A BRIEF HISTORY OF THE INTERNET
Barry M. Leiner, Vinton G. Cerf, David D. Clark,
Robert E. Kahn, Leonard Kleinrock, Daniel C. Lynch,
Jon Postel, Larry G. Roberts, Stephen Wolff
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o Introduction
o Origins of the Internet
o The Initial Internetting
o ConceptsProving the Ideas
o Transition to Widespread Infrastructure
o The Role of Documentation
o Formation of the Broad Community
o Commercialization of the Technology
o History of the Future
o Footnotes
o Timeline
o References
o Authors
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INTRODUCTION
The Internet has revolutionized the computer and communications
world like nothing before. The invention of the telegraph,
telephone, radio, and computer set the stage for this unprecedented
integration of capabilities. The Internet is at once a world-wide
broadcasting capability, a mechanism for information dissemination,
and a medium for collaboration and interaction between individuals
and their computers without regard for geographic location.
The Internet represents one of the most successful examples of the
benefits of sustained investment and commitment to research and
development of information infrastructure. Beginning with the early
research in packet switching, the government, industry and academia
have been partners in evolving and deploying this exciting new
technology. Today, terms like "
[email protected]" and
"
http://www.acm.org" trip lightly off the tongue of the random
person on the street. [1]
This is intended to be a brief, necessarily cursory and incomplete
history. Much material currently exists about the Internet,
covering history, technology, and usage. A trip to almost any
bookstore will find shelves of material written about the Internet.
[2]
In this paper, [3] several of us involved in the development and
evolution of the Internet share our views of its origins and
history. This history revolves around four distinct aspects. There
is the technological evolution that began with early research on
packet switching and the ARPANET (and related technologies), and
where current research continues to expand the horizons of the
infrastructure along several dimensions, such as scale, performance,
and higher level functionality. There is the operations and
management aspect of a global and complex operational
infrastructure. There is the social aspect, which resulted in a
broad community of *Internauts* working together to create and evolve
the technology. And there is the commercialization aspect, resulting
in an extremely effective transition of research results into a
broadly deployed and available information infrastructure.
The Internet today is a widespread information infrastructure, the
initial prototype of what is often called the National (or Global or
Galactic) Information Infrastructure. Its history is complex and
involves many aspects - technological, organizational, and
community. And its influence reaches not only to the technical
fields of computer communications but throughout society as we move
toward increasing use of online tools to accomplish electronic
commerce, information acquisition, and community operations.
ORIGINS OF THE INTERNET
The first recorded description of the social interactions that
could be enabled through networking was a series of memos written by
J.C.R. Licklider of MIT in August 1962 discussing his "Galactic
Network" concept. He envisioned a globally interconnected set of
computers through which everyone could quickly access data and
programs from any site. In spirit, the concept was very much like
the Internet of today. Licklider was the first head of the computer
research program at DARPA, [4] starting in October 1962. While at
DARPA he convinced his successors at DARPA, Ivan Sutherland, Bob
Taylor, and MIT researcher Lawrence G. Roberts, of the importance of
this networking concept.
Leonard Kleinrock at MIT published the first paper on packet
switching theory in July 1961 and the first book on the subject in
1964. Kleinrock convinced Roberts of the theoretical feasibility of
communications using packets rather than circuits, which was a major
step along the path towards computer networking. The other key step
was to make the computers talk together. To explore this, in 1965
working with Thomas Merrill, Roberts connected the TX-2 computer in
Mass. to the Q-32 in California with a low speed dial-up telephone
line creating the first (however small) wide-area computer network
ever built. The result of this experiment was the realization that
the time-shared computers could work well together, running programs
and retrieving data as necessary on the remote machine, but that the
circuit switched telephone system was totally inadequate for the
job. Kleinrock's conviction of the need for packet switching was
confirmed.
In late 1966 Roberts went to DARPA to develop the computer network
concept and quickly put together his plan for the "ARPANET",
publishing it in 1967. At the conference where he presented the
paper, there was also a paper on a packet network concept from the
UK by Donald Davies and Roger Scantlebury of NPL. Scantlebury told
Roberts about the NPL work as well as that of Paul Baran and others
at RAND. The RAND group had written a paper on packet switching
networks for secure voice in the military in 1964. It happened that
the work at MIT (1961-1967), at RAND (1962-1965), and at NPL
(1964-1967) had all proceeded in parallel without any of the
researchers knowing about the other work. The word "packet" was
adopted from the work at NPL and the proposed line speed to be used
in the ARPANET design was upgraded from 2.4 kbps to 50 kbps.
[5]
In August 1968, after Roberts and the DARPA funded community had
refined the overall structure and specifications for the ARPANET, an
RFQ was released by DARPA for the development of one of the key
components, the packet switches called Interface Message Processors
(IMP's). The RFQ was won in December 1968 by a group headed by
Frank Heart at Bolt Beranek and Newman (BBN). As the BBN team worked
on the IMP's with Bob Kahn playing a major role in the overall
ARPANET architectural design, the network topology and economics
were designed and optimized by Roberts working with Howard Frank and
his team at Network Analysis Corporation, and the network
measurement system was prepared by Kleinrock's team at UCLA.
[6]
Due to Kleinrock's early development of packet switching theory and
his focus on analysis, design and measurement, his Network
Measurement Center at UCLA was selected to be the first node on the
ARPANET. All this came together in September 1969 when BBN installed
the first IMP at UCLA and the first host computer was connected.
