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Encyclopedia > OSI model
OSI Model
7 Application layer
6 Presentation layer
5 Session layer
4 Transport layer
3 Network layer
2 Data link layer
1 Physical layer


The Open Systems Interconnection Basic Reference Model (OSI Reference Model or OSI Model for short) is a layered, abstract description for communications and computer network protocol design. It was developed as part of the Open Systems Interconnection (OSI) initiative and is sometimes known as the OSI seven layer model. From top to bottom, the OSI Model consists of the Application, Presentation, Session, Transport, Network, Data Link, and Physical layers. A layer is a collection of related functions that provides services to the layer above it and receives service from the layer below it. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of the path. Image File history File links Question_book-3. ... The application layer is the seventh level of the seven-layer OSI model. ... The presentation layer is the sixth level of the seven layer OSI model. ... The session layer is level five of the seven level OSI model. ... In computing and telecommunications, the transport layer is the second highest layer in the four and five layer TCP/IP reference models, where it responds to service requests from the application layer and issues service requests to the Internet layer. ... The network layer is third layer out of seven in OSI model and it is the third layer out of five in TCP/IP model. ... This article does not cite any references or sources. ... According to the IEEE 802 family of standards, Logical Link Control (LLC) is the upper sublayer of the OSI data link layer. ... The Media Access Control (MAC) data communication protocol sub-layer, also known as the Medium Access Control, is a part of the data link layer specified in the seven-layer OSI model (layer 2). ... This article does not cite any references or sources. ... In networking, a communications protocol or network protocol is the specification of a set of rules for a particular type of communication. ... This article or section does not adequately cite its references or sources. ...


Even though newer IETF, IEEE, and indeed OSI protocol work subsequent to the publication of the original architectural standards that have largely superseded it, the OSI model is an excellent place to begin the study of network architecture. Not understanding that the pure seven-layer model is more historic than current, many beginners make the mistake of trying to fit every protocol they study into one of the seven basic layers. This is not always easy to do as many of the protocols in use on the Internet today were designed as part of the TCP/IP model, and may not fit cleanly into the OSI model. The Internet Engineering Task Force (IETF) is charged with developing and promoting Internet standards. ... The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-ee) is an international non-profit, professional organization incorporated in the State of New York, United States. ... The TCP/IP model or Internet reference model, sometimes called the DoD model (DoD, Department of Defense) ARPANET reference model, is a layered abstract description for communications and computer network protocol design. ...

Contents

History

In 1977, work on a layered model of network architecture, which was to become the OSI model, started in the American National Standards Institute (ANSI) working group on Distributed Systems (DISY).[1] With the DISY work and worldwide input, the International Organization for Standardization (ISO) began to develop its OSI networking suite. The International Organization for Standardization(ISO) is a worldwide federation of national standards bodies from some 130 countries, one from each country.[2] According to Bachman, the term "OSI" came into use on 12 October 1979.[1] OSI has two major components: an abstract model of networking (the Basic Reference Model, or seven-layer model) and a set of concrete protocols. The standard documents that describe OSI can be downloaded from ISO or ITU-T.[citation needed] The American National Standards Institute or ANSI (pronounced an-see) is a nonprofit organization that oversees the development of standards for products, services, processes and systems in the United States. ... “ISO” redirects here. ...


Parts of OSI have influenced Internet protocol development, but none more than the concrete operational system model itself, documented in ISO 7498 and its various agenda. In this model, a networking system is divided into layers. Within each layer, one or more entities implement its functionality. Each entity interacts directly only with the layer immediately beneath it, and provides facilities for use by the layer above it.


In particular, Internet protocols are deliberately not as rigorously designed as the OSI model, but a common version of the TCP/IP model splits it into four layers. The Internet Application Layer includes the OSI Application Layer, Presentation Layer, and most of the Session Layer. Its End-to-End Layer includes the graceful close function of the OSI Session Layer as well as the Transport Layer. Its Internetwork Layer is equivalent to the OSI Network Layer, while its Interface layer includes the OSI Data Link and Physical Layers. These comparisons are based on the original seven-layer protocol model as defined in ISO 7498, rather than refinements in such things as the Internal Organization of the Network Layer document. The TCP/IP model or Internet reference model, sometimes called the DoD model (DoD, Department of Defense) ARPANET reference model, is a layered abstract description for communications and computer network protocol design. ...


Protocols enable an entity in one host to interact with a corresponding entity at the same layer in a remote host. Service definitions abstractly describe the functionality provided to an (N)-layer by an (N-1) layer, where N is one of the seven layers inside the local host.


Description of OSI layers

Remembering The OSI Layers


Various mnemonics have been created over the years to help remember the order, such as: For other uses, see Mnemonic (disambiguation). ...

  • All People Should Try New Diet Pepsi
  • Angry Protestors Strive To Numb Dirty Politics
  • All People Seem To Need Data Processing
  • Please Do Not Tease Stupid Party Animals
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  • People Do Need To See Pamela Anderson
  • Please Do Not Touch Sam‘s Pet Alligator
  • Please Do Not Take Sales-People's Advice
OSI Model
Data unit Layer Function
Host
layers
Data 7. Application Network process to application
6. Presentation Data representation and encryption
5. Session Interhost communication
Segment/Datagram 4. Transport End-to-end connections and reliability (TCP)
Media
layers
Packet 3. Network Path determination and logical addressing (IP)
Frame 2. Data link Physical addressing (MAC & LLC)
Bit 1. Physical Media, signal and binary transmission

The application layer is the seventh level of the seven-layer OSI model. ... The presentation layer is the sixth level of the seven layer OSI model. ... The session layer is level five of the seven level OSI model. ... The network layer is third layer out of seven in OSI model and it is the third layer out of five in TCP/IP model. ... [[Image:Link title]] // [[Image:Media:Example. ... This article does not cite any references or sources. ... This article does not cite any references or sources. ...

