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n-1-4-010.10a
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Subject: N-1-4-010.10
Changing Eras: Evolution of the NSFNET
Eric M. Aupperle
<Eric.M.Aupperle@um.cc.umich.edu>
On Wednesday, 2 December 1992 the T1 NSFNET service ended. All
NSFNET traffic now traverses ANS's T3 backbone infrastructure. The
transition of traffic transport from the T1 to the T3 backbone service
occurred gradually, most notably since March of 1992. As this T1
era ends and a new one advances, it seems appropriate to reflect on
NSFNET's evolution.
The genesis of NSFNET dates back to 1985 when
the National Science Foundation committed support for helping
establish five new supercomputer facilities. With their objective of
sharing these supercomputer resources among the nation's research
universities, NSF required each supercomputer site to provide
network access to a set of participating institutional
partners. An example of this was the San Diego Supercomputer
Center's 1986 implementation of a 56 Kbps American Satellite
system linking distant organizations to their site.
NSF also took other steps during this period to broaden access to
these new advanced computing facilities. They arranged for shared
use of existing national community data networks, i.e., ARPAnet and
BITNET. They funded the National Center for Atmospheric Research's
deployment of the University Satellite Network Project to
interconnect several universities across the United States. They
encouraged the creation of new regional network organizations to
provide yet greater connectivity to the educational and research
community, and partially funded them.
Another key NSF network action occurred in 1986 when they
contracted for the first NSFNET backbone. With the communications
access facilities the supercomputer centers had in place, this
backbone's mission focused on providing inter supercomputer site
connectivity to foster more national resources sharing opportunities.
It's role soon emerged as a network of networks, at the top of a
three-level hierarchy. This initial backbone linked six sites with 56
Kbps data circuits. It quickly became saturated with traffic,
experienced routing difficulties, and lacked the funding and
organizational resources to address these issues. At it's peak this
backbone transported about 115 million packets per month during
the first half of 1988.
A 1987 NSF solicitation process led to an award to Merit Network, in
partnership with IBM and MCI, for managing, operating and
continuing the development of the NSFNET backbone. This
solicitation required providing connectivity for thirteen sites, the six
supercomputer centers and seven regional networks. In July of 1988
the Merit partnership replaced the initial 6 node 56 Kbps network
with a with 13 node network based on T1 data trunks. These 1.5
Mbps T1 data circuits were multiplexed to provide multiple 500
Kbps links among the 13 nodes.
With the new backbone and rapidly expanding regional network
infrastructure, backbone traffic spurted, averaging 20% per month of
growth between July 1988 and July 1989. By mid 1989 the Merit
partnership added new T1 circuits and began operating all of them
as full 1.5 Mbps links in response to this growth. T1 connections also
were installed for two interagency network connection sites named
FIX East and West, and later a fourteenth node was added at NSF's
request. Backbone traffic continued growing rapidly as did the
number of announced networks supported on the backbone. These
factors drove the implementation of the T3 network service which
now fully replaces the T1 network.
The T1 traffic peaked in February 1992, with a load of about 11.3
billion packets for that month. This represented a two order of
magnitude increase of packet traffic over the network it replaced.
It's time had come and gone in less than four years. Meanwhile the
relentless increase in backbone traffic continues. This past
November saw the first occurrence of more than a billion packets
shipped during a single day. The total November monthly traffic was
nearly 24 billion packets. Any bets on the lifetime of the new era?