rfc1077.txt

RFC 的详细文档！

Network Working Group                              Gigabit Working Group
Request for Comments: 1077                             B. Leiner, Editor
                                                           November 1988


              Critical Issues in High Bandwidth Networking


Status of this Memo

   This memo presents the results of a working group on High Bandwidth
   Networking.  This RFC is for your information and you are encouraged
   to comment on the issues presented.  Distribution of this memo is
   unlimited.

ABSTRACT

   At the request of Maj. Mark Pullen and Maj. Brian Boesch of DARPA, an
   ad-hoc working group was assembled to develop a set of
   recommendations on the research required to achieve a ubiquitous
   high-bandwidth network as discussed in the FCCSET recommendations for
   Phase III.

   This report outlines a set of research topics aimed at providing the
   technology base for an interconnected set of networks that can
   provide highbandwidth capabilities.  The suggested research focus
   draws upon ongoing research and augments it with basic and applied
   components.  The major activities are the development and
   demonstration of a gigabit backbone network, the development and
   demonstration of an interconnected set of networks with gigabit
   throughput and appropriate management techniques, and the development
   and demonstration of the required overall architecture that allows
   users to gain access to such high bandwidth.


















Gigabit Working Group                                           [Page 1]

RFC 1077                                                   November 1988


   1.  Introduction and Summary



   1.1.  Background


   The computer communications world is evolving toward both high-
   bandwidth capability and high-bandwidth requirements.  The recent
   workshop conducted under the auspices of the FCCSET Committee on High
   Performance Computing [1] identified a number of areas where
   extremely high-bandwidth networking is required to support the
   scientific research community.  These areas range from remote
   graphical visualization of supercomputer results through the movement
   of high rate sensor data from space to the ground-based scientific
   investigator.  Similar requirements exist for other applications,
   such as military command and control (C2) where there is a need to
   quickly access and act on data obtained from real-time sensors.  The
   workshop identified requirements for switched high-bandwidth service
   in excess of 300 Mbit/s to a single user, and the need to support
   service in the range of a Mbit/s on a low-duty-cycle basis to
   millions of researchers.  When added to the needs of the military and
   commercial users, the aggregate requirement for communications
   service adds up to many billions of bits per second.  The results of
   this workshop were incorporated into a report by the FCCSET [2].

   Fortunately, technology is also moving rapidly.  Even today, the
   installed base of fiber optics communications allows us to consider
   aggregate bandwidths in the range of Gbit/s and beyond to limited
   geographical regions.  Estimates arrived at in the workshop lead one
   to believe that there will be available raw bandwidth approaching
   terabits per second.

   The critical question to be addressed is how this raw bandwidth can
   be used to satisfy the requirements identified in the workshop: 1)
   provide bandwidth on the order of several Gbit/s to individual users,
   and 2) provide modest bandwidth on the order of several Mbit/s to a
   large number of users in a cost-effective manner through the
   aggregation of their traffic.

   Through its research funding, the Defense Advanced Research Projects
   Agency (DARPA) has played a central role in the development of
   packet-oriented communications, which has been of tremendous benefit
   to the U.S. military in terms of survivability and interoperability.
   DARPA-funded research has resulted in the ARPANET, the first packet-
   switched network; the SATNET, MATNET and Wideband Network, which
   demonstrated the efficient utilization of shared-access satellite
   channels for communications between geographically diverse sites;



Gigabit Working Group                                           [Page 2]

RFC 1077                                                   November 1988


   packet radio networks for mobile tactical environments; the Internet
   and TCP/IP protocols for interconnection and interoperability between
   heterogeneous networks and computer systems; the development of
   electronic mail; and many advances in the areas of network security,
   privacy, authentication and access control for distributed computing
   environments.  Recognizing DARPA's past accomplishments and its
   desire to continue to take a leading role in addressing these issues,
   this document provides a recommendation for research topics in
   gigabit networking.  It is meant to be an organized compendium of the
   critical research issues to be addressed in developing the technology
   base needed for such a high bandwidth ubiquitous network.