Layer 7: Application layer

Main article: Application layer

This application layer interface directly performs application services for the application processes; it also issues requests to the presentation layer. Note carefully that this layer provides services to user-defined application processes, and not to the end user. For example, it defines a file transfer protocol, but the end user must go through an application process to invoke file transfer. The OSI model does not include human interfaces. The common application services sublayer provides functional elements including the Remote Operations Service Element (comparable to Internet Remote Procedure Call), Association Control, and Transaction Processing (according to the ACID requirements). The application layer is the seventh level of the seven-layer OSI model. ... The application layer is the seventh level of the seven-layer OSI model. ... For other uses, see acid (disambiguation). ...


Above the common application service sublayer are functions meaningful to user application programs, such as messaging (X.400), directory (X.500), file transfer (FTAM), virtual terminal (VTAM), and batch job manipulation (JTAM). These contrast with user applications that use the services of the application layer, but are not part of the application layer itself.

  1. File Transfer applications using FTAM (OSI protocol) or FTP (TCP/IP Protocol)
  2. Mail Transfer clients using X.400 (OSI protocol) or SMTP/POP3/IMAP (TCP/IP protocols)
  3. Web browsers using HTTP (TCP/IP protocol); no true OSI protocol for web applications

FTAM, an ISO 8571 standard, is an OSI Application layer protocol for File Transfer Access and Management. ... The abbreviation FTP can refer to: The File Transfer Protocol used on the Internet. ... X.400 is a suite of ITU-T Recommendations that define standards for Data Communication Networks for Message Handling Systems (MHS) — more commonly known as E-mail. While X.400 never achieved the universal presence of Internet e-mail, it has seen use within organizations, and as part of proprietary... Simple Mail Transfer Protocol (SMTP) is the de facto standard for email transmission across the Internet. ... Post Office Protocol version 3 (POP3) is an application layer Internet standard protocol used to retrieve email from a remote server to a local client over a TCP/IP connection. ... The Internet Message Access Protocol (commonly known as IMAP, and previously called Interactive Mail Access Protocol) is an application layer Internet protocol used for accessing email on a remote server from a local client. ... HTTP (for HyperText Transfer Protocol) is the primary method used to convey information on the World Wide Web. ...

Layer 6: Presentation layer

Main article: Presentation layer

The presentation layer establishes a context between application layer entities, in which the higher-layer entities can use different syntax and semantics, as long as the Presentation Service understands both and the mapping between them. The presentation service data units are then encapsulated into Session Protocol Data Units, and moved down the stack. The presentation layer is the sixth level of the seven layer OSI model. ... The presentation layer is the sixth level of the seven layer OSI model. ...


The original presentation structure used the Basic Encoding Rules of Abstract Syntax Notation One (ASN.1), with capabilities such as converting an EBCDIC-coded text file to an ASCII-coded file, or serializing objects and other data structures into and out of XML. ASN.1 has a set of cryptographic encoding rules that allows end-to-end encryption between application entities. In telecommunications and computer networking, Abstract Syntax Notation One (ASN.1) is a standard and flexible notation that describes data structures for representing, encoding, transmitting, and decoding data. ... EBCDIC (Extended Binary Coded Decimal Interchange Code) is an 8-bit character encoding (code page) used on IBM mainframe operating systems, like z/OS, OS/390, VM and VSE, as well as IBM minicomputer operating systems like OS/400 and i5/OS. It is also employed on various non-IBM... This article is about computer files and file systems in general terms. ... Image:ASCII fullsvg There are 95 printable ASCII characters, numbered 32 to 126. ... This article is about data structure encoding. ... In strictly mathematical branches of computer science the term object is used in a purely mathematical sense to refer to any thing. While this interpretation is useful in the discussion of abstract theory, it is not concrete enough to serve as a primitive datatype in the discussion of more concrete... A binary tree, a simple type of branching linked data structure. ... The Extensible Markup Language (XML) is a general-purpose markup language. ...


Layer 5: Session layer

Main article: Session layer

The session layer controls the dialogues/connections (sessions) between computers. It establishes, manages and terminates the connections between the local and remote application. It provides for full-duplex, half-duplex, or simplex operation, and establishes checkpointing, adjournment, termination, and restart procedures. The OSI model made this layer responsible for "graceful close" of sessions, which is a property of TCP, and also for session checkpointing and recovery, which is not usually used in the Internet protocols suite. Session layers are commonly used in application environments that make use of remote procedure calls (RPCs). The session layer is level five of the seven level OSI model. ... The session layer is level five of the seven level OSI model. ... A duplex communication system is a system composed of two connected parties or devices which can communicate with one another in both directions. ... In telecommunications, duplex means two-way when referring to communications channels. ... A simplex communication system is one where all signals flow in one direction. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ...


iSCSI, which implements the Small Computer Systems Interface (SCSI) encapsulated into TCP/IP packets, is a session layer protocol increasingly used in Storage Area Networks and internally between processors and high-performance storage devices. iSCSI uses TCP for guaranteed delivery, and carries SCSI command descriptor blocks (CDB) as payload to create a virtual SCSI bus between iSCSI initiators and iSCSI targets. In computing, iSCSI (for Internet SCSI) is a protocol that allows clients (called initiators) to send SCSI commands (CDBs) to SCSI storage devices (targets) on remote servers. ... Scuzzy redirects here. ... In computing, a storage area network (SAN) is a network designed to attach computer storage devices such as disk array controllers and tape libraries to servers. ...