Doug Engelbart's project on "Augmentation of Human Intellect" (which
included NLS, an early hypertext system) at Stanford Research
Institute (SRI) provided a second node. SRI supported the Network
Information Center, led by Elizabeth (Jake) Feinler and including
functions such as maintaining tables of host name to address mapping
as well as a directory of the RFC's. One month later, when SRI was
connected to the ARPANET, the first host-to-host message was sent
from Kleinrock's laboratory to SRI. Two more nodes were added at UC
Santa Barbara and University of Utah. These last two nodes
incorporated application visualization projects, with Glen Culler
and Burton Fried at UCSB investigating methods for display of
mathematical functions using storage displays to deal with the
problem of refresh over the net, and Robert Taylor and Ivan
Sutherland at Utah investigating methods of 3-D representations over
the net. Thus, by the end of 1969, four host computers were
connected together into the initial ARPANET, and the budding
Internet was off the ground. Even at this early stage, it should be
noted that the networking research incorporated both work on the
underlying network and work on how to utilize the network. This
tradition continues to this day.
Computers were added quickly to the ARPANET during the following
years, and work proceeded on completing a functionally complete
Host-to-Host protocol and other network software. In December 1970
the Network Working Group (NWG) working under S. Crocker finished
the initial ARPANET Host-to-Host protocol, called the Network
Control Protocol (NCP). As the ARPANET sites completed implementing
NCP during the period 1971-1972, the network users finally could
begin to develop applications.
In October 1972 Kahn organized a large, very successful
demonstration of the ARPANET at the International Computer
Communication Conference (ICCC). This was the first public
demonstration of this new network technology to the public. It was
also in 1972 that the initial "hot" application, electronic mail,
was introduced. In March Ray Tomlinson at BBN wrote the basic email
message send and read software, motivated by the need of the ARPANET
developers for an easy coordination mechanism. In July, Roberts
expanded its utility by writing the first email utility program to
list, selectively read, file, forward, and respond to messages. From
there email took off as the largest network application for over a
decade. This was a harbinger of the kind of activity we see on the
World Wide Web today, namely, the enormous growth of all kinds of
"people-to-people" traffic.
THE INITIAL INTERNETTING CONCEPTS
The original ARPANET grew into the Internet. Internet was based on
the idea that there would be multiple independent networks of rather
arbitrary design, beginning with the ARPANET as the pioneering
packet switching network, but soon to include packet satellite
networks, ground-based packet radio networks and other networks. The
Internet as we now know it embodies a key underlying technical idea,
namely that of open architecture networking. In this approach, the
choice of any individual network technology was not dictated by a
particular network architecture but rather could be selected freely
by a provider and made to interwork with the other networks through
a meta-level "Internetworking Architecture". Up until that time
there was only one general method for federating networks. This was
the traditional circuit switching method where networks would
interconnect at the circuit level, passing individual bits on a
synchronous basis along a portion of an end-to-end circuit between a
pair of end locations. Recall that Kleinrock had shown in 1961 that
packet switching was a more efficient switching method. Along with
packet switching, special purpose interconnection arrangements
between networks were another possibility. While there were other
limited ways to interconnect different networks, they required that
one be used as a component of the other, rather than acting as a
peer* of the other in offering end-to-end service.
In an open-architecture network, the individual networks may be
separately designed and developed and each may have its own unique
interface which it may offer to users and/or other providers.
including other Internet providers. Each network can be designed in
accordance with the specific environment and user requirements of
that network. There are generally no constraints on the types of
network that can be included or on their geographic scope, although
certain pragmatic considerations will dictate what makes sense to
offer.
The idea of open-architecture networking was first introduced by
Kahn shortly after having arrived at DARPA in 1972. This work was
originally part of the packet radio program, but subsequently became
a separate program in its own right. At the time, the program was
called "Internetting". Key to making the packet radio system work
was a reliable end-end protocol that could maintain effective
communication in the face of jamming and other radio interference,
or withstand intermittent blackout such as caused by being in a
tunnel or blocked by the local terrain. Kahn first contemplated
developing a protocol local only to the packet radio network, since
that would avoid having to deal with the multitude of different
operating systems, and continuing to use NCP.
However, NCP did not have the ability to address networks (and
machines) further downstream than a destination IMP on the ARPANET
and thus some change to NCP would also be required. (The assumption
was that the ARPANET was not changeable in this regard). NCP
relied on ARPANET to provide end-to-end reliability. If any packets
were lost, the protocol (and presumably any applications it
supported) would come to a grinding halt. In this model NCP had no
end-end host error control, since the ARPANET was to be the only
network in existence and it would be so reliable that no error
control would be required on the part of the hosts.
Thus, Kahn decided to develop a new version of the protocol which
could meet the needs of an open-architecture network environment.
This protocol would eventually be called the Transmission Control
Protocol/Internet Protocol (TCP/IP). While NCP tended to act like a
device driver, the new protocol would be more like a communications
protocol.
Four ground rules were critical to Kahn's early thinking:
o Each distinct network would have to stand on its own and no
internal changes could be required to any such network to
connect it to the Internet.
o Communications would be on a best effort basis. If a packet
didn't make it to the final destination, it would shortly be
retransmitted from the source.
o Black boxes would be used to connect the networks; these would
later be called gateways and routers. There would be no
information retained by the gateways about the individual flows
of packets passing through them, thereby keeping them simple and
avoiding complicated adaptation and recovery from various
failure modes.
o There would be no global control at the operations level.
Other key issues that needed to be addressed were:
o Algorithms to prevent lost packets from permanently disabling
communications and enabling them to be successfully
retransmitted from the source.
o Providing for host to host "pipelining" so that multiple
packets could be enroute from source to destination at the
discretion of the participating hosts, if the intermediate
networks allowed it.
o Gateway functions to allow it to forward packets appropriately.
This included interpreting IP headers for routing, handling
interfaces, breaking packets into smaller pieces if necessary,
etc.
o The need for end-end checksums, reassembly of packets from
fragments and detection of duplicates, if any.
o The need for global addressing.
o Techniques for host to host flow control.
o Interfacing with the various operating systems.
o There were also other concerns, such as implementation
efficiency, internetwork performance, but these were secondary
considerations at first.
