The Internet is, of course, a global packet switched data network and the early history of its development centres mainly on the evolotion of packet switching technology - work on this subject happened independently in the UK and in USA and there was also a certain degree of sharing of ideas...

In England, at the NPL (National Physical Laboratory) Teddington site, Dr Donald Davies conceived the idea of a "network" of inter-connected data terminals where the data was broken into small chunks (or "packets" as Davies named them) rather than in a continuous stream, which also avoided the problem of short messages being blocked behind long messages

Davies' ideas were first presented in public in the USA at the ACM symposium, in Gatlinburg in 1967, and in the UK at the IFIP Congress, 1968, in Edinburgh

The NPL packet switching approach was adopted by the US Department of Defense in 1967 and in 1968 aproject called the ARPANET, the forerunner of the internet, was launched

The first ARPANET link was between the University of California and Stanford Research Institute in 1969 and the
first international ARPANET connection was made between London and Norway in 1973

In the USA efforts to interconnect computers had been going on for some time but had focussed on circuit switching rather than packet switching

In 1957, Dr. J.C.R. Licklider left MIT to join Bolt Beranek and Newnan (BBN Technologies), where he advanced the state of many basic ideas, especially the BBN Time-Sharing System

In 1959, a computer scientist, Paul Baran, was working at the RAND Corporation on the idea of interconnecting computers. In 1962, Baran presented a paper titled On Distributed Communications Networks he proposed the computer communication concept of standard message blocks routed as "hot potatoes" in a store-and-forward system

In 1961 Leonard Kleinrock wrote a proposal for his thesis at MIT on "Information Flow in Large Communication Nets" and in 1962 "Message Delay in Communication Nets with Storage" both of which described short message data techniques

In 1962, when Dr Licklider became the first Director of the IPTO (Information Processing Techniques Office) of the ARPA (Advanced Research Projects Agency), he promoted the development of time-sharing one computer at the same time and
in 1963 he proposed an even grander vision: an "Intergalactic Network" of thousands of computers, millions of computers...

In 1965, two computer scientists Dr. Lawrence G. Roberts and Thomas Marill, conducted an experiment to understand what it would take to interconnect two computers, namely a TX-2 computer at MIT Lincoln Lab with a Q-32 computer at System Development Corporation in Santa Monica CA, using a lease-line from Western Union - this experiment highlighted the complexity of the problem and concluded that circuit switching, as used by the telephone network, was a poor solution

In 1968 Dr Roberts beame the program manager for ARPANET and Wesley Clark suggested the use of dedicated computers in a message switching network, which were later called Interface Message Processors (IMPs)

The IMPs together with the telephone lines and the modems would constitute the message-switching, communications network, or "Subnet

Dr Roberts presented a paper titled Multiple Computer Networks and Intercomputer Communications at the ACM symposium, in Gatlinburg in 1967, which he down-played slow speed circuits but stated  that the communication links between IMPs would be 2400 bit/second dial-up circuits

Roger Scantlebury of NPL presented at the aforementioned Gatlinburg conference in 1967 on the local network being developed at NPL (National Physical Laboratory) in the UK by Donald Davies, which used much higher speed circuits - he also saw the US plans for ARPANET and reported back "It would appear then that the ideas in the NPL paper at the moment are more advanced than any proposed in the USA"

Dr Roberts was heavily influenced by the NPL work, stating later "The NPL paper clearly impacted the ARPANET in several ways. The name "packet" was adopted, a much higher speed was selected (50 Kilobit/second vs 2.4 Kilobit/second) for internode lines to reduce delay and generally the NPL analysis helped confirm the concept of packet switching

Here is a video of Larry Roberts (Dr. Lawrence G. Roberts) himself talking about much of the history described above, including talking to Donald Davies of NPL in the UK, about using the term "packets" and faster links (at 11:10)

The key point about the approaches taken in both England and America was that processing power almost dictated that seperate computer systems were used to handle the establishment of communcations between the main computers

