The Internet’s First Turning Point

Watching today’s House debate on net neutrality and discussing Internet architecture in a meeting today reminded me that the Internet’s history is very poorly understood, if it’s understood at all. People who discuss Internet history generally do so in order to make points about the role of government in promoting innovation without a grasp of the underlying facts. Engaging in fact-free dialog about the Internet’s formation allows people to make any point they want, ranging from the argument that government is a grand stimulator of innovation all the way to the opposite extreme, where government only gets in the way.

The field of Internet history got a big boost recently when Alex McKenzie published his account of the birth of the Internet protocols in the IEEE Annals of the History of Computing (Vol 33, No 1, pp 66-71,) INWG and the Conception of the Internet: An Eyewitness Account. McKenzie is one of the people at BB&N who built the ARPANET. Accounts of ARPANET history tend to gloss over the BB&N folks and focus on ARPANET users at USC and elsewhere, but without the work of McKenzie and colleagues such as Dave Walden, there would have been no ARPANET IMPs delivered to USC and SRI in 1969 for tinkering by Len Kleinrock’s grad students. ARPANET wasn’t built at USC, it was built at BB&N.

ARPANET was proof-of concept for packet switching, and a great deal of its value was to show how not to build a packet switched network. Smart people studied its operation and took away lessons that fueled the next phase of network innovation, which was in full swing by 1972, perhaps the most important year in the development of network architecture since the advent of the telegraph. As McKenzie recalls:

1972 was an exciting year in computer networking. The ARPANET, which came to life near the end of 1969, had grown to 29 nodes by August 1972. The National Physical Laboratory in England, under the direction of Donald Davies, had been running a 1-node packet switch interconnecting several NPL computers for several years. The French Research Laboratory IRIA, under the direction of Louis Pouzin, had begun the implementation of a packet-switched system called Cyclades. In July 1972, three people associated with the ARPANET work at BBN formed a new company, Packet Communications, “to engage in the business of providing communication services for computer to terminal, computer to computer, [and] terminal to terminal information transfer.” In November 1971 the European Common Market announced the intention to build a European Informatics Network (EIN) for research and scientific purposes under the direction of Derek Barber from NPL, and planning was underway in 1972. Several national post, telephone, and telegraph (PTT) organizations were beginning to consider building national common-user data networks using packet-switching technology. These included the British Post Office’s Experimental Packet Switched System (EPSS), RCP (French PTT), and a small experimental packet-switched network (PSN) built by the Norwegian PTT during 1971 to 1972 and used for experiments for three months.

As soon as the first generation packet switched network grew to 29 nodes, work started around the world on a second generation system. And yes, this work was funded by a variety of “government” agencies such as universities and PTTs; the initial design of the Internet clearly did not come from the private sector.

The first of the second generation of packet networks to deploy was Louis Pouzin’s CYCLADES in France. CYCLADES was the first example of a packet network built on layers, including a datagram protocol at the network layer and a sliding window protocol at the end-to-end layer. Vint Cerf acknowledges that these features of the Internet protocols (which most acknowledge to be its foundation concepts) were “borrowed” from CYCLADES by way of converstaions with Pouzin and with Gerard LeLann, one of Pouzin’s team who took a sabbatical year at Stanford when the Internet protocols were being designed.

In 1972, before the Internet protocols were designed, researchers came together under the banner of the International Packet Network Working Group (INWG), modeled on the ARPANET Network Working Group, to create a common protocol for packet switched networks. By 1973, this group was at full steam:

The second INWG meeting was held 7–8 June 1973 in New York in conjunction with the American Federation of Information Processing Societies (AFIPS) National Computer Conference. By this time, Pouzin had been instrumental in having INWG be chartered as Working Group 6.1 of the International Federation for Information Processing (IFIP) under Technical Committee (TC) 6, Data Transmission. [CORRECTION 2011/3/14: It was Alec Curran, chair of IFIP TC 6, not Pouzin, who arranged for IFIP to charter INWG.] This sponsorship gave INWG (as IFIP WG 6.1) standing to participate directly in the deliberations of CCITT and ISO, providing technical input on packet networking. At the New York meeting, a small team of engineers with implementation experience in ARPANET (US), Cyclades (F), MERIT (US), and NPL (UK) created a first draft of an International Transmission Protocol (ITP). Vint Cerf served as the editor of this document, which was distributed as a set of supplements to INWG 28. An introduction stated:

If we treat the computer communication system of each network as a complicated communication line joining HOSTs and Gateway[s], then the Gateways appear to be international nodes, joined by 2 or more networks, facilitating communication between HOSTs.

