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 packet watching 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 . 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 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 "". 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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