Interface Message Processors (IMPs) were manufactured by  Bolt Beranek and Newnan (BBN Technologies) and were based on Honywell DDP-516 systems, with a different front panel and 6,000 words of code written by the "IMP Guys" at BBN in Honeywell 516 assembly language

The interface message processor for the ARPA computer network document on the right was written by several BBN employees, such as Robert Kahn, F.E. Heart, S.M. Ornstein, W.R. Crowther, and D.C. Walden

J.M. McQuillan, W.R. Crowther, B.P. Cosell, D.C. Walden, and F.E. Heart also wrote Improvements in the Design and Performance of the ARPA Network

J.M. McQuillan and  D.C. Walden also wrote ARPA Network Design Decisions on the left

In the video on the right, Leonard Kleinrock, talks about what was first probably the message sent on a computer network on Oct. 29th, 1969, between UCLA and Stanford University

The word 
"login" was typed but the system crashed and only "lo" was received

The first IMP had just been installed at UCLA in Kleinrock's lab on that day in October 1969 and the first ARPANET communication was established between with Douglas Engelbart's lab at the Stanford Research Institute (SRI), as the commemorated by the UCLA Office of Public Information below

By December 1969, the fledgling ARPANET had grown to 4 nodes, with the connection of the University of California at Santa Barbara and the University of Utah

In 1972 the second phase of ARPANET produced a major expansion from the 4 original sites to 40 sites across the USA

In 1972 ARPA was renamed the DARPA (Defense Advanced Research Projects Agency) in 1972 - there is an interesting section in RFC 1000, which summarises RFCs 1 to 999, which starts:

The procurement of the ARPANET was initiated in the summer of 1968 -- Remember Vietnam, flower children, etc?  There had been prior experiments at various ARPA sites to link together computer systems, but this was the first version to explore packet-switching on a grand scale.  ("ARPA" didn't become "DARPA" until 1972.)

In 1973 University College of London in England and the Royal Radar Establishment in Norway were connect to ARPANET

In 1975
satellite links to Hawaii and UK were added and there were already 57 nodes in the network and the 1st of July - That year the Defense Communication Agency (DCA) took over direct control of ARPANET, as there was risk to national security because of rapid growth and complete lack of control over access and activity

In 1976 Queen Elizabeth II made history by sending an email announcing that the Royal Signals and Radar Establishment in Malvern was available on the ARPANET

The video in the right, celebrating the 50th Anniversary of ARPANET shows its evolution during the 1970s and the interntetworking between various elements, which is also covered below

By 1977 ARPANET has grown as depicted below

Key contributors mentioned earlier, such as J.C.R. Licklider, Lawrence G. Roberts and Donald Davies appear in the video on the left explaining the operation of ARPANET and the design techniques used by BBN Technologies  

 Robert Kahn of BBN also explains the network topology and resilience, with the aid of diagrams drawn on a whiteboard - he is very probably the industry's very first SE (Systems or Sales Engineer) - he goes on to detail such familar topics as store & forward devices, network management, remote admin and code upgrades

As Robert Kahn explains, the IMP (Interface Message Processors) used to form the ARPANET were also suplemented by TIPs (Terminal Interface Processors), which allowed connection of simpler terminals and were therfore early terminal servers

Peter T. Kirstein in England is often recognised as the father of the European Internet as he was responsible for the first ARPANET connected system outside of America

Kirstein recalls his early work in Early Experiences with the ARPANET and INTERNET in the UK

The British side of the story is remembered by members of the original NPL (National Physical Laboratory) team in this video

The comparison with visiting ARPANET people from America is mentioned and the connection of the NPL network with it - most likely the first example of InterNetworking

Even an example of a data network carrying encoded speech is explained - probably the first example of VOIP in the 1970s

This diagram of the ARPANET protocols shows a multi-layered approach, much like the OSI 7 layer model and TCP/IP 5 layer model, which it obviously predates by many years, albeit with only 3 layers

IMPs are interconnected at the first layer with physical circuits and communicate via packets

Hosts are interconnected at the second layer with virtual links and commicate via messages

Users processes are interconnected at the third layer with virtual connections and communicate via byte streams

The ARPANET host-to-host communication used 1822 protocol, as covered in the specification document on the left, along with hardware and interfacing details

Data messages contained the destination host's address and the data message being sent and the 1822 hardware interface allowed the IMP to deliver the message to that destination address, either to a locally connected host, or to a downstream IMP the last IMP in the path transmitted a Ready for Next Message (RFNM) acknowledgement to the sending host IMP.

