Contents 1 History 2 Description of OSI layers 2.1 Layer 1: Physical Layer 2.2 Layer 2: Data Link Layer 2.3 Layer 3: Network Layer 2.4 Layer 4: Transport Layer 2.5 Layer 5: Session Layer 2.6 Layer 6: Presentation Layer 2.7 Layer 7: Application Layer 3 Cross-layer functions 4 Interfaces 5 Examples 6 Comparison with TCP/IP model 7 See also 8 References 9 External links

History[edit] In the late 1970s, one project was administered by the International Organization for Standardization (ISO), while another was undertaken by the International Telegraph and Telephone Consultative Committee (CCITT, from French: Comité Consultatif International Téléphonique et Télégraphique). These two international standards bodies each developed a document that defined similar networking models. In 1983, these two documents were merged to form a standard called The Basic Reference Model for Open Systems Interconnection. The standard is usually referred to as the Open Systems Interconnection Reference Model, the OSI Reference Model, or simply the OSI model. It was published in 1984 by both the ISO, as standard ISO 7498, and the renamed CCITT (now called the Telecommunications Standardization Sector of the International Telecommunication Union or ITU-T) as standard X.200. OSI had two major components, an abstract model of networking, called the Basic Reference Model or seven-layer model, and a set of specific protocols. The concept of a seven-layer model was provided by the work of Charles Bachman at Honeywell Information Services. Various aspects of OSI design evolved from experiences with the ARPANET, NPLNET, EIN, CYCLADES network and the work in IFIP WG6.1. The new design was documented in ISO 7498 and its various addenda. In this model, a networking system was divided into layers. Within each layer, one or more entities implement its functionality. Each entity interacted directly only with the layer immediately beneath it, and provided facilities for use by the layer above it. Protocols enable an entity in one host to interact with a corresponding entity at the same layer in another host. Service definitions abstractly described the functionality provided to an (N)-layer by an (N-1) layer, where N was one of the seven layers of protocols operating in the local host. The OSI standards documents are available from the ITU-T as the X.200-series of recommendations.[1] Some of the protocol specifications were also available as part of the ITU-T X series. The equivalent ISO and ISO/IEC standards for the OSI model were available from ISO. Not all are free of charge.[2]

Description of OSI layers[edit] The recommendation X.200 describes seven layers, labeled 1 to 7. Layer 1 is the lowest layer in this model. OSI Model Layer Protocol data unit (PDU) Function[3] Host layers 7. Application Data High-level APIs, including resource sharing, remote file access 6. Presentation Translation of data between a networking service and an application; including character encoding, data compression and encryption/decryption 5. Session Managing communication sessions, i.e. continuous exchange of information in the form of multiple back-and-forth transmissions between two nodes 4. Transport Segment (TCP) / Datagram (UDP) Reliable transmission of data segments between points on a network, including segmentation, acknowledgement and multiplexing Media layers 3. Network Packet Structuring and managing a multi-node network, including addressing, routing and traffic control 2. Data link Frame Reliable transmission of data frames between two nodes connected by a physical layer 1. Physical Bit Transmission and reception of raw bit streams over a physical medium At each level N, two entities at the communicating devices (layer N peers) exchange protocol data units (PDUs) by means of a layer N protocol. Each PDU contains a payload, called the service data unit (SDU), along with protocol-related headers or footers. Data processing by two communicating OSI-compatible devices is done as such: The data to be transmitted is composed at the topmost layer of the transmitting device (layer N) into a protocol data unit (PDU). The PDU is passed to layer N-1, where it is known as the service data unit (SDU). At layer N-1 the SDU is concatenated with a header, a footer, or both, producing a layer N-1 PDU. It is then passed to layer N-2. The process continues until reaching the lowermost level, from which the data is transmitted to the receiving device. At the receiving device the data is passed from the lowest to the highest layer as a series of SDUs while being successively stripped from each layer's header or footer, until reaching the topmost layer, where the last of the data is consumed. Some orthogonal aspects, such as management and security, involve all of the layers (See ITU-T X.800 Recommendation[4]). These services are aimed at improving the CIA triad - confidentiality, integrity, and availability - of the transmitted data. In practice, the availability of a communication service is determined by the interaction between network design and network management protocols. Appropriate choices for both of these are needed to protect against denial of service.[citation needed] Layer 1: Physical Layer[edit] This section may need to be rewritten entirely to comply with Wikipedia's quality standards. You can help. The discussion page may contain suggestions. (August 2017) The physical layer defines the electrical and physical specifications of the data connection. It defines the relationship between a device and a physical transmission medium (for example, an electrical cable, an optical fiber cable, or a radio frequency link). This includes the layout of pins, voltages, line impedance, cable specifications, signal timing and similar characteristics for connected devices and frequency (5 GHz or 2.4 GHz etc.) for wireless devices. It is responsible for transmission and reception of unstructured raw data in a physical medium. Bit rate control is done at the physical layer. It may define transmission mode as simplex, half duplex, and full duplex. It defines the network topology as bus, mesh, or ring being some of the most common. The physical layer is the layer of low-level networking equipment, such as some hubs, cabling, and repeaters. The physical layer is never concerned with protocols or other such higher-layer items. Examples of hardware in this layer are network adapters, repeaters, network hubs, modems, and fiber media converters. Layer 2: Data Link Layer[edit] The data link layer provides node-to-node data transfer—a link between two directly connected nodes. It detects and possibly corrects errors that may occur in the physical layer. It defines the protocol to establish and terminate a connection between two physically connected devices. It also defines the protocol for flow control between them. IEEE 802 divides the data link layer into two sublayers:[5] Medium access control (MAC) layer – responsible for controlling