134-704: The Internet protocol suite , commonly known as TCP/IP , is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP). Early versions of this networking model were known as
268-743: A Ph.D. degree from Princeton University in 1964, he worked for AT&T Bell Laboratories , as an assistant professor at MIT. He moved to Bolt Beranek & Newman (BBN) where he was the principal designer of the IMP subnetwork and the IMP-Host protocol for the ARPANET. In 1972, he joined the IPTO within ARPA , where he worked on both satellite packet networks (which led to SATNET ) and ground-based radio packet networks (which led to PRNET ), and recognized
402-585: A protocol stack . Internet communication protocols are published by the Internet Engineering Task Force (IETF). The IEEE (Institute of Electrical and Electronics Engineers) handles wired and wireless networking and the International Organization for Standardization (ISO) handles other types. The ITU-T handles telecommunications protocols and formats for the public switched telephone network (PSTN). As
536-524: A router is provided with an interface to each network. It forwards network packets back and forth between them. Originally a router was called gateway , but the term was changed to avoid confusion with other types of gateways . In March 1982, the US Department of Defense declared TCP/IP as the standard for all military computer networking. In the same year, NORSAR / NDRE and Peter Kirstein 's research group at University College London adopted
670-402: A tunneling arrangement to accommodate the connection of dissimilar networks. For example, IP may be tunneled across an Asynchronous Transfer Mode (ATM) network. Protocol layering forms the basis of protocol design. It allows the decomposition of single, complex protocols into simpler, cooperating protocols. The protocol layers each solve a distinct class of communication problems. Together,
804-540: A board member of the Internet Society and numerous other Internet-related volunteer positions. Crocker is chair of the board of ICANN. For this work, Crocker was awarded the 2002 IEEE Internet Award "for leadership in creation of key elements in open evolution of Internet protocols". In 2012, Crocker was inducted into the Internet Hall of Fame by the Internet Society . Jon Postel (1943–1998)
938-447: A close analogy between protocols and programming languages: protocols are to communication what programming languages are to computations . An alternate formulation states that protocols are to communication what algorithms are to computation . Multiple protocols often describe different aspects of a single communication. A group of protocols designed to work together is known as a protocol suite; when implemented in software they are
1072-519: A coarse hierarchy of functional layers defined in the Internet Protocol Suite . The first two cooperating protocols, the Transmission Control Protocol (TCP) and the Internet Protocol (IP) resulted from the decomposition of the original Transmission Control Program, a monolithic communication protocol, into this layered communication suite. The OSI model was developed internationally based on experience with networks that predated
1206-599: A computer environment (such as ease of mechanical parsing and improved bandwidth utilization ). Network applications have various methods of encapsulating data. One method very common with Internet protocols is a text oriented representation that transmits requests and responses as lines of ASCII text, terminated by a newline character (and usually a carriage return character). Examples of protocols that use plain, human-readable text for its commands are FTP ( File Transfer Protocol ), SMTP ( Simple Mail Transfer Protocol ), early versions of HTTP ( Hypertext Transfer Protocol ), and
1340-464: A computer network. The 1968 paper, "The Computer as a Communication Device", that he wrote together with J.C.R. Licklider starts out: "In a few years, men will be able to communicate more effectively through a machine than face to face." And while their vision would take more than "a few years", the paper lays out the future of what the Internet would eventually become. From 1970 to 1983, he managed
1474-560: A de facto standard operating system like Linux does not have this negative grip on its market, because the sources are published and maintained in an open way, thus inviting competition. Yogen Dalal Instead of having a single inventor, the Internet was developed by many people over many years. The following people are Internet pioneers who have been recognized for their contribution to its early and ongoing development. These contributions include theoretical foundations, building early networks, specifying protocols, and expansion beyond
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#17327718803811608-482: A detailed architecture for distributed adaptive message block switching . The proposal was composed of three key ideas: use of a decentralized network with multiple paths between any two points; dividing user messages into message blocks; and delivery of these messages by store and forward switching. Baran's network design was never built; it was intended for voice communication using low-cost electronics and did not feature software switches. He provided input to
1742-535: A few programmers. Jay Elinsky and Oleg Vishnepolsky of IBM Research wrote TCP/IP stacks for VM/CMS and OS/2, respectively. In 1984 Donald Gillies at MIT wrote a ntcp multi-connection TCP which runs atop the IP/PacketDriver layer maintained by John Romkey at MIT in 1983–84. Romkey leveraged this TCP in 1986 when FTP Software was founded. Starting in 1985, Phil Karn created a multi-connection TCP application for ham radio systems (KA9Q TCP). The spread of TCP/IP
1876-463: A four-layer model, with the layers having names, not numbers, as follows: The protocols of the link layer operate within the scope of the local network connection to which a host is attached. This regime is called the link in TCP/IP parlance and is the lowest component layer of the suite. The link includes all hosts accessible without traversing a router. The size of the link is therefore determined by
2010-487: A fundamental reformulation, in which the differences between local network protocols were hidden by using a common internetwork protocol , and, instead of the network being responsible for reliability, as in the existing ARPANET protocols, this function was delegated to the hosts. Cerf credits Louis Pouzin and Hubert Zimmermann , designers of the CYCLADES network, with important influences on this design. The new protocol
2144-651: A host-host protocol, the Network Control Program (NCP). 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 1972, Bob Kahn joined the DARPA Information Processing Technology Office , where he worked on both satellite packet networks and ground-based radio packet networks, and recognized
2278-456: A machine rather than a human being. Binary protocols have the advantage of terseness, which translates into speed of transmission and interpretation. Binary have been used in the normative documents describing modern standards like EbXML , HTTP/2 , HTTP/3 and EDOC . An interface in UML may also be considered a binary protocol. Getting the data across a network is only part of the problem for
