rfc1017.txt

来自「RFC 的详细文档！」· 文本 代码 · 共 1,067 行 · 第 1/4 页

Network Working Group                                    Barry M. Leiner
Request for Comments: 1017                                         RIACS
                                                             August 1987

              Network Requirements for Scientific Research

              Internet Task Force on Scientific Computing

STATUS OF THIS MEMO

   This RFC identifies the requirements on communication networks for
   supporting scientific research.  It proposes some specific areas for
   near term work, as well as some long term goals.  This is an "idea"
   paper and discussion is strongly encouraged.  Distribution of this
   memo is unlimited.

INTRODUCTION

   Computer networks are critical to scientific research.  They are
   currently being used by portions of the scientific community to
   support access to remote resources (such as supercomputers and data
   at collaborator's sites) and collaborative work through such
   facilities as electronic mail and shared databases.  There is
   considerable movement in the direction of providing these
   capabilities to the broad scientific community in a unified manner,
   as evidence by this workshop. In the future, these capabilities will
   even be required in space, as the Space Station becomes a reality as
   a scientific research resource.

   The purpose of this paper is to identify the range of requirements
   for networks that are to support scientific research.  These
   requirements include the basic connectivity provided by the links and
   switches of the network through the basic network functions to the
   user services that need to be provided to allow effective use of the
   interconnected network.  The paper has four sections.  The first
   section discusses the functions a user requires of a network.  The
   second section discusses the requirements for the underlying link and
   node infrastructure while the third proposes a set of specifications
   to achieve the functions on an end-to-end basis.  The fourth section
   discusses a number of network-oriented user services that are needed
   in addition to the network itself.  In each section, the discussion
   is broken into two categories.  The first addresses near term
   requirements: those capabilities and functions that are needed today
   and for which technology is available to perform the function.  The
   second category concerns long term goals: those capabilities for
   which additional research is needed.

   This RFC was produced by the IAB Task force a Scientific Computing,



Leiner                                                          [Page 1]

RFC 1017          Requirements for Scientific Research       August 1987


   which is chartered to investigate advanced networking requirements
   that result from scientific applications.  Work reported herein was
   supported in part by Cooperative Agreement NCC 2-387 from the
   National Aeronautics and Space Administration (NASA) to the
   Universities Space Research Association (USRA).

1.  NETWORK FUNCTIONS

   This section addresses the functions and capabilities that networks
   and particularly internetworks should be expected to support in the
   near term future.

Near Term Requirements

   There are many functions that are currently available to subsets of
   the user community.  These functions should be made available to the
   broad scientific community.

User/Resource Connectivity

   Undoubtedly the first order of business in networking is to provide
   interconnectivity of users and the resources they need.  The goal in
   the near term for internetworking should be to extend the
   connectivity as widely as possible, i.e. to provide ubiquitous
   connectivity among users and between users and resources.  Note that
   the existence of a network path between sites does not necessarily
   imply interoperability between communities and or resources using
   non-compatible protocol suites.  However, a minimal set of functions
   should be provided across the entire user community, independent of
   the protocol suite being used.  These typically include electronic
   mail at a minimum, file transfer and remote login capabilities must
   also be provided.

Home Usage

   One condition that could enhance current scientific computing would
   be to extend to the home the same level of network support that the
   scientist has available in his office environment.  As network access
   becomes increasingly widespread, the extension to the home will allow
   the user to continue his computing at home without dramatic changes
   in his work habits, based on limited access.

Charging

   The scientific user should not have to worry about the costs of data
   communications any more than he worries about voice communications
   (his office telephone), so that data communications becomes an
   integral and low-cost part of our national infrastructure.  This



Leiner                                                          [Page 2]

RFC 1017          Requirements for Scientific Research       August 1987


   implies that charges for network services must NOT be volume
   sensitive and must NOT be charged back to the individual.  Either of
   these conditions forces the user to consider network resources as
   scarce and therefore requiring his individual attention to conserve
   them.  Such attention to extraneous details not only detracts from
   the research, but fundamentally impacts the use and benefit that
   networking is intended to supply.  This does not require that
   networking usage is free.  It should be either be low enough cost
   that the individual does not have to be accountable for "normal"
   usage or managed in such a manner that the individual does not have
   to be concerned with it on a daily basis.