how devices in a network gain access to a medium and permission to transmit data. Logical link control (LLC) layer – responsible for identifying and encapsulating network layer protocols, and controls error checking and frame synchronization. The MAC and LLC layers of IEEE 802 networks such as 802.3 Ethernet, 802.11 Wi-Fi, and 802.15.4 ZigBee operate at the data link layer. The Point-to-Point Protocol (PPP) is a data link layer protocol that can operate over several different physical layers, such as synchronous and asynchronous serial lines. The ITU-T standard, which provides high-speed local area networking over existing wires (power lines, phone lines and coaxial cables), includes a complete data link layer that provides both error correction and flow control by means of a selective-repeat sliding-window protocol. Layer 3: Network Layer[edit] The network layer provides the functional and procedural means of transferring variable length data sequences (called datagrams) from one node to another connected in "different networks". A network is a medium to which many nodes can be connected, on which every node has an address and which permits nodes connected to it to transfer messages to other nodes connected to it by merely providing the content of a message and the address of the destination node and letting the network find the way to deliver the message to the destination node, possibly routing it through intermediate nodes. If the message is too large to be transmitted from one node to another on the data link layer between those nodes, the network may implement message delivery by splitting the message into several fragments at one node, sending the fragments independently, and reassembling the fragments at another node. It may, but does not need to, report delivery errors. Message delivery at the network layer is not necessarily guaranteed to be reliable; a network layer protocol may provide reliable message delivery, but it need not do so. 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.[6] Layer 4: Transport Layer[edit] The transport layer provides the functional and procedural means of transferring variable-length data sequences from a source to a destination host via one or more networks, while maintaining the quality of service functions. An example of a transport-layer protocol in the standard Internet stack is Transmission Control Protocol (TCP), usually built on top of the Internet Protocol (IP). 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 re-transmit those that fail. The transport layer also provides the acknowledgement of the successful data transmission and sends the next data if no errors occurred. The transport layer creates packets out of the message received from the application layer. Packetizing is a process of dividing the long message into smaller messages. OSI defines five classes of connection-mode transport protocols ranging from class 0 (which is also known as TP0 and provides the fewest features) to class 4 (TP4, designed for less reliable networks, similar to the Internet). Class 0 contains no error recovery, and was designed for use on network layers that provide error-free connections. Class 4 is closest to TCP, although TCP contains functions, such as the graceful close, which OSI assigns to the session layer. Also, all OSI TP connection-mode protocol classes provide expedited data and preservation of record boundaries. Detailed characteristics of TP0-4 classes are shown in the following table:[7] Feature name TP0 TP1 TP2 TP3 TP4 Connection-oriented network Yes Yes Yes Yes Yes Connectionless network No No No No Yes Concatenation and separation No Yes Yes Yes Yes Segmentation and reassembly Yes Yes Yes Yes Yes Error recovery No Yes Yes Yes Yes Reinitiate connectiona No Yes No Yes No Multiplexing / demultiplexing over single virtual circuit No No Yes Yes Yes Explicit flow control No No Yes Yes Yes Retransmission on timeout No No No No Yes Reliable transport service No Yes No Yes Yes a If an excessive number of PDUs are unacknowledged. 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. Although not developed under the OSI Reference Model and not strictly conforming to the OSI definition of the transport layer, the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) of the Internet Protocol Suite are commonly categorized as layer-4 protocols within OSI. Layer 5: Session Layer[edit] The session layer controls the dialogues (connections) 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 the Transmission Control Protocol, and also for session checkpointing and recovery, which is not usually used in the Internet Protocol Suite. The session layer is commonly implemented explicitly in application environments that use remote procedure calls. Layer 6: Presentation Layer[edit] The presentation layer establishes context between application-layer entities, in which the application-layer entities may use different syntax and semantics if the presentation service provides a mapping between them. If a mapping is available, presentation service data units are encapsulated into session protocol data units and passed down the protocol stack. This layer provides independence from data representation by translating between application and network formats. The presentation layer transforms data into the form that the application accepts. This layer formats data to be sent across a network. It is sometimes called the syntax layer.[8] The presentation layer can include compression functions.[9] The Presentation Layer negotiates the Transfer Syntax. 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 serialization of objects and other data structures from and to XML. ASN.1 effectively makes an application protocol invariant with respect to syntax. Layer 7: Application Layer[edit] The application layer is the OSI layer closest to the end user, which means both the OSI application layer and the user interact directly with the software application. This layer interacts with software applications that implement a communicating component. Such application programs fall outside the scope of the OSI model. Application-layer functions typically include identifying communication partners, determining resource availability, and synchronizing communication. When identifying communication partners, the application layer determines the identity and availability of communication partners for an application with data to transmit. The most important distinction in the application layer is the distinction between the application-entity and the application. For example, a reservation website might have two application-entities: one using HTTP to communicate with its users, and one for a remote database protocol to record reservations. Neither of these protocols have anything to do with reservations. That logic is in the application itself. The application layer per se has no means to determine the availability of resources in the network.

