 1 is to obtain
         the benefits of standard commercial products in the
         communication protocol area at an early date.  Benefits include
         smaller development, procurement, and support costs; more
         timely updates; and a wider product availability. By
         immediately committing to TP-4 as a costandard for new systems,
         Option 1 minimizes the number of systems that have to be
         converted eventually from TCP.  The ability to manage the
         transition is better than with Option 2 since the number of
         systems changed would be smaller and the time duration of mixed
         TCP and TP-4 operation would be shorter. Interoperability with
         external systems (NATO, government, commercial), which
         presumably will also use TP-4, would be brought about more
         quickly. Option 1 involves greater risk, however, since it
         commits to a new approach without as complete a demonstration
         of its viability.

         As with Option 1, a primary benefit of following Option 2 would
         be obtaining the use of standard commercial products.  Unit
         procurement costs probably would be lower than with Option 1
         because the commercial market for TP-4 will have expanded
         somewhat by the time DOD would begin to buy TP-4 products.
         Risk is smaller, compared to Option 1, because testing and
         demonstration of the suitability for military use will have
         preceded the commitment to the ISO protocols.  Transition and
         support costs would be higher than for Option 1, however,


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RFC 939                                                    February 1985
Executive Summary of the NRC Report Transport on Protocols


         because more networks and systems would already have been
         implemented with TCP.  Also this is perhaps the most difficult
         option to manage since the largest number of system conversions
         and the longest interval of mixed TCP and TP-4 operations would
         occur.  In addition, interoperability with external networks
         through standardization would be delayed.

         The principal benefit of exercising Option 3 would be the
         elimination of transition cost and the risk of faulty system
         behavior and delay.  It would allow the most rapid achievement
         of full internal interoperability among DOD systems.
         Manageability should be good because only one set of protocols
         would be in use (one with which the DOD already has much
         experience), and because the DOD would be in complete control
         of system evolution. Procurement costs for TCP systems would