Following the deployment of the
Computer Science Network (CSNET), a network that provided Internet services to academic
computer science departments, in 1981, the U.S.
National Science Foundation (NSF) aimed to create an academic research network facilitating access by researchers to the
supercomputing centers funded by NSF in the United States. In 1985, NSF began funding the creation of five new supercomputing centers: •
John von Neumann Center at
Princeton University •
Cornell Theory Center at
Cornell University •
Pittsburgh Supercomputing Center (PSC), a joint effort of
Carnegie Mellon University, the
University of Pittsburgh, and
Westinghouse •
National Center for Supercomputing Applications (NCSA) at the
University of Illinois at Urbana–Champaign •
San Diego Supercomputer Center (SDSC) on the campus of the
University of California, San Diego (UCSD) Also in 1985, under the leadership of
Dennis Jennings, the NSF established the National Science Foundation Network (NSFNET). NSFNET was to be a general-purpose research network, a hub to connect the five supercomputing centers along with the NSF-funded
National Center for Atmospheric Research (NCAR) to each other and to the regional research and education networks that would in turn connect campus networks. Using this three-tier network architecture NSFNET would provide access between the supercomputer centers and other sites over the backbone network at no cost to the centers or to the regional networks using the open
TCP/IP protocols initially deployed successfully on the
ARPANET.
56kbit/s backbone The NSFNET initiated operations in 1986 using
TCP/IP. Its six backbone sites were interconnected with leased 56-
kbit/s links, built by a group including the
University of Illinois National Center for Supercomputing Applications (
NCSA),
Cornell University Theory Center,
University of Delaware, and
Merit Network.
PDP-11/73 minicomputers with routing and management software, called
Fuzzballs, served as the network routers since they already implemented the TCP/IP standard. This original 56kbit/s backbone was overseen by the supercomputer centers themselves with the lead taken by
Ed Krol at the
University of Illinois at Urbana–Champaign. PDP-11/73
Fuzzball routers were configured and run by Hans-Werner Braun at the
Merit Network and statistics were collected by
Cornell University. Support for NSFNET end-users was provided by the NSF Network Service Center (NNSC), located at
BBN Technologies and included publishing the softbound "Internet Manager's Phonebook" which listed the contact information for every issued domain name and IP address in 1990. Incidentally, Ed Krol also authored the ''
Hitchhiker's Guide to the Internet'' to help users of the NSFNET understand its capabilities. The Hitchhiker's Guide became one of the first help manuals for the
Internet. As regional networks grew the 56kbit/s NSFNET backbone experienced rapid increases in network traffic and became seriously congested. In June 1987 NSF issued a new solicitation to upgrade and expand NSFNET.
1.5Mbit/s (T-1) backbone IBM and
MCI jointly won the NSF contract in November 1987, with a switching system from the former and digital network from the latter. That month, a report by the Federal Coordinating Council for Science, Engineering, and Technology Committee on Computer Research and Applications proposed that scientific computer networks should provide 1.5 Mbit/s connections between 200 and 300 American research institutions by 1990. As a result of the award to
Merit Network, a networking consortium by public universities in
Michigan, the original 56kbit/s network was expanded to include 13 nodes interconnected at 1.5
Mbit/s (
T-1) by July 1988. Additional links were added to form a multi-path network, and a node located in
Atlanta was added. Each of the backbone nodes was a router called the Nodal Switching System (NSS). The NSSes were a collection of multiple (typically nine)
IBM RT PC systems connected by a
Token Ring local area network. The RT PCs ran
AOS, IBM's version of
Berkeley UNIX, and was dedicated to a particular packet processing task. Under its cooperative agreement with NSF, Merit was the lead organization in a partnership that included IBM, MCI, and the
State of Michigan. Merit provided overall project coordination, network design and engineering, a Network Operations Center (NOC), and information services to assist the regional networks. IBM provided equipment, software development, installation, maintenance and operations support. MCI provided the T-1 data circuits at reduced rates. The state of Michigan provided funding for facilities and personnel. Eric M. Aupperle, Merit's president, was the NSFNET project director, and Hans-Werner Braun was the co-principal investigator. From 1987 to 1994, Merit organized a series of "Regional-Techs" meetings, where technical staff from the regional networks met to discuss operational issues of common concern with each other and the Merit engineering staff. During this period, but separate from its support for the NSFNET backbone, NSF funded: • the NSF Connections Program that helped colleges and universities obtain or upgrade connections to regional networks; • regional networks to obtain or upgrade equipment and data communications circuits; • the NNSC, and successor Network Information Services Manager (aka InterNIC) information help desks; • the International Connections Manager (ICM), a task performed by