Kahn began work on a communications-oriented set of operating
system principles while at BBN and documented some of his early
thoughts in an internal BBN memorandum entitled "
Communications Principles for Operating Systems". At this point he
realized it would be necessary to learn the implementation details
of each operating system to have a chance to embed any new protocols
in an efficient way. Thus, in the spring of 1973, after starting the
internetting effort, he asked Vint Cerf (then at Stanford) to work
with him on the detailed design of the protocol. Cerf had been
intimately involved in the original NCP design and development and
already had the knowledge about interfacing to existing operating
systems. So armed with Kahn's architectural approach to the
communications side and with Cerf's NCP experience, they teamed up
to spell out the details of what became TCP/IP.
The give and take was highly productive and the first written
version [7] of the resulting approach was distributed at a special
meeting of the International Network Working Group (INWG) which had
been set up at a conference at Sussex University in September 1973.
Cerf had been invited to chair this group and used the occasion to
hold a meeting of INWG members who were heavily represented at the
Sussex Conference.
Some basic approaches emerged from this collaboration between Kahn
and Cerf:
o Communication between two processes would logically consist of a
very long stream of bytes (they called them octets). The
position of any octet in the stream would be used to identify
it.
o Flow control would be done by using sliding windows and
acknowledgments (acks). The destination could select when to
acknowledge and each ack returned would be cumulative for all
packets received to that point.
o It was left open as to exactly how the source and destination
would agree on the parameters of the windowing to be used.
Defaults were used initially.
o Although Ethernet was under development at Xerox PARC at that
time, the proliferation of LANs were not envisioned at the
time, much less PCs and workstations. The original model was
national level networks like ARPANET of which only a relatively
small number were expected to exist. Thus a 32 bit IP address
was used of which the first 8 bits signified the network and the
remaining 24 bits designated the host on that network. This
assumption, that 256 networks would be sufficient for the
foreseeable future, was clearly in need of reconsideration when
LANs began to appear in the late 1970s.
The original Cerf/Kahn paper on the Internet described one
protocol, called TCP, which provided all the transport and
forwarding services in the Internet. Kahn had intended that the TCP
protocol support a range of transport services, from the totally
reliable sequenced delivery of data* (virtual circuit model*) to a
datagram* service in which the application made direct use of the
underlying network service, which might imply occasional lost,
corrupted or reordered packets.
However, the initial effort to implement TCP resulted in a version
that only allowed for virtual circuits. This model worked fine for
file transfer and remote login applications, but some of the early
work on advanced network applications, in particular packet voice in
the 1970s, made clear that in some cases packet losses should not be
corrected by TCP, but should be left to the application to deal
with. This led to a reorganization of the original TCP into two
protocols, the simple IP which provided only for addressing and
forwarding of individual packets, and the separate TCP, which was
concerned with service features such as flow control and recovery
from lost packets. For those applications that did not want the
services of TCP, an alternative called the User Datagram Protocol
(UDP) was added in order to provide direct access to the basic
service of IP.
A major initial motivation for both the ARPANET and the Internet
was resource sharing - for example allowing users on the packet
radio networks to access the time sharing systems attached to the
ARPANET. Connecting the two together was far more economical that
duplicating these very expensive computers. However, while file
transfer and remote login (Telnet) were very important
applications, electronic mail has probably had the most significant
impact of the innovations from that era. Email provided a new model
of how people could communicate with each other, and changed the
nature of collaboration, first in the building of the Internet
itself (as is discussed below) and later for much of society.
There were other applications proposed in the early days of the
Internet, including packet based voice communication (the precursor
of Internet telephony), various models of file and disk sharing,
and early "worm" programs that showed the concept of agents (and, of
course, viruses). A key concept of the Internet is that it was not
designed for just one application, but as a general infrastructure
on which new applications could be conceived, as illustrated later
by the emergence of the World Wide Web. It is the general purpose
nature of the service provided by TCP and IP that makes this
possible.
PROVING THE IDEAS
DARPA let three contracts to Stanford (Cerf), BBN (Ray Tomlinson)
and UCL (Peter Kirstein) to implement TCP/IP (it was simply called
TCP in the Cerf/Kahn paper but contained both components). The
Stanford team, led by Cerf, produced the detailed specification and
within about a year there were three independent implementations of
TCP that could interoperate.
This was the beginning of long term experimentation and
development to evolve and mature the Internet concepts and
technology. Beginning with the first three networks (ARPANET, Packet
Radio, and Packet Satellite) and their initial research communities,
the experimental environment has grown to incorporate essentially
every form of network and a very broad-based research and
development community. [REK78] With each expansion has come new
challenges.
The early implementations of TCP were done for large time sharing
systems such as Tenex and TOPS 20. When desktop computers first
appeared, it was thought by some that TCP was too big and complex to
run on a personal computer. David Clark and his research group at
MIT set out to show that a compact and simple implementation of TCP
was possible. They produced an implementation, first for the Xerox
Alto (the early personal workstation developed at Xerox PARC) and
then for the IBM PC. That implementation was fully interoperable
with other TCPs, but was tailored to the application suite and
performance objectives of the personal computer, and showed that
workstations, as well as large time-sharing systems, could be a part
of the Internet. In 1976, Kleinrock published the
first book on the ARPANET. It included an emphasis on the complexity
of protocols and the pitfalls they often introduce. This book was
influential in spreading the lore of packet switching networks to a
very wide community.
Widespread development of LANS, PCs and workstations in the 1980s
allowed the nascent Internet to flourish. Ethernet technology,
developed by Bob Metcalfe at Xerox PARC in 1973, is now probably the
dominant network technology in the Internet and PCs and
workstations the dominant computers. This change from having a few
networks with a modest number of time-shared hosts (the original
ARPANET model) to having many networks has resulted in a number of
new concepts and changes to the underlying technology. First, it
resulted in the definition of three network classes (A, B, and C) to
accommodate the range of networks. Class A represented large
national scale networks (small number of networks with large numbers
of hosts); Class B represented regional scale networks; and Class C
represented local area networks (large number of networks with
relatively few hosts).
