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NSFNET 20th Anniversary

20th Anniversary of First National High-Speed Network

The NSFNET Changed Computer Networking and Set the Stage for Today's Internet

By Brian Warkoczeski & Andy Rosenzweig

ANN ARBOR - July 1, 2008 marked the 20th anniversary of the T1 backbone of the NSFNET, the nation's first high-speed backbone network. This significant technological achievement signaled the start of a revolution in computer networking and spurred the development of the modern-day Internet. 

When it was originally launched in 1985, the NSFNET connected six super computer centers across the United States via a 56Kbps backbone network. In late 1987, NSF selected Merit Network and its partners MCI, IBM and the State of Michigan, to re-engineer the backbone service and deploy a new high-speed T1 backbone network, which began service on July 1, 1988. 

The NSFNET's high-speed backbone changed the paradigm for a national computer network, moving beyond a network of interconnected supercomputers to a national network interconnecting campus networks, regional networks, and organizations. 

At its launch, the NSFNET T1 backbone featured 13 backbone nodes and connected 217 networks across the U.S. At 1.5 megabits per second, the T1-based network was 24 times faster than the original 56 Kbps NSFNET network. 

The network was an enormous success and by 1989 was experiencing a traffic load of over 500 million packets per month. As more networks and organizations connected to the NSFNET, network usage grew exponentially. Traffic across the backbone increased more than 20 percent per month and doubled every seven months. 

The surge in traffic posed many challenges to the NSFNET management team. The network was re-engineered in 1989 to accommodate a greater number of T1 connections. By 1990, testing of a new T3 network began, and Advanced Network & Services, Inc. (ANS) was formed as a separate nonprofit corporation to provide the NSFNET backbone service as a subcontractor to Merit. ANS began to phase in the new network in 1991, initially running it in parallel with the existing T1 network. Implementation of the new T3 backbone network was completed in 1992.

A New U.S. Internet

The move to a new T3 network posed many technological obstacles and also stirred debate in the networking community about the evolution and commercialization of the U.S. Internet. Internet Service providers were popping up across the country, from small dial-up service providers to large T1 and T3 providers. In 1992, the National Science Board began developing a new national networking strategy that would accommodate the growing role of commercial providers and allow the NSF to step back from managing a network in order to concentrate on supporting leading-edge research initiatives. 

In 1994, NSF awarded Merit Network, USC's Information Science Institute, MCI, Sprint, MFS Datanet, and Bellcore with the roles in building the new network architecture. NSF also awarded Merit Network a transition extension for the NSFNET, which would be decommissioned in April 1995 when all network connections were switched over to the new service. 

As with the deployment of the T3 network, the move to a new network architecture created new challenges. 

Two Network Access Points (NAPS), the Metropolitan Area Ethernet (MAE-East) and the Sprint Network Access Point, were deployed in 1994 and began to carry much of the U.S. Internet traffic when the networks were moved off the NSFNET. Network Access Points deployed by PacBell and Ameritech went into production several months later. 

Routing Servers were implemented to peer with a providers at the NAPS, and the Policy Routing Database used to configure the NSFNET's backbone routers was replaced by the Routing Arbiter Database and databases maintained by RIPE NCC, internetMCI, CA*net, and ANSnet. 

NSF and Merit coordinated the move of regional networks from the NSFNET to new Internet Service Providers, with internetMCI and SprintLink absorbing the NSFNET regionals as their customers. 

On April 25, 1995, the peering sessions on the Exterior Nodal Switching Subsystem (ENSS) were commented out, essentially terminating the NSFNET backbone service. On the following night, Merit Network and ANS staff gathered at the University of Michigan NOC to turn off each ENSS, one by one at midnight in each respective time zone. 

The NSFNET high-speed backbone service had officially ended, leaving behind a legacy of computer networking innovation and collaborative excellence. At its launch, the NSFNET was connected to 217 networks. By April 1995, the high-speed network was connected to more than 50,000 networks via 19 backbone sites across the United States.

Michigan's Role in the NSFNET

Throughout the NSFNET project, organizations in Michigan played an important part in supporting the backbone network and leading innovations in computer networking. 

Merit Network, an Ann Arbor-based organization governed by Michigan's public universities, managed and re-engineered the NSFNET Backbone Service project. Merit worked with NSF, ANS, IBM, MCI, and the State of Michigan to create the NSFNET's T1 and T3 backbone networks. Merit's MichNet statewide network connected universities, community colleges, K12 organizations, and research institutions to the NSFNET backbone network. 

The State of Michigan's key role was a $5 million contribution to the NSFNET project from the Michigan Strategic Fund, a funding pool established to benefit the overall development of Michigan's economy. The contribution added value to the Merit/IBM/MCI funding proposal, thereby strengthening the proposal and ensuring its success. 

As the NSFNET project drew to a close, Merit also developed the Routing Assets Database (RADb) with assistance from University of Southern California's Information Sciences Institute. The RADb is a public registry of routing information for networks in the Internet. 

The University of Michigan hosted the NSFNET Network Operations Center at the U-M Computer Center Building and staffed the facility around the clock to monitor the network.

About Merit Network

Merit Network, Inc., a non-profit corporation governed by Michigan's public universities, owns and operates America's longest-running regional research and education network. Founded in 1966, Merit supports the high-performance networking needs of Michigan's universities, colleges, K-12 schools, libraries, state government, healthcare, and other non-profit organizations. Through Merit, Michigan's research and education organizations have access to leading-edge network research, state and national collaborative initiatives and international peering. www.merit.edu