Cross-layer functions[edit] Cross-layer functions are services that are not tied to a given layer, but may affect more than one layer. Examples include the following: Security service (telecommunication)[4] as defined by ITU-T X.800 recommendation. Management functions, i.e. functions that permit to configure, instantiate, monitor, terminate the communications of two or more entities: there is a specific application-layer protocol, common management information protocol (CMIP) and its corresponding service, common management information service (CMIS), they need to interact with every layer in order to deal with their instances. Multiprotocol Label Switching (MPLS) MPLS, ATM, and X.25 are 3a protocols. OSI divides the Network Layer into 3 roles: 3a) Subnetwork Access, 3b) Subnetwork Dependent Convergence and 3c) Subnetwork Independent Convergence. It was designed to provide a unified data-carrying service for both circuit-based clients and packet-switching clients which provide a datagram-based service model. It can be used to carry many different kinds of traffic, including IP packets, as well as native ATM, SONET, and Ethernet frames. Sometimes one sees reference to a Layer 2.5. This is a fiction create by those who are unfamiliar with the OSI Model and ISO 8648, Internal Organization of the Network Layer in particular. ARP determines the mapping of an IPv4 address to the underlying MAC address. This is not a translation function. If it were IPv4 and the MAC address would be at the same layer. The implementation of the MAC protocol decodes the MAC PDU and delivers the User-Data to the IP-layer. Because Ethernet is a multi-access media, a device sending a PDU on an Ethernet segment needs to know what IP address maps to what MAC address. DHCP, DHCP assigns IPv4 addresses to new systems joining a network. There is no means to derive or obtain an IPv4 address from an Ethernet address. Domain Name Service is an Application Layer service which is used to look up the IP address of a given domain name. Once a reply is received from the DNS server, it is then possible to form a Layer 4 connection or flow to the desired host. There are no connections at Layer 3. Cross MAC and PHY Scheduling is essential in wireless networks because of the time varying nature of wireless channels. By scheduling packet transmission only in favorable channel conditions, which requires the MAC layer to obtain channel state information from the PHY layer, network throughput can be significantly improved and energy waste can be avoided.[10]

Interfaces[edit] Neither the OSI Reference Model nor OSI protocols specify any programming interfaces, other than deliberately abstract service specifications. Protocol specifications precisely define the interfaces between different computers, but the software interfaces inside computers, known as network sockets are implementation-specific. For example, Microsoft Windows' Winsock, and Unix's Berkeley sockets and System V Transport Layer Interface, are interfaces between applications (layer 5 and above) and the transport (layer 4). NDIS and ODI are interfaces between the media (layer 2) and the network protocol (layer 3). Interface standards, except for the physical layer to media, are approximate implementations of OSI service specifications.

