Editing History of the Internet (section)

===From ARPANET to NSFNET===
{{Main|2 = NSFNET}}

[[File:InetCirca85.jpg|thumb|320px|[[BBN Technologies]] TCP/IP Internet map of early 1986]]

After the ARPANET had been up and running for several years, ARPA looked for another agency to hand off the network to; ARPA's primary mission was funding cutting-edge research and development, not running a communications utility. In July 1975, the network was turned over to the [[Defense Communications Agency]], also part of the [[United States Department of Defense|Department of Defense]]. In 1983, the [[U.S. military]] portion of the ARPANET was broken off as a separate network, the [[MILNET]]. MILNET subsequently became the unclassified but military-only [[NIPRNET]], in parallel with the SECRET-level [[SIPRNET]] and [[JWICS]] for TOP SECRET and above. NIPRNET does have controlled security gateways to the public Internet.

The networks based on the ARPANET were government funded and therefore restricted to noncommercial uses such as research; unrelated commercial use was strictly forbidden.<ref>{{Cite web |date=December 1985 |title=ARPANET Information Brochure |url=https://apps.dtic.mil/sti/pdfs/ADA164353.pdf |publisher=Defense Communication Agency}}</ref> This initially restricted connections to military sites and universities. During the 1980s, the connections expanded to more educational institutions, and a growing number of companies such as [[Digital Equipment Corporation]] and [[Hewlett-Packard]], which were participating in research projects or providing services to those who were. Data transmission speeds depended upon the type of connection, the slowest being analog telephone lines and the fastest using optical networking technology.

Several other branches of the [[Federal government of the United States|U.S. government]], the [[National Aeronautics and Space Administration]] (NASA), the [[National Science Foundation]] (NSF), and the [[United States Department of Energy|Department of Energy]] (DOE) became heavily involved in Internet research and started development of a successor to ARPANET. In the mid-1980s, all three of these branches developed the first Wide Area Networks based on TCP/IP. NASA developed the [[NASA Science Network]], NSF developed [[CSNET]] and DOE evolved the [[Energy Sciences Network]] or ESNet.

[[File:NSFNET-backbone-T3.png|thumb|320px|T3 NSFNET Backbone, c. 1992]]
NASA developed the TCP/IP based NASA Science Network (NSN) in the mid-1980s, connecting space scientists to data and information stored anywhere in the world. In 1989, the [[DECnet]]-based Space Physics Analysis Network (SPAN) and the TCP/IP-based NASA Science Network (NSN) were brought together at NASA Ames Research Center creating the first multiprotocol wide area network called the NASA Science Internet, or NSI. NSI was established to provide a totally integrated communications infrastructure to the NASA scientific community for the advancement of earth, space and life sciences. As a high-speed, multiprotocol, international network, NSI provided connectivity to over 20,000 scientists across all seven continents.

In 1981, NSF supported the development of the [[CSNET|Computer Science Network]] (CSNET). CSNET connected with ARPANET using TCP/IP, and ran TCP/IP over [[X.25]], but it also supported departments without sophisticated network connections, using automated dial-up mail exchange. CSNET played a central role in popularizing the Internet outside the ARPANET.<ref name=":10" />

In 1986, the NSF created [[NSFNET]], a 56&nbsp;kbit/s [[Internet backbone|backbone]] to support the NSF-sponsored [[supercomputer|supercomputing]] centers. The NSFNET also provided support for the creation of regional research and education networks in the United States, and for the connection of university and college campus networks to the regional networks.<ref>{{cite web |author1=David Roessner |author2=Barry Bozeman |author3=Irwin Feller |author4=Christopher Hill |author5=Nils Newman |title=The Role of NSF's Support of Engineering in Enabling Technological Innovation |year=1997 |url=http://www.sri.com/policy/csted/reports/techin/inter2.html |access-date=May 28, 2009  |archive-url=https://web.archive.org/web/20081219114437/http://www.sri.com/policy/csted/reports/techin/inter2.html |archive-date=December 19, 2008 }}</ref> The use of NSFNET and the regional networks was not limited to supercomputer users and the 56&nbsp;kbit/s network quickly became overloaded. NSFNET was upgraded to 1.5&nbsp;Mbit/s in 1988 under a cooperative agreement with the [[Merit Network]] in partnership with [[IBM]], [[MCI Communications|MCI]], and the [[State of Michigan]]. The existence of NSFNET and the creation of [[Federal Internet Exchange]]s (FIXes) allowed the ARPANET to be decommissioned in 1990.

NSFNET was expanded and upgraded to dedicated fiber, optical lasers and optical amplifier systems capable of delivering T3 start up speeds or 45&nbsp;Mbit/s in 1991. However, the T3 transition by MCI took longer than expected, allowing Sprint to establish a coast-to-coast long-distance commercial Internet service. When NSFNET was decommissioned in 1995, its optical networking backbones were handed off to several commercial Internet service providers, including MCI, [[PSINet|PSI Net]] and Sprint.<ref>{{cite report | title=Internet Traffic Exchange | series=OECD Digital Economy Papers | publisher=Organisation for Economic Co-Operation and Development (OECD) | date=1 April 1998 | doi=10.1787/236767263531| doi-access=free }}</ref> As a result, when the handoff was complete, Sprint and its Washington DC Network Access Points began to carry Internet traffic, and by 1996, Sprint was the world's largest carrier of Internet traffic.<ref>{{cite press release |title=Sprint Boosts Fiber-Optic Network Capacity 1600 Percent |url=https://www.ciena.com/about/newsroom/press-releases/sprint-boosts-fiber-optic-network-capacity-1600-percent-prx.html |location=Kansas City, MO |publisher=Ciena Corporation |date=June 11, 1996 |access-date=December 20, 2022}}</ref>

The research and academic community continues to develop and use advanced networks such as [[Internet2]] in the United States and [[JANET]] in the United Kingdom.