2412-541: A modern data-communications context in an April 1967 memorandum entitled A Protocol for Use in the NPL Data Communications Network . He proposed the use of packet switching in the ARPANET at the inaugural Symposium on Operating Systems Principles in October 1967 and convinced Larry Roberts the economics were favorable to message switching . During the 1970s, he was a major figure in
2546-457: A networking protocol, the protocol software modules are interfaced with a framework implemented on the machine's operating system. This framework implements the networking functionality of the operating system. When protocol algorithms are expressed in a portable programming language the protocol software may be made operating system independent. The best-known frameworks are the TCP/IP model and
2680-417: A packet-switched network, rather than this being a service of the network itself. His team was the first to tackle the highly complex problem of providing user applications with a reliable virtual circuit service while using a best-effort service , an early contribution to what will be the Transmission Control Protocol (TCP). Bob Metcalfe and others at Xerox PARC outlined the idea of Ethernet and
2814-489: 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. The technical standards underlying the Internet protocol suite and its constituent protocols have been delegated to the Internet Engineering Task Force (IETF). The characteristic architecture of
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#17327718803812948-738: A period of time. In this process, the specifics of protocol components and their layering changed. 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. The following table shows various such networking models. The number of layers varies between three and seven. Communication protocol A communication protocol
3082-554: A protocol. The data received has to be evaluated in the context of the progress of the conversation, so a protocol must include rules describing the context. These kinds of rules are said to express the syntax of the communication. Other rules determine whether the data is meaningful for the context in which the exchange takes place. These kinds of rules are said to express the semantics of the communication. Messages are sent and received on communicating systems to establish communication. Protocols should therefore specify rules governing
3216-460: A reference model for communication standards led to the OSI model , published in 1984. For a period in the late 1980s and early 1990s, engineers, organizations and nations became 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. The information exchanged between devices through a network or other media
3350-493: A reliable data-link protocol such as the High-Level Data Link Control (HDLC). The User Datagram Protocol (UDP) is a connectionless datagram protocol. Like IP, it is a best-effort, unreliable protocol. Reliability is addressed through error detection using a checksum algorithm. UDP is typically used for applications such as streaming media (audio, video, Voice over IP , etc.) where on-time arrival
3484-553: A research tool to wide deployment. This list includes people who were: Among the pioneers, along with Cerf and Kahn, Bob Metcalfe , Donald Davies , Louis Pouzin , Steve Crocker and Ray Tomlinson meet three out of the four criteria above; as well as Jon Postel , considering the 2003 IEEE Internet award on which he is cited. Davies and Kahn are featured in the 1972 documentary film Computer Networks: The Heralds of Resource Sharing along with several early pioneers. Other Internet pioneers, who have made notable contributions to
3618-399: A response from a range of possible responses predetermined for that particular situation. The specified behavior is typically independent of how it is to be implemented . Communication protocols have to be agreed upon by the parties involved. To reach an agreement, a protocol may be developed into a technical standard . A programming language describes the same for computations, so there is
3752-478: A set of cooperating processes that manipulate shared data to communicate with each other. This communication is governed by well-understood protocols, which can be embedded in the process code itself. In contrast, because there is no shared memory , communicating systems have to communicate with each other using a shared transmission medium . Transmission is not necessarily reliable, and individual systems may use different hardware or operating systems. To implement
3886-447: A set of protocols to send its data down the layers. The data is further encapsulated at each level. An early pair of architectural documents, RFC 1122 and 1123 , titled Requirements for Internet Hosts , emphasizes architectural principles over layering. RFC 1122/23 are structured in sections referring to layers, but the documents refer to many other architectural principles, and do not emphasize layering. They loosely defines
4020-456: A standardization process. Such protocols are referred to as de facto standards . De facto standards are common in emerging markets, niche markets, or markets that are monopolized (or oligopolized ). They can hold a market in a very negative grip, especially when used to scare away competition. From a historical perspective, standardization should be seen as a measure to counteract the ill-effects of de facto standards. Positive exceptions exist;
4154-430: A transfer mechanism of a protocol is comparable to a central processing unit (CPU). The framework introduces rules that allow the programmer to design cooperating protocols independently of one another. In modern protocol design, protocols are layered to form a protocol stack. Layering is a design principle that divides the protocol design task into smaller steps, each of which accomplishes a specific part, interacting with
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4288-459: A unique protocol number : for example, Internet Control Message Protocol (ICMP) and Internet Group Management Protocol (IGMP) are protocols 1 and 2, respectively. The Internet Protocol is the principal component of the internet layer, and it defines two addressing systems to identify network hosts and to locate them on the network. The original address system of the ARPANET and its successor,
4422-505: Is a system of rules that allows two or more entities of a communications system to transmit information via any variation of a physical quantity . The protocol defines the rules, syntax , semantics , and synchronization of communication and possible error recovery methods . Protocols may be implemented by hardware , software , or a combination of both. Communicating systems use well-defined formats for exchanging various messages. Each message has an exact meaning intended to elicit
4556-453: Is governed by rules and conventions that can be set out in communication protocol specifications. The nature of communication, the actual data exchanged and any state -dependent behaviors, is defined by these specifications. In digital computing systems, the rules can be expressed by algorithms and data structures . Protocols are to communication what algorithms or programming languages are to computations. Operating systems usually contain