Examples[edit] Layer OSI protocols TCP/IP protocols Signaling System 7[11] AppleTalk IPX SNA UMTS Miscellaneous examples No. Name 7 Application FTAM X.400 X.500 DAP ROSE RTSE ACSE[12] CMIP[13] INAP MAP TCAP ISUP TUP AFP ZIP RTMP NBP SAP APPC HL7 Modbus 6 Presentation ISO/IEC 8823 X.226 ISO/IEC 9576-1 X.236 MIME SSL TLS XDR AFP TDI ASCII EBCDIC MIDI MPEG 5 Session ISO/IEC 8327 X.225 ISO/IEC 9548-1 X.235 Sockets (session establishment in TCP / RTP / PPTP) ASP ADSP PAP NWLink DLC? Named pipes NetBIOS SAP half duplex full duplex simplex RPC SOCKS 4 Transport ISO/IEC 8073 TP0 TP1 TP2 TP3 TP4 (X.224) ISO/IEC 8602 X.234 TCP UDP SCTP DCCP DDP SPX NBF 3 Network ISO/IEC 8208 X.25 (PLP) ISO/IEC 8878 X.223 ISO/IEC 8473-1 CLNP X.233 ISO/IEC 10589 IS-IS IP IPsec ICMP IGMP OSPF RIP SCCP MTP ATP (TokenTalk / EtherTalk) IPX RRC / BMC NBF Q.931 NDP IS-IS 2 Data link ISO/IEC 7666 X.25 (LAPB) Token Bus X.222 ISO/IEC 8802-2 LLC (type 1 / 2)[14] PPP SBTV SLIP MTP Q.710 LocalTalk ARA PPP IEEE 802.3 framing Ethernet II framing SDLC PDCP[15] LLC MAC ARP ARQ ATM Bit stuffing CDP CRC DOCSIS FDDI FDP Fibre Channel Frame Relay HDP HDLC IEEE 802.3 (Ethernet) IEEE 802.11a/b/g/n (Ethernet MAC and LLC) IEEE 802.1Q (VLAN) ISL ITU-T DLL Linux interface bonding PPP Q.921 Token Ring 1 Physical X.25 (X.21bis EIA/TIA-232 EIA/TIA-449 EIA-530 G.703)[14] MTP Q.710 RS-232 RS-422 PhoneNet Twinax UMTS air interfaces RS-232 Full duplex RJ45 (8P8C) V.35 V.34 I.430 I.431 T1 E1 10BASE-T 100BASE-TX 1000BASE-T POTS SONET SDH DSL 802.11a/b/g/n PHY ITU-T PHY CAN bus DOCSIS DWDM OTN

Comparison with TCP/IP model[edit] The design of protocols in the TCP/IP model of the Internet does not concern itself with strict hierarchical encapsulation and layering.[16] RFC 3439 contains a section entitled "Layering considered harmful".[17] TCP/IP does recognize four broad layers of functionality which are derived from the operating scope of their contained protocols: the scope of the software application; the end-to-end transport connection; the internetworking range; and the scope of the direct links to other nodes on the local network.[18] Despite using a different concept for layering than the OSI model, these layers are often compared with the OSI layering scheme in the following way: The Internet application layer includes the OSI application layer, presentation layer, and most of the session layer. Its end-to-end transport layer includes the graceful close function of the OSI session layer as well as the OSI transport layer. The internetworking layer (Internet layer) is a subset of the OSI network layer. The link layer includes the OSI data link layer and sometimes the physical layers, as well as some protocols of the OSI's network layer. 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.[citation needed] The presumably strict layering of the OSI model as it is usually described does not present contradictions in TCP/IP, as it is permissible that protocol usage does not follow the hierarchy implied in a layered model. Such examples exist in some routing protocols (for example OSPF), or in the description of tunneling protocols, which provide a link layer for an application, although the tunnel host protocol might well be a transport or even an application-layer protocol in its own right.[citation needed]

See also[edit] Hierarchical internetworking model Management plane Layer 8 Protocol stack Service layer WAP protocol suite List of information technology acronyms IBM Systems Network Architecture Internet protocol suite

References[edit] ^ ITU-T X-Series Recommendations ^ "Publicly Available Standards". 2010-07-30. Retrieved 2010-09-11.  ^ "The OSI Model's Seven Layers Defined and Functions Explained". Microsoft Support. Retrieved 2014-12-28.  ^ a b "ITU-T Recommendataion X.800 (03/91), Security architecture for Open Systems Interconnection for CCITT applications". ITU. Retrieved 14 August 2015.  ^ "5.2 RM description for end stations". IEEE Std 802-2014, IEEE Standard for Local and Metropolitan Area Networks: Overview and Architecture. ieee.  ^ International Organization for Standardization (1989-11-15). "ISO/IEC 7498-4:1989 -- Information technology -- Open Systems Interconnection -- Basic Reference Model: Naming and addressing". ISO Standards Maintenance Portal. ISO Central Secretariat. Retrieved 2015-08-17.  ^ "ITU-T Recommendation X.224 (11/1995) ISO/IEC 8073, Open Systems Interconnection - Protocol for providing the connection-mode transport service". ITU.  ^ Grigonis, Richard (2000). Computer telephony- encyclopaedia. CMP. p. 331. ISBN 9781578200450.  ^ "ITU-T X.200 - Information technology – Open Systems Interconnection – Basic Reference Model: The basic model".  ^ Miao, Guowang; Song, Guocong (2014). Energy and spectrum efficient wireless network design. Cambridge University Press. ISBN 1107039886.  ^ "ITU-T Recommendation Q.1400 (03/1993)], Architecture framework for the development of signaling and OA&M protocols using OSI concepts". ITU. pp. 4, 7.  ^ ITU Rec. X.227 (ISO 8650), X.217 (ISO 8649). ^ X.700 series of recommendations from the ITU-T (in particular X.711) and ISO 9596. ^ a b "Internetworking Technology Handbook - Internetworking Basics [Internetworking]". Cisco. 15 January 2014. Retrieved 14 August 2015.  ^ "3GPP specification: 36.300". Retrieved 14 August 2015.  ^ RFC 3439 ^ "RFC 3439 - Some Internet Architectural Guidelines and Philosophy". Retrieved 14 August 2015.  ^ Walter Goralski. The Illustrated Network: How TCP/IP Works in a Modern Network (PDF). Morgan Kaufmann. p. 26. ISBN 978-0123745415. 

