Internet protocol suite

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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 the Department of Defense (DoD) model because the research and development were funded by the United States Department of Defense through DARPA.

Contents

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. [1] [2] An implementation of 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 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.

History

Internet history timeline

Early research and development:

Merging the networks and creating the Internet:

Commercialization, privatization, broader access leads to the modern Internet:

Examples of Internet services:

Early research

Diagram of the first internetworked connection SRI First Internetworked Connection diagram.jpg
Diagram of the first internetworked connection
An SRI International Packet Radio Van, used for the first three-way internetworked transmission SRI Packet Radio Van.jpg
An SRI International Packet Radio Van, used for the first three-way internetworked transmission

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. [3] After DARPA initiated the pioneering ARPANET in 1969, Steve Crocker established a "Networking Working Group" which developed a host-host protocol, the Network Control Program (NCP). [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 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 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. [5] [6] They drew on the experience from the ARPANET research community, the International Network Working Group, which Cerf chaired, and researchers at Xerox PARC. [7] [8] [9]

By the summer of 1973, Kahn and Cerf had worked out 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. [10] [11] The new protocol was implemented as the Transmission Control Program in 1974 by Cerf, Yogen Dalal and Carl Sunshine. [12]

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. [13] Several versions were developed through the Internet Experiment Note series. [14] 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; [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. [17] Postel stated, "We are screwing up in our design of Internet protocols by violating the principle of layering." [18] Encapsulation of different mechanisms was intended to create an environment where 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. [19] [20] [21] [nb 1]

The design of 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, [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. 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."[ citation needed ] Years later, as a joke in 1999, the IP over Avian Carriers formal protocol specification was created [25] and successfully tested two years later. 10 years later still, it was adapted for IPv6. [26]

DARPA contracted with BBN Technologies, Stanford University, and the University College London to develop operational versions of the protocol on several hardware platforms. [27] 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 the protocol that is still in use in the Internet, alongside its current successor, Internet Protocol version 6 (IPv6).

Early implementation

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. [14]

A computer called a router is provided with an interface to each network. It forwards network packets back and forth between them. [28] Originally a router was called gateway, but the term was changed to avoid confusion with other types of gateways. [29]

Adoption

In March 1982, the US Department of Defense declared TCP/IP as the standard for all military computer networking. [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. [30] [34]

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, 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. [35] [36]

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 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. [37] The first VM/CMS TCP/IP stack came from the University of Wisconsin. [38]

Some of the early TCP/IP stacks were written single-handedly by a few programmers. Jay Elinsky and Oleg Vishnepolsky of IBM Research wrote TCP/IP stacks for VM/CMS and OS/2, respectively.[ citation needed ] 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. [39] [40] Starting in 1985, Phil Karn created a multi-connection TCP application for ham radio systems (KA9Q TCP). [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. 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 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 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. [42] [43] [44]

Formal specification and standards

The technical standards underlying the Internet protocol suite and its constituent protocols have been delegated to the Internet Engineering Task Force (IETF). [45] [46]

The characteristic architecture of 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. [1] [2] These have stood the test of time, as 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. [44]

Key architectural principles

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, 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. IP stack connections.drawio.png
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, 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 UDP encapsulation.svg
Encapsulation of application data descending through the layers described in RFC 1122

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 the like have forced changes in this principle. [47]

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)." [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." [1] : 13 

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 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. [49] 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 a four-layer model, with the layers having names, not numbers, as follows: [1] [2]

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 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 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 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.

Internet layer

Internetworking requires sending data from 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 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 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, 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.

Transport layer

The transport layer establishes basic data channels that applications use for task-specific data exchange. The layer establishes host-to-host connectivity in 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 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 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 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 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 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 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.

Application layer

The application layer includes the protocols used by most applications for providing user services or exchanging application data over 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). [54] 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 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 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 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. [1] : §1.1.3  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 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 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).[ citation needed ] It is also sometimes necessary for Applications affected by NAT to consider the application payload.

Layering evolution and representations in the literature

The Internet protocol suite evolved through research and development funded over 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.