A major shift occurred as a result of the increase in scale of the
Internet and its associated management issues. To make it easy for
people to use the network, hosts were assigned names, so that it was
not necessary to remember the numeric addresses. Originally, there
were a fairly limited number of hosts, so it was feasible to
maintain a single table of all the hosts and their associated names
and addresses. The shift to having a large number of independently
managed networks (e.g., LANs) meant that having a single table of
hosts was no longer feasible, and the Domain Name System (DNS) was
invented by Paul Mockapetris of USC/ISI. The DNS permitted a
scalable distributed mechanism for resolving hierarchical host names
(e.g. www.acm.org) into an Internet address.
The increase in the size of the Internet also challenged the
capabilities of the routers. Originally, there was a single
distributed algorithm for routing that was implemented uniformly by
all the routers in the Internet. As the number of networks in the
Internet exploded, this initial design could not expand as
necessary, so it was replaced by a hierarchical model of routing,
with an Interior Gateway Protocol (IGP) used inside each region of
the Internet, and an Exterior Gateway Protocol (EGP) used to tie the
regions together. This design permitted different regions to use a
different IGP, so that different requirements for cost, rapid
reconfiguration, robustness and scale could be accommodated. Not
only the routing algorithm, but the size of the addressing tables,
stressed the capacity of the routers. New approaches for address
aggregation, in particular classless inter-domain routing (CIDR),
have recently been introduced to control the size of router tables.
As the Internet evolved, one of the major challenges was how to
propagate the changes to the software, particularly the host
software. DARPA supported UC Berkeley to investigate modifications
to the Unix operating system, including incorporating TCP/IP
developed at BBN. Although Berkeley later rewrote the BBN code to
more efficiently fit into the Unix system and kernel, the
incorporation of TCP/IP into the Unix BSD system releases proved to
be a critical element in dispersion of the protocols to the research
community. Much of the CS research community began to use Unix BSD
for their day-to-day computing environment. Looking back, the
strategy of incorporating Internet protocols into a supported
operating system for the research community was one of the key
elements in the successful widespread adoption of the Internet.
One of the more interesting challenges was the transition of the
ARPANET host protocol from NCP to TCP/IP as of January 1, 1983. This
was a "flag-day" style transition, requiring all hosts to convert
simultaneously or be left having to communicate via rather ad-hoc
mechanisms. This transition was carefully planned within the
community over several years before it actually took place and went
surprisingly smoothly (but resulted in a distribution of buttons
saying "I survived the TCP/IP transition").
TCP/IP was adopted as a defense standard three years earlier in
1980. This enabled defense to begin sharing in the DARPA Internet
technology base and led directly to the eventual partitioning of the
military and non- military communities. By 1983, ARPANET was being
used by a significant number of defense R&D and operational
organizations. The transition of ARPANET from NCP to TCP/IP
permitted it to be split into a MILNET supporting operational
requirements and an ARPANET supporting research needs.
Thus, by 1985, Internet was already well established as a
technology supporting a broad community of researchers and
developers, and was beginning to be used by other communities for
daily computer communications. Electronic mail was being used
broadly across several communities, often with different systems,
but interconnection between different mail systems was demonstrating
the utility of broad based electronic communications between
people.
TRANSITION TO WIDESPREAD INFRASTRUCTURE
At the same time that the Internet technology was being
experimentally validated and widely used amongst a subset of
computer science researchers, other networks and networking
technologies were being pursued. The usefulness of computer
networking - especially electronic mail - demonstrated by DARPA and
Department of Defense contractors on the ARPANET was not lost on
other communities and disciplines, so that by the mid-1970s computer
networks had begun to spring up wherever funding could be found for
the purpose. The U.S. Department of Energy (DoE) established MFENet
for its researchers in Magnetic Fusion Energy, whereupon DoE's High
Energy Physicists responded by building HEPNet. NASA Space
Physicists followed with SPAN, and Rick Adrion, David Farber, and
Larry Landweber established CSNET for the (academic and industrial)
Computer Science community with an initial grant from the U.S.
National Science Foundation (NSF). AT&T's free-wheeling
dissemination of the UNIX computer operating system spawned USENET,
based on UNIX' built-in UUCP communication protocols, and in 1981
Ira Fuchs and Greydon Freeman devised BITNET, which linked academic
mainframe computers in an "email as card images" paradigm.
With the exception of BITNET and USENET, these early networks
(including ARPANET) were purpose-built - i.e., they were intended
for, and largely restricted to, closed communities of scholars;
there was hence little pressure for the individual networks to be
compatible and, indeed, they largely were not. In addition,
alternate technologies were being pursued in the commercial sector,
including XNS from Xerox, DECNet, and IBM's SNA.
[8] It remained for the British JANET (1984) and U.S. NSFNET (1985)
programs to explicitly announce their intent to serve the entire
higher education community, regardless of discipline. Indeed, a
condition for a U.S. university to receive NSF funding for an
Internet connection was that "... the connection must be made
available to ALL qualified users on campus."
In 1985, Dennis Jennings came from Ireland to spend a year at NSF
leading the NSFNET program. He worked with the community to help NSF
make a critical decision - that TCP/IP would be mandatory for the
NSFNET program. When Steve Wolff took over the NSFNET program in
1986, he recognized the need for a wide area networking
infrastructure to support the general academic and research
community, along with the need to develop a strategy for
establishing such infrastructure on a basis ultimately independent
of direct federal funding. Policies and strategies were adopted (see
below) to achieve that end.
NSF also elected to support DARPA's existing Internet
organizational infrastructure, hierarchically arranged under the
(then) Internet Activities Board (IAB). The public declaration of
this choice was the joint authorship by the IAB's Internet
Engineering and Architecture Task Forces and by NSF's Network
Technical Advisory Group of RFC 985 (Requirements for Internet
Gateways ), which formally ensured interoperability of DARPA's and
NSF's pieces of the Internet.
