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Network Working Group V. Cerf
Request for Comments: 1167 CNRI
July 1990


Status of this Memo

The memo provides a brief outline of a National Research and
Education Network (NREN). This memo provides information for the
Internet community. It does not specify any standard. It is not a
statement of IAB policy or recommendations.

Distribution of this memo is unlimited.


This contribution seeks to outline and call attention to some of the
major factors which will influence the form and structure of a
National Research and Education Network (NREN). It is implicitly
assumed that the system will emerge from the existing Internet.


The author gratefully acknowledges support from the National Science
Foundation, The Defense Advanced Research Projects Agency, the
Department of Energy and the National Aeronautics and Space
Administration through cooperative agreement NCR-8820945. The author
also acknowledges helpful comments from colleagues Ira Richer, Barry
Leiner, Hans-Werner Braun and Robert Kahn. The opinions expressed in
this paper are the personal opinions of the author and do not
represent positions of the U.S. Government, the Corporation for
National Research Initiatives or of the Internet Activities Board.
In fact, the author isn't sure he agrees with everything in the
paper, either!


The expression "national research and education network" is taken to
mean "the U.S. National Research and Education Network" in the
material which follows. It is implicitly assumed that similar
initiatives may arise in other countries and that a kind of Global
Research and Education Network may arise out of the existing
international Internet system. However, the primary focus of this
paper is on developments in the U.S.

Cerf [Page 1]

RFC 1167 NREN July 1990


1. The NREN in the U.S. will evolve from the existing Internet base.
By implication, the U.S. NREN will have to fit into an international
environment consisting of a good many networks sponsored or owned and
operated by non-U.S. organizations around the world.

2. There will continue to be special-purpose and mission-oriented
networks sponsored by the U.S. Government which will need to link
with, if not directly support, the NREN.

3. The basic technical networking architecture of the system will
include local area networks, metropolitan, regional and wide-area
networks. Some nets will be organized to support transit traffic and
others will be strictly parasitic.

4. Looking towards the end of the decade, some of the networks may be
mobile (digital, cellular). A variety of technologies may be used,
including, but not limited to, high speed Fiber Data Distribution
Interface (FDDI) nets, Distributed-Queue Dual Bus (DQDB) nets,
Broadband Integrated Services Digital Networks (B-ISDN) utilizing
Asynchronous Transfer Mode (ATM) switching fabrics as well as
conventional Token Ring, Ethernet and other IEEE 802.X technology.
Narrowband ISDN and X.25 packet switching technology network services
are also likely play a role along with Switched Multi-megabit Data
Service (SMDS) provided by telecommunications carriers. It also
would be fair to ask what role FTS-2000 might play in the system, at
least in support of government access to the NREN, and possibly in
support of national agency network facilities.

5. The protocol architecture of the system will continue to exhibit a
layered structure although the layering may vary from the present-day
Internet and planned Open Systems Interconnection structures in some

6. The system will include servers of varying kinds required to
support the general operation of the system (for example, network
management facilities, name servers of various types, email, database
and other kinds of information servers, multicast routers,
cryptographic certificate servers) and collaboration support tools
including video/teleconferencing systems and other "groupware"
facilities. Accounting and access control mechanisms will be

7. The system will support multiple protocols on an end to end basis.
At the least, full TCP/IP and OSI protocol stacks will be supported.
Dealing with Connectionless and Connection-Oriented Network Services
in the OSI area is an open issue (transport service bridges and

Cerf [Page 2]

RFC 1167 NREN July 1990

application level gateways are two possibilities).

8. Provision must be made for experimental research in networking to
support the continued technical evolution of the system. The NREN
can no more be a static, rigid system than the Internet has been
since its inception. Interconnection of experimental facilities with
the operational NREN must be supported.

9. The architecture must accommodate the use of commercial services,
private and Government-sponsored networks in the NREN system.

Apart from the considerations listed above, it is also helpful to
consider the constituencies and stakeholders who have a role to play
in the use of, provision of and evolution of NREN services. Their
interests will affect the architecture of the NREN and the course of
its creation and evolution.