External links[edit] Wikimedia Commons has media related to OSI model. Microsoft Knowledge Base: The OSI Model's Seven Layers Defined and Functions Explained ISO/IEC standard 7498-1:1994 (PDF document inside ZIP archive) (requires HTTP cookies in order to accept licence agreement) ITU-T X.200 (the same contents as from ISO) "INFormation CHanGe Architectures and Flow Charts powered by Google App Engine". The ISO OSI Reference Model, Beluga graph of data units and groups of layers. Archived from the original on 2012-05-26.  Zimmermann, Hubert (April 1980). "OSI Reference Model — The ISO Model of Architecture for Open Systems Interconnection". IEEE Transactions on Communications. 28 (4): 425–432. CiteSeerX . doi:10.1109/TCOM.1980.1094702.  Cisco Systems Internetworking Technology Handbook v t e ISO standards by standard number List of ISO standards / ISO romanizations / IEC standards 1–9999 1 2 3 4 5 6 7 9 16 31 -0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 128 216 217 226 228 233 259 269 302 306 428 518 519 639 -1 -2 -3 -5 -6 646 690 732 764 843 898 965 1000 1004 1007 1073-1 1413 1538 1745 1989 2014 2015 2022 2047 2108 2145 2146 2240 2281 2709 2711 2788 2848 2852 3029 3103 3166 -1 -2 -3 3297 3307 3602 3864 3901 3977 4031 4157 4217 4909 5218 5428 5775 5776 5800 5964 6166 6344 6346 6385 6425 6429 6438 6523 6709 7001 7002 7098 7185 7200 7498 7736 7810 7811 7812 7813 7816 8000 8178 8217 8571 8583 8601 8632 8652 8691 8807 8820-5 8859 -1 -2 -3 -4 -5 -6 -7 -8 -8-I -9 -10 -11 -12 -13 -14 -15 -16 8879 9000/9001 9075 9126 9293 9241 9362 9407 9506 9529 9564 9594 9660 9897 9899 9945 9984 9985 9995 10000–19999 10005 10006 10007 10116 10118-3 10160 10161 10165 10179 10206 10218 10303 -11 -21 -22 -28 -238 10383 10487 10585 10589 10646 10664 10746 10861 10957 10962 10967 11073 11170 11179 11404 11544 11783 11784 11785 11801 11898 11940 (-2) 11941 11941 (TR) 11992 12006 12182 12207 12234-2 13211 -1 -2 13216 13250 13399 13406-2 13450 13485 13490 13567 13568 13584 13616 14000 14031 14224 14289 14396 14443 14496 -2 -3 -6 -10 -11 -12 -14 -17 -20 14644 14649 14651 14698 14750 14764 14882 14971 15022 15189 15288 15291 15292 15398 15408 15444 -3 15445 15438 15504 15511 15686 15693 15706 -2 15707 15897 15919 15924 15926 15926 WIP 15930 16023 16262 16612-2 16750 16949 (TS) 17024 17025 17100 17203 17369 17442 17799 18000 18004 18014 18245 18629 18916 19005 19011 19092 (-1 -2) 19114 19115 19125 19136 19439 19500 19501 19502 19503 19505 19506 19507 19508 19509 19510 19600:2014 19752 19757 19770 19775-1 19794-5 19831 20000+ 20000 20022 20121 20400 21000 21047 21500 21827:2002 22000 23270 23271 23360 24517 24613 24617 24707 25178 25964 26000 26300 26324 27000 series 27000 27001 27002 27006 27729 28000 29110 29148 29199-2 29500 30170 31000 32000 38500 40500 42010 55000 80000 -1 -2 -3 Category Retrieved from "" Categories: OSI modelISO standardsITU-T recommendationsReference modelsComputer-related introductions in 1979Hidden categories: Pages using RFC magic linksAll articles with unsourced statementsArticles with unsourced statements from April 2013Wikipedia articles needing rewrite from August 2017All articles needing rewriteArticles with unsourced statements from November 2013

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Abstraction LayerApplication LayerNetwork News Transfer ProtocolSession Initiation ProtocolSimple Sensor Interface ProtocolDomain Name SystemFile Transfer ProtocolGopher (protocol)Hypertext Transfer ProtocolNetwork File System (protocol)Network Time ProtocolShort Message Peer-to-PeerSimple Mail Transfer ProtocolSimple Network Management ProtocolTelnetDynamic Host Configuration ProtocolNetconfCategory:Application Layer ProtocolsPresentation LayerMIMEExternal Data RepresentationSession LayerNamed PipeNetBIOSSession Announcement