A Brief History of
the Internet
Barry
M. Leiner, Vinton G. Cerf, David
D. Clark,
Robert E. Kahn, Leonard Kleinrock,
Daniel C. Lynch,
Jon Postel, Larry G. Roberts,
Stephen Wolff
Introduction
The Internet has revolutionized
the computer and communications world like nothing before. The invention of
the telegraph, telephone, radio, and computer set the stage for this unprecedented
integration of capabilities. The Internet is at once a world-wide broadcasting
capability, a mechanism for information dissemination, and a medium for collaboration
and interaction between individuals and their computers without regard for
geographic location.
The Internet represents
one of the most successful examples of the benefits of sustained investment
and commitment to research and development of information infrastructure.
Beginning with the early research in packet switching, the government, industry
and academia have been partners in evolving and deploying this exciting new
technology. Today, terms like "bleiner@computer.org" and "http://www.acm.org"
trip lightly off the tongue of the random person on the street. 1
This is intended to be
a brief, necessarily cursory and incomplete history. Much material currently
exists about the Internet, covering history, technology, and usage. A trip
to almost any bookstore will find shelves of material written about the Internet.
2
In this paper, 3
several of us involved in the development and evolution of the Internet share
our views of its origins and history. This history revolves around four distinct
aspects. There is the technological evolution that began with early research
on packet switching and the ARPANET (and related technologies), and where
current research continues to expand the horizons of the infrastructure along
several dimensions, such as scale, performance, and higher level functionality.
There is the operations and management aspect of a global and complex operational
infrastructure. There is the social aspect, which resulted in a broad community
of Internauts working together to create and evolve the technology.
And there is the commercialization aspect, resulting in an extremely effective
transition of research results into a broadly deployed and available information
infrastructure.
The Internet today is
a widespread information infrastructure, the initial prototype of what is
often called the National (or Global or Galactic) Information Infrastructure.
Its history is complex and involves many aspects - technological, organizational,
and community. And its influence reaches not only to the technical fields
of computer communications but throughout society as we move toward increasing
use of online tools to accomplish electronic commerce, information acquisition,
and community operations.
Origins of the Internet
The first recorded description
of the social interactions that could be enabled through networking was a
series of memos written by J.C.R. Licklider of MIT in
August 1962 discussing his "Galactic Network" concept. He envisioned
a globally interconnected set of computers through which everyone could quickly
access data and programs from any site. In spirit, the concept was very much
like the Internet of today. Licklider was the first head of the computer research
program at DARPA, 4 starting in October 1962.
While at DARPA he convinced his successors at DARPA, Ivan Sutherland, Bob
Taylor, and MIT researcher Lawrence G. Roberts, of the importance of this
networking concept.
Leonard Kleinrock at MIT
published the first paper on packet switching theory in
July 1961 and the first book on the subject in 1964. Kleinrock
convinced Roberts of the theoretical feasibility of communications using packets
rather than circuits, which was a major step along the path towards computer
networking. The other key step was to make the computers talk together. To
explore this, in 1965 working with Thomas Merrill, Roberts connected the TX-2
computer in Mass. to the Q-32 in California with a low speed dial-up telephone
line creating the first (however small) wide-area computer
network ever built. The result of this experiment was the realization
that the time-shared computers could work well together, running programs
and retrieving data as necessary on the remote machine, but that the circuit
switched telephone system was totally inadequate for the job. Kleinrock's
conviction of the need for packet switching was confirmed.
In late 1966 Roberts went
to DARPA to develop the computer network concept and quickly put together
his plan for the "ARPANET", publishing it in
1967. At the conference where he presented the paper, there was also a paper
on a packet network concept from the UK by Donald Davies and Roger Scantlebury
of NPL. Scantlebury told Roberts about the NPL work as well as that of Paul
Baran and others at RAND. The RAND group had written a paper
on packet switching networks for secure voice in the military in 1964.
