rfc1015.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

    provide this capability was MFEnet [11].  It was established in the
    early 1970's to provide DOE-supported users access to
    supercomputers, particularly a Cray 1 at Lawrence Livermore National



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RFC 1015                      IRI Plan                         July 1987


    Labs. Because MFEnet was established prior to widespread adoption of
    the TCP/IP protocol suite (to be discussed below), the MFEnet uses a
    different set of protocols. However, interfaces have been developed
    between the MFEnet and other networks, and a migration plan is
    currently under development.

    NASA Ames Research Center has long been in the forefront of using
    advanced computers to support scientific research.  The latest
    computing facility, the Numerical Aerodynamic Simulator, uses a Cray
    2 and other machines along  with a number of networking technologies
    to provide support to computational fluid dynamics researchers [14].
    This system uses the TCP/IP protocol suite both locally and remotely
    and provides easy access through advanced workstations.

    Recognizing the importance of advanced computers in carrying out
    scientific research, NSF in 1984 embarked on an ambitious program to
    provide supercomputer access to researchers. This program involved
    both the provision of supercomputers themselves (through purchase of
    computer time initially, and establishment of supercomputer centers)
    and provision of access to those supercomputers through an extensive
    networking program, NSFnet [15]. The NSFnet uses a number of
    existing networks (e.g. Arpanet, BITNET, MFEnet) and exploratory
    networks interconnected using the TCP/IP protocol suite (discussed
    below) to permit scientists widespread access to the supercomputer
    centers and each other. The NSFnet is also taking advantage of the
    widespread installation of campus and regional networks to achieve
    this connectivity in a cost effective manner.

    The above are only a small number of the current and existing
    networks being used to support research.  Quarterman [11] provides a
    good synopsis of the networks currently in operation. It is obvious
    from this that effective interconnection of the networks can provide
    cost-efficient and reliable services.

    Starting in the early 1970's, recognizing that the military had a
    need to interconnect various networks (such as packet radio for
    mobile operation with long-line networks like the Arpanet), DARPA
    initiated the development of the internet technologies [16].
    Beginning with the development of the protocols for interconnection
    and reliable transport (TCP/IP), the program  has developed methods
    for providing electronic mail, remote login, file transfer and
    similar functions between differing computers over dissimilar
    networks [4,3].  Today, using that technology, thousands of
    computers are able to communicate with each other over a "virtual
    network" of approximately 200 networks using a common set of
    protocols. The concepts developed are being used in the reference
    model and protocols of the Open Systems Interconnection model being
    developed by the International Standards Organization (ISO) [17].



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RFC 1015                      IRI Plan                         July 1987


    This is becoming even more important with the widespread use of
    local area networks.  As institutions install their own networks,
    and need to establish communications with computers at other sites,
    it is important to have a common set of protocols and a means for
    interconnecting the local networks to wide area networks.

Internet Model

    The DARPA Internet system uses a naming and addressing protocol,
    called the Internet Protocol (IP), to interconnect networks into a
    single virtual network. Figure 1 shows the interconnection of a
    variety of networks into the Internet system.  The naming and
    addressing structure allows any computer on any network to address
    in a uniform manner any computer on any other network. Special
    processors, called Gateways, are installed at the interfaces between
    two or more networks and provide both routing amongst the various
    networks as well as the appropriate translation from internet
    addresses to the address required for the attached networks. Thus,
    packets of data can flow between computers on the internet.

    Because of the possiblity of packet loss or errors, the Transmission
    Control Protocol (TCP) is used above the IP to provide for
    reliability and sequencing. TCP together with IP and the various
    networks and gateways then provides for reliable and ordered
    delivery of data between computers. A  variety of functions can use
    this connection to provide service to the users. A summary of the
    functions provided by the current internet system is given in [4].

    To assure interoperability between military users of the system, the
    Office of the Secretary of Defense mandated the use of the TCP/IP
    protocol suite wherever there is a need for interoperable packet
    switched communications. This led to the standardization of the
    protocols [18, 19, 20, 21, 22].


















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RFC 1015                      IRI Plan                         July 1987