Layer 4: Transport layer

Main article: Transport layer

The transport layer provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers. The transport layer controls the reliability of a given link through flow control, segmentation/desegmentation, and error control. Some protocols are state and connection oriented. This means that the transport layer can keep track of the segments and retransmit those that fail. In computing and telecommunications, the transport layer is the second highest layer in the four and five layer TCP/IP reference models, where it responds to service requests from the application layer and issues service requests to the Internet layer. ... In computing and telecommunications, the transport layer is the second highest layer in the four and five layer TCP/IP reference models, where it responds to service requests from the application layer and issues service requests to the Internet layer. ... For other uses, see Data (disambiguation). ...


Although it was not developed under the OSI Reference Model and does not strictly conform to the OSI definition of the Transport layer, the best known examples of a layer 4 protocol are the Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ... User Datagram Protocol (UDP) is one of the core protocols of the Internet protocol suite. ...


Of the actual OSI protocols, there are five classes of transport protocols ranging from class 0 (which is also known as TP0 and provides the least error recovery) to class 4 (which is also known as TP4 and is designed for less reliable networks, similar to the Internet). Class0 is closest to UDP. Class 4 is closest to TCP, although TCP contains functions, such as the graceful close, which OSI assigns to the Session Layer. Detailed characteristics of TP0-4 classes are shown in the following table [3] [4]

Feature Name TP0 TP1 TP2 TP3 TP4
Connection oriented - - - Yes Yes
Connectionless - - - No Yes
Segmentation/Fragmentation Yes Yes Yes Yes Yes
Reassembly Yes Yes Yes Yes Yes
Error Recovery No Yes No No Yes
Reinitiate connection (if an excessive number of PDUs are unacknowledged) No Yes No Yes Yes
multiplexing and demultiplexing over a single virtual circuit No No Yes Yes Yes
Reliable Transport Service No Yes Yes Yes Yes

Perhaps an easy way to visualize the transport layer is to compare it with a Post Office, which deals with the dispatch and classification of mail and parcels sent. Do remember, however, that a post office manages the outer envelope of mail. Higher layers may have the equivalent of double envelopes, such as cryptographic presentation services that can be read by the addressee only. Roughly speaking, tunneling protocols operate at the transport layer, such as carrying non-IP protocols such as IBM's SNA or Novell's IPX over an IP network, or end-to-end encryption with IPsec. While Generic Routing Encapsulation (GRE) might seem to be a network layer protocol, if the encapsulation of the payload takes place only at endpoint, GRE becomes closer to a transport protocol that uses IP headers but contains complete frames or packets to deliver to an endpoint. L2TP carries PPP frames inside transport packet. In telecommunications and computer networks, a virtual circuit (VC), synonymous to virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication. ... For other uses, see IBM (disambiguation) and Big Blue. ... Systems Network Architecture (SNA) is IBMs proprietary networking architecture created in 1974. ... For the road bicycle racing team previously known as Novell, see Rabobank (cycling). ... Internetwork Packet Exchange (IPX) is at the Network layer of the OSI model and is part of the IPX/SPX protocol stack. ... IPsec (IP security) is a suite of protocols for securing Internet Protocol (IP) communications by authenticating and/or encrypting each IP packet in a data stream. ... Generic Routing Encapsulation (GRE) is a tunneling protocol designed to encapsulate a wide variety of network layer packets inside IP tunneling packets. ... In computer networking, the Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks (VPNs). ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ...


Layer 3: Network layer

Main article: Network layer

The network layer provides the functional and procedural means of transferring variable length data sequences from a source to a destination via one or more networks, while maintaining the quality of service requested by the Transport layer. The Network layer performs network routing functions, and might also perform fragmentation and reassembly, and report delivery errors. Routers operate at this layer—sending data throughout the extended network and making the Internet possible. This is a logical addressing scheme – values are chosen by the network engineer. The addressing scheme is hierarchical. The network layer is third layer out of seven in OSI model and it is the third layer out of five in TCP/IP model. ... The network layer is third layer out of seven in OSI model and it is the third layer out of five in TCP/IP model. ... For other uses, see Data (disambiguation). ... In the fields of packet-switched networks and computer networking, the traffic engineering term Quality of Service, abbreviated QoS, refers to resource reservation control mechanisms. ... This article is about routing in computer networks. ... This article is about a computer networking device. ...


The best-known example of a layer 3 protocol is the Internet Protocol (IP). It manages the connectionless transfer of data one hop at a time, from end system to ingress router, to router to router, and from egress router to destination end system. It is not responsible for reliable delivery to a next hop, but only for the detection of errored packets so they may be discarded. When the medium of the next hop cannot accept a packet in its current length, IP is responsible for fragmenting into sufficiently small packets that the medium can accept it. The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... In telecommunications, connectionless describes communication between two network end points in which a message can be sent from one end point to another without prior arrangement. ...


A number of layer management protocols, a function defined in the Management Annex, ISO 7498/4, belong to the network layer. These include routing protocols, multicast group management, network layer information and error, and network layer address assignment. It is the function of the payload that makes these belong to the network layer, not the protocol that carries them.