4690-482: Is message-stream-oriented, not byte-stream-oriented like TCP, and provides multiple streams multiplexed over a single connection. It also provides multihoming support, in which a connection end can be represented by multiple IP addresses (representing multiple physical interfaces), such that if one fails, the connection is not interrupted. It was developed initially for telephony applications (to transport SS7 over IP). Reliability can also be achieved by running IP over
4824-581: Is more important than reliability, or for simple query/response applications like DNS lookups, where the overhead of setting up a reliable connection is disproportionately large. Real-time Transport Protocol (RTP) is a datagram protocol that is used over UDP and is designed for real-time data such as streaming media . The applications at any given network address are distinguished by their TCP or UDP port. By convention, certain well-known ports are associated with specific applications. The TCP/IP model's transport or host-to-host layer corresponds roughly to
4958-449: Is referred to as communicating sequential processes (CSP). Concurrency can also be modeled using finite state machines , such as Mealy and Moore machines . Mealy and Moore machines are in use as design tools in digital electronics systems encountered in the form of hardware used in telecommunication or electronic devices in general. The literature presents numerous analogies between computer communication and programming. In analogy,
5092-408: Is the synchronization of software for receiving and transmitting messages of communication in proper sequencing. Concurrent programming has traditionally been a topic in operating systems theory texts. Formal verification seems indispensable because concurrent programs are notorious for the hidden and sophisticated bugs they contain. A mathematical approach to the study of concurrency and communication
5226-621: The Department of Defense ( DoD ) model because the research and development were funded by the United States Department of Defense through DARPA . The Internet protocol suite provides end-to-end data communication specifying how data should be packetized, addressed, transmitted, routed , and received. This functionality is organized into four abstraction layers , which classify all related protocols according to each protocol's scope of networking. An implementation of
5360-928: The File Transfer Protocol (FTP) for network mail on the ARPANET was proposed in RFC 469 in March 1973. Through RFC 561 , RFC 680 , RFC 724 , and finally RFC 733 in November 1977, a standardized framework was developed for "electronic mail" using FTP mail servers on the ARPANET. Tomlinson discussed a network mail protocol among the International Network Working Group in INWG Protocol note 2 , in September 1974, although it
5494-536: The International Network Working Group (INWG) through which he was an early contributor to concepts used in the Transmission Control Program which became part of the Internet protocol suite . He was acknowledged by Cerf and Kahn in their seminal 1974 paper on internetworking . Robert W. Taylor (1932–2017) was director of ARPA 's Information Processing Techniques Office (IPTO) from 1966 through 1969, where he convinced ARPA to fund
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5628-674: The Internet Experiment Note (IEN) series. In September 1980, Postel and Suzanne Sluizer published RFC 772 which proposed the Mail Transfer Protocol to enable servers to transmit "computer mail" on the ARPANET as a replacement for FTP. RFC 780 of May 1981 removed all references to FTP. In November 1981, Postel published RFC 788 describing the Simple Mail Transfer Protocol (SMTP) protocol, which
5762-485: The Internet Hall of Fame by the Internet Society . Frank Heart (1929–2018) worked for Bolt, Beranek and Newman (BBN) from 1966 to 1994, during which time he managed the team that designed and implemented the Interface Message Processors (IMPs), the routing computers for the ARPANET . Robert E. "Bob" Kahn (born 1938) is an American engineer and computer scientist . After earning
5896-569: The Network Startup Resource Center , helping dozens of countries to establish connections with FidoNet , UseNet , and when possible the Internet . In 2003, he received an International Committee for Information Technology Standards Merit Award . In 2007, he was inducted as a Fellow of the Association for Computing Machinery for contributions to networking standards and Internet applications. In 2012, Klensin
6030-423: The OSI model . At the time the Internet was developed, abstraction layering had proven to be a successful design approach for both compiler and operating system design and, given the similarities between programming languages and communication protocols, the originally monolithic networking programs were decomposed into cooperating protocols. This gave rise to the concept of layered protocols which nowadays forms
6164-556: The PARC Universal Packet (PUP) for internetworking. Research in the early 1970s by Bob Kahn and Vint Cerf led to the formulation of the Transmission Control Program (TCP). Its RFC 675 specification was written by Cerf with Yogen Dalal and Carl Sunshine in December 1974, still a monolithic design at this time. The International Network Working Group agreed on a connectionless datagram standard which
6298-686: The SDC Q-32 computer in Santa Monica . In 1967, he became a program manager in the ARPA Information Processing Techniques Office (IPTO), where he managed the development of the ARPANET , the first wide area packet switching network. Roberts applied Donald Davies' concepts of packet switching in the ARPANET, and sought input from Paul Baran and other researchers on network design. After Robert Taylor left ARPA in 1969, Roberts became director of
6432-561: The Simple Mail Transfer Protocol (SMTP) and the co-creator and longtime administrator of the Internet Assigned Numbers Authority (IANA). His beard and sandals made him "the most recognizable archetype of an Internet pioneer". The International Network Working Group (INWG) discussed protocols for electronic mail in 1979, which was referenced by Postel in his early work on Internet email. Postel first proposed an Internet Message Protocol in 1979 as part of
6566-547: The finger protocol . Text-based protocols are typically optimized for human parsing and interpretation and are therefore suitable whenever human inspection of protocol contents is required, such as during debugging and during early protocol development design phases. A binary protocol utilizes all values of a byte , as opposed to a text-based protocol which only uses values corresponding to human-readable characters in ASCII encoding. Binary protocols are intended to be read by
6700-485: The 1970s, Kleinrock carried out theoretical work to measure and mathematically model the performance of the ARPANET, which underpinned the development of the network and the Transmission Control Program. His theoretical work on hierarchical routing in the late 1970s with student Farouk Kamoun remains critical to the operation of the Internet today. In 2012, Kleinrock was inducted into
6834-661: The ARPANET and Internet communities since their inception. As a UCLA graduate student in the 1960s, he led the creation of the ARPANET host-to-host protocol, the Network Control Protocol . He also created the Request for Comments (RFC) series, authoring the very first RFC and many more. He was instrumental in creating the ARPA Network Working Group, the forerunner of the modern Internet Engineering Task Force . In 1972, Crocker moved to