In addition to the selection of TCP/IP for the NSFNET program,
Federal agencies made and implemented several other policy
decisions which shaped the Internet of today.
o Federal agencies shared the cost of common infrastructure, such
as trans-oceanic circuits. They also jointly supported "managed
interconnection points" for interagency traffic; the Federal
Internet Exchanges (FIX-E and FIX-W) built for this purpose
served as models for the Network Access Points and "*IX"
facilities that are prominent features of today's Internet
architecture.
o To coordinate this sharing, the Federal Networking Council
[9] was formed. The FNC also cooperated with other international
organizations, such as RARE in Europe, through the Coordinating
Committee on Intercontinental Research Networking, CCIRN, to
coordinate Internet support of the research community
worldwide.
o This sharing and cooperation between agencies on
Internet-related issues had a long history. An unprecedented
1981 agreement between Farber, acting for CSNET and the NSF, and
DARPA's Kahn, permitted CSNET traffic to share ARPANET
infrastructure on a statistical and no-metered-settlements
basis.
o Subsequently, in a similar mode, the NSF encouraged its
regional (initially academic) networks of the NSFNET to seek
commercial, non-academic customers, expand their facilities to
serve them, and exploit the resulting economies of scale to
lower subscription costs for all.
o On the NSFNET Backbone - the national-scale segment of the
NSFNET - NSF enforced an "Acceptable Use Policy" (AUP) which
prohibited Backbone usage for purposes "not in support of
Research and Education." The predictable (and intended) result
of encouraging commercial network traffic at the local and
regional level, while denying its access to national-scale
transport, was to stimulate the emergence and/or growth of
"private", competitive, long-haul networks such as PSI, UUNET,
ANS CO+RE, and (later) others. This process of
privately-financed augmentation for commercial uses was
thrashed out starting in 1988 in a series of NSF-initiated
conferences at Harvard's Kennedy School of Government on "The
Commercialization and Privatization of the Internet" - and on
the "com-priv" list on the net itself.
o In 1988, a National Research Council committee, chaired by
Kleinrock and with Kahn and Clark as members, produced a report
commissioned by NSF titled "Towards a National Research Network".
This report was influential on then Senator Al Gore, and
ushered in high speed networks that laid the networking
foundation for the future information superhighway.
o In 1994, a National Research Council report, again chaired by
Kleinrock (and with Kahn and Clark as members again), Entitled
"Realizing The Information Future: The Internet and Beyond" was
released. This report, commissioned by NSF, was the document in
which a blueprint for the evolution of the information
superhighway was articulated and which has had a lasting affect
on the way to think about its evolution. It anticipated the
critical issues of intellectual property rights, ethics,
pricing, education, architecture and regulation for the
Internet.
o NSF's privatization policy culminated in April, 1995, with the
defunding of the NSFNET Backbone. The funds thereby recovered
were (competitively) redistributed to regional networks to buy
national-scale Internet connectivity from the now numerous,
private, long-haul networks.
The backbone had made the transition from a network built from
routers out of the research community (the "Fuzzball" routers from
David Mills) to commercial equipment. In its 8 1/2 year lifetime,
the Backbone had grown from six nodes with 56 kbps links to 21 nodes
with multiple 45 Mbps links. It had seen the Internet grow to over
50,000 networks on all seven continents and outer space, with
approximately 29,000 networks in the United States.
Such was the weight of the NSFNET program's ecumenism and funding
($200 million from 1986 to 1995) - and the quality of the protocols
themselves - that by 1990 when the ARPANET itself was finally
decommissioned[10], TCP/IP had supplanted or marginalized most other
wide-area computer network protocols worldwide, and IP was well on
its way to becoming THE bearer service for the Global Information
Infrastructure.
THE ROLE OF DOCUMENTATION
A key to the rapid growth of the Internet has been the free and
open access to the basic documents, especially the specifications of
the protocols.
The beginnings of the ARPANET and the Internet in the university
research community promoted the academic tradition of open
publication of ideas and results. However, the normal cycle of
traditional academic publication was too formal and too slow for the
dynamic exchange of ideas essential to creating networks.
In 1969 a key step was taken by S. Crocker (then at UCLA) in
establishing the Request for Comments (or RFC) series of notes.
These memos were intended to be an informal fast distribution way to
share ideas with other network researchers. At first the RFCs were
printed on paper and distributed via snail mail. As the File
Transfer Protocol (FTP) came into use, the RFCs were prepared as
online files and accessed via FTP. Now, of course, the RFCs are
easily accessed via the World Wide Web at dozens of sites around the
world. SRI, in its role as Network Information Center, maintained
the online directories. Jon Postel acted as RFC Editor as well as
managing the centralized administration of required protocol number
assignments, roles that he continues to this day.
The effect of the RFCs was to create a positive feedback loop, with
ideas or proposals presented in one RFC triggering another RFC with
additional ideas, and so on. When some consensus (or a least a
consistent set of ideas) had come together a specification document
would be prepared. Such a specification would then be used as the
base for implementations by the various research teams.
Over time, the RFCs have become more focused on protocol standards
(the "official" specifications), though there are still
informational RFCs that describe alternate approaches, or provide
background information on protocols and engineering issues. The RFCs
are now viewed as the "documents of record" in the Internet
engineering and standards community.
The open access to the RFCs (for free, if you have any kind of a
connection to the Internet) promotes the growth of the Internet
because it allows the actual specifications to be used for examples
in college classes and by entrepreneurs developing new systems.
Email has been a significant factor in all areas of the Internet,
and that is certainly true in the development of protocol
specifications, technical standards, and Internet engineering. The
very early RFCs often presented a set of ideas developed by the
researchers at one location to the rest of the community. After
email came into use, the authorship pattern changed - RFCs were
presented by joint authors with common view independent of their
locations.
