While working at the University of Southern California in early 1978 he tackled another big project to simplify the flow of information sent across the network while providing reliable delivery of every packet. The current protocol at the time was the UDP protocol, but it wasn't reliable. The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. Using TCP, applications on networked hosts can create connections to one another, over which they can exchange streams of data using Stream Sockets. He worked with a very small team who ended up splitting the Transmission Control Protocol (TCP) into two separate parts.
The TCP would be the host to host protocol and a second part called the internetwork protocol (IP) would handle the passing of packets between machines. This became known as TCP/IP.