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#17327718803816968-629: The ARPANET and research in Europe and Japan. He carried out simulation work on datagram networks on a scale to provide data communication to much of the United Kingdom and designed an adaptive method of congestion control , which he called isarithmic . In the 1970s, Davies worked on internetworking and secure communication . He was acknowledged by Vint Cerf and Bob Kahn in their seminal 1974 paper on internetworking, A Protocol for Packet Network Intercommunication. Davies received
7102-603: The ARPANET host-to-host protocol, the Network Control Program . Cerf was an assistant professor at Stanford University from 1972 to 1976, where he conducted research on packet network interconnection protocols and co-designed the DoD TCP/IP protocol suite. He authored the seminal paper on internetworking , A Protocol for Packet Network Intercommunication , in May 1974 with Bob Kahn ; the first specification of TCP with Yogen Dalal and Carl Sunshine in December that year; and edited
7236-446: The ARPANET in 1971. His message was sent from one Digital Equipment Corporation PDP-10 computer to another PDP-10, placed next to each other. Tomlinson initiated the use of the " @ " sign to separate the names of the user and the user's machine. Tomlinson's idea for "network mail" was adopted on the ARPANET, which significantly increased network traffic. As a result, he has been called "the inventor of modern email". The use of
7370-406: The ARPANET project on distributed communications and dynamic routing. Baran received the inaugural SIGCOMM Award in 1989, the inaugural IEEE Internet Award in 2000 and the inaugural Internet Hall of Fame "pioneers" award from the Internet Society in 2012. Donald Davies (1924–2000) independently invented and named the concept of packet switching for data communications in 1965 at
7504-485: The ARPANET that used the same principle, irrespective of other local characteristics, thereby solving Kahn's initial internetworking problem. A popular expression is that TCP/IP, the eventual product of Cerf and Kahn's work, can run over "two tin cans and a string." Years later, as a joke in 1999, the IP over Avian Carriers formal protocol specification was created and successfully tested two years later. 10 years later still, it
7638-497: The Advanced Research Projects Agency (ARPA) to become a program manager. He formed the International Network Working Group (INWG), then his research interests shifted to artificial intelligence . He was acknowledged by Cerf and Kahn in their seminal 1974 paper on internetworking . He was a senior researcher at USC 's Information Sciences Institute (ISI) where he contributed to discussions on
7772-759: The Computer Science Laboratory of the Xerox Palo Alto Research Center (PARC), where technologies such as Ethernet and the Xerox Alto were developed. He was the founder and manager of Digital Equipment Corporation 's Systems Research Center until 1996. Lawrence G. "Larry" Roberts (1937–2018) was an American computer scientist . After earning his PhD in electrical engineering from MIT in 1963, Roberts continued to work at MIT's Lincoln Laboratory where in 1965 he connected Lincoln Lab's TX-2 computer to
7906-588: The IETF has never modified this structure. As such a model of networking, the Internet protocol suite predates the OSI model, a more comprehensive reference framework for general networking systems. The end-to-end principle has evolved over time. Its original expression put the maintenance of state and overall intelligence at the edges, and assumed the Internet that connected the edges retained no state and concentrated on speed and simplicity. Real-world needs for firewalls, network address translators, web content caches and
8040-461: The IPTO. In 1973, he left ARPA to commercialize the nascent technology in the form of Telenet , which became one of the first public data networks in the world, and served as its CEO from 1973 to 1980. In 2012, Roberts was inducted into the Internet Hall of Fame by the Internet Society . Leonard Kleinrock (born 1934) became involved in the ARPANET project in early 1967. He had studied
8174-483: The Internet protocol suite and its constituent protocols are maintained by the Internet Engineering Task Force (IETF). The Internet protocol suite predates the OSI model , a more comprehensive reference framework for general networking systems. Early research and development: Merging the networks and creating the Internet: Commercialization, privatization, broader access leads to
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#17327718803818308-408: The Internet protocol suite is its broad division into operating scopes for the protocols that constitute its core functionality. The defining specifications of the suite are RFC 1122 and 1123, which broadly outlines four abstraction layers (as well as related protocols); the link layer, IP layer, transport layer, and application layer, along with support protocols. These have stood the test of time, as
8442-513: The Internet, is Internet Protocol version 4 (IPv4). It uses a 32-bit IP address and is therefore capable of identifying approximately four billion hosts. This limitation was eliminated in 1998 by the standardization of Internet Protocol version 6 (IPv6) which uses 128-bit addresses. IPv6 production implementations emerged in approximately 2006. The transport layer establishes basic data channels that applications use for task-specific data exchange. The layer establishes host-to-host connectivity in
8576-507: The OSI model. Application layer protocols are often associated with particular client–server applications, and common services have well-known port numbers reserved by the Internet Assigned Numbers Authority (IANA). For example, the HyperText Transfer Protocol uses server port 80 and Telnet uses server port 23. Clients connecting to a service usually use ephemeral ports , i.e., port numbers assigned only for
8710-595: The PSTN and Internet converge , the standards are also being driven towards convergence. The first use of the term protocol in a modern data-commutation context occurs in April 1967 in a memorandum entitled A Protocol for Use in the NPL Data Communications Network. Under the direction of Donald Davies , who pioneered packet switching at the National Physical Laboratory in the United Kingdom, it
8844-711: The Transmission Control Program in August 1977. He was a founder and director of the Computer Science Laboratory at The Aerospace Corporation and a vice president at Trusted Information Systems . In 1994, Crocker was one of the founders and chief technology officer of CyberCash , Inc. He has also been an IETF security area director, a member of the Internet Architecture Board , chair of the Internet Corporation for Assigned Names and Numbers (ICANN) Security and Stability Advisory Committee,
8978-458: The United Kingdom's National Physical Laboratory (NPL). In the same year, he proposed a national commercial data network in the UK employing high-speed switching nodes. He refined his ideas in a paper written in 1966, which included the first description of an "interface computer" to act as a router . Later that year, he established a team which produced a design for a local-area network to serve
