TCP/IP: One Protocol to Rule Them All
As packet-switching networks began to pop up in different areas of the world, the desire to have them all communicate with one another increased. Working off of the ideas used to create Cyclades, Robert Kahn and Vinton Cerf began to work on a new protocol to replace NCP. Transmission Control Protocol (TCP) was being tested on ARPANET as an alternative in 1974.
TCP improved the reliability of data transfer across the network, but it was only half of the puzzle. Cerf and Kahn added Internet Protocol (IP) to form the complementary TCP/IP protocol that is still in use today. TCP/IP allowed for end-to-end connectivity and specified how data passing through the network would be:
Again, the RFC system was integral to refining these protocols, and TCP/IP borrowed many features from the protocols designed by other organizations.
With TCP/IP we began to see a new practice of collecting a group of other procotols – we will inaccurately call them sub-protocols for the purpose of this explanation – and group them together into a parent protocol, which is considered a standard unto itself.
Over this same period, ARPA was renamed the Defense Advanced Research Projects Agency (DARPA), and steps were taken to segment a military network from research-based ARPRANET. This military network was officially launched in 1983 under the name MILNET.
TCP/IP Connects the Dots
TCP/IP served as the Swiss army knife of protocols, allowing diverse machines and network hardware to connect to a common network. It was officially implemented by ARPANET in 1983. By this time, ARPANET was just one of many established networks, some of which were already using TCP/IP, while others were using X.25.
Throughout the U.S. and Europe, these packet-switching networks were adding more and more nodes. Major networks were used as backbone networks, forming cores that served as high-traffic routes for data to pass through on the way to its destination. In addition to Mark II, Cyclades, Telenet and so on, some of these networks included NSFNET, a network funded by the National Science Foundation (NSF) to link educational institutions and CSNET, a network tied into ARPANET over a dial-up connection using X.25.
After some competition between protocols, TCP/IP was chosen as a standard protocol, making it possible to start connecting the dots across the world. In the U.S., NSFNET played a vital role by providing many of the Internet backbones and helping establish federal Internet exchanges. Theses spelled the end of ARPANET as a central player in the story of the Internet.