Layer 2: Data Link layer

Main article: Data link layer

The data link layer provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the physical layer. Originally, this layer was intended for point-to-point and point-to-multipoint media, characteristic of wide area media in the telephone system. Local area network architecture, which included broadcast-capable multiaccess media, was developed independently of the ISO work, in IEEE Project 802. IEEE work assumed sublayering and management functions not required for WAN use. In modern practice, only error detection, not flow control using sliding window, is present in modern data link protocols such as Point-to-Point Protocol (PPP), and, on local area networks, the IEEE 802.2 LLC layer is not used for most protocols on Ethernet, and, on other local area networks, its flow control and acknowledgment mechanisms are rarely used. Sliding window flow control and acknowledgment is used at the transport layers by protocols such as TCP, but is still used in niches where X.25 offers performance advantages. This article does not cite any references or sources. ... This article does not cite any references or sources. ... IEEE 802 refers to a family of IEEE standards about local area networks and metropolitan area networks. ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ... X.25 is an ITU-T standard protocol suite for wide area networks using leased lines, the phone or ISDN system as the networking hardware. ...


Both WAN and LAN services arrange bits, from the physical layer, into logical sequences called frames. Not all physical layer bits necessarily go into frames, as some of these bits are purely intended for physical layer functions. For example, every fifth bit of the FDDI bit stream is not used by the data link layer. In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ...


WAN Protocol Architecture

Connection-oriented WAN data link protocols, in addition to framing, detect and may correct errors. They also are capable of controlling the rate of transmission. A WAN data link layer might implement a sliding window flow control and acknowledgment mechanism to provide reliable delivery of frames; that is the case for SDLC and HDLC, and derivatives of HDLC such as LAPB and LAPD. A connection-oriented networking protocol is one which identifies traffic flows by some connection identifier rather than by explicitly listing source and destination addresses. ... In transmit flow control, sliding window is a variable-duration window that allows a sender to transmit a specified number of data units before an acknowledgement is received or before a specified event occurs. ... Synchronous Data Link Control (SDLC) is a computer communications protocol. ... It has been suggested that the section HDLC from the article Measuring_data_throughput be merged into this article or section. ... LAPB state Diagram LAPB (Link Access Protocol, Balanced) is a data link layer protocol in the X.25 protocol stack. ... Link Access Procedures on the D channel (LAPD), specified in ITU-T Q.920 and ITU-T Q.921, is the second layer protocol on the ISDN protocol stack in the D channel. ...


IEEE 802 LAN Architecture

Practical, connectionless LANs began with the pre-IEEE Ethernet specification, which is the ancestor of IEEE 802.3. This layer manages the interaction of devices with a shared medium, which is the function of a Media Access Control sublayer. Above this MAC sublayer is the media-independent IEEE 802.2 Logical Link Control (LLC) sublayer, which deals with addressing and multiplexing on multiaccess media. In a packet-switched network, connectionless mode transmission is transmission in which each packet is prepended with a header containing a destination address sufficient to permit the independent delivery of the packet without the aid of additional instructions. ... Ethernet is a large, diverse family of frame-based computer networking technologies that operate at many speeds for local area networks (LANs). ... IEEE 802. ... The Media Access Control (MAC) data communication protocol sub-layer, also known as the Medium Access Control, is a part of the data link layer specified in the seven-layer OSI model (layer 2). ... IEEE 802. ... According to the IEEE 802 family of standards, Logical Link Control (LLC) is the upper sublayer of the OSI data link layer. ...


While IEEE 802.3 is the dominant wired LAN protocol and IEEE 802.11 the wireless LAN protocol, obsolescent MAC layers include Token Ring and FDDI. The MAC sublayer detects but does not correct errors. IEEE 802. ... Token-Ring local area network (LAN) technology was developed and promoted by IBM in the early 1980s and standardised as IEEE 802. ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ...


Layer 1: Physical layer

Main article: Physical layer

The physical layer defines all the electrical and physical specifications for devices. In particular, it defines the relationship between a device and a physical medium. This includes the layout of pins, voltages, cable specifications, Hubs, repeaters, network adapters, Host Bus Adapters (HBAs used in Storage Area Networks) and more. This article does not cite any references or sources. ... This article does not cite any references or sources. ... In electronics, a lead is an electrical connection, usually a wire, coming from an electronic device and often connecting to another. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ... For other uses, see Cable (disambiguation). ... Specification may refer to several different concepts: Specification (standards) refers to specific standards Specificatio - a legal concept Specification (regression) refers to the practice of translating theory into a regression model Category: ... In general, a hub is a centre point: a wheels hub, which is the center of the wheel with spokes radiating out from it. ... For other uses, see Repeater (disambiguation). ... A network card, network adapter or NIC (network interface controller) is a piece of computer hardware designed to allow computers to communicate over a computer network. ... Fibre Channel Host Bus Adapter (64-bit PCI-X card) SCSI Host Bus Adapter (16-bit ISA card) In computer hardware, a host controller, host adapter, or host bus adapter (HBA) connects a host system (the computer) to other network and storage devices. ... In computing, a storage area network (SAN) is an architecture to attach remote computer storage devices such as disk array controllers, tape libraries and CD arrays to servers in such a way that to the operating system the devices appear as locally attached devices. ...


To understand the function of the physical layer in contrast to the functions of the data link layer, think of the physical layer as concerned primarily with the interaction of a single device with a medium, where the data link layer is concerned more with the interactions of multiple devices (i.e., at least two) with a shared medium. The physical layer will tell one device how to transmit to the medium, and another device how to receive from it (in most cases it does not tell the device how to connect to the medium). Obsolescent physical layer standards such as RS-232 do use physical wires to control access to the medium. RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ...