ProtocolPoint-to-Point Tunneling ProtocolReal-time Transport ProtocolSOCKSSPDYTransport LayerTransmission Control ProtocolUser Datagram ProtocolStream Control Transmission ProtocolDatagram Congestion Control ProtocolIPX/SPXNetwork LayerInternet ProtocolIPv4IPv6Internet Control Message ProtocolIPsecInternet Group Management ProtocolInternetwork Packet ExchangeAppleTalkX.25Packet Layer ProtocolData Link LayerAsynchronous Transfer ModeAddress Resolution ProtocolIS-ISSynchronous Data Link ControlHigh-Level Data Link ControlCompressed Serial Line Internet ProtocolSerial Line Internet ProtocolGeneric Framing ProcedureParallel Line Internet ProtocolIEEE 802.2Logical Link ControlMedia Access ControlLayer 2 Tunneling ProtocolIEEE 802.3Frame RelayG.hnPoint-to-Point ProtocolX.25LAPBLink Access Procedures, D ChannelLink Access Procedure For Frame RelayPhysical LayerEIA/TIA-232EIA/TIA-449ITU-T V-Series RecommendationsI.430I.431Plesiochronous Digital HierarchySONET/SDHPassive Optical NetworkOptical Transport NetworkDigital Subscriber LineIEEE 802.3IEEE 802.11IEEE 802.15IEEE 802.16IEEE 1394G.hnUniversal Serial BusBluetoothRS-232RS-449Template:OSI ModelTemplate Talk:OSI ModelConceptual ModelTelecommunicationAbstraction LayerOpen Systems InterconnectionInternational Organization For StandardizationEnlargeInternational Telegraph And Telephone Consultative CommitteeInternational Telecommunication UnionITU-TCharles BachmanARPANETCYCLADESProtocol Data UnitApplication LayerData (computing)APIPresentation LayerCharacter EncodingData CompressionEncryptionSession LayerSession (computer Science)Transport LayerPacket SegmentationDatagramPacket SegmentationAcknowledgement (data Networks)MultiplexingNetwork LayerNetwork PacketAddress SpaceRoutingNetwork Traffic ControlData Link LayerFrame (networking)Physical LayerBitProtocol Data UnitService Data UnitProtocol Data UnitService Data UnitConcatenationSecurity Service (telecommunication)ITU-TInformation SecurityConfidentialityIntegrityAvailabilityNetwork DesignNetwork ManagementDenial Of ServiceWikipedia:Citation NeededWikipedia:Manual Of StyleTalk:OSI ModelPhysical LayerElectricalTransmission MediumElectrical CableOptical Fiber CableLead (electronics)VoltageCharacteristic ImpedanceSpecificationBit RateSimplex CommunicationDuplex (telecommunications)Duplex (telecommunications)Network TopologyBus NetworkMesh NetworkingRing NetworkEthernet HubRepeaterData Link LayerNode-to-node Data TransferFlow Control (data)IEEE 802Medium Access ControlLogical Link Control802.3Ethernet802.11Wi-Fi802.15.4ZigBeePoint-to-Point ProtocolAsynchronous Serial CommunicationITU-TG.hnError CorrectionSelective RepeatSliding Window ProtocolNetwork LayerDataDatagramsRoutingTransport LayerTransmission Control ProtocolInternet ProtocolPacket SegmentationCommunications ProtocolVirtual CircuitProtocol Data UnitTunneling ProtocolIBMIBM Systems Network ArchitectureNovellInternetwork Packet ExchangeIPsecGeneric Routing EncapsulationLayer 2 Tunneling ProtocolPoint-to-Point ProtocolTransmission Control ProtocolUser Datagram ProtocolSession LayerDuplex (telecommunications)Half-duplexSimplex CommunicationTransmission Control ProtocolRemote Procedure CallPresentation LayerBasic Encoding RulesAbstract Syntax Notation OneEBCDICComputer FileASCIISerializationObject (computer Science)Data StructureXMLApplication LayerSecurity Service (telecommunication)ITU-TCommon Management Information ProtocolCommon Management Information ServiceMultiprotocol Label SwitchingDatagramAddress Resolution ProtocolDHCPDomain Name ServiceNetwork SocketMicrosoft WindowsWinsockUnixBerkeley SocketsUNIX System VTransport Layer InterfaceNetwork Driver Interface SpecificationOpen Data-Link InterfaceOpen Systems InterconnectionInternet Protocol SuiteSignaling System 7AppleTalkInternetwork Packet