Topological considerations in the design of the ARPA computer network

The ARPA Network will provide store-and-forward communication paths between a set of computer centers distributed across the continental United States. The message handling tasks at each node in the network are performed by a special purpose Interface Message Processor (IMP) located at each computer center. The centers will be interconnected through the IMPs by fully duplex telephone lines, of typically 50 kilobit/sec capacity.