The first router I ever worked on was one of these:
or rather, one of these boxes. The picture shows a
"Torn-Tape Relay Center". Each of those rack-sized boxes
contains two "Printing Reperforators" and three "Transmitting
Distributors", plus power-supplies and a mess of relays.
Messages came in on the two Re-perfs, being punched into chadless
tape with printing along the top edge. Operators tore each message
off individually, read the "headers", and placed the message
in the TD (tape reader to computer-folks) corresponding to its next
hop. The third TD on each box was fed from a prepared roll of sequence
numbers. When the operator hit the "GO" button, that TD would
send the next message-ID, which would end in a number. When the
"letters-shift" code at the end of the number was detected
(mechanically!), the selected "message" TD would start and
send the message. Each "link" ran at a blazing 45.45 baud.
Anybody want to figure out how many of these boxes would be needed
to equal the bandwidth of a CRS-1?