The major functions and services performed by the physical layer are:

Parallel SCSI buses operate in this layer, although it must be remembered that the logical SCSI protocol is a transport-layer protocol that runs over this bus. Various physical-layer Ethernet standards are also in this layer; Ethernet incorporates both this layer and the data-link layer. The same applies to other local-area networks, such as Token ring, FDDI, and IEEE 802.11, as well as personal area networks such as Bluetooth and IEEE 802.15.4. An electrical connector is a conductive device for joining electrical circuits together. ... For other uses, see Communication (disambiguation). ... A transmission medium is any material substance, such as fiber-optic cable, twisted-wire pair, coaxial cable, dielectric-slab waveguide, water, or air, that can be used for the propagation of signals, usually in the form of modulated radio, light, or acoustic waves, from one point to another. ... This article or section is in need of attention from an expert on the subject. ... The flow control mechanism is used for controlling the flow of data in a network under well-defined conditions, while congestion control is used for controlling the flow of data when congestion has actually occurred . ... In telecommunications, modulation is the process of varying a periodic waveform, i. ... A digital system is one that uses discrete values rather than a continuous spectrum of values: compare analog. ... Channel, in communications (sometimes called communications channel), refers to the medium used to convey information from a sender (or transmitter) to a receiver. ... Optical fibers An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length. ... Electromagnetic radiation is a propagating wave in space with electric and magnetic components. ... Parallel SCSI is a computer term used to describe one of the physical implementations of SCSI communications. ... Scuzzy redirects here. ... IBM token ring refers to IBMs implementation of token ring technology for linking personal computers in a local area network (LAN). ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ... IEEE 802. ... Bluetooth logo This article is about the electronic protocol named after Harald Bluetooth Gormson. ... IEEE 802. ...


Interfaces

Neither the OSI Reference Model nor OSI protocols specify any programming interfaces, other than as deliberately abstract service specifications. Protocol specifications precisely define the interfaces between different computers, but the software interfaces inside computers are implementation-specific.


For example, Microsoft Windows' Winsock, and Unix's Berkeley sockets and System V Transport Layer Interface, are interfaces between applications (layers 5 and above) and the transport (layer 4). NDIS and ODI are interfaces between the media (layer 2) and the network protocol (layer 3). Windows redirects here. ... Windows Sockets API version 2. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... The Berkeley sockets application programming interface (API) comprises a library for developing applications in the C programming language that perform inter-process communication, most commonly across a computer network. ... It has been suggested that Traditional Unix be merged into this article or section. ... In computer software, specifically networking, the Transport Layer Interface (TLI) was the networking API provided by AT&T UNIX System V Release 3. ... The Network Driver Interface Specification (NDIS) is an application programming interface (API) for network interface cards (NICs). ... The Open Data-Link Interface (ODI), developed by Apple and Novell, serves the same function as Microsoft and 3COMs Network Driver Interface Specification (NDIS). ...


Interface standards, except for the physical layer to media, are approximate implementations of OSI Service Specifications.


Examples

Layer Misc. examples TCP/IP suite SS7 AppleTalk suite OSI suite IPX suite SNA UMTS
# Name
7 Application HL7, Modbus NNTP, SIP, SSI, DNS, FTP, Gopher, HTTP, NFS, NTP, DHCP, SMPP, SMTP, SNMP, Telnet, ISUP, INAP, MAP, TUP, TCAP, AFP, ZIP, RTMP, NBP FTAM, X.400, X.500, DAP RIP, SAP APPC
6 Presentation TDI, ASCII, EBCDIC, MIDI, MPEG MIME, XDR, SSL, TLS (Not a separate layer) AFP ISO 8823, X.226
5 Session Named Pipes, NetBIOS, SAP, Half Duplex,Full Duplex,Simplex,SDP Sockets. Session establishment in TCP. SIP. (Not a separate layer with standardized API.) ASP, ADSP, PAP ISO 8327, X.225 NWLink DLC?
4 Transport NBF, nanoTCP, nanoUDP TCP, UDP,PPTP, L2TP, SCTP, SCCP, RTP DDP TP0, TP1, TP2, TP3, TP4 SPX
3 Network NBF, Q.931 IP, IPsec, ARP, ICMP, RIP, OSPF, BGP, IGMP, IS-IS MTP-3 ATP (TokenTalk or EtherTalk) X.25 (PLP), CLNP IPX RRC (Radio Resource Control) PDCP (Packet Data Convergence Protocol) and Broadcast/Multicast Control (BMC)
2 Data Link 802.3 (Ethernet), 802.11a/b/g/n MAC/LLC, 802.1Q (VLAN), ATM, HDP, FDDI, Fibre Channel, Frame Relay, HDLC, ISL, PPP, Q.921, Token Ring, CDP PPP, SLIP MTP-2 LocalTalk,AppleTalk Remote Access, PPP X.25 (LAPB), Token Bus IEEE 802.3 framing, Ethernet II framing SDLC LLC (Logical Link Control), MAC (Media Access Control)
1 Physical RS-232, V.35, V.34, I.430, I.431, T1, E1, 10BASE-T, 100BASE-TX, POTS, SONET, SDH,DSL, 802.11a/b/g/n PHY MTP-1 RS-232, RS-422, STP, PhoneNet X.25 (X.21bis, EIA/TIA-232, EIA/TIA-449, EIA-530, G.703) Twinax UMTS L1 (UMTS Physical Layer)

