Internet protocol suite

The Internet protocol suite predates the OSI model, a more comprehensive reference framework for general networking systems.

[4] In the early 1970s, DARPA started work on several other data transmission technologies, including mobile packet radio, packet satellite service, local area networks, and other data networks in the public and private domains.

In the spring of 1973, Vinton Cerf joined Kahn with the goal of designing the next protocol generation for the ARPANET to enable internetworking.

[10][11] The new protocol was implemented as the Transmission Control Program in 1974 by Cerf, Yogen Dalal and Carl Sunshine.

Advocates included Bob Metcalfe and Yogen Dalal at Xerox PARC;[15][16] Danny Cohen, who needed it for his packet voice work; and Jonathan Postel of the University of Southern California's Information Sciences Institute, who edited the Request for Comments (RFCs), the technical and strategic document series that has both documented and catalyzed Internet development.

This end-to-end principle was pioneered by Louis Pouzin in the CYCLADES network,[22] based on the ideas of Donald Davies.

[23][24] Using this design, it became possible to connect other networks to the ARPANET that used the same principle, irrespective of other local characteristics, thereby solving Kahn's initial internetworking problem.

[30][31][32] In the same year, NORSAR/NDRE and Peter Kirstein's research group at University College London adopted the protocol.

[33] The migration of the ARPANET from NCP to TCP/IP was officially completed on flag day January 1, 1983, when the new protocols were permanently activated.

They navigated the corporate politics to get a stream of TCP/IP products for various IBM systems, including MVS, VM, and OS/2.

At the same time, several smaller companies, such as FTP Software and the Wollongong Group, began offering TCP/IP stacks for DOS and Microsoft Windows.

[41] The spread of TCP/IP was fueled further in June 1989, when the University of California, Berkeley agreed to place the TCP/IP code developed for BSD UNIX into the public domain.

For Windows 3.1, the dominant PC operating system among consumers in the first half of the 1990s, Peter Tattam's release of the Trumpet Winsock TCP/IP stack was key to bringing the Internet to home users.

The typical home PC of the time had an external Hayes-compatible modem connected via an RS-232 port with an 8250 or 16550 UART which required this type of stack.

Nonetheless, for a period in the late 1980s and early 1990s, engineers, organizations and nations were polarized over the issue of which standard, the OSI model or the Internet protocol suite, would result in the best and most robust computer networks.

Real-world needs for firewalls, network address translators, web content caches and the like have forced changes in this principle.

"[48]: 23  "The second part of the principle is almost as important: software on other hosts may contain deficiencies that make it unwise to exploit legal but obscure protocol features.

In general, an application (the highest level of the model) uses a set of protocols to send its data down the layers.

The processes of transmitting and receiving packets on the link can be controlled in the device driver for the network card, as well as in firmware or by specialized chipsets.

For the purpose of providing process-specific transmission channels for applications, the layer establishes the concept of the network port.

Whilst it is technically carried via UDP packets it seeks to offer enhanced transport connectivity relative to TCP.

In addition, parallel research and commercial interests from industry associations competed with design features.

In particular, efforts in the International Organization for Standardization led to a similar goal, but with a wider scope of networking in general.

Efforts to consolidate the two principal schools of layering, which were superficially similar, but diverged sharply in detail, led independent textbook authors to formulate abridging teaching tools.

RPC provides reliable record transmission, so it can safely use the best-effort UDP transport.

The IETF has repeatedly stated[45][failed verification] that Internet Protocol and architecture development is not intended to be OSI-compliant.

Session-layer functionality is also realized with the port numbering of the TCP and UDP protocols, which are included in the transport layer of the TCP/IP suite.

The OSI routing protocol IS-IS belongs to the network layer, and does not depend on CLNS for delivering packets from one router to another, but defines its own layer-3 encapsulation.

It only requires that hardware and a software layer exists that is capable of sending and receiving packets on a computer network.

In addition to IP, ICMP, TCP, UDP, Internet Protocol version 6 requires Neighbor Discovery Protocol (NDP), ICMPv6, and Multicast Listener Discovery (MLD) and is often accompanied by an integrated IPSec security layer.

Diagram of the first internetworked connection
An SRI International Packet Radio Van , used for the first three-way internetworked transmission
Conceptual data flow in a simple network topology of two hosts (A and B) connected by a link between their respective routers. The application on each host executes read and write operations as if the processes were directly connected to each other by some kind of data pipe. After establishment of this pipe, most details of the communication are hidden from each process, as the underlying principles of communication are implemented in the lower protocol layers. In a common application analogy, Host A's web browser appears directly connected to Host B's web server via an Application Layer HTTP session identified by an address like a cookie. At the transport layer the communication appears as process-to-process communication, [ 6 ] each process addressed by a port number, without knowledge of the application data structures and the connecting routers. Finally, at the internetworking layer using the Internet Protocol (IP), packets of bytes traverse individual network boundaries as each router forwards a packet towards its destination IP address.
Encapsulation of application data descending through the layers described in RFC 1122