Messages had a total length of 8159 bits, the first 96 bits were reserved for the "leader", or header, and the remainder was data

1822 messages had guaranteed delivery and if a message did fail to be delivered, the IMP sent to the originating host a message informing it as such - this system proved not to be foolproof though

Later versions of the 1822 protocol, such as 1822L, are described in RFC 802 and its successors

Stephen D. Crocker, a graduate student at UCLA, created and led the Network Working Group (NWG) and wrote the very first Network Working Group Request for Comment (RFC) which summaried the IMP Software, the Host-to-Host Software and the Host Software - Click the image on the right for the original copy

RFC 2 explained how to write RFCs and added that the Network Working Group "seems to consist of Steve Carr of Utah, Jeff Rulifson and Bill Duvall at SRI, and Steve Crocker and Gerard Deloche at UCLA. Membership is not closed"

The problem with unreliable message delivery on the ARPANET was addressed with the Network Control Program (NCP), which provided a standard method to establish reliable, flow-controlled, bidirectional communications links among different processes in different host computers.

The NCP interface allowed application software to connect across the ARPANET by implementing higher-level communication protocols, an early example of the protocol layering concept later incorporated in the OSI model

NCP was developed under the leadership of Stephen D. Crocker, then a graduate student at UCLA. Crocker created and led the Network
Working Group (NWG) which was made up of a collection of graduate students at universities and research laboratories sponsored by ARPA
to carry out the development of the ARPANET and the software for the host computers that supported applications

NCP was discussed in An Official Protocol Proffering RFC 54 and it was finalised and deployed in December 1970, with its Prototypical Implemenatation is described in RFC 55

RFC 384  lists all the OFFICIAL SITE IDENTS FOR ORGANIZATIONS IN THE ARPA NETWORK in August 1972- it only amounts to 4 pages

The ARPANET Completion Report on the right describes much of the history covered above and also has more diagrams showing its growth in the glossary at the end

In 1980 the whole ARPANET came to a complete halt because of a message timestamp issue, which mimicked a DDoS attack - the details were recorded in RFC 789 - at that time ARPANET had 213 hosts, with a new host added approximately once every 20 days

The NCP protocol had some critical limitations:
Error control was never deemed necessary for the ARPANET as it was designed as the only
network in existence

As changes in the ARPANET were ruled out, it was clear that new protocol to replace NCP would be required - the new protocol would need to operate more like a communications protocol, rather than a device driver orientated approach that NCP took

In 1974 Vinton Cerf and Bob Kahn wrote the paper on the left detailing a new protocol called TCP (Transmission Control Protocol), to correct all of the shortcomings of NCP by itself

This early TCP implementation worked well with file transfer and remote login but problems emerged with packet voice experimentation in the 1970s, which showed that packet loss would be better corrected by the application, outside of TCP

The answer was to split all of the functions of the original TCP into two protocols and in 1978 TCP was split into:
  1. A simple internetworking protocol to provide only packet addressing and forwarding
  2. An advanced protocol providing flow control and packet loss recovery

These protocols, namely Internet Protocol (IP) andTransmission Control Protocol (TCP) were combined into a protocol suite, commonly known as TCP/IP for ARPANET

By 1983 the DCA (Defense Communication Agency) and DARPA had made the historic move to establish these two new protocols as de facto for the ARPANET - The Department of Defence (DoD) also adopted TCP/IP and the paper on the right by Vint Cerf and Edward Cain describes the implementation within the DoD

Peter T. Kirstein was instrumental in defining and implementing TCP/IP alongside Vint Cerf and Bob Kahn

Vint Cerf himself describes his work and collaboration with all others invloved in this video, including the TCP and TCP/IP protocols

He also covers need for interworking, stemming from the decision to allow seperate networks, with   and "Gateways"between them, which would later be renamed "Routers"

This need for internetworking is illustrated well by the diagram on the right, which shows how ARPANET and MILNET, the part of the network that carried unclassified United States Department of Defense traffic, was physically separated in 1983.

