RFC 939

RFC 939 💖 Executive Summary of the NRC Report on Transport Protocols for DoD Data Networks

okay bestie, let's get into it 🧚 this is an RFC from February 1985, written by the Network Working Group with the National Research Council as the organization behind it. it's a copy of the front matter of an NRC report, and it's distributed for information only ✨ its title block doesn't list anything it obsoletes or updates, so it doesn't replace or change any older RFC 🎀

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Status of This Memo 🌸

okay so this one is just here to share info (it's not an official rulebook) 📚 it does not set any policy for the DARPA research community or the DDN operational community 🙅‍♀️ and distribution is unlimited, so share away 💅

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Introduction 🍓

this RFC basically reposts the "front pages" of a report from the National Research Council 💜 that report studied the DOD's Internet Protocol (IP) and Transmission Control Protocol (TCP) and compared them to the ISO Internet Protocol (ISO-IP) and Transport Protocol level 4 (TP-4) 👀 the whole point is to get the Executive Summary out to people quickly 🚀 the order of stuff was shuffled around a bit and the page numbers changed, so don't be confused if it looks different from the original 💀

here's the full title of the report, verbatim:

                        Transport Protocols for
                         Department of Defense
                             Data Networks

                  Report to the Department of Defense
                  and the National Bureau of Standards

         Committee on Computer-Computer Communication Protocols

   Board on Telecommunications and Computer Applications Commission on
                   Engineering and Technical Systems
                       National Research Council

                         National Academy Press
                    Washington, D.C.  February 1985

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Overview ✨

so the project behind this report got the green light from the Governing Board of the National Research Council 🌈 that board's members come from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine 🏛️ the committee members were picked for their special skills, and the group cared about having a good balance of people 🫶

the report was also reviewed by a group that didn't write it 🔍 that review followed procedures approved by a Report Review Committee made up of members of those same three academies 💅

some background, because it's giving history class 📜 the National Research Council was set up by the National Academy of Sciences in 1916 🎓 its whole job is connecting the science and tech community with the Academy's goals of spreading knowledge and advising the federal government 🧠 it runs under the general policies the Academy sets, which come from the Academy's congressional charter of 1863. that charter makes the Academy a private, nonprofit, self-governing membership corporation 🏅 the Council is the main operating agency for both the National Academy of Sciences and the National Academy of Engineering when they serve the government, the public, and the science and engineering communities 💜 both Academies and the Institute of Medicine run it together 🤝 the National Academy of Engineering and the Institute of Medicine were founded in 1964 and 1970, respectively, under the National Academy of Sciences' charter ✨

this work was funded by Contract No. DCA-83-C-0051 between the U.S. Defense Communications Agency and the National Academy of Sciences 💖 the Department of Defense and the National Bureau of Standards underwrote it together 🎀

if you want your own copy of the full report, here's where to get it 📬

   Board on Telecommunications and Computer Applications Commission
   on Engineering and Technical Systems
   National Research Council
   2101 Constitution Avenue, N.W.
   Washington, D.C. 20418

more to come bestie 🧚💜 part 2 is next, and it's got the Preface and the start of the Executive Summary 👑

Okay so, interoperability is a huge DOD need 🫶 Ideally, DOD networks would let operators at any terminal access, or be accessed by, applications on any computer. That means more network power for users, integration of independently developed systems, better use of resources, and increased survivability ✨ To help make this happen, the Office of the Secretary of Defense has mandated the use of TCP for the Defense Communication System's Defense Data Network (DDN), unless waivers are granted. The Defense Communication Agency (DCA) is also setting standards for three higher-level "utility" protocols for file transfer, terminal access, and electronic mail 📬 Partly because of all this, it's become super clear that there's growing momentum toward accepting interoperability, and people recognize it as an important operational need 💜

Here's the thing, though: functional interoperability only happens with full generality when two communication nodes can interoperate at all protocol levels 🎀 For the DOD, the relevant levels are:

1. Internet, using IP;
2. Transport, using TCP;
3. Utility, using file, terminal, or mail protocols; and
4. Specific applications that use the above protocols for their particular purpose.

