Requirements for the Internet

The requirements for the Internet emerged in part from the practical experiences drawn from the development, deployment and use of the ARPANET. Each distinct network would have to stand on its own and no internal changes could be required to any such network to connect it to the Internet. Communications would be on a best effort basis. If a packet didn't make it to the final destination, it would shortly be retransmitted from the source. Black boxes would be used to connect the networks; these would later be called gateways and routers. There would be no information retained by the gateways about the individual flows of packets passing through them, thereby keeping them simple and avoiding complicated adaptation and recovery from various failure modes. There would be no global control at the operations level.