EARN was a computer network connecting universities and research institutions across Europe, and was connected via transatlantic circuits to BITNET, its peer, in the United States (here you will find a brief history of BITNET).

Services available on  EARN/BITNET included electronic mail, file transfer, real-time terminal messages, and access to EARN server machines which provided  information retrieval  services. Gateways existed from EARN to the ARPA Internet (ARPANET, MILNET, NSFNET, CSNET X25Net), CSNET, UUCP, JANET (Great Britain’s Joint Academic  Network),  and more than 10 other national academic and research networks. There also was limited access to VNET, IBM’s internal communications network.

 

EARN International Backbone 1985

 

At the physical layer the network backbone was initially comprised of a set of dedicated telephone circuits connected via pairs of synchronous modems with speed varying from 1.2Kbps to 9.6Kbps. Each country in Europe managed its own national backbone, which was then connected via one international circuit to the European backbone.

 

A 9.6kb synchronous modem board

In the early stages the entire traffic between the European backbone and the United States BITNET backbone was carried over a single 4.8Kbps circuit and afterwards, for quite some time, over a single 9.6Kbps circuit using a pair of IBM synchronous modems similar to this one (nowadays turned into a piece of modern art)

EARN International backbone in 1989

Later, at the end of the 80’s, the backbone bandwidth was gradually augmented to accommodate for the increased traffic but given the very high prices for dedicated telephone circuits at the time it became soon clear EARN could no longer afford a dedicated European backbone.

After the IBM sponsorship of international and transatlantic lines had stopped each European country member of EARN, typically the organization in charge of each national academic network, was paying its own line to connect to the European backbone and was sharing the cost of the transatlantic connectivity via the EARN annual contribution.

The IP connections in Europe in 1990

 

Roughly at the same time the first embryo of what was to become the first Academic European Internet backbone, was taking shape. In the early 90’s the advent of the WWW and other more bandwidth-consuming applications, and the increased request for native TCP/IP connectivity to the Internet, forced the European Academic and Research community to consolidate its efforts toward a common backbone infrastructure.

EARN International backbone in 1991