The ARPANET served the academic research community

Gateways relayed electronic mail between the two networks

Other direct connectivity between the networks was disconnected


SATNET, or the Atlantic Packet Satellite Network as it was also known, was an early satellite network that was an important part of the first heterogeneous computer network and the fledgling Internet

As the diagrams on the left and below show, SATNET was an international link across the Atlantic Ocean to England and mainland Europe, which used the Intelsat IV and Intelsat V geostationary communication satellite

Goonhilly, in Helston, Cornwall provided the satellite link from the UK and, surprisingly, a mobile van from Stanford Research Institute, as part of PRNET (Packet Radio Network)

The SRI van looked much like a bread van but was actually a full ARPANET node, equipped with a DEC LSI-11, packet radio kit, a shielded generator and air conditioning

In 1976 on the 27th of August, the van was parked next to a well-known Portola Valley, California biker bar called Rossotti's (now the Alpine Inn), with cables running to a picnic tables and it was then that first two-network TCP/IP transmission was conducted between the van and ARPANET

The first demonstration, linking SATNET, the ARPANET, and PRNET took place on the 22nd of November 1977, when data flowed through the mobile SRI van at Menlo Park, California and the University of Southern California in Los Angeles via London, England, across three different types of network: packet radio, satellite, and the ARPANET, thus demonstarting the first Internet transmission between three disparate networks.

From 1977 to 1978, the SRI van was also used for the first VOIP (Voice over IP) tests, using ARPA's Network Speech Compression Program, over the Mickey Mouse phone in the van

The video on the left Robert Kahn talks about various parts of ARPANET, including IMPs, packet radio and the invention of gateways, which eventually became "routers" in the Internet 

The report on the left details testing conducted on SATNET in 1988 for TCP throughput perfomance, round trip, packet loss etc. as well as its structure

as standard Domain Name System or DNS is introduced to identify the type of institution which represents the host
The various application protocols such as TELNET for remote time-sharing access, File Transfer Protocol (FTP) and rudimentary electronic mail protocols were
developed and eventually ported to run over the TCP/IP protocol suite or replaced in the case of email by the Simple Mail Transport

In the same year the Domain Name Server (DNS) was developed at the University of Wisconsin. This allowed users to refer to sites by name and became the largest distributed database ever. By the following year DNS was introduced to the network and it had over 1000 hosts � small by today�s standards.

1970 – ARPANET started using Network Control Protocol
1972 – Telnet was implemented
1973 – FTP was introduced
1974 – TCP was specified
1981 – IP was specified
1983 – ARPANET changed to TCP/IP
1984 – DNS was introduced

1984: EGP

1988Internet Relay Chat (IRC) is developed by Jarkko Oikarinen.
1989 – 1991: BGP-1, 2 and 3

1994: BGP-4

1991WAIS, invented by Brewster Kahle, is released by Thinking Machines Corporation.Gopher is introduced by Paul Lindner and Mark P. McCahill from the University of Minnesota.

1993 – WWW invented

 World-Wide Web (WWW) is released by CERN in Geneva, Switzerland.British researcher, Tim Berner-Lee creates HTMLThe web as we know it is born!


Bob Metcalfe's paper on Packet Communication for MIT

Bob Metcalfe's article on Distributed Packet Switching


Sorry but there's only pictures to look at here so far - I'll add some words when I get time!!

Until then though, this TCP/IP Bible may prove useful! - Here's some more detailed info on OSPF and BGP ..... plus a Design Guide for large IP networks (covering OSPF & BGP)