The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. ... Signaling System #7 (SS7) is a set of telephony signaling protocols which are used to set up the vast majority of the worlds PSTN telephone calls. ... AppleTalk is a proprietary suite of protocols developed by Apple Inc for computer networking. ... This article or section does not adequately cite its references or sources. ... See also Ericsson IPX Internetwork Packet Exchange (IPX) is the OSI-model Network layer protocol in the IPX/SPX protocol stack. ... Systems Network Architecture (SNA) is IBMs proprietary networking architecture created in 1974. ... Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) mobile phone technologies. ... Health Level 7 (HL7) is the leading international standard for data exchange between computer systems in healthcare. ... Modbus is a serial communications protocol published by Modicon in 1979 for use with its programmable logic controllers (PLCs). ... The Network News Transfer Protocol or NNTP is an Internet application protocol used primarily for reading and posting Usenet articles, as well as transferring news among news servers. ... The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. ... // Overview SSI (Simple Sensor Interface) protocol is a simple communications protocol designed for data transfer between computers or user terminals and smart sensors. ... The Domain Name System or DNS is a system that stores information about host names and domain names in a kind of distributed database on networks, such as the Internet. ... This article is about the File Transfer Protocol standardised by the IETF. For other file transfer protocols, see File transfer protocol (disambiguation). ... Gopher is a distributed document search and retrieval network protocol designed for the Internet. ... HTTP (for HyperText Transfer Protocol) is the primary method used to convey information on the World Wide Web. ... For network file systems in general, see network file system. ... The Network Time Protocol (NTP) is a protocol for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. ... DHCP redirects here. ... The short message peer-to-peer protocol (SMPP) is a telecommunications industry protocol for exchanging SMS messages between SMS peer entities such as short message service centres. ... Simple Mail Transfer Protocol (SMTP) is the de facto standard for e-mail transmissions across the Internet. ... The Simple Network Management Protocol (SNMP) forms part of the internet protocol suite as defined by the Internet Engineering Task Force (IETF). ... For the packet switched network, see Telenet. ... The ISDN User Part or ISUP is part of the Signaling System #7 which is used to set up telephone calls in Public Switched Telecom Networks. ... The Intelligent Network Application Part (INAP) is a signalling protocol used in the intelligent network architecture. ... Mobile Application Part ... Telephone User Part (TUP) provides conventional PSTN telephony services across the SS7 network. ... Transaction Capabilities Application Part, from ITU-T recommendations Q.771-Q.775 or ANSI T1. ... The Apple Filing Protocol (AFP) is a layer 6 (presentation layer) network protocol that offers file services for Mac OS X and Classic Mac OS. In Mac OS X, AFP is one of several file services supported including Server Message Block (SMB), Network File System (NFS), File Transfer Protocol (FTP... AppleTalk is a proprietary suite of protocols developed by Apple Computer for computer networking. ... Routing Table Maintenance Protocol (RTMP) is a communication protocol used by AppleTalk to ensure that all routers on the network have consistent routing information. ... AppleTalk is a proprietary suite of protocols developed by Apple Inc for computer networking. ... FTAM, an ISO 8571 standard, is an OSI Application layer protocol for File Transfer Access and Management. ... X.400 is a suite of ITU-T Recommendations that define standards for Data Communication Networks for Message Handling Systems (MHS) — more commonly known as E-mail. While X.400 never achieved the universal presence of Internet e-mail, it has seen use within organizations, and as part of proprietary... X.500 is the set of ITU-T computer networking standards covering electronic directory services such as white pages, Knowbot and whois. ... Directory Access Protocol (DAP) is a computer networking standard promulgated by ITU-T and ISO in 1988 for accessing an X.500 directory service. ... In computing, Advanced Program to Program Communication or APPC is a protocol which computer programs can use to communicate over a network. ... In the area of graphical user interfaces, a tabbed document interface (TDI) is one that allows multiple documents to be contained within a single window, using tabs to navigate between them. ... Image:ASCII fullsvg There are 95 printable ASCII characters, numbered 32 to 126. ... EBCDIC (Extended Binary Coded Decimal Interchange Code) is an 8-bit character encoding (code page) used on IBM mainframe operating systems, like z/OS, OS/390, VM and VSE, as well as IBM minicomputer operating systems like OS/400 and i5/OS. It is also employed on various non-IBM... MIDI redirects here. ... The Moving Picture Experts Group or MPEG is a working group of ISO/IEC charged with the development of video and audio encoding standards. ... For mime as an art form, see mime artist. ... eXternal Data Representation (XDR) is an IETF standard from 1995 of the presentation layer in the OSI model. ... Secure Sockets Layer (SSL) and Transport Layer Security (TLS), its successor, are cryptographic protocols which provide secure communications on the Internet. ... Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL), are cryptographic protocols that provide secure communications on the Internet for such things as web browsing, e-mail, Internet faxing, instant messaging and other data transfers. ... The Apple Filing Protocol (AFP) is a layer 6 (presentation layer) network protocol that offers file services for Mac OS X and Classic Mac OS. In Mac OS X, AFP is one of several file services supported including Server Message Block (SMB), Network File System (NFS), File Transfer Protocol (FTP... In computing, a named pipe (also FIFO for its behaviour) is an extension to the classical pipe concept on UNIX and UNIX-like systems, and is one of the methods of interprocess communication. ... NetBEUI redirects here. ... Session Announcement Protocol (SAP) is a protocol for broadcasting multicast session information. ... Duplex is the having of two principal elements or parts. ... A 3-simplex or tetrahedron In geometry, a simplex (plural simplexes or simplices) or n-simplex is an n-dimensional analogue of a triangle. ... Session Description Protocol (SDP), is a format for describing streaming media initialization parameters. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ... The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. ... AppleTalk is a proprietary suite of protocols developed by Apple Inc for computer networking. ... AppleTalk is a proprietary suite of protocols developed by Apple Inc for computer networking. ... NWLink is a IPX/SPX-compatible protocol developed by Microsoft and used in its Windows NT product line. ... In the OSI networking model, Data Link Control (DLC) is the service provided by the data link layer. ... NetBIOS Frames or NBF protocol is an unrouted (non-routable) network- and transport-level data protocol most commonly used as one of the layers of Microsoft Windows networking. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ... User Datagram Protocol (UDP) is one of the core protocols of the Internet protocol suite. ... Point-to-point tunneling protocol (PPTP) is a protocol from Microsoft for virtual private networks. ... In computer networking, the Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks (VPNs). ... In the field of computer networking, the IETF Signaling Transport (SIGTRAN) working group defined the Stream Control Transmission Protocol (SCTP) as a transport layer protocol in 2000. ... // Signaling Connection and Control Part (SCCP) is a transport layer protocol which provides extended routing, flow control, segmentation, connection-orientation, and error correction facilities in Signaling System 7 telecommunications networks. ... The Real-time Transport Protocol (or RTP) defines a standardized packet format for delivering audio and video over the Internet. ... Datagram Delivery Protocol (DDP) is a member of the AppleTalk networking protocol suite. ... Sequenced Packet Exchange (SPX) is an old Novell protocol used to manage the Novell Internetwork Packet Exchange (IPX) that allowed Novell Servers and clients to communicate over LAN (Local Area Networks) and WAN (Wide Area Networks). ... NetBIOS Frames or NBF protocol is an unrouted (non-routable) network- and transport-level data protocol