So if a network is built on one transport protocol, it generally won't be able to interoperate functionally with other networks using that same transport protocol, unless both networks are also using the higher-level utility and application protocols 😭 When evaluating whether to convert to TP-4 and when developing a transition plan, the following factors must be considered:

• The DOD has tons of communities of interest whose main need is to interoperate within their own members, independently 🧚 These communities usually 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 mainly needed between the higher layer application programs that are initially unique to each community of interest.
• There are many different kinds of operations needed between communities of interest 🌈 Examples include headquarters needing access to several subordinate communities, and the communities needing some minimum functional interoperability with each other (like mail exchange).
• The need for functional interoperability can pop up unexpectedly and urgently, during a crisis or when better management opportunities are discovered 🚨 Widespread standardization of TP-4 and higher-level protocols can readily help meet 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 goals that have pushed 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 shows they're functionally equivalent and provide essentially similar services 💅 Since a great deal of care and experience went into writing the TP-4 specifications, the committee is confident that TP-4 will meet military requirements 🫶

Although the two protocols are different, those differences don't compromise DOD requirements 🌸 And even though they handle the data transfer interface, flow control, connection establishment, and out-of-band services in different ways, neither one seems intrinsically superior 👑

So, while existing applications may need some modification if they're moved from TCP to TP-4, new applications can be written to use either protocol with a similar level of effort ✨

TCP and TP-4 are sufficiently equivalent in their security-related properties, in that there are no significant technical points favoring one over the other 🔥

Okay, but while TCP currently has the edge in maturity of implementation, TP-4 is gaining rapidly because of 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 using TCP exclusively 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 🌈

TP-4, on the other hand, hasn't been implemented in any large operational system yet 🙈 It has been tested experimentally, though, and has been endorsed by many commercial vendors worldwide. Substantial portions of TP-4 were also demonstrated at the National Computer Conference in July 1984 💜

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

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

Even though the DOD networks were a model for the ISO transport standards, 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 isn't realistic to hope TP-4 can be altered to conform with TCP 🙈 That raises the question of what action the DOD should take with respect to the ISO standard 🤔

SOME ECONOMIC CONSIDERATIONS 💰

The DOD has a large and growing commitment to 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 for upgrading 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 upgrades. Once those 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'll become interoperable and multilevel secure using an advanced technology that's currently under development. If these plans go ahead on schedule, a delay of several years in moving to TP-4 would mean the DOD networks in the late 1980s would be virtually all TCP-based. Converting to international standards later would be very expensive if it were hastily attempted in order to maintain established DOD interoperability and gain interoperability with a large body of users 💸

As DOD policy recognizes, there are significant advantages to using commercial vendor products if they meet the department's operational needs 🛍️ The major advantages are:

• 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 🌟 So the DOD may eventually be able 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's impossible to give a precise estimate of the savings from 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 they won't generally be commercially available for many months. Still, this committee believes the principles they're based on are well-established, and the protocols can be made to fully satisfy DOD's needs 💖 The committee recommends that the DOD move toward adopting TP-4 as costandard with TCP, and toward exclusive use of TP-4 ✨

Transitioning to the ISO standards, however, must be managed in a way that maintains DOD's operational capabilities and minimizes risks 🛡️ So the timing of the transition is a major concern ⏰

Two options that take this requirement into account are described below. 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 costandard along with TCP 🌈 In addition, the DOD would develop a military specification for TP-4 that also covers DOD requirements for the 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 🧚

Okay so the whole plan is a three-way fork in the road 🛣️✨ and I need you to see every branch, bestie 💅

Existing networks that already run TCP, plus new networks that are fully committed to TCP-based systems, could keep buying TCP implementations 🎀 The DOD should carefully review each case, though, to check whether it's worth delaying or changing some of those purchases so it can use commercial TP-4 products 👀 For each community of users, the question is when it's most operationally or economically smart to swap out current or planned systems so they conform to ISO standards, without wrecking continued operations 🫶

United States government test facilities would be built to validate TP-4 products (4) 🧪 The Department of Defense would either require that products get validated at these test facilities or require that vendors certify them 💼 The test facilities could also be used to track down multivendor protocol compatibility problems 🔍 The existing NBS validation tools should be the base for the DOD test facilities 🛠️

Here's the tea 🍵 Under this option, TCP-based and TP-4-based networks would coexist for a while, so several capabilities that help networks talk to each other would need to be developed 🌉 The Department of Defense generally won't find these commercially available 😭 Examples are gateways between networks, or specialized hosts that provide services like electronic mail 📧 The department would need to start or modify development programs to deliver these capabilities, and a test and demonstration network would be required 🧚

Option 2

Under Option 2, the Department of Defense would immediately announce that it plans to adopt TP-4 as a transport protocol costandard with TCP, once a satisfactory demonstration shows it's suitable for military networks 📣 The final commitment would wait until the demonstration has been evaluated and TP-4 is commercially available ⏳

The demonstration should take at most eighteen months 🗓️ and should involve building TP-4 implementations and installing them 🛠️ This option differs from Option 1 mainly by postponing the adoption of a TP-4 standard and, as a result, the issuance of RFPs based on TP-4, until a demonstration is successfully completed 🙈 The department, however, should still move ahead with the parts of Option 1 that can be finished in parallel with the demonstration 🏃‍♀️ Early issuance of a TP-4 military specification, development of validation procedures, and putting in place means for interoperability would be especially important here 🔥

