Brief History of the Internet
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 "
bleiner@computer.org" 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.
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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.
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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:
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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.
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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.
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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.
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There would be no global control at the operations level.
Other key issues that needed to be addressed were:
-
Algorithms to prevent lost packets from permanently disabling
communications and enabling them to be successfully retransmitted from
the source.
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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.
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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.
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The need for end-end checksums, reassembly of packets from fragments and detection of duplicates, if any.
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The need for global addressing
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Techniques for host-to-host flow control.
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Interfacing with the various operating systems
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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
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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:
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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.
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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.
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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.
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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.
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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.
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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.
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To coordinate this sharing, the Federal Networking Council9
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.
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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.
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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.
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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.
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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.
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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.
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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 continued to play until his death, October 16, 1998.
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 its 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 1970s, 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 exceed 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 composed 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 new services such 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, e.g. broadband residential access and
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 stakeholders. 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.
Timeline
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 decommissioning of the ARPANET was commemorated on its 20th anniversary by a UCLA symposium in 1989.
References
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G. Cerf and R. E. Kahn, "A protocol for packet network
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S. Crocker, RFC001 Host software, Apr-07-1969.
R. Kahn, Communications Principles for Operating Systems. Internal BBN memorandum, Jan. 1972.
Proceedings
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