On October 29, 1969, the very first message was sent over the internet: LO. Simple and elegant at just two letters long, this was the communication that heralded the forthcoming days of rapid networked connections throughout the country and the world. And so what was the hidden meaning behind these letters sent on this auspicious occasion? Not as deliberate a message as you might have hoped. In truth, the engineers that night were trying to send the word “login,” but the receiving computer crashed just two letters into the message. They got it up and running again quickly and re-sent the full word, and despite this minor setback, went on to use this connection and many others to build the foundation for the modern internet.
It was called ARPANET, named for the Advanced Research Projects Agency that was constructing it. The idea was to connect remote computers together into a network to ease communication between far away research stations. The challenge was to do so in a way that multiple computers could be connected and sending messages at any one time, instead of a direct connection between two points. The protocol they developed to solve this problem (eventually named the Transmission Control Protocol, and the TCP in the ubiquitous TCP/IP), made all subsequent network development possible.
Computers had been linked together before using direct and unbroken connections. The reason ARPA’s new protocol, dubbed packet switching, was so important is because it made these direct connections unnecessary. Messages could be sent out into a network, and as long as the recipient was connected, they would make their way on their own. Think of direct connections as an old-fashioned phone network with operators moving cables about on one of those massive switchboards. When someone phoned in, the operator would then have to physically create a closed circuit by moving cables around to link it all together. Then, once the call was over, the operator would break the circuit and connect another. In a packet switching network, all of those connections are already made, and all the circuits are always connected. The operator, or the revolutionary Interface Message Processor (IMP), takes in all messages, reads their destinations, and then sends them along the requisite connection. And this all happens in a fraction of a second.
In a larger network, these IMPs become even more important, acting as the guideposts that direct messages to their proper destinations. Another feature of packet messaging is that your message is divided up into smaller data packets, which can then take any number of routes to their designation. In this early ARPANET, there was only one route, but as they added more IMPs and more destinations around the country and the globe, there were hundreds of routes available to any message. Depending on bandwidth restrictions, your computer would send out data packets to the nearest IMP, which would then route them to the next IMP based on processing availability there. This would happen over and over again, until the packets all arrived at the IMP that was connected to the destination computer, where they would be reassembled and delivered.
This distributed IMP model was integral to creating the internet as we know it today. It is completely decentralized in that there is no hub through which all messages must travel. As long as your computer and the recipient computer are connected to each other by even one route, your message can get there. This means the internet is largely protected from cataclysms related to weather and war, but also from attack and control. No one person or entity controls the internet, because it simply doesn’t work that way. When these ARPA engineers developed their packet switching technology, they were creating a framework that didn’t just allow for the internet to develop, but allowed it to develop in a way that made it the populist and free communications network it has become.