It happened that the work at MIT (1961-1967), at RAND (1962-1965), and at
NPL (1964-1967) had all proceeded in parallel without any of the researchers
knowing about the other work. The word "packet" was adopted from
the work at NPL and the proposed line speed to be used in the ARPANET design
was upgraded from 2.4 kbps to 50 kbps. 5
In August 1968, after
Roberts and the DARPA funded community had refined the overall structure and
specifications for the ARPANET, an RFQ was released by DARPA for the development
of one of the key components, the packet switches called Interface Message
Processors (IMP's). The RFQ was won in December 1968 by a group headed by
Frank Heart at Bolt Beranek and Newman (BBN). As the BBN team worked on the
IMP's with Bob Kahn playing a major role in the overall ARPANET architectural
design, the network topology and economics were designed and optimized by
Roberts working with Howard Frank and his team at Network Analysis Corporation,
and the network measurement system was prepared by Kleinrock's team at UCLA.
6
Due to Kleinrock's early
development of packet switching theory and his focus on analysis, design and
measurement, his Network Measurement Center at UCLA was selected to be the
first node on the ARPANET. All this came together in September 1969 when BBN
installed the first IMP at UCLA and the first host computer was connected.
Doug Engelbart's project on "Augmentation of Human Intellect" (which
included NLS, an early hypertext system) at Stanford Research Institute (SRI)
provided a second node. SRI supported the Network Information Center, led
by Elizabeth (Jake) Feinler and including functions such as maintaining tables
of host name to address mapping as well as a directory of the RFC's. One month
later, when SRI was connected to the ARPANET, the first host-to-host message
was sent from Kleinrock's laboratory to SRI. Two more nodes were added at
UC Santa Barbara and University of Utah. These last two nodes incorporated
application visualization projects, with Glen Culler and Burton Fried at UCSB
investigating methods for display of mathematical functions using storage
displays to deal with the problem of refresh over the net, and Robert Taylor
and Ivan Sutherland at Utah investigating methods of 3-D representations over
the net. Thus, by the end of 1969, four host computers were connected together
into the initial ARPANET, and the budding Internet was off the ground. Even
at this early stage, it should be noted that the networking research incorporated
both work on the underlying network and work on how to utilize the network.
This tradition continues to this day.
Computers were added quickly
to the ARPANET during the following years, and work proceeded on completing
a functionally complete Host-to-Host protocol and other network software.
In December 1970 the Network Working Group (NWG) working under S. Crocker
finished the initial ARPANET Host-to-Host protocol, called the Network Control
Protocol (NCP). As the ARPANET sites completed implementing NCP during the
period 1971-1972, the network users finally could begin to develop applications.
In October 1972 Kahn organized
a large, very successful demonstration of the ARPANET at the International
Computer Communication Conference (ICCC). This was the first public demonstration
of this new network technology to the public. It was also in 1972 that the
initial "hot" application, electronic mail, was introduced. In March
Ray Tomlinson at BBN wrote the basic email message send and read software,
motivated by the need of the ARPANET developers for an easy coordination mechanism.
In July, Roberts expanded its utility by writing the first email utility program
to list, selectively read, file, forward, and respond to messages. From there
email took off as the largest network application for over a decade. This
was a harbinger of the kind of activity we see on the World Wide Web today,
namely, the enormous growth of all kinds of "people-to-people" traffic.
The Initial Internetting
Concepts
The original ARPANET grew
into the Internet. Internet was based on the idea that there would be multiple
independent networks of rather arbitrary design, beginning with the ARPANET
as the pioneering packet switching network, but soon to include packet satellite
networks, ground-based packet radio networks and other networks. The Internet
as we now know it embodies a key underlying technical idea, namely that of
open architecture networking. In this approach, the choice of any individual
network technology was not dictated by a particular network architecture but
rather could be selected freely by a provider and made to interwork with the
other networks through a meta-level "Internetworking Architecture".
Up until that time there was only one general method for federating networks.
This was the traditional circuit switching method where networks would interconnect
at the circuit level, passing individual bits on a synchronous basis along
a portion of an end-to-end circuit between a pair of end locations. Recall
that Kleinrock had shown in 1961 that packet switching was a more efficient
switching method. Along with packet switching, special purpose interconnection
arrangements between networks were another possibility. While there were other
limited ways to interconnect different networks, they required that one be
used as a component of the other, rather than acting as a peer of the
other in offering end-to-end service.