   1.2.  Ongoing Activities


   The OSTP report referred to above recommended a three-phase approach
   to achieving the required high-bandwidth networking for the
   scientific and research community.  Some of this work is now well
   underway.  An ad-hoc committee, the Federal Research Internet
   Coordinating Committee (FRICC) is coordinating the interconnection of
   the current wide area networking systems in the government; notably
   those of DARPA, Department of Energy (DoE), National Science
   Foundation (NSF), National Aeronautics and Space Administration
   (NASA), and the Department of Health and Human Services (HHS).  In
   accordance with Phases I and II of the OSTP report, this activity
   will provide for an interconnected set of networks to support
   research and other scholarly pursuits, and provide a basis for future
   networking for this community.  The networking is being upgraded
   through shared increased bandwidth (current plans are to share a 45
   Mbit/s backbone) and coordinated interconnection with the rest of the
   world.  In particular, the FRICC is working with the European
   networking community under the auspices of another ad-hoc group, the
   Coordinating Committee for Intercontinental Research Networks
   (CCIRN), to establish effective US-Europe networking.

   However, as the OSTP recommendations note, the required bandwidth for
   the future is well beyond currently planned public, private, and
   government networks.  Achieving the required gigabit networking
   capabilities will require a strong research activity.  There is
   considerable ongoing research in relevant areas that can be drawn
   upon; particularly in the areas of high-bandwidth communication
   links, high-speed computer switching, and high-bandwidth local area
   networks.  Appendix A provides some pointers to current research
   efforts.






Gigabit Working Group                                           [Page 3]

RFC 1077                                                   November 1988


   1.3.  Document Overview


   This report outlines a set of research topics aimed at providing the
   technology base for an interconnected set of networks that can
   provide the required high-bandwidth capabilities discussed above.
   The suggested research focus draws upon ongoing research and augments
   it with basic and applied components.  The major activities are the
   development and demonstration of a Gigabit Backbone network (GB) [3],
   the development and demonstration of an interconnected set of
   networks with gigabit throughput and appropriate management
   techniques, and the development and demonstration of the required
   overall architecture that allows users to gain access to such high
   bandwidth.  Section 2 discusses functional and performance goals
   along with the anticipated benefits to the ultimate users of such a
   system.  Section 3 provides the discussion of the critical research
   issues needed to achieve these goals.  It is organized into the major
   areas of technology that need to be addressed: general architectural
   issues, high-bandwidth switching, high-bandwidth host interfaces,
   network management algorithms, and network services.  The discussion
   in some cases contains examples of ongoing relevant research or
   potential approaches.  These examples are intended to clarify the
   issues and not to propose that particular approach.  A discussion of
   the relationship of the suggested research to other ongoing
   activities and optimal methods for pursuing this research is provided
   in Section 4.


   2.  Functional and Performance Goals


   In this section, we provide an assessment of the types of services a
   GN (four or five orders of magnitude faster than the current
   networks) should provide to its users.  In instances where we felt
   there would be a significant impact on performance, we have provided
   an estimate of the amount of bandwidth needed and delay allowable to
   provide these services.


   2.1.  Networking Application Support


   It is envisioned that the GN will be capable of supporting all of the
   following types of networking applications.







Gigabit Working Group                                           [Page 4]

RFC 1077                                                   November 1988


   Currently Provided Packet Services

      It is important that the network provide the users with the
      equivalent of services that are already available in packet-
      switched networks, such as interactive data exchange, mail
      service, file transfer, on-line access to remote computing
      resources, etc., and allow them to expand to other more advanced
      services to meet their needs as they become available.

   Multi-Media Mail

      This capability will allow users to take advantage of different
      media types (e.g., graphics, images, voice, and video as well as
      text and computer data) in the transfer of messages, thereby
      increasing the effectiveness of message exchange.

   Multi-Media Conferencing

      Such conferencing requires the exchange of large amounts of
      information in short periods of time.  Hence the requirement for
      high bandwidth at low delay.  We estimate that the bandwidth would
      range from 1.5 to 100 Mbit/s, with an end-to-end delay of no more
      than a few hundred msec.

   Computer-Generated Real-time Graphics

      Visualizing computer results in the modern world of supercomputers
      requires large amounts of real time graphics.  This in turn will
      require about 1.5 Mbit/s of bandwidth and no more than several
      hundred msec.  delay.

   High-Speed Transaction Processing

      One of the most important reasons for having an ultra-high-speed
      network is to take advantage of supercomputing capability.  There
      are several scenarios in which this capability could be utilized.
      For example, there could be instances where a non-supercomputer
      may require a supercomputer to perform some processing and provide
      some intermediate results that will be used to perform still
      further processing, or the exchange may be between several
      supercomputers operating in tandem and periodically exchanging
      results, such as in a battle management, war gaming, or process
      control applications.  In such cases, extremely short response
      times are necessary to accomplish as many as hundreds of
      interactions in real time.  This requires very high bandwidth, on
      the order of 100 Mbit/s, and minimum delay, on the order of
      hundreds of msec.