Option 3

Under the third option, the DOD would keep using TCP as the accepted transport standard and defer any decision on TP-4 indefinitely 🧊 The department would be expected to stay well informed about how the new protocol is developed and used in the commercial and international arena 👀 Working with the National Bureau of Standards, it would also work on ways 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 through an evolutionary conversion to TP-4 🦋

Comparison of Options

The committee believes all three options equally satisfy the functional objectives of the DOD, including matters of security 🛡️ It also believes the two protocols are similar enough, and that no significant differences in performance should be expected, as long as the chosen protocol implementation is of equal quality and is optimized for its environment 💖

The main reason to recommend Option 1 is to get the benefits of standard commercial products in the communication protocol area early 🚀 Those benefits include smaller development, procurement, and support costs, more timely updates, and wider product availability 🌈 By committing to TP-4 as a costandard for new systems right away, Option 1 minimizes the number of systems that will eventually have to be converted away from TCP 🙌 Managing the transition is easier than with Option 2, since fewer systems would change and the mixed TCP and TP-4 period would be shorter ⏱️ Interoperability with external systems (NATO, government, commercial), which will presumably also use TP-4, would arrive sooner too 🤝 Option 1 is riskier, though, because it commits to a new approach without as complete a demonstration of its viability 😬

Just like Option 1, the big win of Option 2 is getting standard commercial products 🛍️ Unit procurement costs would probably be lower than under Option 1, because the commercial market for TP-4 will have grown somewhat by the time DOD starts buying TP-4 products 📈 Risk is lower than Option 1, because testing and demonstration of military suitability would happen before the commitment to the ISO protocols 🧘‍♀️ Transition and support costs would be higher than Option 1, though, because more networks and systems would already be running TCP 💸 This is also probably the hardest option to manage, since it has the largest number of system conversions and the longest stretch of mixed TCP and TP-4 operation 😵‍💫 On top of that, interoperability with external networks through standardization would be delayed 🐢

The main payoff of Option 3 would be no transition cost and no risk of faulty system behavior or delay 🎉 It would allow the fastest route to full internal interoperability among DOD systems 🏁 Manageability should be good, because only one set of protocols would be in use (one the DOD already has lots of experience with), and because the DOD would be in complete control of system evolution 🎛️ Procurement costs for TCP systems would stay high compared with standard ISO protocol products, though, and implementations for new systems and releases would stay limited 📦 External interoperability with non-DOD systems would be limited and inefficient 😤

Okay, the summary 📝 Option 1 gives the fastest path toward commercial products and interoperability with external systems 🏎️ Option 2 reduces risk but involves somewhat more delay and expense 🐌 Option 3 has the least risk and gives the quickest route to interoperability inside the Defense Department at the lowest short-term cost 💎 But those come with penalties: incompatibility with NATO and other external systems, and higher life-cycle costs 💀

Notes ✨

(1) The Advanced Research Projects Agency (ARPA) was reorganized and became the Defense Advanced Research Projects Agency (DARPA) in 1973. 🫧

(2) The ISO Transport Protocol and ISO Internetwork Protocol became Draft International Standards in September 1983 and April 1984, respectively. Commercial vendors normally consider Draft International Standards to be ready for implementation. 🎀

(3) Except where noted, the abbreviation TCP generally refers to both the DOD's Transmission Control Protocol and its Internet Protocol. Similarly, the abbreviation TP-4 refers to both the ISO Transport Protocol class 4 and its Internetwork Protocol. (Transport Protocol classes 0 to 3 are used for special purposes not related to those of this study.) 🧩

(4) Validation means a systematic and thorough state-of-the-art testing of the products to assure that all technical specifications are being achieved. 🔬

CONTENTS OF THE FULL REPORT 📚

   PREFACE .........................................................  ix

   EXECUTIVE SUMMARY ...............................................  xi

   I     Introduction ...............................................  1

   II    Review of NBS and DOD Objectives ...........................  3

   III   Comparison of DOD and ISO Protocols .......................  13

   IV    Status of DOD and ISO Protocol
         Implementations and Specifications .......................   25

   V     Markets ...................................................  31

   VI    Development of Standard Commercial versus
         Special Commercial Products ...............................  39

   VII   Responsiveness of International Standards
         Process to Change .........................................  43

   VIII  Options for DOD and NBS ...................................  45

   IX    Cost Comparison of Options ...............................   47

   X     Evaluation of Options .....................................  53

   XI    Recommendations ...........................................  61

Committee 🌸

          BOARD ON TELECOMMUNICATIONS -- COMPUTER APPLICATIONS
         COMMITTEE ON COMPUTER-COMPUTER COMMUNICATION PROTOCOLS

   Chairman

      C. CHAPIN CUTLER, Professor of Applied Physics, Stanford
      University, Stanford, California

   Members

      HERBERT D. BENINGTON, Technical Director, System Development
      Corporation, McLean, Virginia