Arpanet Reference Model
(RFC 871)		Internet Standard
(RFC 1122)		Internet model
(Cisco Academy [55] )		TCP/IP 5-layer reference model
(Kozierok, [56] Comer [57] )		TCP/IP 5-layer reference model
(Tanenbaum [58] )		TCP/IP protocol suite or Five-layer Internet model
(Forouzan, [59] Kurose [60] )		TCP/IP model
(Stallings [61] )		OSI model
(ISO/IEC 7498-1:1994 [62] )
Three layersFour layersFour layersFour+one layersFive layersFive layersFive layersSeven layers
Application/ ProcessApplicationApplicationApplicationApplicationApplicationApplicationApplication
Presentation
Session
Host-to-hostTransportTransportTransportTransportTransportHost-to-host or transportTransport
InternetInternetworkInternetInternetNetworkInternetNetwork
Network interfaceLinkNetwork interfaceData link (Network interface)Data linkData linkNetwork accessData link
———(Hardware)PhysicalPhysicalPhysicalPhysical

Some of the networking models are from textbooks, which are secondary sources that may conflict with the intent of RFC 1122 and other IETF primary sources. [63]

Comparison of TCP/IP and OSI layering

The three top layers in the OSI model, i.e. the application layer, the presentation layer and the session layer, are not distinguished separately in the TCP/IP model which only has an application layer above the transport layer. While some pure OSI protocol applications, such as X.400, also combined them, there is no requirement that a TCP/IP protocol stack must impose monolithic architecture above the transport layer. For example, the NFS application protocol runs over the External Data Representation (XDR) presentation protocol, which, in turn, runs over a protocol called Remote Procedure Call (RPC). RPC provides reliable record transmission, so it can safely use the best-effort UDP transport.

Different authors have interpreted the TCP/IP model differently, and disagree whether the link layer, or any aspect of the TCP/IP model, covers OSI layer 1 (physical layer) issues, or whether TCP/IP assumes a hardware layer exists below the link layer. Several authors have attempted to incorporate the OSI model's layers 1 and 2 into the TCP/IP model since these are commonly referred to in modern standards (for example, by IEEE and ITU). This often results in a model with five layers, where the link layer or network access layer is split into the OSI model's layers 1 and 2.[ citation needed ]

The IETF protocol development effort is not concerned with strict layering. Some of its protocols may not fit cleanly into the OSI model, although RFCs sometimes refer to it and often use the old OSI layer numbers. The IETF has repeatedly stated [45] [ failed verification ] that Internet Protocol and architecture development is not intended to be OSI-compliant. RFC 3439, referring to the internet architecture, contains a section entitled: "Layering Considered Harmful". [63]

For example, the session and presentation layers of the OSI suite are considered to be included in the application layer of the TCP/IP suite. The functionality of the session layer can be found in protocols like HTTP and SMTP and is more evident in protocols like Telnet and the Session Initiation Protocol (SIP). 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. Functions of the presentation layer are realized in the TCP/IP applications with the MIME standard in data exchange.

Another difference is in the treatment of routing protocols. 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. In contrast, OSPF, RIP, BGP and other routing protocols defined by the IETF are transported over IP, and, for the purpose of sending and receiving routing protocol packets, routers act as hosts. As a consequence, routing protocols are included in the application layer. [28] Some authors, such as Tanenbaum in Computer Networks, describe routing protocols in the same layer as IP, reasoning that routing protocols inform decisions made by the forwarding process of routers.

IETF protocols can be encapsulated recursively, as demonstrated by tunnelling protocols such as Generic Routing Encapsulation (GRE). GRE uses the same mechanism that OSI uses for tunnelling at the network layer.

Implementations

The Internet protocol suite does not presume any specific hardware or software environment. It only requires that hardware and a software layer exists that is capable of sending and receiving packets on a computer network. As a result, the suite has been implemented on essentially every computing platform. A minimal implementation of TCP/IP includes the following: Internet Protocol (IP), Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Internet Group Management Protocol (IGMP). 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.

See also

Notes

  1. ↑ For records of discussions leading up to the TCP/IP split, see the series of Internet Experiment Notes at the Internet Experiment Notes Index.

Related Research Articles

In computer network engineering, an Internet Standard is a normative specification of a technology or methodology applicable to the Internet. Internet Standards are created and published by the Internet Engineering Task Force (IETF). They allow interoperation of hardware and software from different sources which allows internets to function. As the Internet became global, Internet Standards became the lingua franca of worldwide communications.

Internetworking is the practice of interconnecting multiple computer networks, such that any pair of hosts in the connected networks can exchange messages irrespective of their hardware-level networking technology. The resulting system of interconnected networks is called an internetwork, or simply an internet.

The Internet Control Message Protocol (ICMP) is a supporting protocol in the Internet protocol suite. It is used by network devices, including routers, to send error messages and operational information indicating success or failure when communicating with another IP address. For example, an error is indicated when a requested service is not available or that a host or router could not be reached. ICMP differs from transport protocols such as TCP and UDP in that it is not typically used to exchange data between systems, nor is it regularly employed by end-user network applications.

