rfc942.txt

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  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, 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

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RFC 942                                                    February 1985
Report Transport on Protocols

  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 remain high compared with standard ISO protocol
  products, however, and availability of implementations for new systems
  and releases would remain limited.  External interoperability with
  non-DOD systems would be limited and inefficient.

  In summary, Option 1 provides the most rapid path toward the use of
  commercial products and interoperability with external systems.
  Option 2 reduces the risk but involves somewhat greater delay and
  expense.  Option 3 involves the least risk and provides the quickest
  route to interoperability within the Defense Department at the least
  short-term cost.  These are, however, accompanied by penalties of
  incompatibility with NATO and other external systems and higher
  life-cycle costs.






























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RFC 942                                                    February 1985
Report Transport on Protocols

                                      

     



















































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RFC 942                                                    February 1985
Report Transport on Protocols

                            I.  INTRODUCTION

For the past two decades industry and government have experienced an
increasing need to share software programs, transfer data, and exchange
information among computers.  As a result, computer-to-computer data
communications networks and, therefore, communication formats and
procedures, or protocols, have proliferated.  The need to interconnect
these networks is obvious, but the problems in establishing agreements
among users on the protocols have heightened.

The Department of Defense (DOD) has been conducting research and
development on protocols and communication standards for more than
fifteen years.  In December 1978 the DOD promulgated versions of the
Defense Advanced Research Projects Agency's (DARPA) Transmission Control
Protocol (TCP) and Internet Protocol (IP) as standards within DOD.  With
the participation of major manufacturers and systems houses, the DOD has
implemented successfully over twenty different applications of these
standards in DOD operational data communications networks.

The Institute for Computer Sciences and Technology (ICST) of the
National Bureau of Standards (NBS) is the government agency responsible
for developing network protocols and interface standards to meet the
needs of federal agencies.  The Institute has been actively helping
national and international voluntary standards organizations develop
sets of protocol standards that can be incorporated into commercial
products.

Working with both industry and government agencies, the ICST has
developed protocol requirements based, in terms of functions and
services, on the DOD's TCP.  These requirements were submitted to the
International Standards Organization (ISO) and resulted in the
development of a transport protocol (TP-4) that has the announced
support of twenty computer manufacturers.

Although the ISO's TP-4 is based on the DOD's TCP, the two protocols are
not compatible.  Thus manufacturers who wish to serve DOD, while
remaining able to capture a significant share of the worldwide market,
have to field two product lines that are incompatible but perform the
same function.  The Institute for Computer Sciences and Technology would
like to have a single set of protocol standards that serves both the
DOD, other government agencies, and commercial vendors.

It would be to the advantage of the DOD to use the same standards as the
rest of the world.  The dilemma, however, is understandable:  The DOD










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RFC 942                                                    February 1985
Report Transport on Protocols

has well satisfied its requirements by its own tried and proven
protocols, the agency has invested heavily in systems operating
successfully with TCP, and the Armed Forces is increasingly adopting the
protocol.  Thus, although DOD's policy is to use commercial standards
whenever suitable, it is hesitant about converting to the ISO TP-4
protocols.  In addition, the DOD is not certain whether the ISO TP-4
completely satisfies military requirements.

In 1983 both DOD and the ICST agreed that an objective study of the
situation was needed.  Each requested assistance from the National
Research Council.  The National Research Council, through its Board on
Telecommunications and Computer Applications (BOTCAP), appointed a
special Committee on Computer-Computer Communication Protocols to study
the issues and develop recommendations and guidelines for ways to
resolve the differences in a mutually beneficial manner.

 The six items composing the committee's scope of work are as follows:

 1.   Review the technical aspects of the DOD transmission control and
      ICST transport protocols.

 2.   Review the status of the implementation of these protocols.

 3.   Review the industrial and government markets for these protocols.

 4.   Analyze the technical and political implications of the DOD and
      ICST views on the protocols.

 5.   Report on time and cost implications to the DOD, other federal
      entities, and manufacturers of the DOD and ICST positions.

 6.   Recommend courses of action toward resolving the differences
      between the DOD and ICST on these protocol standards.

The committee devoted considerable effort to reviewing the objectives
and goals of the DOD and NBS that relate to data communications, the
technical aspects of the two protocols, the status of their
implementation in operating networks, and the market conditions
pertaining to their use. This process included hearing government and
industry presentations and reviewing pertinent literature.  The results
of this part of the study are presented in Sections II through VII.
Concurrent with this research and analysis, the committee developed ten
possible options that offered plausible resolutions of the problem.
These ranged from maintaining the status quo to an immediate switchover
from one protocol to the other. From these ten initial options three
were determined to hold the greatest potential for resolving the
problem.

Section VIII describes the three options, Section IX provides a cost
comparison, and Section X provides an overall evaluation of the three
options.  Section XI presents the committee's basic and detailed
recommendations for how best the DOD might approach the differences
between its protocol and the ISO protocol.

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RFC 942                                                    February 1985
Report Transport on Protocols

                 II.  REVIEW OF NBS AND DOD OBJECTIVES

The National Bureau of Standards and the Department of Defense are such
disparate organizations that the committee felt it needed to begin its
study with a definition of the roles and expectations of each with
regard to the protocol issues in question.  The following provides a
review of each organization's objectives (5).

NBS OBJECTIVES

 The National Bureau of Standards has three primary goals in computer
 networking:

  1.   To develop networking and protocol standards that meet U.S.
       government and industry requirements and that will be implemented
       in off-the-shelf, commercial products.

  2.   To develop testing methodologies to support development and
       implementation of computer network protocols.

  3.   To assist government and industry users in the application of
       advanced networking technologies and computer and communications
       equipment manufacturers in the implementation of standard
       protocols.

 Development of Networking and Protocol Standards

  The Bureau accomplishes the first objective through close coordination
  and cooperation with U.S. computer manufacturers and communications
  system developers.  Technical specifications are developed
  cooperatively with U.S. industry and other government agencies and
  provided as proposals to voluntary standards organizations.

  Because the Department of Defense is potentially the largest
  government client of these standards, DOD requirements are carefully
  factored into these proposals.  In addition, protocols for
  computer-to-computer communications developed within the DOD research
  community are used as an

  










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(5)  The objectives were reviewed by representatives of NBS and DOD,
respectively.

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RFC 942                                                    February 1985
Report Transport on Protocols

  exact statement of DOD functional needs for a particular protocol and
  form a basis for the functions, features, and services of NBS-proposed
  standards.

  To further the development of commercial products that implement
  standards, the NBS gives priority to the needs of U.S. computer
  manufacturers who wish to market their products nationally and
  internationally, not just to the U.S. government.  The NBS
  participates, therefore, in national and international voluntary
  standards organizations toward the development of an international
  consensus based on United States needs.  Specifications, formal
  description techniques, testing methodologies, and test results
  developed by the NBS are used to further the international
  standardization process.

 Development of Testing Methodologies

  The National Bureau of Standards has laboratory activities where
  prototypes of draft protocol standards are implemented and tested in a
  variety of communications environments supporting different
  applications on different kinds and sizes of computers.
  Communications environments include, for example, global networks,
  local networks, and office system networks.  Applications may, for
  example, include file transfer or message processing.  The primary
  purposes are to advance the state of the art in measurement
  methodologies for advanced computer networking technologies and
  determine protocol implementation correctness and performance.

  The NBS views testing as a cooperative research effort and works with
  other agencies, private-sector companies, and other countries in the
  development of methodologies.  At this time, this cooperation involves