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THINK  Cyclades

A Technical History of CYCLADES

The Cyclades Packet Switching Network has its roots in the ARPANET. Sometime in 1970 a French delegation while on a trip to the United States discovered the ARPANET and from this trip quite a few reports were generated and interest in France developed for a French instantiation of a heterogeneous computer network located in universities and research centers.  The end result was the development in 1972 of the Cyclades network. [Recherche N328

The Cyclades network had many of the markings of a modern computer network and indeed the modern Internet owes much to the Cyclades network. Cyclades had a layered architecture composed of three main layers, a Data Transmission Layer, a Transport Layer, and an Application Layer, of which the Virtual Terminal Protocol is an example. More importantly the Cyclades network had the first true implementation of a datagram utilizing adaptive routing and an unreliable out of order delivery service. CIGALE was the packet switching data transmission layer of the Cyclades network. The ARPANET would borrow from this technology when it developed the TCP-IP in 1974. [Recherche N328]  

Furthermore Cyclades demonstrated "complexity at the network's edge", which means the work takes place within intelligent end-systems (the hosts) had the intelligence. The only job of CIGALE was to provide a best effort delivery service, for example, fragmentation and reassembly of packets is handled by the Transport Layer.  

So with all of this technology why is the ARPANET generally recognized as the parent of the modern Internet and the Cyclades network relegated to a footnote (albeit an important one) in the history of the Internet?  For that the French can thank the European postal and telecom authorities adoption of the X.25 standard which used Virtual Circuits instead of Packet Switching as the Data Transmission Protocol. With the X.25 standard in place these authorities carried on a crusade against packet switched networks and the datagram which led to a reduction in funding for the Cyclades network, and its eventual dissolution.   

Indeed in 1986, "in a book largely considered in France a kind of bible of signal processing, one can see the Internet dispatched in some lines from which the comic side will not escape the reader from the year 2000: 'the need for having protocols from beginning to end was solved by architecture TCP-IP [... ]. This architecture is obsolete now' ". [Recherche N328] Against this backdrop during the 1980s the French development of packet switching technology and products withered, while at the same time across the Atlantic in America thanks to local area networks (LANs) and ARPA contracts, American research continued and American companies developed a wide array of products derived from the ARPANET and later the Internet.

  • Timeline
    A timeline of major events in the history of CYCLADES.
  • Tour of CYCLADES
    A quick overview of the CYCLADES with links to specifics on the architecture.
  • Bibliographies
    Annotated references on CYCLADES. Includes all of the references sited in this web page.
  • Resources
    A listing of digitally archived historical resources, and links to relevant resources on other sites.




Written by the THINK Protocols team, CS Dept, UT Austin
Please direct comments to Chris Edmondson-Yurkanan.

This document was last modified on Tuesday, 11-Jun-2002 10:18:01 CDT.