<span class="mw-page-title-main">IPv4</span> Fourth version of the Internet Protocol

Internet Protocol version 4 (IPv4) is the first version of the Internet Protocol (IP) as a standalone specification. It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. IPv4 was the first version deployed for production on SATNET in 1982 and on the ARPANET in January 1983. It is still used to route most Internet traffic today, even with the ongoing deployment of Internet Protocol version 6 (IPv6), its successor.

The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet.

<span class="mw-page-title-main">OSI model</span> Model of communication of seven abstraction layers

The Open Systems Interconnection (OSI) model is a reference model from the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems interconnection." In the OSI reference model, the communications between systems are split into seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonly referred to as TCP/IP. TCP provides reliable, ordered, and error-checked delivery of a stream of octets (bytes) between applications running on hosts communicating via an IP network. Major internet applications such as the World Wide Web, email, remote administration, and file transfer rely on TCP, which is part of the Transport layer of the TCP/IP suite. SSL/TLS often runs on top of TCP.

In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages to other hosts on an Internet Protocol (IP) network. Within an IP network, UDP does not require prior communication to set up communication channels or data paths.

A datagram is a basic transfer unit associated with a packet-switched network. Datagrams are typically structured in header and payload sections. Datagrams provide a connectionless communication service across a packet-switched network. The delivery, arrival time, and order of arrival of datagrams need not be guaranteed by the network.

In the seven-layer OSI model of computer networking, the network layer is layer 3. The network layer is responsible for packet forwarding including routing through intermediate routers.

<span class="mw-page-title-main">Transport layer</span> Layer in the OSI and TCP/IP models providing host-to-host communication services for applications

In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet protocol suite and the OSI model. The protocols of this layer provide end-to-end communication services for applications. It provides services such as connection-oriented communication, reliability, flow control, and multiplexing.

The Network Control Protocol (NCP) was a communication protocol for a computer network in the 1970s and early 1980s. It provided the transport layer of the protocol stack running on host computers of the ARPANET, the predecessor to the modern Internet.

A network socket is a software structure within a network node of a computer network that serves as an endpoint for sending and receiving data across the network. The structure and properties of a socket are defined by an application programming interface (API) for the networking architecture. Sockets are created only during the lifetime of a process of an application running in the node.

In computer networking, a port or port number is a number assigned to uniquely identify a connection endpoint and to direct data to a specific service. At the software level, within an operating system, a port is a logical construct that identifies a specific process or a type of network service. A port at the software level is identified for each transport protocol and address combination by the port number assigned to it. The most common transport protocols that use port numbers are the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP); those port numbers are 16-bit unsigned numbers.

The internet layer is a group of internetworking methods, protocols, and specifications in the Internet protocol suite that are used to transport network packets from the originating host across network boundaries; if necessary, to the destination host specified by an IP address. The internet layer derives its name from its function facilitating internetworking, which is the concept of connecting multiple networks with each other through gateways.

An IPv6 packet is the smallest message entity exchanged using Internet Protocol version 6 (IPv6). Packets consist of control information for addressing and routing and a payload of user data. The control information in IPv6 packets is subdivided into a mandatory fixed header and optional extension headers. The payload of an IPv6 packet is typically a datagram or segment of the higher-level transport layer protocol, but may be data for an internet layer or link layer instead.

A communication protocol 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.

In computer networking, the link layer is the lowest layer in the Internet protocol suite, the networking architecture of the Internet. The link layer is the group of methods and communications protocols confined to the link that a host is physically connected to. The link is the physical and logical network component used to interconnect hosts or nodes in the network and a link protocol is a suite of methods and standards that operate only between adjacent network nodes of a network segment.

The Stream Control Transmission Protocol (SCTP) is a computer networking communications protocol in the transport layer of the Internet protocol suite. Originally intended for Signaling System 7 (SS7) message transport in telecommunication, the protocol provides the message-oriented feature of the User Datagram Protocol (UDP), while ensuring reliable, in-sequence transport of messages with congestion control like the Transmission Control Protocol (TCP). Unlike UDP and TCP, the protocol supports multihoming and redundant paths to increase resilience and reliability.