9112-477: 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. Postel stated, "We are screwing up in our design of Internet protocols by violating the principle of layering." Encapsulation of different mechanisms was intended to create an environment where
9246-469: The applications are usually aware of key qualities of the transport layer connection such as the endpoint IP addresses and port numbers, application layer protocols generally treat the transport layer (and lower) protocols as black boxes which provide a stable network connection across which to communicate. The transport layer and lower-level layers are unconcerned with the specifics of application layer protocols. Routers and switches do not typically examine
9380-456: The approval or support of a standards organization , which initiates the standardization process. The members of the standards organization agree to adhere to the work result on a voluntary basis. Often the members are in control of large market shares relevant to the protocol and in many cases, standards are enforced by law or the government because they are thought to serve an important public interest, so getting approval can be very important for
9514-448: The basis of protocol design. Systems typically do not use a single protocol to handle a transmission. Instead they use a set of cooperating protocols, sometimes called a protocol suite . Some of the best-known protocol suites are TCP/IP , IPX/SPX , X.25 , AX.25 and AppleTalk . The protocols can be arranged based on functionality in groups, for instance, there is a group of transport protocols . The functionalities are mapped onto
9648-769: The board and as ICANN Chairman from 2000 to 2007. His many awards include the National Medal of Technology , the Turing Award , the Presidential Medal of Freedom , and membership in the National Academy of Engineering and the Internet Society's Internet Hall of Fame . Douglas Engelbart (1925–2013) was an early researcher at the Stanford Research Institute . His Augmentation Research Center laboratory became
9782-442: The content being carried: text-based and binary. A text-based protocol or plain text protocol represents its content in human-readable format , often in plain text encoded in a machine-readable encoding such as ASCII or UTF-8 , or in structured text-based formats such as Intel hex format , XML or JSON . The immediate human readability stands in contrast to native binary protocols which have inherent benefits for use in
9916-480: 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 . The first VM/CMS TCP/IP stack came from the University of Wisconsin. Some of the early TCP/IP stacks were written single-handedly by
10050-399: The development of the Internet but do not meet any of the four criteria above, are listed in the final section of the article . This article is in chronological order mirroring the development process for the Internet. Joseph Carl Robnett Licklider (1915–1990) was a faculty member of Massachusetts Institute of Technology (MIT), and researcher at Bolt, Beranek and Newman . He developed
10184-412: The duration of the transaction at random or from a specific range configured in the application. At the application layer, the TCP/IP model distinguishes between user protocols and support protocols . Support protocols provide services to a system of network infrastructure. User protocols are used for actual user applications. For example, FTP is a user protocol and DNS is a support protocol. Although
10318-520: The encapsulated traffic, rather they just provide a conduit for it. However, some firewall and bandwidth throttling applications use deep packet inspection to interpret application data. An example is the Resource Reservation Protocol (RSVP). It is also sometimes necessary for Applications affected by NAT to consider the application payload. The Internet protocol suite evolved through research and development funded over
10452-673: The field of computer networking, it has been historically criticized by many researchers as abstracting the protocol stack in this way may cause a higher layer to duplicate the functionality of a lower layer, a prime example being error recovery on both a per-link basis and an end-to-end basis. Commonly recurring problems in the design and implementation of communication protocols can be addressed by software design patterns . Popular formal methods of describing communication syntax are Abstract Syntax Notation One (an ISO standard) and augmented Backus–Naur form (an IETF standard). Finite-state machine models are used to formally describe
10586-462: The first Interop conference focused on network interoperability by broader adoption of TCP/IP. The conference was founded by Dan Lynch, an early Internet activist. From the beginning, large corporations, such as IBM and DEC, attended the meeting. IBM, AT&T and DEC were the first major corporations to adopt TCP/IP, this despite having competing proprietary protocols . In IBM, from 1984, Barry Appelman 's group did TCP/IP development. They navigated
10720-595: The form of end-to-end message transfer services that are independent of the underlying network and independent of the structure of user data and the logistics of exchanging information. Connectivity at the transport layer can be categorized as either connection-oriented , implemented in TCP, or connectionless , implemented in UDP. The protocols in this layer may provide error control , segmentation , flow control , congestion control , and application addressing ( port numbers ). For
10854-424: The fourth layer in the OSI model, also called the transport layer. QUIC is rapidly emerging as an alternative transport protocol. Whilst it is technically carried via UDP packets it seeks to offer enhanced transport connectivity relative to TCP. HTTP/3 works exclusively via QUIC. The application layer includes the protocols used by most applications for providing user services or exchanging application data over
10988-426: The horizontal message flows (and protocols) are between systems. The message flows are governed by rules, and data formats specified by protocols. The blue lines mark the boundaries of the (horizontal) protocol layers. The software supporting protocols has a layered organization and its relationship with protocol layering is shown in figure 5. To send a message on system A, the top-layer software module interacts with
11122-580: The idea of a universal computer network at the Information Processing Techniques Office (IPTO) of the United States Department of Defense Advanced Research Projects Agency (ARPA). He headed the IPTO from 1962 to 1963, and again from 1974 to 1975. His 1960 paper " Man-Computer Symbiosis " envisions that mutually-interdependent, "living together", tightly coupled human brains and computing machines would prove to complement each other's strengths. In 2013, Licklider
11256-448: The inaugural IEEE Internet Award in 2000 and the inaugural Internet Hall of Fame "pioneers" award from the Internet Society in 2012. Roger Scantlebury (born 1936) led the pioneering work to implement packet switching and associated communication protocols at the NPL in the late 1960s. Scantlebury and his colleague Keith Bartlett were the first to describe the term protocol in
