NSFNET (1986)

By the 1980s ARPANET worked well — for the few places allowed on it. Thousands of colleges wanted a network too, and they wanted to use the new, very powerful supercomputers that only a handful of centres owned.

1What NSFNET was

NSFNET

NSFNET stands for National Science Foundation Network. It was built in 1986 by the National Science Foundation, a US government body that pays for science research. It was faster than ARPANET and open to every university and researcher, not only defence projects.

It began by linking six supercomputer centres across the USA: San Diego, Boulder, Urbana, Pittsburgh, Princeton and Cornell. Watch them appear — ARPANET’s older lines are still there, dimmed, in orange, until 1990.

NSFNET, 1986 to 1990

Press Play. Pink is NSFNET; the dimmer orange lines are the older ARPANET.

198623 sites on the map

1986 · NSFNET. The National Science Foundation links six supercomputer centres with a faster network, open to every university.

Places are shown where they really are. The lines are simplified: they show which places were connected, not the real cable routes.

2A backbone, with networks plugged into it

NSFNET did not wire every college directly. It built a backbone — a set of very fast main lines between the big centres. Groups of nearby colleges formed regional networks, and each regional network joined the backbone.

Highways and local roads

The backbone is the national highway. A regional network is the road from your town to the highway. You drive a short way on the local road, join the highway for the long part, and leave it near where you are going.

This idea — many smaller networks joined through a fast backbone — is exactly how the Internet is still built.

3How fast it got

Speed on a network is measured in bits per second — how many 0s and 1s the line carries each second. kbps means thousand bits per second and Mbps means million. (There is a full lesson on this in Data Communication.)

NSFNET’s backbone started at 56 kbps in 1986, was upgraded to about 1.5 Mbps in 1988, and to about 45 Mbps in 1991. Race them:

Send one 1 MB photo

All three lines start together. This runs in real time — nothing is sped up.

clock: 0.0 s

1986 · 56 kbps0%

1988 · 1.5 Mbps (T1)0%

1991 · 45 Mbps (T3)0%

Worked out, not guessed: 1 MB is 8,000,000 bits. At 56,000 bits per second that is 2 min 23 s; at 1.5 Mbps, 5.2 s; at 45 Mbps, 0.18 s.

4ARPANET and NSFNET side by side

	ARPANET	NSFNET
Full form	Advanced Research Projects Agency Network	National Science Foundation Network
Started	1969	1986
Built by	ARPA, US Department of Defense	National Science Foundation
Who could use it	Defence-funded research sites	Every university and researcher
Speed	Slower	Much faster, and upgraded twice
Ended	Switched off in 1990	Retired in 1995

5What came next

In 1990 ARPANET was switched off — NSFNET was doing its job better. At first NSFNET was only for education and research. But businesses and ordinary people wanted in too. Companies started building networks of their own and joining them together, and in 1995 NSFNET was retired. What those joined-up networks became is the next lesson: the Internet.