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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
"bleiner@computer.org" and
"http://www.acm.org" trip lightly off the
tongue of the random person on the street.
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.
In
this paper, 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,
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.
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.
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:
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.
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.
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.
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.
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.
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.
The
need for end-end checksums, reassembly of packets from
fragments and detection of duplicates, if any.
The
need for global addressing
Techniques
for host to host flow control.
Interfacing
with the various operating systems
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 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:
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.
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.
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.
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.
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.
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.
To
coordinate this sharing, the Federal Networking Council
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.
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.
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.
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.
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.
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.
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, 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.
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