most commonly used as one of the layers of Microsoft Windows networking. ... The ITU-T Recommendation Q.931 is ISDNs connection control protocol, roughly comparable to TCP in the Internet Protocol stack. ... The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... IPsec (IP security) is a suite of protocols for securing Internet Protocol (IP) communications by authenticating and/or encrypting each IP packet in a data stream. ... In computer networking, the Address Resolution Protocol (ARP) is the standard method for finding a hosts hardware address when only its network layer address is known. ... The Internet Control Message Protocol (ICMP) is one of the core protocols of the Internet protocol suite. ... This article is chiefly about the Routing Information Protocol (RIP) for the Internet Protocol, but also discusses some other routing information protocols. ... The Open Shortest Path First (OSPF) protocol is a hierarchical interior gateway protocol (IGP) for routing in Internet Protocol, using a link-state in the individual areas that make up the hierarchy. ... The Border Gateway Protocol (BGP) is the core routing protocol of the Internet. ... The Internet Group Management Protocol (IGMP) is a communications protocol used to manage the membership of Internet Protocol multicast groups. ... Is Is is Yeah Yeah Yeahs third EP, to be released on July 24, 2007. ... The Message Transfer Part is part of the Signalling System 7 (SS7) which is used for communication in Public Switched Telephone Network. ... AppleTalk is a proprietary suite of protocols developed by Apple Inc for computer networking. ... AppleTalk is a suite of protocols developed by Apple Computer for computer networking. ... AppleTalk is a suite of protocols developed by Apple Computer for computer networking. ... X.25 is an ITU-T standard protocol suite for wide area networks using leased lines, the phone or ISDN system as the networking hardware. ... PLP abbreviates Packet-Layer Protocol. ... CLNS is an abbreviation of Connectionless Network Service. ... See also Ericsson IPX Internetwork Packet Exchange (IPX) is the OSI-model Network layer protocol in the IPX/SPX protocol stack. ... The Radio Resource Control (RRC) belong to the UMTS WCDMA protocal stack and handles the control plane signalling of Layer 3 between the UEs and UTRAN and perform functions for connection establishment and release, broadcast of system information, Radio Bearer establishmet/reconfiguration and releases, RRC Connection mobility procedures, paging notification... The Radio Resource Control (RRC) belong to the UMTS WCDMA protocal stack and handles the control plane signalling of Layer 3 between the UEs and UTRAN and perform functions for connection establishment and release, broadcast of system information, Radio Bearer establishmet/reconfiguration and releases, RRC Connection mobility procedures, paging notification... Ethernet is a large, diverse family of frame-based computer networking technologies that operate at many speeds for local area networks (LANs). ... IEEE 802. ... IEEE 802. ... Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header information) fixed-sized cells. ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ... Fibre Channel is a gigabit-speed network technology primarily used for storage networking. ... In the context of computer networking, frame relay consists of an efficient data transmission technique used to send digital information quickly and cheaply in a relay of frames to one or many destinations from one or many end-points. ... It has been suggested that the section HDLC from the article Measuring_data_throughput be merged into this article or section. ... Cisco Inter-Switch Link (ISL) is a Cisco Systems proprietary protocol that maintains VLAN information as traffic flows between switches and routers, or switches and switches. ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ... Token-Ring local area network (LAN) technology was developed and promoted by IBM in the early 1980s and standardised as IEEE 802. ... The Cisco Discovery Protocol (CDP) is a proprietary network protocol at layer 2 developed by Cisco Systems which runs on most Cisco equipment and is used to share information about other directly connected Cisco equipment such as the operating system version and IP address. ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ... In telecommunications, a slip is a positional displacement in a sequence of transmitted symbols that causes the loss or insertion of one or more symbols. ... The Message Transfer Part is part of the Signalling System 7 (SS7) which is used for communication in Public Switched Telephone Network. ... LocalTalk is a particular implementation of the physical layer of the AppleTalk networking system from Apple Computer. ... AppleTalk Remote Access, or ARA, was a protocol stack that allowed AppleTalk to be run over modems. ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ... X.25 is an ITU-T standard protocol suite for wide area networks using leased lines, the phone or ISDN system as the networking hardware. ... LAPB state Diagram LAPB (Link Access Protocol, Balanced) is a data link layer protocol in the X.25 protocol stack. ... Token bus is token ring over a virtual ring on a coaxial cable. ... IEEE 802. ... Ethernet v2 framing, also known as DIX Ethernet (named after the major participants in the framing of the protocol: Digital Equipment Corporation, Intel, Xerox) differs from IEEE 802. ... Synchronous Data Link Control (SDLC) is a computer communications protocol. ... According to the IEEE 802 family of standards, Logical Link Control (LLC) is the upper sublayer of the OSI data link layer. ... According to the IEEE 802 family of standards, Logical Link Control (LLC) is the upper sublayer of the OSI data link layer. ... The Media Access Control (MAC) data communication protocol sub-layer, also known as the Medium Access Control, is a part of the data link layer specified in the seven-layer OSI model (layer 2). ... The Media Access Control (MAC) data communication protocol sub-layer, also known as the Medium Access Control, is a part of the data link layer specified in the seven-layer OSI model (layer 2). ... RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ... It is an ITU-T standard (International Telecommunication Union Telecommunication Standardization Sector) Located on layer 1 on the OSI model Max speed of 2 Mbit/s See also V.24 ... V.34 is: The communication protocol from ITU for 28. ... Two Network Interface Units, one with a single card, the other with two In telecommunications, T-carrier is the generic designator for any of several digitally multiplexed telecommunications carrier systems originally developed by Bell Labs and used in North America and Japan. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... 10BASE-T cable 10BASE-T plug 10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. ... 100BASE-TX is the predominant form of Fast Ethernet, providing 100 Mbit/s Ethernet. ... Plain old telephone service, or POTS, are the services available from analogue telephones prior to the introduction of electronic telephone exchanges into the public switched telephone network. ... Synchronous optical networking, is a method for communicating digital information using lasers or light-emitting diodes (LEDs) over optical fiber. ... Synchronous optical networking, is a method for communicating digital information using lasers or light-emitting diodes (LEDs) over optical fiber. ... DSL redirects here. ... IEEE 802. ... The Message Transfer Part is part of the Signalling System 7 (SS7) which is used for communication in Public Switched Telephone Network. ... RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ... EIA-422 (formerly RS-422) is a serial data communication protocol which specifies 4-wire, full-duplex, differential line, multi-drop communications. ... 25 Pair Color Code Chart 10BASE-T UTP Cable Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of cancelling out electromagnetic interference known as crosstalk. ... PhoneNet is an implementation of the LocalTalk network physical layer created by Farallon Computing (now Netopia). ... X.25 is an ITU-T standard protocol suite for wide area networks using leased lines, the phone or ISDN system as the networking hardware. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... In telecommunications, RS-232 is a standard for serial binary data interconnection between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ... The RS-449 specifiecs the functional and mechanical characteristics of the interface between data terminal equipment and data communications equipment. ... EIA-530 is a balanced serial interface standard that generally uses a 25 pin connector. ... G.703 is a ITU-T standard for transmitting voice or data over digital carriers such as T1 and E1. ...