The Protocol Wars were a long-running debate in computer science that occurred from the 1970s to the 1990s, when engineers, organizations and nations became polarized over the issue of which communication protocol would result in the best and most robust networks. This culminated in the Internet–OSI Standards War in the 1980s and early 1990s, which was ultimately "won" by the Internet protocol suite (TCP/IP) by the mid-1990s when it became the dominant protocol suite through rapid adoption of the Internet.

References

  1. 1 2 3 4 5 R. Braden, ed. (October 1989). Requirements for Internet Hosts -- Communication Layers. Network Working Group. doi: 10.17487/RFC1122 . STD 3. RFC 1122.Internet Standard 3. Updated by RFC  1349, 4379, 5884, 6093, 6298, 6633, 6864, 8029 and 9293.
  2. 1 2 3 R. Braden, ed. (October 1989). Requirements for Internet Hosts -- Application and Support. Network Working Group. doi: 10.17487/RFC1123 . STD 3. RFC 1123.Internet Standard 3. Updated by RFC  1349, 2181, 5321, 5966 and 7766.
  3. ↑ Cerf, Vinton G. & Cain, Edward (October 1983). "The DoD Internet Architecture Model". Computer Networks. 7 (5). North-Holland: 307–318. doi:10.1016/0376-5075(83)90042-9.
  4. ↑ J. Reynolds; J. Postel (November 1987). THE REQUEST FOR COMMENTS REFERENCE GUIDE. Network Working Group. doi: 10.17487/RFC1000 . RFC 1000.Status Unknown. Obsoletes RFC  84, 100, 160, 170, 200, 598, 699, 800, 899 and 999.
  5. ↑ Hafner, Katie; Lyon, Matthew (1996). Where wizards stay up late : the origins of the Internet. Internet Archive. New York : Simon & Schuster. p. 263. ISBN   978-0-684-81201-4.
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  7. ↑ Abbate, Janet (2000). Inventing the Internet. MIT Press. pp. 123–4. ISBN   978-0-262-51115-5. Archived from the original on January 17, 2023. Retrieved May 15, 2020.
  8. ↑ Taylor, Bob (October 11, 2008), "Oral History of Robert (Bob) W. Taylor" (PDF), Computer History Museum Archive, CHM Reference number: X5059.2009: 28
  9. ↑ Isaacson, Walter (2014). The innovators : how a group of hackers, geniuses, and geeks created the digital revolution. Internet Archive. New York : Simon & Schuster. ISBN   978-1-4767-0869-0.
  10. ↑ Cerf, V.; Kahn, R. (1974). "A Protocol for Packet Network Intercommunication" (PDF). IEEE Transactions on Communications. 22 (5): 637–648. doi:10.1109/TCOM.1974.1092259. ISSN   1558-0857. Archived (PDF) from the original on October 10, 2022. Retrieved October 18, 2015. The authors wish to thank a number of colleagues for helpful comments during early discussions of international network protocols, especially R. Metcalfe, R. Scantlebury, D. Walden, and H. Zimmerman; D. Davies and L. Pouzin who constructively commented on the fragmentation and accounting issues; and S. Crocker who commented on the creation and destruction of associations.
  11. ↑ "The internet's fifth man". Economist. December 13, 2013. Archived from the original on April 19, 2020. Retrieved September 11, 2017. In the early 1970s Mr Pouzin created an innovative data network that linked locations in France, Italy and Britain. Its simplicity and efficiency pointed the way to a network that could connect not just dozens of machines, but millions of them. It captured the imagination of Dr Cerf and Dr Kahn, who included aspects of its design in the protocols that now power the internet.
  12. ↑ V. Cerf; Y. Dalal; C. Sunshine (December 1974). SPECIFICATION OF INTERNET TRANSMISSION CONTROL PROGRAM. Network Working Group. doi: 10.17487/RFC0675 . RFC 675.Obsolete. Obsoleted by RFC  7805. NIC 2. INWG 72.
  13. ↑ Cerf, Vinton (March 1977). "Specification of Internet Transmission Control Protocol TCP (Version 2)" (PDF). Archived (PDF) from the original on May 25, 2022. Retrieved August 4, 2022.
  14. 1 2 Cerf, Vinton G. (April 1, 1980). "Final Report of the Stanford University TCP Project".
  15. ↑ Panzaris, Georgios (2008). Machines and romances: the technical and narrative construction of networked computing as a general-purpose platform, 1960–1995. Stanford University. p. 128. Archived from the original on January 17, 2023. Retrieved September 5, 2019.
