RFC 1109: Report of the Second Ad Hoc Network Management Review Group (1989)
It was recognized in this process that the definition of the layer BELOW IP was a difficult task. IP is sufficiently simple and general that it has been moved in encapsulated form over many media including the MAC level of various local nets, X.25 packet level, serial line protocols, multiplexors, tunnels and, it is rumored, tin cans and string.
IP over Two Tin Cans and a Piece of Wet String. [local copy in pdf].
Should Tin Cans and String Comply With CALEA?.
People ask how the Tin Cans and String network handles routing. We use a military technology called torn tape relay (local copy in pdf).