Inventing the Internet by Janet Abbate

Author:Janet Abbate [Abbate, Janet]
Language: eng
Format: epub
Tags: science, History
ISBN: 9780262261333
Google: 9BfZxFZpElwC
Publisher: MIT Press
Published: 2000-07-24T00:35:32.694013+00:00

Figure 4.3

Diagram of 1977 Internet demonstration.

The successful three-way interconnection of the ARPANET, PRNET, and SATNET represented the beginning of the Internet as an operational system. The design of the Internet made it possible for the networks to operate independently but still communicate, which benefited ARPA’s experimental network projects. For instance, SATNET researchers could use the ARPANET to coordinate project personnel, monitor SATNET equipment, and generate test traffic; at the same time, SATNET remained a separate system from the ARPANET, which gave researchers the freedom to conduct possibly disruptive experiments on SATNET without disturbing ARPANET users (Jacobs et al. 1978, pp. 1462–1464). The ability of local networks to maintain their autonomy while participating in the Internet also made it easier to include networks from outside ARPA. After the demonstration, a number of new defense and research networks joined ARPA’s evolving Internet, including the Defense Communications Agency’s Experimental Data Network, the Army’s Fort Bragg packet radio network, various Ethernet LANs at Xerox PARC, an experimental packet radio network at BBN, the network of MIT’s Laboratory of Computer Science, and the British Post Office’s Experimental Packet Switching System (Cerf and Kirstein 1978, p. 302).

To encourage sites to adopt TCP, ARPA began funding implementations of it for various operating systems. In 1977, ARPA funded BBN to incorporate TCP/IP into the popular Unix operating system, and one of the system’s creators, Bill Joy, added TCP/IP to the Berkeley version of Unix.18 ARPA also funded implementations for IBM machines, for the DEC TOPS-20 system, and for other operating systems (McKenzie 1997).

The ARPANET, however, did not adopt TCP/IP immediately. ARPA managers encouraged host sites to implement the new protocol, but did not force them to do so. Most sites chose to continue using NCP: the old protocol was providing perfectly adequate service within the ARPANET, and researchers who were not actively involved in internetworking experiments had no immediate motivation to switch protocols. Implementing TCP was difficult; to make matters worse, the specification kept changing as the Internet team adopted new ideas and as experimental use revealed shortcomings in the design. It was not ARPA’s research community, therefore, that pushed for the transition from the ARPANET to the Internet.

Military Involvement in the Internet

The impetus for adopting TCP/IP came from the operational branches of the military (the armed forces and the agencies that support their day-to-day operations). Not all commanders were eager to adopt ARPA’s new networking techniques, and there was often a clash of cultures between the ARPANET’s research and military communities. But a combination of circumstances caused the Defense Communications Agency, which provided communications services for the armed forces, to view the ARPANET as an important part of its own system-building plans. As the DCA began to depend on the ARPANET, its managers took an active role in guiding the system’s technical evolution and eventually championed full adoption of the Internet protocols.

The operational defense agencies first became interested in the ARPANET as a model for replacing their existing networks with more advanced technology. The National Security Agency

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