11390-643: The internet as a reference model for general communication with much stricter rules of protocol interaction and rigorous layering. Typically, application software is built upon a robust data transport layer. Underlying this transport layer is a datagram delivery and routing mechanism that is typically connectionless in the Internet. Packet relaying across networks happens over another layer that involves only network link technologies, which are often specific to certain physical layer technologies, such as Ethernet . Layering provides opportunities to exchange technologies when needed, for example, protocols are often stacked in
11524-423: The invention of the computer mouse , and the development of hypertext , networked computers, and precursors to graphical user interfaces . John Klensin' s involvement with Internet began in 1969, when he worked on the File Transfer Protocol . Klensin was involved in the early procedural and definitional work for DNS administration and top-level domain definitions and was part of the committee that worked out
11658-410: The involvement of service discovery or directory services . Because IP provides only a best-effort delivery , some transport-layer protocols offer reliability. TCP is a connection-oriented protocol that addresses numerous reliability issues in providing a reliable byte stream : The newer Stream Control Transmission Protocol (SCTP) is also a reliable, connection-oriented transport mechanism. It
11792-486: The layers for a particular application forms a protocol stack . From lowest to highest, the layers are the link layer , containing communication methods for data that remains within a single network segment (link); the internet layer , providing internetworking between independent networks; the transport layer , handling host-to-host communication; and the application layer , providing process-to-process data exchange for applications. The technical standards underlying
11926-476: The layers make up a layering scheme or model. Computations deal with algorithms and data; Communication involves protocols and messages; So the analog of a data flow diagram is some kind of message flow diagram. To visualize protocol layering and protocol suites, a diagram of the message flows in and between two systems, A and B, is shown in figure 3. The systems, A and B, both make use of the same protocol suite. The vertical flows (and protocols) are in-system and
12060-427: The layers, each layer solving a distinct class of problems relating to, for instance: application-, transport-, internet- and network interface-functions. To transmit a message, a protocol has to be selected from each layer. The selection of the next protocol is accomplished by extending the message with a protocol selector for each layer. There are two types of communication protocols, based on their representation of
12194-404: The like have forced changes in this principle. The robustness principle states: "In general, an implementation must be conservative in its sending behavior, and liberal in its receiving behavior. That is, it must be careful to send well-formed datagrams, but must accept any datagram that it can interpret (e.g., not object to technical errors where the meaning is still clear)." "The second part of
12328-598: The modern Internet: Examples of Internet services: Initially referred to as the DOD Internet Architecture Model , the Internet protocol suite has its roots in research and development sponsored by the Defense Advanced Research Projects Agency ( DARPA ) in the late 1960s. After DARPA initiated the pioneering ARPANET in 1969, Steve Crocker established a "Networking Working Group" which developed
12462-402: The module directly below it and hands over the message to be encapsulated. The lower module fills in the header data in accordance with the protocol it implements and interacts with the bottom module which sends the message over the communications channel to the bottom module of system B. On the receiving system B the reverse happens, so ultimately the message gets delivered in its original form to
12596-426: The needs of NPL and prove the feasibility of packet switching while developing a more formal design proposal for a national network based on a high-level network connected to local networks. Davies gave the first public presentation on packet switching in 1968. He built the local-area NPL network , the first implementation of packet switching in early 1969 and the first to use high-speed links. His work influenced
12730-523: The network addressing methods used in the Internet Protocol to link-layer addresses, such as media access control (MAC) addresses. All other aspects below that level, however, are implicitly assumed to exist and are not explicitly defined in the TCP/IP model. The link layer in the TCP/IP model has corresponding functions in Layer 2 of the OSI model. Internetworking requires sending data from
12864-824: The network connections established by the lower-level protocols. This may include some basic network support services such as routing protocols and host configuration. Examples of application layer protocols include the Hypertext Transfer Protocol (HTTP), the File Transfer Protocol (FTP), the Simple Mail Transfer Protocol (SMTP), and the Dynamic Host Configuration Protocol (DHCP). Data coded according to application layer protocols are encapsulated into transport layer protocol units (such as TCP streams or UDP datagrams), which in turn use lower layer protocols to effect actual data transfer. The TCP/IP model does not consider
12998-485: The network included the recognition that it should provide only the functions of efficiently transmitting and routing traffic between end nodes and that all other intelligence should be located at the edge of the network, in the end nodes. This end-to-end principle was pioneered by Louis Pouzin in the CYCLADES network, based on the ideas of Donald Davies . Using this design, it became possible to connect other networks to
13132-404: The networking hardware design. In principle, TCP/IP is designed to be hardware independent and may be implemented on top of virtually any link-layer technology. This includes not only hardware implementations but also virtual link layers such as virtual private networks and networking tunnels . The link layer is used to move packets between the internet layer interfaces of two different hosts on
13266-489: The optimization of message delays in communication networks using queueing theory in his Ph.D. thesis, Message Delay in Communication Nets with Storage, at MIT in 1962. After this, he moved to UCLA . In 1969, under his supervision, a team at UCLA connected a computer to an Interface Message Processor (IMP), becoming the first node on the ARPANET. Building on his earlier work on queueing theory, during
13400-415: The other parts of the protocol only in a small number of well-defined ways. Layering allows the parts of a protocol to be designed and tested without a combinatorial explosion of cases, keeping each design relatively simple. The communication protocols in use on the Internet are designed to function in diverse and complex settings. Internet protocols are designed for simplicity and modularity and fit into