  16. ↑ Pelkey, James L. (2007). "Yogen Dalal". Entrepreneurial Capitalism and Innovation: A History of Computer Communications, 1968–1988. Archived from the original on October 8, 2022. Retrieved October 8, 2020.
  17. ↑ Internet Hall of Fame
  18. ↑ Postel, Jon (August 15, 1977), 2.3.3.2 Comments on Internet Protocol and TCP, IEN 2, archived from the original on May 16, 2019, retrieved June 11, 2016
  19. ↑ Abbate, Inventing the Internet, 129–30.
  20. ↑ Vinton G. Cerf (October 1980). "Protocols for Interconnected Packet Networks". ACM SIGCOMM Computer Communication Review. 10 (4): 10–11.
  21. ↑ Russell, Andrew L. (2007). "Industrial Legislatures": Consensus Standardization in the Second and Third Industrial Revolutions (PDF) (PhD thesis). Johns Hopkins University. Archived (PDF) from the original on December 28, 2022. Retrieved December 28, 2022.
  22. ↑ Bennett, Richard (September 2009). "Designed for Change: End-to-End Arguments, Internet Innovation, and the Net Neutrality Debate" (PDF). Information Technology and Innovation Foundation. pp. 7, 11. Retrieved September 11, 2017.
  23. ↑ Pelkey, James. "8.3 CYCLADES Network and Louis Pouzin 1971-1972". Entrepreneurial Capitalism and Innovation: A History of Computer Communications 1968-1988. Archived from the original on June 17, 2021. Retrieved November 21, 2021. The inspiration for datagrams had two sources. One was Donald Davies' studies. He had done some simulation of datagram networks, although he had not built any, and it looked technically viable. The second inspiration was I like things simple. I didn't see any real technical motivation to overlay two levels of end-to-end protocols. I thought one was enough.
  24. ↑ Davies, Donald; Bartlett, Keith; Scantlebury, Roger; Wilkinson, Peter (October 1967). A Digital Communication Network for Computers Giving Rapid Response at remote Terminals (PDF). ACM Symposium on Operating Systems Principles. Archived (PDF) from the original on October 10, 2022. Retrieved September 15, 2020. all users of the network will provide themselves with some kind of error control
  25. ↑ D. Waitzman (April 1, 1990). A Standard for the Transmission of IP Datagrams on Avian Carriers. Network Working Group. doi: 10.17487/RFC1149 . RFC 1149.Experimental. This is an April Fools' Day Request for Comments.
  26. ↑ B. Carpenter; R. Hinden (April 1, 2011). Adaptation of RFC 1149 for IPv6. Internet Engineering Task Force. doi: 10.17487/RFC6214 . ISSN   2070-1721. RFC 6214.Informational. This is an April Fools' Day Request for Comments.
  27. ↑ by Vinton Cerf, as told to Bernard Aboba (1993). "How the Internet Came to Be". Archived from the original on September 26, 2017. Retrieved September 25, 2017. We began doing concurrent implementations at Stanford, BBN, and University College London. So effort at developing the Internet protocols was international from the beginning.
  28. 1 2 F. Baker, ed. (June 1995). Requirements for IP Version 4 Routers. Network Working Group. doi: 10.17487/RFC1812 . RFC 1812.Proposed Standard. Obsoletes RFC  1716 and 1009. Updated by RFC  2644 and 6633.
  29. ↑ Crowell, William; Contos, Brian; DeRodeff, Colby (2011). Physical and Logical Security Convergence: Powered By Enterprise Security Management. Syngress. p. 99. ISBN   9780080558783.
  30. 1 2 Ronda Hauben. "From the ARPANET to the Internet". TCP Digest (UUCP). Archived from the original on July 21, 2009. Retrieved July 5, 2007.
  31. ↑ IEN 207.
  32. ↑ IEN 152.
  33. ↑ Hauben, Ronda (2004). "The Internet: On its International Origins and Collaborative Vision". Amateur Computerist. 12 (2). Retrieved May 29, 2009. Mar '82 – Norway leaves the ARPANET and become an Internet connection via TCP/IP over SATNET. Nov '82 – UCL leaves the ARPANET and becomes an Internet connection.
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  39. ↑ Baker, Steven; Gillies, Donald W. "Desktop TCP/IP at middle age". Archived from the original on August 21, 2015. Retrieved September 9, 2016.
