TCP/IP protocol set has laid the technical foundation of Internet. The development of TCP/IP began with the plan of the US Department of Defense. IETF (Internet Engineering Task Force), a working group under IAB (Internet Architecture Committee), has developed most of these protocols. IAB was originally initiated by the American government, and now it has been transformed into an open and autonomous institution. IAB cooperates in researching and developing the underlying structure of TCP/IP protocol set to guide the development of Internet. The TCP/IP protocol set is recorded in the Exposure Draft (RFC) document, which is drafted, discussed, circulated and approved by the IETF Committee. All these documents are open and free, and can be found in the resources listed on the IETF website.

TCP/IP protocol covers six layers in the seven-layer model of OSI network structure, and supports the functions of applications such as multi-protocol label switching (the second layer) to mail service. The core functions of TCP/IP are addressing and routing (IP/IPV6 in the network layer) and transmission control (TCP and UDP in the transport layer).

IP (internet protocol)

In network communication, the addressing of network components is very important for information routing and transmission. The message transmission between two machines in the same network has its own technical protocol. A LAN sends messages between machines by providing a unique identifier ("MAC" address) of 6 bytes. Every machine in SNA network has a logical unit and its corresponding network address. DECNET, AppleTalk and Novell IPX all have configurations to assign numbers to local networks and workstations.

In addition to the local or specific provider's network address, IP also assigns a unique number, namely IP address, to each network device in the world. The IP address of IPV4 is 4 bytes. Conventionally, each byte is converted to decimal (0-255) and separated by dots. The IP address of IPV6 has been increased to 16 bytes. The detailed descriptions of IP and IPV6 protocols are given in related literature.

transmission control protocol (TCP)

By serializing replies and retransmitting packets when necessary, TCP provides reliable transport stream and virtual connection services for applications. TCP mainly provides data flow, reliable transmission, effective flow control, full-duplex operation and multiplexing technology. See the TCP section for details.