External links

The ZIP file format is a popular data compression and archival format. ... “PDF” redirects here. ... A kibibyte (a contraction of kilo binary byte) is a unit of information or computer storage, commonly abbreviated KiB (never kiB). 1 kibibyte = 210 bytes = 1,024 bytes The kibibyte is closely related to the kilobyte, which can be used either as a synonym for kibibyte or to refer to...

References

  1. ^ a b Bachman, Charles. Charles W. Bachman Papers, 1951-1996. Finding Aid. ANSI/SPARC/DISY, 1978-1981. Charles Babbage Institute Center for the History of Information Technology. University of Minnesota.. Retrieved on 2007-09-21.
  2. ^ Stallings, William Richard (1998). The Origins of OSI. Retrieved on 2007-09-21.
  3. ^ ISO-TP: OSI Transport Layer Protocols: TP0, TP1, TP2, TP3,TP4. Retrieved on 2008-03-17.
  4. ^ ISO Document 8073. Retrieved on 2008-03-18.
Charles W. Bachman is a prominent computer scientist, particularly in the area of databases. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 264th day of the year (265th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 264th day of the year (265th in leap years) in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 76th day of the year (77th in leap years) in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 77th day of the year (78th in leap years) in the Gregorian calendar. ...

  Results from FactBites:
 
Computer Networks and Protocol - The OSI Reference Model (2769 words)
OSI is the acronym for Open Systems Interconnection, which was an effort formed by the International Organization for Standardization in 1982 with the goal of producing a standard reference model for the hardware and software connection of digital equipment.
While OSI Layer 4 protocols may attempt to compensate for this collision by retransmitting packets until they have reached the destination node without issue, this degrades network performance exponentially as the number of nodes on a network grows.
The OSI Reference Model exists not to make hard rules or to shape the industry, but to provide a logical, well-researched, and tested model after which the world's best communication protocol "stacks" are modeled.
OSI model - Wikipedia, the free encyclopedia (1470 words)
The OSI reference model is a hierarchical structure of seven layers that defines the requirements for communications between two computers.
The OSI model made this layer responsible for "graceful close" of sessions, which is a property of TCP, and also for session checkpointing and recovery, which is not usually used in the Internet protocols suite.
The OSI model has also been jokingly called the "Taco Bell model", since the restaurant chain has been known for their 7 layer burrito.
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