The use of specialized email mailing lists has been long used in
the development of protocol specifications, and continues to be an
important tool. The IETF now has in excess of 75 working groups,
each working on a different aspect of Internet engineering. Each of
these working groups has a mailing list to discuss one or more draft
documents under development. When consensus is reached on a draft
document it may be distributed as an RFC.
As the current rapid expansion of the Internet is fueled by the
realization of its capability to promote information sharing, we
should understand that the network's first role in information
sharing was sharing the information about it's own design and
operation through the RFC documents. This unique method for
evolving new capabilities in the network will continue to be
critical to future evolution of the Internet.
FORMATION OF THE BROAD COMMUNITY
The Internet is as much a collection of communities as a
collection of technologies, and its success is largely attributable
to both satisfying basic community needs as well as utilizing the
community in an effective way to push the infrastructure forward.
This community spirit has a long history beginning with the early
ARPANET. The early ARPANET researchers worked as a close-knit
community to accomplish the initial demonstrations of packet
switching technology described earlier. Likewise, the Packet
Satellite, Packet Radio and several other DARPA computer science
research programs were multi-contractor collaborative activities
that heavily used whatever available mechanisms there were to
coordinate their efforts, starting with electronic mail and adding
file sharing, remote access, and eventually World Wide Web
capabilities. Each of these programs formed a working group,
starting with the ARPANET Network Working Group. Because of the
unique role that ARPANET played as an infrastructure supporting the
various research programs, as the Internet started to evolve, the
Network Working Group evolved into Internet Working Group.
In the late 1970's, recognizing that the growth of the Internet was
accompanied by a growth in the size of the interested research
community and therefore an increased need for coordination
mechanisms, Vint Cerf, then manager of the Internet Program at
DARPA, formed several coordination bodies - an International
Cooperation Board (ICB), chaired by Peter Kirstein of UCL, to
coordinate activities with some cooperating European countries
centered on Packet Satellite research, an Internet Research Group
which was an inclusive group providing an environment for general
exchange of information, and an Internet Configuration Control Board
(ICCB), chaired by Clark. The ICCB was an invitational body to
assist Cerf in managing the burgeoning Internet activity.
In 1983, when Barry Leiner took over management of the Internet
research program at DARPA, he and Clark recognized that the
continuing growth of the Internet community demanded a restructuring
of the coordination mechanisms. The ICCB was disbanded and in its
place a structure of Task Forces was formed, each focused on a
particular area of the technology (e.g. routers, end-to-end
protocols, etc.). The Internet Activities Board (IAB) was formed
from the chairs of the Task Forces. It of course was only a
coincidence that the chairs of the Task Forces were the same people
as the members of the old ICCB, and Dave Clark continued to act as
chair.
After some changing membership on the IAB, Phill Gross became chair
of a revitalized Internet Engineering Task Force (IETF), at the time
merely one of the IAB Task Forces. As we saw above, by 1985 there
was a tremendous growth in the more practical/engineering side of
the Internet. This growth resulted in an explosion in the attendance
at the IETF meetings, and Gross was compelled to create substructure
to the IETF in the form of working groups.
This growth was complemented by a major expansion in the
community. No longer was DARPA the only major player in the funding
of the Internet. In addition to NSFNet and the various US and
international government-funded activities, interest in the
commercial sector was beginning to grow. Also in 1985, both Kahn and
Leiner left DARPA and there was a significant decrease in Internet
activity at DARPA. As a result, the IAB was left without a primary
sponsor and increasingly assumed the mantle of leadership.
The growth continued, resulting in even further substructure
within both the IAB and IETF. The IETF combined Working Groups into
Areas, and designated Area Directors. An Internet Engineering
Steering Group (IESG) was formed of the Area Directors. The IAB
recognized the increasing importance of the IETF, and restructured
the standards process to explicitly recognize the IESG as the major
review body for standards. The IAB also restructured so that the
rest of the Task Forces (other than the IETF) were combined into an
Internet Research Task Force (IRTF) chaired by Postel, with the old
task forces renamed as research groups.
The growth in the commercial sector brought with it increased
concern regarding the standards process itself. Starting in the
early 1980's and continuing to this day, the Internet grew beyond
its primarily research roots to include both a broad user community
and increased commercial activity. Increased attention was paid to
making the process open and fair. This coupled with a recognized
need for community support of the Internet eventually led to the
formation of the Internet Society in 1991, under the auspices of
Kahn's Corporation for National Research Initiatives (CNRI) and the
leadership of Cerf, then with CNRI.
In 1992, yet another reorganization took place. In 1992, the
Internet Activities Board was re-organized and re-named the Internet
Architecture Board operating under the auspices of the Internet
Society. A more "peer" relationship was defined between the new IAB
and IESG, with the IETF and IESG taking a larger responsibility for
the approval of standards. Ultimately, a cooperative and mutually
supportive relationship was formed between the IAB, IETF, and
Internet Society, with the Internet Society taking on as a goal the
provision of service and other measures which would facilitate the
work of the IETF.
The recent development and widespread deployment of the World Wide
Web has brought with it a new community, as many of the people
working on the WWW have not thought of themselves as primarily
network researchers and developers. A new coordination organization
was formed, the World Wide Web Consortium (W3C). Initially led from
MIT's Laboratory for Computer Science by Tim Berners-Lee (the
inventor of the WWW) and Al Vezza, W3C has taken on the
responsibility for evolving the various protocols and standards
associated with the Web.
Thus, through the over two decades of Internet activity, we have
seen a steady evolution of organizational structures designed to
support and facilitate an ever-increasing community working
collaboratively on Internet issues.
