A central control component of this model was the "Transmission Control Program" that incorporated both connection-oriented links and datagram services between hosts. The monolithic Transmission Control Program was later divided into a modular architecture consisting of the "Transmission Control Protocol" and the "Internet Protocol". This resulted in a networking model that became known informally as "TCP/IP", although formally it was variously referred to as the Department of Defense (DOD) model, and ARPANET model, and eventually also as the "Internet Protocol Suite".