Structure

"ARPA came up with the concept of creating a network whereby if you, as a researcher, wanted access to my resources,
you log on to my machine through the network and run your job on my machine for the special resources you were looking for."
- Leonard Kleinrock, 3/13/13
Picture
The Structure of the ARPANET. (Click to enlarge)


Hosts/Terminals connect to IMPs/TIPs, forming a subnet that relays the packets through nodes until they reach their destination. Remote connections travel through modems across telephone lines.
"As the ARPANET proved the 15:1 cost advantage over circuit switching (the telephone network) and allowed far greater speed potential,
it led the way. It then grew into the Internet."
- Larry Roberts, 3/21/13






The first connection was between UCLA and Stanford Research Institute. Later that year, University of California, Santa Barbara and University of Utah were added.
Picture
The first 4 nodes of the ARPANET, 1969. (Click to enlarge)