      DONALD L. BOYD, Director, Honeywell Corporate Computer Sciences
      Center, Honeywell Corporate Technology Center, Bloomington,
      Minnesota

      DAVID J. FARBER, Professor of Electrical Engineering and Professor
      of Computer Science, Department of Electrical Engineering,
      University of Delaware, Newark, Delaware

      LAWRENCE H. LANDWEBER, Professor, Computer Sciences Department,
      University of Wisconsin, Madison, Wisconsin

      ANTHONY G. LAUCK, Manager, Distributed Systems Architecture and
      Advanced Development, Digital Equipment Corporation, Tewksbury,
      Massachusetts

      KEITH A. LUCKE, General Manager of Control Data Technical
      Standards, Control Data Corporation, Minneapolis, Minnesota

      MISCHA SCHWARTZ, Professor of Electrical Engineering and Computer
      Science, Columbia University, New York, New York

      ROBERT F. STEEN, Director of Architecture, Communication Products
      Division IBM Corporation, Research Triangle Park, North Carolina

      CARL A. SUNSHINE, Principal Engineer, Sytek, Incorporated, Los
      Angeles Operation, Culver City, California

      DANIEL J. FINK, (Ex-officio), President, D.J. Fink Associates,
      Inc., Arlington, Virginia

      JAMES L. FLANAGAN, (CETS LIAISON MEMBER), Head, Acoustics Research
      Department, AT&T Bell Laboratories, Murray Hill, New Jersey

   Staff

      RICHARD B. MARSTEN, Executive Director
      JEROME D. ROSENBERG, Senior Staff Officer and Study Director
      LOIS A. LEAK, Administrative Secretary

            COMMISSION ON ENGINEERING AND TECHNICAL SYSTEMS
          BOARD ON TELECOMMUNICATIONS -- COMPUTER APPLICATIONS

   Chairman

      DANIEL J. FINK, President, D.J. Fink Associates, Inc., Arlington,
      Virginia

   Past Chairman

      BROCKWAY MCMILLAN, Vice President (Retired), Bell Laboratories,
      Sedgwick, Maine

   Members

ARTHUR G. ANDERSON, Vice President (Retired), IBM Corporation, San Jose, California 🎀

DANIEL BELL, Henry Ford II Professor of Social Sciences, Department of Sociology, Harvard University, Cambridge, Massachusetts 📚

HERBERT D. BENINGTON, Technical Director, System Development Corporation, McLean, Virginia 💜

ELWYN R. BERLEKAMP, Professor of Mathematics, Department of Mathematics, University of California, Berkeley, California 🧮

ANTHONY J. DEMARIA, Assistant Director of Research for Electronics and Electro-Optics Technology, United Technologies Research Center, East Hartford, Connecticut ⭐

GERALD P. DINNEEN, Vice President, Science and Technology, Honeywell Incorporated, Minneapolis, Minnesota 🌸

GEORGE GERBNER, Professor and Dean, The Annenberg School of Communications, University of Pennsylvania, Philadelphia, Pennsylvania 🦋

ANNE P. JONES, Partner, Sutherland, Asbill and Brennan, Washington, D.C. 👑

ADRIAN M. MCDONOUGH, Professor of Management and Decision Sciences (Retired), The Wharton School, University of Pennsylvania, Havertown, Pennsylvania 🍓

WILBUR L. PRITCHARD, President, Satellite Systems Engineering, Inc., Bethesda, Maryland 🛰️

MICHAEL B. PURSLEY, Professor of Electrical Engineering, University of Illinois, Urbana, Illinois 💅

IVAN SELIN, Chairman of the Board, American Management Systems, Inc., Arlington, Virginia 🫶

MISCHA SCHWARTZ, Professor of Electrical Engineering and Computer Science, Columbia University, New York, New York 🌈

ERIC E. SUMNER, Vice President, Operations System and Network Planning, AT&T Bell Laboratories, Holmdel, New Jersey ⚡

KEITH W. UNCAPHER, Executive Director, USC-Information Sciences Institute Associate Dean, School of Engineering, University of Southern California, Marina del Rey, California 🧚

JAMES L. FLANAGAN, (CETS LIAISON MEMBER), Head, Acoustics Research Department, AT&T Bell Laboratories, Murray Hill, New Jersey 🎧

Staff

Richard B. Marsten, Executive Director 🌟

Jerome D. Rosenberg, Senior Staff Officer 🌷

Karen Laughlin, Administrative Coordinator 🗂️

Carmen A. Ruby, Administrative Assistant 💖

Lois A. Leak, Administrative Secretary 🩷

And that's the whole squad, bestie! 🌈✨