13534-544: The packet switching and routing software for the Interface Message Processor (IMP) of the ARPANET . He proposed what became known as the Walden message switching protocol, and was acknowledged by Cerf and Kahn in their seminal 1974 paper on internetworking . Ray Tomlinson (1941–2016) worked for BBN. He carried out the first experimental message transfer between separate computer systems on
13668-457: The possible interactions of the protocol. and communicating finite-state machines For communication to occur, protocols have to be selected. The rules can be expressed by algorithms and data structures. Hardware and operating system independence is enhanced by expressing the algorithms in a portable programming language. Source independence of the specification provides wider interoperability. Protocol standards are commonly created by obtaining
13802-407: The principle is almost as important: software on other hosts may contain deficiencies that make it unwise to exploit legal but obscure protocol features." Encapsulation is used to provide abstraction of protocols and services. Encapsulation is usually aligned with the division of the protocol suite into layers of general functionality. In general, an application (the highest level of the model) uses
13936-497: The protocol that is still in use in the Internet, alongside its current successor, Internet Protocol version 6 (IPv6). In 1975, a two-network IP communications test was performed between Stanford and University College London. In November 1977, a three-network IP test was conducted between sites in the US, the UK, and Norway . Several other IP prototypes were developed at multiple research centers between 1978 and 1983. A computer called
14070-401: The protocol, creating incompatible versions on their networks. In some cases, this was deliberately done to discourage users from using equipment from other manufacturers. There are more than 50 variants of the original bi-sync protocol. One can assume, that a standard would have prevented at least some of this from happening. In some cases, protocols gain market dominance without going through
14204-539: The protocol. The need for protocol standards can be shown by looking at what happened to the Binary Synchronous Communications (BSC) protocol invented by IBM . BSC is an early link-level protocol used to connect two separate nodes. It was originally not intended to be used in a multinode network, but doing so revealed several deficiencies of the protocol. In the absence of standardization, manufacturers and organizations felt free to enhance
14338-501: The protocol. 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. In 1985, the Internet Advisory Board (later Internet Architecture Board ) held a three-day TCP/IP workshop for the computer industry, attended by 250 vendor representatives, promoting the protocol and leading to its increasing commercial use. In 1985,
14472-415: The purpose of providing process-specific transmission channels for applications, the layer establishes the concept of the network port . This is a numbered logical construct allocated specifically for each of the communication channels an application needs. For many types of services, these port numbers have been standardized so that client computers may address specific services of a server computer without
14606-435: The responsibility of sending packets across potentially multiple networks. With this functionality, the internet layer makes possible internetworking, the interworking of different IP networks, and it essentially establishes the Internet. The internet layer does not distinguish between the various transport layer protocols. IP carries data for a variety of different upper layer protocols . These protocols are each identified by
14740-443: The same link. 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 . These perform functions, such as framing, to prepare the internet layer packets for transmission, and finally transmit the frames to the physical layer and over a transmission medium . The TCP/IP model includes specifications for translating
14874-424: The second node on the ARPANET in October 1969, and SRI became the early Network Information Center, which evolved into the domain name registry . Engelbart was a committed, vocal proponent of the development and use of computers and computer networks to help cope with the world's increasingly urgent and complex problems. He is best known for his work on the challenges of human–computer interaction , resulting in
15008-512: The second version of TCP in March 1977. He was a program manager for the Advanced Research Projects Agency (ARPA) from 1976 to 1982 overseeing the first internetworking experiments with SATNET and PRNET . Cerf was instrumental in the formation of both the Internet Society and Internet Corporation for Assigned Names and Numbers (ICANN), serving as founding president of the Internet Society from 1992 to 1995 and in 1999 as chairman of
15142-435: The source network to the destination network. This process is called routing and is supported by host addressing and identification using the hierarchical IP addressing system. The internet layer provides an unreliable datagram transmission facility between hosts located on potentially different IP networks by forwarding datagrams to an appropriate next-hop router for further relaying to its destination. The internet layer has
15276-461: The specifics of formatting and presenting data and does not define additional layers between the application and transport layers as in the OSI model (presentation and session layers). According to the TCP/IP model, such functions are the realm of libraries and application programming interfaces . The application layer in the TCP/IP model is often compared to a combination of the fifth (session), sixth (presentation), and seventh (application) layers of
15410-461: The top module of system B. Program translation is divided into subproblems. As a result, the translation software is layered as well, allowing the software layers to be designed independently. The same approach can be seen in the TCP/IP layering. The modules below the application layer are generally considered part of the operating system. Passing data between these modules is much less expensive than passing data between an application program and
15544-505: The transition of DNS-related responsibilities between USC-ISI and what became ICANN. His career includes 30 years as a principal research scientist at MIT , a stint as INFOODS Project Coordinator for the United Nations University , Distinguished Engineering Fellow at MCI WorldCom , and Internet Architecture Vice President at AT&T ; he is now an independent consultant. In 1992 Randy Bush and John Klensin created
15678-506: The transmission. In general, much of the following should be addressed: Systems engineering principles have been applied to create a set of common network protocol design principles. The design of complex protocols often involves decomposition into simpler, cooperating protocols. Such a set of cooperating protocols is sometimes called a protocol family or a protocol suite, within a conceptual framework. Communicating systems operate concurrently. An important aspect of concurrent programming
15812-406: The transport layer. The boundary between the application layer and the transport layer is called the operating system boundary. Strictly adhering to a layered model, a practice known as strict layering, is not always the best approach to networking. Strict layering can have a negative impact on the performance of an implementation. Although the use of protocol layering is today ubiquitous across