The Users

Extrapolating from the present Internet, the users of the system
will be diverse. By legislative intent, it will include colleges
and universities, government research organizations (e.g.,
research laboratories of the Departments of Defense, Energy,
Health and Human Services, National Aeronautics and Space
Administration), non-profit and for-profit research and
development organizations, federally funded research and
development centers (FFRDCs), R&D activities of private
enterprise, library facilities of all kinds, and primary and
secondary schools. The system is not intended to be discipline-

It is critical to recognize that even in the present Internet, it
has been possible to accommodate a remarkable amalgam of private
enterprise, academic institutions, government and military
facilities. Indeed, the very ability to accept such a diverse
constituency turns on the increasing freedom of the so-called
intermediate-level networks to accept an unrestricted set of
users. The growth in the size and diversity of Internet users, if
it can be said to have been constrained at all, has been limited
in part by usage constraints placed on the federally-sponsored
national agency networks (e.g., NSFNET, NASA Science Internet,
Energy Sciences Net, High Energy Physics Net, the recently
deceased ARPANET, Defense Research Internet, etc.). Given the
purposes of these networks and the fiduciary responsibilities of
the agencies that have created them, such usage constraints seem
highly appropriate. It may be beneficial to search for less

Cerf [Page 3]

RFC 1167 NREN July 1990

constraining architectural paradigms, perhaps through the use of
backbone facilities which are not federally-sponsored.

The Internet does not quite serve the public in the same sense
that the telephone network(s) do (i.e., the Internet is not a
common carrier), although the linkages between the Internet and
public electronic mail systems, private bulletin board systems
such as FIDONET and commercial network services such as UUNET,
ALTERNET and PSI, for example, make the system extremely
accessible to a very wide variety of users.

It will be important to keep in mind that, over time, an
increasing number of institutional users will support local area
networks and will want to gain access to NREN by that means.
Individual use will continue to rely on dial-up access and, as it
is deployed, narrow-band ISDN. Eventually, metropolitan area
networks and broadband ISDN facilities may be used to support
access to NREN. Cellular radio or other mobile communication
technologies may also become increasingly popular as access tools.

The Service Providers

In its earliest stages, the Internet consisted solely of
government-sponsored networks such as the Defense Department's
ARPANET, Packet Radio Networks and Packet Satellite Networks.
With the introduction of Xerox PARC's Ethernet, however, things
began to change and privately owned and operated networks became
an integral part of the Internet architecture.

For a time, there was a mixture of government-sponsored backbone
facilities and private local area networks. With the introduction
of the National Science Foundation NSFNET, however, the
architecture changed again to include intermediate-level networks
consisting of collections of commercially-produced routers and
trunk or access lines which connected local area network
facilities to the government-sponsored backbones. The
government-sponsored supercomputer centers (such as the National
Aerospace Simulator at NASA/AMES, the Magnetic Fusion Energy
Computing Center at Lawrence Livermore Laboratory and the half-
dozen or so NSF-sponsored supercomputer centers) fostered the
growth of communications networks specifically to support
supercomputer access although, over time, these have tended to
look more and more like general-purpose intermediate-level

Many, but not all, of the intermediate-level networks applied for
and received seed funding from the National Science Foundation.
It was and continues to be NSF's position, however, that such

Cerf [Page 4]

RFC 1167 NREN July 1990

direct subsidies should diminish over time and that the
intermediate networks should become self-sustaining. To
accomplish this objective, the intermediate-level networks have
been turning to an increasingly diverse user constituency (see
section above).

The basic model of government backbones, consortium intermediate
level nets and private local area networks has served reasonably
well during the 1980's but it would appear that newer
telecommunications technologies may suggest another potential
paradigm. As the NSFNET moves towards higher speed backbone
operation in the 45 Mb/s range, the importance of carrier
participation in the enterprise has increased. The provision of
backbone capacity at attractive rates by the inter-exchange
carrier (in this case, MCI Communications Corporation) has been
crucial to the feasibility of deploying such a high speed system.

As the third phase of the NREN effort gets underway, it is
becoming increasingly apparent that the "federally-funded
backbone" model may and perhaps even should or must give way to a
vision of commercially operated, gigabit speed systems to which
the users of the NREN have access. If there is federal subsidy in
the new paradigm, it might come through direct provision of
support for networking at the level of individual research grant
or possibly through a system of institutional vouchers permitting
and perhaps even mandating institution-wide network planning and
provision. This differs from the present model in which the
backbone networks are essentially federally owned and operated or
enjoy significant, direct federal support to the provider of the

The importance of such a shift in service provision philosophy
cannot be over-emphasized. In the long run, it eliminates
unnecessary restrictions on the use and application of the
backbone facilities, opening up possibilities for true ubiquity of
access and use without the need for federal control, except to the
extent that any such services are considered in need of
regulation, perhaps. The same arguments might be made for the
intermediate level systems (metropolitan and regional area access
networks). This does NOT mean that private networks ranging from
local consortia to inter-continental systems will be ruled out.
The economics of private networking may still be favorable for
sufficiently heavy usage. It does suggest, however, that
achieving scale and ubiquity may largely rely on publicly
accessible facilities.

