The TCP/IP protocol suite establishes the technical foundation of the Internet. (UDP/IP is part of the the family). Development of the TCP/IP was started by DOD projects and now, most protocols in the suite are developed by the industry non-for-profit organization named Internet Engineering Task Force (IETF) under the Internet Architecture Board (IAB), an organization initially sponsored by the US government and now an open and autonomous organization. The IAB provides the coordination for the R&D underlying the TCP/IP protocols and guides the evolution of the Internet. The TCP/IP protocols are well documented by the Request For Comments (RFC), which are drafted, discussed, circulated and approved by the IETF committees. All documents are open and free and could be found online in the IETF site listed in the reference.
TCP/IP architecture does not exactly match the OSI model. Unfortunately, there is no universal agreement regarding how to describe TCP/IP with a layered model. It is generally agreed that TCP/IP has fewer levels (from three to five layers) than the seven layers of the OSI model. In this article, we force TCP/IP protocols into the OSI 7 layers structure for comparison purpose.
The TCP/IP suite's core functions are addressing and routing (IP/IPv 6 in the networking layer) and transportation control (TCP, UDP in the transport layer).
IP - Internet Protocol
Addressing of network components is a critical issue in the network communications for information routing and transmission. Each technology has its own convention for transmitting messages between two machines within the same network. On a LAN, messages are sent between machines by supplying the six byte unique identifier (the "MAC" address). In an SNA network, every machine has Logical Units with their own network address. DECNET, Appletalk, and Novell IPX all have a scheme for assigning numbers to each local network and to each workstation attached to the network.
On top of these local or vendor specific network addresses, IP assigns a unique number to every network device in the world, which is called IP address. This IP address is a four byte value in IPv4 that, by convention, is expressed by converting each byte into a decimal number (0 to 255) and separating the bytes with a period. In IPv6, the IP address has been increased to 16 bytes. Please click IP and IPv6 for more details.
TCP - Transmission Control Protocol
TCP provides a reliable stream delivery and virtual connection service to applications through the use of sequenced acknowledgment with retransmission of packets when necessary. Among the services TCP provides are stream data transfer, reliability, efficient flow control, full-duplex operation, and multiplexing. Click the TCP for more details.
In the TCP/IP protocol table below, we list all the protocols according to their functions in mapping to the OSI 7 layers network communication reference model. However, the TCP/IP architecture does not follow the OSI model closely, for example, most the TCP/IP applications are directly running on top of the transport layer protocols TCP and UDP without the presentation and session layers in between.
Related protocol suites: LAN, MAN, WAN, SAN, Security/VPN
Sponsor Source: IETF, DARPA, ISO