What is TCP/IP?
TCP/IP refers to the combination of TCP (Transmission Control Protocol) and IP (Internet Protocol), which together form the most widely used set of protocols for data exchange on the internet.
TCP/IP originated as part of packet communication research conducted by DARPA (Defense Advanced Research Projects Agency) for wide-area networks. It became the protocol for ARPANET, the precursor to the internet, and gained widespread adoption due to support in UNIX-based operating systems, allowing interoperability between computers from different vendors. Today, TCP/IP has become the standard protocol, not only for the internet but also for many other networks.
Within the OSI reference model, TCP is positioned at Layer 4 (Transport Layer), handling session establishment and disconnection between ports, as well as communication control. IP operates at Layer 3 (Network Layer), managing routing and communication paths, which are essential for internet functionality. Beneath IP is the Data Link Layer, where protocols like Ethernet are positioned.
While the Data Link Layer is responsible for direct communication between devices within a limited range, the Network Layer (IP) enables data exchange across extended areas via routers. This capability of connecting different networks is why IP is called the "Inter-net" Protocol. Before the advent of the internet, networks referred to direct communication pathways, but the introduction of IP revolutionized this paradigm by enabling the interconnection of disparate networks.
TCP is a protocol that operates on top of IP to ensure reliable data transmission. It features mechanisms for packet retransmissions in the event of loss, reordering packets, and verifying source IP addresses, making highly reliable communication possible. Other transport layer protocols that operate on top of IP include UDP and SCTP.