Cerf [Page 5]

RFC 1167 NREN July 1990

The Vendors

Apart from service provision, the technology available to the
users and the service providers will come largely from commercial
sources. A possible exception to this may be the switches used in
the gigabit testbed effort, but ultimately, even this technology
will have to be provided commercially if the system is to achieve
the scale necessary to serve as the backbone of the NREN.

An important consequence of this observation is that the NREN
architecture should be fashioned in such a way that it can be
constructed from technology compatible with carrier plans and
available from commercial telecommunications equipment suppliers.
Examples include the use of SONET (Synchronous Optical Network)
optical transmission technology, Switched Multimegabit Data
Services offerings (metropolitan area networks), Asynchronous
Transmission Mode (ATM) switches, frame relays, high speed,
multi-protocol routers, and so on. It is somewhat unclear what
role the public X.25 networks will play, especially where narrow
and broadband ISDN services are available, but it is also not
obvious that they ought to be written off at this point. Where
there is still research and development activity (such as in
network management), the network R&D community can contribute
through experimental efforts and through participation in
standards-making activities (e.g., ANSI, NIST, IAB/IETF, Open


It seems clear that the current Internet and the anticipated NREN
will have to function in a highly distributed fashion. Given the
diversity of service providers and the richness of the constituent
networks (as to technology and ownership), there will have to be a
good deal of collaboration and cooperation to make the system work.
One can see the necessity for this, based on the existing voice
network in the U.S. with its local and inter-exchange carrier (IEC)
structure. It should be noted that in the presence of the local and
IEC structure, it has proven possible to support private and virtual
private networking as well. The same needs to be true of the NREN.

A critical element of any commercial service is accounting and
billing. It must be possible to identify users (billable parties,
anyway) and to compute usage charges. This is not to say that the
NREN component networks must necessarily bill on the basis of usage.
It may prove preferable to have fixed access charges which might be
modulated by access data rate, as some of the intermediate-level
networks have found. It would not be surprising to find a mixture of
charging policies in which usage charges are preferable for small

Cerf [Page 6]

RFC 1167 NREN July 1990

amounts of use and flat rate charges are preferred for high volume

It will be critical to establish a forum in which operational matters
can be debated and methods established to allow cooperative operation
of the entire system. A number of possibilities present themselves:
use of the Internet Engineering Task Force as a basis, use of
existing telecommunication carrier organizations, or possibly a
consortium of all service providers (and private network operators?).
Even if such an activity is initiated through federal action, it may
be helpful, in the long run, if it eventually embraces a much wider

Agreements are needed on the technical foundations for network
monitoring and management, for internetwork accounting and exchange
payments, for problem identification, tracking, escalation and
resolution. A framework is needed for the support of users of the
aggregate NREN. This suggests cooperative agreements among network
information centers, user service and support organizations to begin
with. Eventually, the cost of such operations will have to be
incorporated into the general cost of service provision. The federal
role, even if it acts as catalyst in the initial stages, may
ultimately focus on the direct support of the users of the system
which it finds it appropriate to support and subsidize (e.g., the
research and educational users of the NREN).

A voucher system has been proposed, in the case of the NREN, which
would permit users to choose which NREN service provider(s) to
engage. The vouchers might be redeemed by the service providers in
the same sort of way that food stamps are redeemed by supermarkets.
Over time, the cost of the vouchers could change so that an initial
high subsidy from the federal government would diminish until the
utility of the vouchers vanished and decisions would be made to
purchase telecommunications services on a pure cost/benefit basis.


The initial technical architecture should incorporate commercial
service provision where possible so as to avoid the creation of a
system which is solely reliant on the federal government for its
support and operation. It is anticipated that a hybrid system will
develop but, for example, it is possible that the gigabit backbone
components of the system might be strictly commercial from the start,
even if the lower speed components of the NREN vary from private, to
public to federally subsidized or owned and operated.

Cerf [Page 7]

RFC 1167 NREN July 1990


The idea of creating a National Research and Education Network has
captured the attention and enthusiasm of an extraordinarily broad
collection of interested parties. I believe this is in part a
consequence of the remarkable range of new services and facilities
which could be provided once the network infrastructure is in place.
If the technology of the NREN is commercially viable, one can readily
imagine that an economic engine of considerable proportions might
result from the widespread accessibility of NREN-like facilities to
business sector.

Security Considerations

Security issues are not discussed in this memo.

Author's Address

Vinton G. Cerf
Corporation for National Research Initiatives
1895 Preston White Drive, Suite 100
Reston, VA 22091

EMail: vcerf@NRI.Reston.VA.US

Phone: (703) 620-8990

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