rfc1015.txt
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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,
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