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  41. ↑ Phil Karn, KA9Q TCP Download Website
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  44. 1 2 Davies, Howard; Bressan, Beatrice (April 26, 2010). A History of International Research Networking: The People who Made it Happen. John Wiley & Sons. ISBN   978-3-527-32710-2. Archived from the original on January 17, 2023. Retrieved November 7, 2020.
  45. 1 2 "Introduction to the IETF". IETF. Retrieved February 27, 2024.
  46. ↑ Morabito, Roberto; Jimenez, Jaime (June 2020). "IETF Protocol Suite for the Internet of Things: Overview and Recent Advancements". IEEE Communications Standards Magazine. 4 (2): 41–49. arXiv: 2003.10279 . doi:10.1109/mcomstd.001.1900014. ISSN   2471-2825.
  47. ↑ Blumenthal, Marjory S.; Clark, David D. (August 2001). "Rethinking the design of the Internet: The end-to-end arguments vs. the brave new world" (PDF). Archived (PDF) from the original on October 8, 2022. Retrieved October 8, 2022.
  48. ↑ J. Postel, ed. (September 1981). INTERNET PROTOCOL - DARPA INTERNET PROGRAM PROTOCOL SPECIFICATION. IETF. doi: 10.17487/RFC0791 . STD 5. RFC 791.IEN 128, 123, 111, 80, 54, 44, 41, 28, 26.Internet Standard 5. Obsoletes RFC  760. Updated by RFC  1349, 2474 and 6864.
  49. ↑ B. Carpenter, ed. (June 1996). Architectural Principles of the Internet. Network Working Group. doi: 10.17487/RFC1958 . RFC 1958.Informational. Updated by RFC  3439.
  50. ↑ Hunt, Craig (2002). TCP/IP Network Administration (3rd ed.). O'Reilly. pp. 9–10. ISBN   9781449390785.
  51. ↑ Guttman, E. (1999). "Service location protocol: automatic discovery of IP network services". IEEE Internet Computing. 3 (4): 71–80. doi:10.1109/4236.780963. ISSN   1089-7801.
  52. 1 2 Zheng, Kai (July 2017). "Enabling "Protocol Routing": Revisiting Transport Layer Protocol Design in Internet Communications". IEEE Internet Computing. 21 (6): 52–57. doi:10.1109/mic.2017.4180845. ISSN   1089-7801.
  53. ↑ Huang, Jing-lian (April 7, 2009). "Cross layer link adaptation scheme in wireless local area network". Journal of Computer Applications. 29 (2): 518–520. doi:10.3724/sp.j.1087.2009.00518 (inactive November 1, 2024). ISSN   1001-9081.{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)
  54. ↑ Stevens, W. Richard (February 1994). TCP/IP Illustrated: the protocols. Addison-Wesley. ISBN   0-201-63346-9. Archived from the original on April 22, 2012. Retrieved April 25, 2012.
  55. ↑ Dye, Mark; McDonald, Rick; Rufi, Antoon (October 29, 2007). Network Fundamentals, CCNA Exploration Companion Guide. Cisco Press. ISBN   9780132877435 . Retrieved September 12, 2016– via Google Books.
  56. ↑ Kozierok, Charles M. (January 1, 2005). The TCP/IP Guide: A Comprehensive, Illustrated Internet Protocols Reference. No Starch Press. ISBN   9781593270476 . Retrieved September 12, 2016– via Google Books.
  57. ↑ Comer, Douglas (January 1, 2006). Internetworking with TCP/IP: Principles, protocols, and architecture. Prentice Hall. ISBN   0-13-187671-6 . Retrieved September 12, 2016– via Google Books.
  58. ↑ Tanenbaum, Andrew S. (January 1, 2003). Computer Networks . Prentice Hall PTR. p.  42. ISBN   0-13-066102-3 . Retrieved September 12, 2016– via Internet Archive. networks.
  59. ↑ Forouzan, Behrouz A.; Fegan, Sophia Chung (August 1, 2003). Data Communications and Networking. McGraw-Hill Higher Education. ISBN   9780072923544 . Retrieved September 12, 2016– via Google Books.
  60. ↑ Kurose, James F.; Ross, Keith W. (2008). Computer Networking: A Top-Down Approach. Pearson/Addison Wesley. ISBN   978-0-321-49770-3. Archived from the original on January 23, 2016. Retrieved July 16, 2008.
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  62. ↑ ISO/IEC 7498-1:1994 Information technology — Open Systems Interconnection — Basic Reference Model: The Basic Model.
  63. 1 2 R. Bush; D. Meyer (December 2002). Some Internet Architectural Guidelines and Philosophy. Network Working Group. doi: 10.17487/RFC3439 . RFC 3439.Informational. Updates RFC  1958.

Bibliography

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