ExchangeSystems Network ArchitectureUniversal Mobile Telecommunications SystemFTAMX.400X.500Directory Access ProtocolRemote Operations Service Element ProtocolAssociation Control Service ElementCommon Management Information ProtocolINAPMobile Application PartTransaction Capabilities Application PartISDN User PartTelephone User PartApple Filing ProtocolZone Information ProtocolRouting Table Maintenance ProtocolAppleTalkService Advertising ProtocolIBM Advanced Program-to-Program CommunicationHL7ModbusMIMESecure Sockets LayerTransport Layer SecurityExternal Data RepresentationApple Filing ProtocolTabbed Document InterfaceASCIIEBCDICMusical Instrument Digital InterfaceMPEGNetwork SocketTransmission Control ProtocolReal-time Transport ProtocolPPTPAppleTalkAppleTalkAppleTalkNWLinkData Link ControlNamed PipesNetBIOSSession Announcement ProtocolHalf DuplexFull DuplexSimplex CommunicationRemote Procedure CallSOCKSTransmission Control ProtocolUser Datagram ProtocolStream Control Transmission ProtocolDatagram Congestion Control ProtocolDatagram Delivery ProtocolSequenced Packet ExchangeNetBIOS Frames ProtocolX.25Packet-Layer ProtocolCONSCLNSIS-ISInternet ProtocolInternet Protocol SecurityInternet Control Message ProtocolInternet Group Management ProtocolOpen Shortest Path FirstRouting Information ProtocolSignalling Connection Control PartMessage Transfer PartAppleTalkTokenTalkEtherTalkIPXRadio Resource ControlBroadcast/Multicast ControlNetBIOS Frames ProtocolQ.931Nortel Discovery ProtocolIS-ISX.25LAPBToken BusIEEE 802.2Point-to-Point ProtocolSBTVSLIPMessage Transfer PartMessage Transfer PartLocalTalkAppleTalk Remote AccessPoint-to-Point ProtocolIEEE 802.3Ethernet II FramingSynchronous Data Link ControlPDCPLogical Link ControlMedia Access ControlAddress Resolution ProtocolAutomatic Repeat-requestAsynchronous Transfer ModeBit StuffingCisco Discovery ProtocolCyclic Redundancy CheckDOCSISFDDIFoundry Discovery ProtocolFibre ChannelFrame RelayHDLCEthernetIEEE 802.11IEEE 802.1QCisco Inter-Switch LinkG.hnLink AggregationPoint-to-Point ProtocolQ.921Token RingX.25X.21bisEIA/TIA-232EIA/TIA-449EIA-530G.703Message Transfer PartMessage Transfer PartRS-232RS-422PhoneNetTwinaxial CablingUniversal Mobile Telecommunications SystemRS-232Full Duplex8P8CV.35 (recommendation)V.34 (recommendation)I.430I.431T-carrierE-carrier10BASE-T100BASE-TX1000BASE-TPlain Old Telephone ServiceSynchronous Optical NetworkingSynchronous Digital HierarchyDigital Subscriber LineIEEE 802.11G.hnCAN BusDOCSISDWDMOptical Transport NetworkTCP/IP ModelConsidered HarmfulApplication LayerTransport LayerInternet LayerLink LayerWikipedia:Citation NeededOSPFTunneling ProtocolWikipedia:Citation NeededHierarchical Internetworking ModelManagement PlaneLayer 8Protocol StackService LayerWAP Protocol SuiteList Of Information Technology AcronymsIBM Systems Network ArchitectureInternet Protocol SuiteInternational Organization For StandardizationInternational Standard Book NumberSpecial:BookSources/9781578200450Guowang MiaoCambridge University PressInternational Standard Book NumberSpecial:BookSources/1107039886Morgan KaufmannInternational Standard Book NumberSpecial:BookSources/978-0123745415Portable Document FormatZIP (file Format)HTTP CookiesCiteSeerXDigital Object IdentifierTemplate:ISO StandardsTemplate Talk:ISO StandardsInternational Organization For StandardizationList Of International Organization For Standardization StandardsList Of ISO RomanizationsList Of IEC StandardsISO 1ISO 2Preferred NumberISO 4ISO 5ISO 6ISO 7ISO 9A440 (pitch Standard)ISO 31ISO 31-0ISO 31-1ISO 31-2ISO 31-3ISO 31-4ISO 31-5ISO 31-6ISO 31-7ISO 31-8ISO 31-9ISO 31-10ISO 31-11ISO 31-12ISO 31-13ISO 128ISO 216ISO 217ISO 226British Standard Pipe ThreadISO 233ISO 259EnvelopeKappa NumberVicat Softening PointISO 428ISO 518ISO 519ISO 639ISO 