COMMERCIALIZATION OF THE TECHNOLOGY
Commercialization of the Internet involved not only the
development of competitive, private network services, but also the
development of commercial products implementing the Internet
technology. In the early 1980s, dozens of vendors were incorporating
TCP/IP into their products because they saw buyers for that approach
to networking. Unfortunately they lacked both real information about
how the technology was supposed to work and how the customers
planned on using this approach to networking. Many saw it as a
nuisance add-on that had to be glued on to their own proprietary
networking solutions: SNA, DECNet, Netware, NetBios. The DoD had
mandated the use of TCP/IP in many of its purchases but gave little
help to the vendors regarding how to build useful TCP/IP products.
In 1985, recognizing this lack of information availability and
appropriate training, Dan Lynch in cooperation with the IAB
arranged to hold a three day workshop for ALL vendors to come learn
about how TCP/IP worked and what it still could not do well. The
speakers came mostly from the DARPA research community who had both
developed these protocols and used them in day to day work. About
250 vendor personnel came to listen to 50 inventors and
experimenters. The results were surprises on both sides: the vendors
were amazed to find that the inventors were so open about the way
things worked (and what still did not work) and the inventors were
pleased to listen to new problems they had not considered, but were
being discovered by the vendors in the field. Thus a two way
discussion was formed that has lasted for over a decade.
After two years of conferences, tutorials, design meetings and
workshops, a special event was organized that invited those vendors
whose products ran TCP/IP well enough to come together in one room
for three days to show off how well they all worked together and
also ran over the Internet. In September of 1988 the first Interop
trade show was born. 50 companies made the cut. 5,000 engineers from
potential customer organizations came to see if it all did work as
was promised. It did. Why? Because the vendors worked extremely hard
to ensure that everyone's products interoperated with all of the
other products - even with those of their competitors. The Interop
trade show has grown immensely since then and today it is held in 7
locations around the world each year to an audience of over 250,000
people who come to learn which products work with each other in a
seamless manner, learn about the latest products, and discuss the
latest technology.
In parallel with the commercialization efforts that were
highlighted by the Interop activities, the vendors began to attend
the IETF meetings that were held 3 or 4 times a year to discuss new
ideas for extensions of the TCP/IP protocol suite. Starting with a
few hundred attendees mostly from academia and paid for by the
government, these meetings now often exceeds a thousand attendees,
mostly from the vendor community and paid for by the attendees
themselves. This self-selected group evolves the TCP/IP suite in a
mutually cooperative manner. The reason it is so useful is that it
is comprised of all stakeholders: researchers, end users and
vendors.
Network management provides an example of the interplay between the
research and commercial communities. In the beginning of the
Internet, the emphasis was on defining and implementing protocols
that achieved interoperation. As the network grew larger, it became
clear that the sometime ad hoc procedures used to manage the
network would not scale. Manual configuration of tables was replaced
by distributed automated algorithms, and better tools were devised
to isolate faults. In 1987 it became clear that a protocol was
needed that would permit the elements of the network, such as the
routers, to be remotely managed in a uniform way. Several protocols
for this purpose were proposed, including Simple Network Management
Protocol or SNMP (designed, as its name would suggest, for
simplicity, and derived from an earlier proposal called SGMP) , HEMS
(a more complex design from the research community) and CMIP (from
the OSI community). A series of meeting led to the decisions that
HEMS would be withdrawn as a candidate for standardization, in order
to help resolve the contention, but that work on both SNMP and CMIP
would go forward, with the idea that the SNMP could be a more
near-term solution and CMIP a longer-term approach. The market could
choose the one it found more suitable. SNMP is now used almost
universally for network based management.
In the last few years, we have seen a new phase of
commercialization. Originally, commercial efforts mainly comprised
vendors providing the basic networking products, and service
providers offering the connectivity and basic Internet services. The
Internet has now become almost a "commodity" service, and much of
the latest attention has been on the use of this global information
infrastructure for support of other commercial services. This has
been tremendously accelerated by the widespread and rapid adoption
of browsers and the World Wide Web technology, allowing users easy
access to information linked throughout the globe. Products are
available to facilitate the provisioning of that information and
many of the latest developments in technology have been aimed at
providing increasingly sophisticated information services on top of
the basic Internet data communications.
HISTORY OF THE FUTURE
On October 24, 1995, the FNC unanimously passed a resolution
defining the term Internet. This definition was developed
in consultation with members of the internet and intellectual
property rights communities. *RESOLUTION:* *The Federal Networking
Council (FNC) agrees that the following language reflects our
definition of the term "Internet". "Internet" refers to the global
information system that -- **(i) is logically linked together by a
globally unique address space based on the Internet Protocol (IP) or
its subsequent extensions/follow-ons;* *(ii) is able to support
communications using the Transmission Control Protocol/Internet
Protocol (TCP/IP) suite or its subsequent extensions/follow-ons,
and/or other IP-compatible protocols; and* *(iii) provides, uses or
makes accessible, either publicly or privately, high level services
layered on the communications and related infrastructure described
herein.*
The Internet has changed much in the two decades since it came into
existence. It was conceived in the era of time-sharing, but has
survived into the era of personal computers, client-server and
peer-to-peer computing, and the network computer. It was designed
before LANs existed, but has accommodated that new network
technology, as well as the more recent ATM and frame switched
services. It was envisioned as supporting a range of functions from
file sharing and remote login to resource sharing and collaboration,
and has spawned electronic mail and more recently the World Wide
Web. But most important, it started as the creation of a small band
of dedicated researchers, and has grown to be a commercial success
with billions of dollars of annual investment.
One should not conclude that the Internet has now finished
changing. The Internet, although a network in name and geography, is
a creature of the computer, not the traditional network of the
telephone or television industry. It will, indeed it must, continue
to change and evolve at the speed of the computer industry if it is
to remain relevant. It is now changing to provide such new services
as real time transport, in order to support, for example, audio and
video streams. The availability of pervasive networking (i.e., the
Internet) along with powerful affordable computing and
communications in portable form (i.e., laptop computers, two-way
pagers, PDAs, cellular phones), is making possible a new paradigm of
nomadic computing and communications.