Sprint, that encouraged connections between the NSFNET backbone and international research and education networks; and • various ad hoc grants to organizations such as the Federation of American Research Networks (FARNET). The NSFNET became the principal Internet backbone starting in the Summer of 1986, when
MIDnet, the first NSFNET regional backbone network became operational. By 1988, in addition to the five NSF supercomputer centers, NSFNET included connectivity to the regional networks BARRNet, JVNCNet,
Merit/MichNet, MIDnet, NCAR, NorthWestNet, NYSERNet, SESQUINET, SURAnet, and Westnet, which in turn connected about 170 additional networks to the NSFNET. Three new nodes were added as part of the upgrade to T-3: NEARNET in Cambridge, Massachusetts; Argone National Laboratory outside of Chicago; and SURAnet in Atlanta, Georgia. NSFNET connected to other federal government networks including the NASA Science Internet, the Energy Science Network (
ESnet), and others. Connections were also established to research and education networks in other countries starting in 1988 with Canada, France,
NORDUnet (serving Denmark, Finland, Iceland, Norway, and Sweden), the Netherlands, and many other countries in subsequent years. Two
Federal Internet Exchanges (FIXes) were established in June 1989 under the auspices of the Federal Engineering Planning Group (FEPG). FIX East, at the
University of Maryland in
College Park and FIX West, at the
NASA Ames Research Center in
Mountain View, California. The existence of NSFNET and the FIXes allowed the
ARPANET to be phased out in mid-1990. Starting in August 1990 the NSFNET backbone supported the
OSI Connectionless Network Protocol (CLNP) in addition to TCP/IP. However, CLNP usage remained low when compared to TCP/IP. Traffic on the network continued its rapid growth, doubling every seven months. Projections indicated that the T-1 backbone would become overloaded sometime in 1990. A critical routing technology,
Border Gateway Protocol (BGP), originated during this period of Internet history. BGP allowed routers on the NSFNET backbone to differentiate routes originally learned via multiple paths. Prior to BGP, interconnection between IP network was inherently hierarchical, and careful planning was needed to avoid routing loops. BGP turned the Internet into a meshed topology, moving away from the centric architecture which the ARPANET emphasized.
45Mbit/s (T-3) backbone The November 1987 report proposed a national research network with 45Mbit/s connections between 1000 sites by the early 1990s, and deployment of 3Gbit/s connections within 15 years. During 1991, an upgraded backbone built with 45Mbit/s (
T-3) transmission circuits was deployed to interconnect 16 nodes. The routers on the upgraded backbone were
IBM RS/6000 servers running AIX UNIX. Core nodes were located at MCI facilities with end nodes at the connected regional networks and supercomputing centers. Completed in November 1991, the transition from T-1 to T-3 did not go as smoothly as the previous transition from 56kbit/s DDS to 1.5 mbit/s T-1, as it took longer than planned. As a result, there was at times serious congestion on the overloaded T-1 backbone. Following the transition to T-3, portions of the T-1 backbone were left in place to act as a backup for the new T-3 backbone. In anticipation of the T-3 upgrade and the approaching end of the 5-year NSFNET cooperative agreement, in September 1990 Merit, IBM, and MCI formed
Advanced Network and Services (ANS), a new non-profit corporation with a more broadly based Board of Directors than the Michigan-based Merit Network. Under its cooperative agreement with NSF, Merit remained ultimately responsible for the operation of NSFNET, but subcontracted much of the engineering and operations work to ANS. Both IBM and MCI made substantial new financial and other commitments to help support the new venture. Allan Weis left IBM to become ANS's first president and managing director.
Douglas Van Houweling, former Chair of the Merit Network Board and Vice Provost for Information Technology at the
University of Michigan, was Chairman of the ANS Board of Directors. The new T-3 backbone was named ANSNet and provided the physical infrastructure used by Merit to deliver the NSFNET Backbone Service. ==Regional networks==