639-1ISO 639-2ISO 639-3ISO 639-5ISO 639-6ISO/IEC 646ISO 690ISO 732Antimagnetic WatchISO 843ISO 898ISO 965ISO 1000Magnetic Ink Character Recognition135 FilmOCR-A FontISO 1413ALGOL 60ISO 1745ISO 1989ISO 2014ISO 2015ISO/IEC 2022ISO 2047International Standard Book NumberISO 2145ISO 2146ISO 2240Water Resistant MarkISO 2709ISO 2711ISO 2788ISO 2848ISO 2852126 FilmISO 3103ISO 3166ISO 3166-1ISO 3166-2ISO 3166-3International Standard Serial NumberISO 3307Kunrei-shiki RomanizationISO 3864International Standard Recording CodeISO 3977ISO 4031ISO 4157ISO 4217ISO/IEC 4909ISO/IEC 5218ISO 5428ISO 5775ISO 5776ISO 5800ISO 5964ISO 6166ISO 6344ISO 6346ISO 6385Water Resistant MarkANSI Escape CodeISO 6438ISO 6523ISO 6709ISO 7001ISO 7002PinyinPascal (programming Language)ISO 7200ISO 7736ISO/IEC 7810ISO/IEC 7811ISO/IEC 7812ISO/IEC 7813ISO/IEC 7816ISO 8000ISO 8178Fuel OilFTAMISO 8583ISO 8601Computer Graphics MetafileISO/IEC 8652ISO 8691Language Of Temporal Ordering SpecificationISO/IEC 8820-5ISO/IEC 8859ISO/IEC 8859-1ISO/IEC 8859-2ISO/IEC 8859-3ISO/IEC 8859-4ISO/IEC 8859-5ISO/IEC 8859-6ISO/IEC 8859-7ISO/IEC 8859-8ISO-8859-8-IISO/IEC 8859-9ISO/IEC 8859-10ISO/IEC 8859-11ISO/IEC 8859-12ISO/IEC 8859-13ISO/IEC 8859-14ISO/IEC 8859-15ISO/IEC 8859-16Standard Generalized Markup LanguageISO 9000SQLISO/IEC 9126File Allocation TableISO 9241ISO 9362Shoe SizeManufacturing Message SpecificationISO 9529ISO 9564X.500ISO 9660ISO 9897C (programming Language)POSIXISO 9984ISO 9985ISO/IEC 9995ISO 10005ISO 10006ISO 10007ISO/IEC 10116Whirlpool (cryptography)ISO 10160ISO 10161Guidelines For The Definition Of Managed ObjectsDocument Style Semantics And Specification LanguageISO 10206ISO 10218ISO 10303EXPRESS (data Modeling Language)ISO 10303-21ISO 10303-22ISO 10303-28STEP-NCISO 10383ISO 10487ArmSCIIIS-ISUniversal Coded Character SetTorxRM-ODPMultibusInternational Standard Music NumberISO 10962ISO/IEC 10967ISO/IEEE 11073ISO 11170ISO/IEC 11179ISO/IEC 11404JBIGISO 11783ISO 11784 & 11785ISO 11784 & 11785ISO/IEC 11801ISO 11898ISO 11940ISO 11940-2ISO/TR 11941ISO/TR 11941ISO 11992ISO 12006ISO/IEC TR 12182ISO/IEC 12207Tag Image File Format / Electronic PhotographyPrologPrologPrologIsofixTopic MapsISO 13399ISO 13406-2110 FilmISO 13485ISO 13490ISO 13567Z NotationISO 13584International Bank Account NumberISO 14000ISO 14031ISO 14224PDF/UAHorsepowerISO/IEC 14443MPEG-4MPEG-4 Part 2MPEG-4 Part 3Delivery Multimedia Integration FrameworkH.264/MPEG-4 AVCMPEG-4 Part 11MPEG-4 Part 12MPEG-4 Part 14MPEG-4 Part 14MPEG-4 Part 14ISO 14644STEP-NCISO 14651ISO 14698ISO 14750Software MaintenanceC++ISO 14971ISO 15022ISO 15189ISO/IEC 15288Ada Semantic Interface SpecificationISO 15292ISO 15398Common CriteriaJPEG 2000Motion JPEG 2000HTMLPDF417ISO/IEC 15504International Standard Identifier For Libraries And Related OrganizationsISO 15686ISO/IEC 15693International Standard Audiovisual NumberISO 15706-2International Standard Musical Work CodeISO 15897ISO 15919ISO 15924ISO 15926ISO 15926 WIPPDF/XMaxiCodeECMAScriptPDF/VTISO 16750ISO/TS 16949ISO/IEC 17024ISO/IEC 17025ISO 17100:2015Open Virtualization FormatSDMXLegal Entity IdentifierISO/IEC 27002ISO/IEC 18000QR CodeISO/IEC 18014ISO 18245Process Specification LanguagePhotographic Activity TestPDF/AISO 19011ISO 19092-1ISO 19092-2ISO 19114ISO 19115Simple Feature AccessISO 19136ISO 19439Common Object Request Broker ArchitectureUnified Modeling LanguageMeta-Object FacilityXML Metadata InterchangeUnified Modeling LanguageKnowledge Discovery MetamodelObject Constraint LanguageMeta-Object FacilityXML Metadata InterchangeBusiness Process Model And NotationISO 19600:2014ISO/IEC 19752RELAX NGISO/IEC 19770X3DISO/IEC 19794-5Cloud Infrastructure Management InterfaceISO/IEC 20000ISO 20022ISO 20121ISO 20400MPEG-21International Standard Text 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