    +---+   +---+      +---+                   +---+  +---+ +---+
    | FS|   | SC|      | SC|                   | SC|  | SC| | SC|
    +-+-+   +-+-+      +-+-+                   +-+-+  +-+-+ +-+-+
      |       |          |                       |      |     |
    --+-------+-----+-----+-------+--LAN--     --+------+-+---+----LAN--
      |       |     |     |       |                       |
    +-+--+  +-+--+ +-+--+ +-+--+  |                       |
    | WS |  | WS | | WS | | WS |  |                       |
    +-+--+  +-+--+ +-+--+ +-+--+  |                       |
                               +-+-+                    +-+-+
                               | G |                    | G |
                               +-+-+                    +-+-+
                                 |                        |
                         +--------------+         +--------------+
                         |  Agency      |  +-+-+  |    Agency    |
                         |  Network     |--| G |--|    Network   |
                         +------+-------+  +---+  +------+-----+-+
                                |                        |     |
                              +-+-+                    +-+-+   |
                              | G |                    | G |   |
                              +-+-+                    +-+-+   |
                               /                        /    +-------+
                              /                        /     |  TS   |
                             /                        /      +-+-----+
                     +--------------+        +--------------+ | |...|
                     |  Regional    |        | Commercial   | T T   T
                     |   Network    |        |  Network     |
                     +-----+--------+        +------+-------+
                           |                        |
                         +-+-+                      |
                         | G |                      |
                         +-+-+                      |
                           |                      +-+-+
                           |                      | H |
                           |                      +---+
    ----+------+-----+-----+------LAN----
        |      |     |     |
    +-+--+ +-+--+ +-+--+ +-+--+        +-------------------------+
    | WS | | WS | | WS | | WS |        | H  - Host               |
    +-+--+ +-+--+ +-+--+ +-+--+        | WS - Workstation        |
                                       | SC - Supercomputer      |
                                       | TS - Terminal Server    |
                                       | FS - File Server        |
                                       | G  - Gateway            |
                                       +-------------------------+

                            Figure 1: Internet System




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RFC 1015                      IRI Plan                         July 1987


    Thus, the TCP/IP protocol suite and associated mechanisms (e.g.
    gateways) provides a way to interconnect heterogeneous computers on
    heterogenous networks. Routing and addressing functions are taken
    care of automatically and transparently to the users.The ISO is
    currently developing a set of standards for interconnection which
    are very similar in function to the DARPA developed technologies.
    Although ISO is making great strides, and the  National Bureau of
    Standards is working with a set of manufacturers to develop and
    demonstrate these standards,  the TCP/IP protocol suite still
    represents the most available and tested technology for
    interconnection of computers and networks. It is for that reason
    that several agencies/programs, including the Department of Defense,
    NSF and NASA/NAS, have all adopted the TCP/IP suite as the most
    viable set of standards currently. As the international standards
    mature, and products supporting them appear, it can be expected that
    the various networks will switch to using those standards.

TECHNICAL APPROACH

    The Internet technology described above provides the basis for
    interconnection of the various agency networks. The means to
    interconnect must satisfy a number of constraints if it is to be
    viable in a multi-agency environment.

    Each agency must retain control of its own networks. Networks have
    been established to support agency-specific missions as well as
    general computer communications within the agency and its
    contractors. To assure that these missions continue to be supported
    appropriately, as well as assure appropriate accountability for the
    network operation, the mechanism for interconnection must not
    prevent the agencies from retaining control over their individual
    networks.

    This is not to say that agencies may not choose to have their
    individual networks operated by the IRI, or even turned over to the
    IRI if they determine that to be appropriate.

    Appropriate access control, privacy, and accounting mechanisms must
    be incorporated. This includes access control to data, resources,
    and the networks themselves, privacy of user data, and accounting
    mechanisms to support both cost allocation and cost auditing [23].

    The technical and adminstrative approach must allow (indeed
    encourage) the incorporation of evolving technologies. In
    particular, the network must evolve towards provision of high
    bandwidth, type of service routing, and other advanced techniques to
    allow effective use of new computing technology in a distributed
    research environment.



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RFC 1015                      IRI Plan                         July 1987


Communications Infrastructure

    The communications infrastructure provides connectivity between user
    machines, workstations, and centralized resources such as
    supercomputers and database machines. This roughly corresponds to
    communications services at and below the transport layer in the ISO
    OSI reference model.  There are two different types of networks. The
    first are local networks, meaning those which are internal to a
    facility, campus, etc. The second are networks which provide transit
    service between facilities. These transit networks can connect
    directly to computers, but are evolving in a direction of connecting
    local networks. The networks supported by the individual agencies
    directly are mainly in the category of transit (or long-haul)
    networks, as they typically provide nationwide connectivity, and
    usually leave communications within a facility to be dealt with by
    the facility itself. The IRI communications infrastructure thus
    deals mainly with the interconnection of transit networks.

    The internet model described above provides a simple method for
    interconnecting transit networks (as well as local networks.)  By
    using IP gateways between the agency networks, packet transport
    service can be provided between computers on any of the various
    networks. The placement of the gateways and their capacity will have
    to be determined by an initial engineering study. In addition, as
    the IRI evolves, it may be cost-effective to install one or more
    wide area networks (or designate certain existing ones) to be IRI
    transit networks, to be used by all agencies on a cost  sharing
    basis. Thus, the IRI communications infrastructure would consist of
    the interconnecting gateways plus any networks used specifically as
    transit networks. Using IP as the standard for interconnection of
    networks and global addressing provides a common virtual network
    packet transport service, upon which can be built various other
    network services such as file transfer and electronic mail.  This
    will allow sharing of the communication facilities (channels,