Applications

   Most applications, in the near term, which must be supported in an
   internetwork environment are essentially extensions of current ones.
   Particularly:

      Electronic Mail

         Electronic mail will increase in value as the extended
         interconnectivity provided by internetworking provides a much
         greater reachability of users.

      Multimedia Mail

         An enhancement to text based mail which includes capabilities
         such as figures, diagrams, graphs, and digitized voice.

      Multimedia Conferencing

         Network conferencing is communication among multiple people
         simultaneously.  Conferencing may or may not be done in "real
         time", that is all participants may not be required to be on-
         line at the same time.  The multimedia supported may include
         text, voice, video, graphics, and possibly other capabilities.

      File Transfer

         The ability to transfer data files.

      Bulk Transfer

         The ability to stream large quantities of data.

      Interactive Remote Login

         The ability to perform remote terminal connections to hosts.



Leiner                                                          [Page 3]

RFC 1017          Requirements for Scientific Research       August 1987


      Remote Job Entry

         The ability to submit batch jobs for processing to remote hosts
         and receive output.

         Applications which need support in the near term but are NOT
         extensions of currently supported applications include:

      Remote Instrument Control

         This normally presumes to have a human in the "control loop".
         This condition relaxes the requirements on the (inter)network
         somewhat as to response times and reliability.  Timing would be
         presumed to be commensurate with human reactions and
         reliability would not be as stringent as that required for
         completely automatic control.

      Remote Data Acquisition

         This supports the collection of experimental data where the
         experiment is remotely located from the collection center.
         This requirement can only be satisfied when the bandwidth,
         reliability, and predictability of network response are
         sufficient.  This cannot be supported in the general sense
         because of the enormous bandwidth, very high reliability,
         and/or guaranteed short response time required for many
         experiments.

   These last two requirements are especially crucial when one considers
   remote experimentation such as will be performed on the Space
   Station.

Capabilities

   The above applications could be best supported on a network with
   infinite bandwidth, zero delay, and perfect reliability.
   Unfortunately, even currently feasible approximations to these levels
   of capabilities can be very expensive. Therefore, it can be expected
   that compromises will be made for each capability and between them,
   with different balances struck between different networks.  Because
   of this, the user must be given an opportunity to declare which
   capability or capabilities is/are of most interest-most likely
   through a "type-of-service" required declaration.  Some examples of
   possible trade-offs: File Transport Normally requires high
   reliability primarily and high bandwidth secondarily. Delay is not as
   important.





Leiner                                                          [Page 4]

RFC 1017          Requirements for Scientific Research       August 1987


      Bulk Transport

         Some applications such as digitized video might require high
         bandwidth as the most important capability.  Depending on the
         application, delay would be second, and reliability of lesser
         importance.  Image transfers of scientific data sometimes will
         invert the latter two requirements.

      Interactive Traffic

         This normally requires low delay as a primary consideration.
         Reliability may be secondary depending on the application.
         Bandwidth would usually be of least importance.

Standards

    The use of standards in networking is directed toward
    interoperability and availability of commercial equipment.  However,
    as stated earlier, full interoperability across the entire
    scientific community is probably not a reasonable goal for
    internetworking in the near term because of the protocol mix now
    present.  That is not to say, though, that the use of standards
    should not be pursued on the path to full user interoperability.
    Standards, in the context of near term goal support, include:

Media Exchange Standards

   Would allow the interchange of equations, graphics, images, and data
   bases as well as text.

Commercially Available Standards

   Plug compatible, commercially available standards will allow a degree
   of interoperability prior to the widespread availability of the ISO
   standard protocols.

Long Term Goals