In an open-architecture
network, the individual networks may be separately designed and developed
and each may have its own unique interface which it may offer to users and/or
other providers. including other Internet providers. Each network can be designed
in accordance with the specific environment and user requirements of that
network. There are generally no constraints on the types of network that can
be included or on their geographic scope, although certain pragmatic considerations
will dictate what makes sense to offer.
The idea of open-architecture
networking was first introduced by Kahn shortly after having arrived at DARPA
in 1972. This work was originally part of the packet radio program, but subsequently
became a separate program in its own right. At the time, the program was called
"Internetting". Key to making the packet radio system work was a
reliable end-end protocol that could maintain effective communication in the
face of jamming and other radio interference, or withstand intermittent blackout
such as caused by being in a tunnel or blocked by the local terrain. Kahn
first contemplated developing a protocol local only to the packet radio network,
since that would avoid having to deal with the multitude of different operating
systems, and continuing to use NCP.
However, NCP did not have
the ability to address networks (and machines) further downstream than a destination
IMP on the ARPANET and thus some change to NCP would also be required. (The
assumption was that the ARPANET was not changeable in this regard). NCP relied
on ARPANET to provide end-to-end reliability. If any packets were lost, the
protocol (and presumably any applications it supported) would come to a grinding
halt. In this model NCP had no end-end host error control, since the ARPANET
was to be the only network in existence and it would be so reliable that no
error control would be required on the part of the hosts.
Thus, Kahn decided to
develop a new version of the protocol which could meet the needs of an open-architecture
network environment. This protocol would eventually be called the Transmission
Control Protocol/Internet Protocol (TCP/IP). While NCP tended to act like
a device driver, the new protocol would be more like a communications protocol.
Four ground rules were
critical to Kahn's early thinking:
- 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 7
of the resulting approach was distributed at a special meeting of the International
Network Working Group (INWG) which had been set up at a conference at Sussex
University in September 1973. Cerf had been invited to chair this group and
used the occasion to hold a meeting of INWG members who were heavily represented
at the Sussex Conference.
Some basic approaches
emerged from this collaboration between Kahn and Cerf:
- 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 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's
free-wheeling dissemination of the UNIX computer operating system spawned
USENET, based on UNIX' built-in UUCP communication protocols, and in 1981
Ira Fuchs and Greydon Freeman devised BITNET, which linked academic mainframe
computers in an "email as card images" paradigm.
With the exception of
BITNET and USENET, these early networks (including ARPANET) were purpose-built
- i.e., they were intended for, and largely restricted to, closed communities
of scholars; there was hence little pressure for the individual networks to
be compatible and, indeed, they largely were not. In addition, alternate technologies
were being pursued in the commercial sector, including XNS from Xerox, DECNet,
and IBM's SNA. 8 It remained for the British
JANET (1984) and U.S. NSFNET (1985) programs to explicitly announce their
intent to serve the entire higher education community, regardless of discipline.
Indeed, a condition for a U.S. university to receive NSF funding for an Internet
connection was that "... the connection must be made available to ALL
qualified users on campus."
In 1985, Dennis Jennings
came from Ireland to spend a year at NSF leading the NSFNET program. He worked
with the community to help NSF make a critical decision - that TCP/IP would
be mandatory for the NSFNET program. When Steve Wolff took over the NSFNET
program in 1986, he recognized the need for a wide area networking infrastructure
to support the general academic and research community, along with the need
to develop a strategy for establishing such infrastructure on a basis ultimately
independent of direct federal funding. Policies and strategies were adopted
(see below) to achieve that end.
NSF also elected to support
DARPA's existing Internet organizational infrastructure, hierarchically arranged
under the (then) Internet Activities Board (IAB). The public declaration of
this choice was the joint authorship by the IAB's Internet Engineering and
Architecture Task Forces and by NSF's Network Technical Advisory Group of
RFC 985 (Requirements for Internet Gateways ), which formally ensured interoperability
of DARPA's and NSF's pieces of the Internet.
In addition to the selection
of TCP/IP for the NSFNET program, Federal agencies made and implemented several
other policy decisions which shaped the Internet of today.
- 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 9
was formed. The FNC also cooperated with other international organizations,
such as RARE in Europe, through the Coordinating Committee on Intercontinental
Research Networking, CCIRN, to coordinate Internet support of the research
community worldwide.
- 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 decommissioned10,
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.
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