The international transmission protocol (ITP) described herein is intended to:

1. Be resistant to failures in intermediate constituent networks and gateways.
2. Be unaffected by the maximum message sizes permitted in constituent networks and by intra- and inter-network timing idiosyncrasies.
3. Be capable of exactly reconstituting a message stream originating in a foreign HOST.
4. Provide for high bandwidth and/or low delay transmission.
5. Require no status information in gateways.
6. Be relatively easy to implement.
7. Permit the receiving HOST to control the flow from the sending HOST.

Messages are made up of a fixed length header, containing control and addressing information, an integral number of fixed length elements containing the text of the message, and space for an optional checksum.

By 1975, INWG had a testbed running one version of the their consensus design, and plans were underway for testing another version on ARPANET:

In May 1974, the IEEE Transactions on Communications published “A Protocol for Packet Network Interconnection” by Cerf and Kahn. This was a greatly updated and refined version of INWG 39.

INWG met again on 10–11 August 1974 in Stockholm. The meeting was attended by 32 people from 11 countries. It was reported that the protocol of INWG 61 was in the test stage, and the protocol of INWG 39 (updated) was in the detailed specification stage. It was also reported that plans were being made for experiments with the updated INWG 39 protocol at ARPA supported sites, and the INWG 61 protocol was being used for experiments between NPL and Cyclades using a Modula 1 computer at NPL as a gateway. Experiments with the INWG 61 protocol were being planned between Cyclades and EIN when EIN became operational in late 1975 or early 1976.

McKenzie, Cerf, and others developed a single consensus protocol in 1975 that bridged the gap between INWG 39 and INWG 61; it was called INWG 96:

In July 1975, Cerf (representing INWG 39 and ARPA), Zimmermann (representing INWG 61 and Cyclades), Roger Scantlebury (representing NPL and EIN), and I (designated as output editor) met in London, agreeing to stay in session for as long as it took to produce a single proposal that INWG could vote on or reach the conclusion that we could not agree. In less than a week we had reached an agreement, which was documented in INWG 96.

INWG 96 was approved by all parties as the common protocol, but DARPA’s Internet people soon backed out of the consensus:

With the formal vote in favor of the INWG 96 protocol, it was expected that the various research groups within INWG would announce plans to convert to the common protocol and carry out their experiments with it. NPL and Cyclades, the two groups already carrying out internetwork tests, announced plans to convert immediately. EIN, still several months away from initial deployment, also announced their intention to use the INWG 96 protocol. But we were all shocked and amazed when Bob Kahn announced that DARPA researchers were too close to completing implementation of the updated INWG 39 protocol to incur the expense of switching to another design.

As events proved, Kahn was wrong (or had other motives); the “final” TCP/IP specification was written in 1980 after at least four revisions. But whether he was right or wrong didn’t matter; DARPA had a bigger research budget than any of the other research organizations, and for this reason, its protocol choice became dominant over time.

INWG continued work on protocol design and formal specification for another 15 or 20 years and then disbanded around the time of the Internet explosion.

The rest is history. DARPA adopted TCP/IP, the somewhat defective version of INWG 39 that lacked a proper addressing model, incorporated an ineffective congestion control system, and failed to clearly distinguish the end-to-end TCP layer from the IP layer (the infamous TCP “pseudo-header” ties TCP sessions to specific network interfaces and sub-networks.) The effort to correct the TCP/IP deficiencies, ISO’s Open System Interconnect project, became mired in politics and missed deadline after deadline, ultimately missing the window for an Internet-wide upgrade, and now we’ve landed in the IPv6 conversion.

The failure of DARPA to cooperate with the European researchers gave us an Internet five years later than the consensus design, and one that is functionally inferior to boot. The cost of the failure to cooperate is paid every day by users and network operators who have to spend more time and money doing their network business than they would if the international effort had been supported rather than undermined by DARPA. The DARPA design “won out” over the INWG design simply because DARPA had deeper pockets than all the other players combined. There’s a lesson in that.

There’s a saying that “World War II was won by British brains, American money, and Russian blood;” We could say that the Internet was the result of “British brains, American money, and French technology” and not be far from the truth. This is among the reasons that our friends in Europe, Asia, and Australia are less than comfortable with America’s control over the Internet’s technical and administrative systems.

Perhaps the best intellectual contribution to the Internet to come from American brains is Section 230 of the Communications Decency Act, the safe harbor for ISPs that makes content-oriented business practical. But that’s a topic for another time.


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