This evolution will bring us new applications - Internet telephone
and, slightly further out, Internet television. It is evolving to
permit more sophisticated forms of pricing and cost recovery, a
perhaps painful requirement in this commercial world. It is changing
to accommodate yet another generation of underlying network
technologies with different characteristics and requirements, from
broadband residential access to satellites. New modes of access and
new forms of service will spawn new applications, which in turn will
drive further evolution of the net itself.
The most pressing question for the future of the Internet is not
how the technology will change, but how the process of change and
evolution itself will be managed. As this paper describes, the
architecture of the Internet has always been driven by a core group
of designers, but the form of that group has changed as the number
of interested parties has grown. With the success of the Internet
has come a proliferation of stakeholders - stakeholders now with an
economic as well as an intellectual investment in the network. We
now see, in the debates over control of the domain name space and
the form of the next generation IP addresses, a struggle to find the
next social structure that will guide the Internet in the future.
The form of that structure will be harder to find, given the large
number of concerned stake-holders. At the same time, the industry
struggles to find the economic rationale for the large investment
needed for the future growth, for example to upgrade residential
access to a more suitable technology. If the Internet stumbles, it
will not be because we lack for technology, vision, or motivation.
It will be because we cannot set a direction and march collectively
into the future.
------*****------
Footnotes
[1] Perhaps this is an exaggeration based on the lead author's
residence in Silicon Valley.
[2] On a recent trip to a Tokyo bookstore, one of the authors
counted 14 English language magazines devoted to the Internet.
[3] An abbreviated version of this article appears in the 50th
anniversary issue of the *CACM*, Feb. 97. The authors would like to
express their appreciation to Andy Rosenbloom, CACM Senior Editor,
for both instigating the writing of this article and his invaluable
assistance in editing both this and the abbreviated version.
[4] The Advanced Research Projects Agency (ARPA) changed its name to
Defense Advanced Research Projects Agency (DARPA) in 1971, then back
to ARPA in 1993, and back to DARPA in 1996. We refer throughout to
DARPA, the current name.
[5] It was from the RAND study that the false rumor started claiming
that the ARPANET was somehow related to building a network
resistant to nuclear war. This was never true of the ARPANET, only
the unrelated RAND study on secure voice considered nuclear war.
However, the later work on Internetting did emphasize robustness and
survivability, including the capability to withstand losses of large
portions of the underlying networks.
[6] Including amongst others Vint Cerf, Steve Crocker, and Jon
Postel. Joining them later were David Crocker who was to play an
important role in documentation of electronic mail protocols, and
Robert Braden, who developed the first NCP and then TCP for IBM
mainframes and also was to play a long term role in the ICCB and
IAB.
[7] This was subsequently published as V. G. Cerf and R. E. Kahn,
"A protocol for packet network interconnection" *IEEE Trans. Comm.
Tech*., vol. COM-22, V 5, pp. 627-641, May 1974.
[8] The desirability of email interchange, however, led to one of the
first "Internet books": *!%@:: A Directory of Electronic Mail
Addressing and Networks*, by Frey and Adams, on email address
translation and forwarding.
[9] Originally named Federal Research Internet Coordinating
Committee, FRICC. The FRICC was originally formed to coordinate U.S.
research network activities in support of the international
coordination provided by the CCIRN.
[10] The decomissioning of the ARPANET was commemorated on its 20th
anniversary by a UCLA symposium in 1989.
------*****------
References
P. Baran, "On Distributed Communications Networks", *IEEE Trans.
Comm. Systems,* March 1964.
V. G. Cerf and R. E. Kahn, "A protocol for packet network
interconnection", *IEEE Trans. Comm. Tech*., vol. COM-22, V 5, pp.
627-641, May 1974.
S. Crocker, *RFC001 Host software,* Apr-07-1969.
R. Kahn, Communications Principles for Operating Systems. Internal
BBN memorandum, Jan. 1972.
*Proceedings of the IEEE*, Special Issue on Packet Communication
Networks, Volume 66, No. 11, November, 1978. (Guest editor: Robert
Kahn, associate guest editors: Keith Uncapher and Harry van Trees)
L. Kleinrock, "Information Flow in Large Communication Nets", RLE
Quarterly Progress Report, July 1961.
L. Kleinrock, *Communication Nets: Stochastic Message Flow and
Delay*, Mcgraw-Hill (New York), 1964.
L. Kleinrock, *Queueing Systems: Vol II, Computer Applications,* John
Wiley and Sons (New York), 1976
J.C.R. Licklider & W. Clark, "On-Line Man Computer Communication",
August 1962.
L. Roberts & T. Merrill, "Toward a Cooperative Network of
Time-Shared Computers", Fall AFIPS Conf., Oct. 1966.
L. Roberts, "Multiple Computer Networks and Intercomputer
Communication", ACM Gatlinburg Conf., October 1967.
------*****------
Authors
Barry M. Leiner is Director of the Research Institute for Advanced
Computer Science.
Vinton G. Cerf is Senior Vice President, Internet Architecture and
Technology, at MCI WorldCom.
David D. Clark is Senior Research Scientist at the
MIT Laboratory for Computer Science.
Robert E. Kahn is President of the Corporation for National
Research Initiatives.
Leonard Kleinrock is Professor of Computer Science at the
University of California, Los Angeles, and is Chairman and Founder
of Nomadix.
Daniel C. Lynch is a founder of CyberCash Inc. and of the Interop
networking trade show and conferences.
Jon Postel served as Director of the Computer Networks Division of
the Information Sciences Institute of the University of Southern
California.
Lawrence G. Roberts is Chairman and CTO of Caspian Networks.
Stephen Wolff is with Cisco Systems, Inc.
------*****------
A Brief History of the Internet, version 3.31
Last revised 4 Aug 2000
Send any comments to Barry Leiner or any of the authors
