Transmission Control Protocol / Internet Protocol

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Transmission Control Protocol / Internet Protocol ( TCP / IP ) is a group of network protocols . At its core, it is the Internet Protocol (IP), the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP) and the Internet Control Message Protocol (ICMP). In a broader sense, the entire Internet protocol family is also referred to as TCP / IP.

The computers participating in the network are identified using IP addresses . A computer or generally a device with an IP address is referred to as a host in TCP / IP jargon . Originally, TCP was developed as a monolithic network protocol, but was later divided into the protocols IP and TCP. The core group of the protocol family is supplemented by UDP as a further transport protocol .


TCP / IP developed from work by DARPA in the early 1970s. After the trend-setting Arpanet was built in the late 1960s , DARPA began working on alternative transmission technologies.

In 1972 Robert E. Kahn was employed at the DARPA Information Processing Technology Office , where he worked on satellite-based packet-switching networks and terrestrial radio networks, where it struck him how important it would be to be able to communicate over all networks regardless of the transmission technology.

In the spring of 1973, Vinton Cerf joined Kahn to work on new open architecture connection models with the aim of creating the next protocol for the Arpanet.

In the summer of 1973, Kahn and Cerf had developed a fundamentally new model that compensates for the differences between physical networks by introducing an abstraction layer in the form of the Internet Protocol (IP). At the same time, in contrast to the Arpanet, the task of ensuring reliability has been shifted from the physical network to the individual host computers. Cerf claims to have been heavily influenced by Hubert Zimmerman and Louis Pouzin , the developers of the CYCLADES network.

With the reduction of the tasks of the physical network to a minimum, almost any network could now be connected, completely independent of their physical implementation.

This idea was further developed into the first TCP specification ( RFC 675 ) at Cerf's research group in Stanford from 1973 to 1974 .

Then DARPA, BBN Technologies , Stanford University and University College London began to develop the first implementations on various hardware platforms. Four versions were developed: TCP v1, TCP v2, the split TCP v3 / IP v3 in the spring of 1978 and then the stable TCP / IP v4, which is still used on the Internet today.

In 1975 a two-network TCP / IP test was conducted between Stanford and University College London (UCL), and in November 1977 a three-network test between the United States, Great Britain and Norway. Between 1978 and 1983 further TCP / IP prototypes were developed at several research institutions. A complete switch to TCP / IP in the Arpanet took place on January 1, 1983.

In March 1982 the US Department of Defense declared TCP / IP as the standard for all military computer networking.

In 1985, the Internet Architecture Board held a three-day workshop on TCP / IP for the computer industry, attended by 250 vendors, which made the protocol more popular and subsequently more widely used.


For a long time, TCP / IP was in competition with protocols such as X.25 ( ITU-T ), IPX / SPX (Novell), AppleTalk (Apple) or NetBEUI ( Microsoft Windows ). It is one of the first network protocols (and the only successful one) that is universally and independently available for all common operating systems and almost every conceivable network. However, due to its universal usability, it can only be configured with a little basic knowledge; The integration of different network segments requires special hardware ( routers ) and in-depth specialist knowledge.

At the latest with the triumphant advance of the Internet, which requires the use of IP addresses, but also due to its great flexibility and routing ability, this network protocol was able to gain general acceptance.

Importance of the protocols

The importance of the Internet protocols emerges from their history and is closely linked to the development of the Internet. Only later, when the Internet was long established, did they become the standard protocol in networks. Apple and Microsoft have long used their own network protocols that have only gradually been replaced with the penetration of the Internet. Until Windows for Workgroups , TCP / IP had to be manually installed under Windows. Dial-up components were only available there with Internet Explorer , and these components also had to be configured individually by hand. With modern operating systems (e.g. Linux or Windows from version 2000 and ME ) and the use of network servers or automatic address acquisition from the Internet service provider , the configuration of the Internet protocols for the end user is practically no longer necessary, which was an important prerequisite for their success.

In the meantime Novell, Apple and Microsoft have largely replaced their own network protocols with TCP / IP. Today routers, printers or print servers, IP telephones, IP radios or hardware firewalls also use this protocol as the standard. In practice, there are also IP connections to other hardware components (such as scanners, PDAs, cell phones integrated into the network, etc.), since implementation is basically simple due to the modularity and openness of this standard.

Due to the address restriction of the Internet Protocol v4 , the Internet layer in the layer model must essentially be replaced by IPv6 . The other layers of this model remain relatively unaffected by this, unless the application layer contains additional addresses, as is the case with FTP , for example .

See also

Web links

Individual evidence

  1. ^ Gilbert Held: The ABCs of TCP / IP . CRC Press, October 29, 2002, ISBN 978-1-4398-3230-1 , p. 32.
  2. V. Cerf et al : Specification of Internet Transmission Control Protocol . December 1974. Request for Comments 675. Retrieved March 4, 2011.
  3. Internet History
  4. ^ Ronda hoods: From the ARPANET to the Internet . TCP Digest (UUCP). Retrieved July 5, 2007.