15946-402: The upper layers could access only what was needed from the lower layers. A monolithic design would be inflexible and lead to scalability issues. In version 4 , written in 1978, Postel split the Transmission Control Program into two distinct protocols, the Internet Protocol as connectionless layer and the Transmission Control Protocol as a reliable connection-oriented service . The design of
16080-416: The value of being able to communicate across both. In the spring of 1973, Vinton Cerf joined Kahn with the goal of designing the next protocol generation for the ARPANET to enable internetworking . They drew on the experience from the ARPANET research community, the International Network Working Group , which Cerf chaired, and researchers at Xerox PARC . By the summer of 1973, Kahn and Cerf had worked out
16214-650: The value of being able to communicate across heterogenous networks. Along with Vint Cerf, he authored the seminal paper on internetworking , A Protocol for Packet Network Intercommunication , in 1974 . Kahn left ARPA in 1986 to found the Corporation for National Research Initiatives (CNRI), a nonprofit organization providing leadership and funding for research and development of the National Information Infrastructure. David Walden (1942–2022) worked for BBN where he implemented
16348-651: Was a researcher at the University of Southern California's (USC's) Information Sciences Institute (ISI). He was editor of much of the early the RFC series as well as versions 3 and 4 of TCP/IP in January 1978 and February 1979, and the final version of TCP and Internet Protocol, which were published in January 1980 by DARPA on behalf of the Defense Communication ;Agency . He was the creator of
16482-522: Was adapted for IPv6. DARPA contracted with BBN Technologies , Stanford University , and the University College London to develop operational versions of the protocol on several hardware platforms. During development of the protocol the version number of the packet routing layer progressed from version 1 to version 4, the latter of which was installed in the ARPANET in 1983. It became known as Internet Protocol version 4 (IPv4) as
16616-415: Was first implemented in 1970. The NCP interface allowed application software to connect across the ARPANET by implementing higher-level communication protocols, an early example of the protocol layering concept. The CYCLADES network, designed by Louis Pouzin in the early 1970s was the first to implement the end-to-end principle , and make the hosts responsible for the reliable delivery of data on
16750-544: 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. Various corporate vendors, including IBM, included this code in commercial TCP/IP software releases. 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
16884-697: Was implemented as the Transmission Control Program in 1974 by Cerf, Yogen Dalal and Carl Sunshine. Initially, the Transmission Control Program (the Internet Protocol did not then exist as a separate protocol) provided only a reliable byte stream service to its users, not datagrams . Several versions were developed through the Internet Experiment Note series. As experience with the protocol grew, collaborators recommended division of functionality into layers of distinct protocols, allowing users direct access to datagram service. Advocates included Bob Metcalfe and Yogen Dalal at Xerox PARC; Danny Cohen , who needed it for his packet voice work; and Jonathan Postel of
17018-426: Was inducted into the Internet Hall of Fame "pioneers" award by the Internet Society . Paul Baran (1926–2011) developed the field of redundant distributed networks while conducting research at RAND Corporation starting in 1960 when Baran began investigating the development of large-scale survivable communication networks. This led to a series of papers titled "On Distributed Communications" that in 1964 described
17152-508: Was inducted into the Internet Hall of Fame by the Internet Society. Vinton G. "Vint" Cerf (born 1943) is an American computer scientist. He is recognized as one of " the fathers of the Internet ", sharing this title with Bob Kahn . He earned his Ph.D. from UCLA in 1972. At UCLA he worked in Professor Leonard Kleinrock's networking group that connected the first two nodes of the ARPANET and contributed to
17286-805: Was key to bringing the Internet to home users. Trumpet Winsock allowed TCP/IP operations over a serial connection ( SLIP or PPP ). 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. Later, Microsoft would release their own TCP/IP add-on stack for Windows for Workgroups 3.11 and a native stack in Windows 95. These events helped cement TCP/IP's dominance over other protocols on Microsoft-based networks, which included IBM's Systems Network Architecture (SNA), and on other platforms such as Digital Equipment Corporation 's DECnet , Open Systems Interconnection (OSI), and Xerox Network Systems (XNS). Nonetheless, for
17420-576: Was never adopted. Furthermore, he participated in the initial design of TCP during 1973-74, was acknowledged in the specification of TCP version 2 in March 1977, and version 3 in January 1978, which says that many of the changes introduced in that version were first described by Tomlinson the previous year when he put forward a "Proposal for TCP 3". Tomlinson received the IEEE Internet Award in 2004, with David H. Crocker , for networked email. Steve Crocker (born 1944) has worked in
17554-588: Was presented to the CCITT in 1975 but was not adopted by the CCITT nor by the ARPANET. Separate international research, particularly the work of Rémi Després , contributed to the development of the X.25 standard, based on virtual circuits , which was adopted by the CCITT in 1976. Computer manufacturers developed proprietary protocols such as IBM's Systems Network Architecture (SNA), Digital Equipment Corporation's DECnet and Xerox Network Systems . TCP software
17688-469: Was redesigned as a modular protocol stack, referred to as TCP/IP. This was installed on SATNET in 1982 and on the ARPANET in January 1983. The development of a complete Internet protocol suite by 1989, as outlined in RFC 1122 and RFC 1123 , laid the foundation for the growth of TCP/IP as a comprehensive protocol suite as the core component of the emerging Internet . International work on
17822-684: Was updated by RFC 821 in August 1982. Addresses were extended to username @ host . domain by RFC 805 in February 1982. RFC 822, written by David H. Crocker , defined the format for messages. The Internet Society 's Postel Award is named in his honor, as is the Postel Center at the Information Sciences Institute. His obituary was written by Vint Cerf and published as RFC 2468 in remembrance of Postel and his work. In 2012, Postel
17956-460: Was written by Roger Scantlebury and Keith Bartlett for the NPL network . On the ARPANET , the starting point for host-to-host communication in 1969 was the 1822 protocol , written by Bob Kahn , which defined the transmission of messages to an IMP. The Network Control Program (NCP) for the ARPANET, developed by Steve Crocker and other graduate students including Jon Postel and Vint Cerf ,
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