protocols used in transport layer of osi model
TP1 TP0 TP3 TP2 TP4
1298247
the transport layers of the Internet protocol suite, the OSI protocol suite, NetWare's IPX/SPX, AppleTalk, and Fibre Channel. ISO/IEC 8073/ITU-T Recommendation X.224, "Information Technology - Open Systems Interconnection - Protocol for providing the connection-mode transport service", defines five classes of connection-mode transport protocols designated class 0 (TP0) to class 4 (TP4). 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. All OSI connection-mode protocol classes provide expedited data and
Transport layer
304514
transport layer can keep track of the segments and re-transmit those that fail delivery. 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 segments out of the message received from the application layer. Segmentation is the process of dividing a 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
OSI model
3788051
19, 1992. The Open Source version is still available, even if only for historic interest. The software was ported to a wide set of Unix and Linux variants. The ISODE stack was an implementation of layers 3 to 6 of the OSI model. While the ISODE implementation could be configured to use one of several X.25 (CONS) or connectionless lower layer protocols, many ISODE deployments were based on RFC1006, the implementation of OSI transport protocol TP0 as a layer atop TCP, in order to use IP-based networks which were becoming increasingly common. The stack also implemented an ASN.1 compiler. The
ISO Development Environment
1298247
the transport layers of the Internet protocol suite, the OSI protocol suite, NetWare's IPX/SPX, AppleTalk, and Fibre Channel. ISO/IEC 8073/ITU-T Recommendation X.224, "Information Technology - Open Systems Interconnection - Protocol for providing the connection-mode transport service", defines five classes of connection-mode transport protocols designated class 0 (TP0) to class 4 (TP4). 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. All OSI connection-mode protocol classes provide expedited data and
Transport layer
1298246
packet loss occasionally can be accepted, for example IP-TV and IP-telephony, and for online computer games. Many non-IP-based networks, such as X.25, Frame Relay and ATM, implement the connection-oriented communication at the network or data link layer rather than the transport layer. In X.25, in telephone network modems and in wireless communication systems, reliable node-to-node communication is implemented at lower protocol layers. The OSI connection-mode transport layer protocol specification defines five classes of transport protocols: "TP0", providing the least error recovery, to "TP4", which is designed for less reliable networks. This list shows some protocols that are commonly placed in
Transport layer
3436682
used in many telecommunications networks around the world because IS-IS (an OSI routing protocol) is mandated by the ITU-T as the protocol for management of Synchronous Digital Hierarchy (SDH) elements. From August 1990 to April 1995 the NSFNET backbone supported CLNP in addition to TCP/IP. However, CLNP usage remained low compared to TCP/IP. CLNS is used by ISO Transport Protocol Class 4 (TP4), one of the five transport layer protocols in the OSI suite. TP4 offers error recovery, performs segmentation and reassembly, and supplies multiplexing and demultiplexing of data streams over a single virtual circuit. TP4 sequences PDUs and retransmits
Connectionless-mode Network Service
1298241
Transport layer In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet Protocol Suite and the Open Systems Interconnection (OSI) reference model. The protocols of this layer provide host-to-host communication services for applications. It provides services such as connection-oriented communication, reliability, flow control, and multiplexing. The details of implementation and semantics of the transport layer of the TCP/IP model, which is the foundation of the Internet, and the OSI model of general networking are different. The protocols in use today in this layer for the
Transport layer
2492368
IPX/SPX IPX/SPX stands for Internetwork Packet Exchange/Sequenced Packet Exchange. IPX and SPX are networking protocols used primarily on networks using the Novell NetWare operating systems. IPX and SPX are derived from Xerox Network Systems' IDP and SPP protocols, respectively. IPX is a network layer protocol (layer 3 of the OSI Model), while SPX is a transport layer protocol (layer 4 of the OSI Model). The SPX layer sits on top of the IPX layer and provides connection-oriented services between two nodes on the network. SPX is used primarily by client–server applications. IPX and SPX both provide connection services similar to
IPX/SPX
304522
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. The design of protocols in the TCP/IP model
OSI model
304517
3 packets to deliver to the endpoint. L2TP carries PPP frames inside transport segments. 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. 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
OSI model
206795
address are distinguished by their TCP or UDP port. By convention certain "well known ports" are associated with specific applications. The TCP/IP model's transport or host-to-host layer corresponds roughly to the fourth layer in the Open Systems Interconnection (OSI) model, also called the transport layer. The application layer includes the protocols used by most applications for providing user services or exchanging application data over the network connections established by the lower level protocols. This may include some basic network support services such as protocols for routing and host configuration. Examples of application layer protocols include the Hypertext Transfer Protocol (HTTP),
Internet protocol suite
881015
Network layer In the seven-layer OSI model of computer networking, the network layer is layer 3. The network layer is responsible for packet forwarding including routing through intermediate routers. The network layer provides the means of transferring variable-length network packets from a source to a destination host via one or more networks. Within the service layering semantics of the OSI network architecture, the network layer responds to service requests from the transport layer and issues service requests to the data link layer. Functions of the network layer include: The TCP/IP model describes the protocols used by the Internet. The TCP/IP
Network layer
304524
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 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
OSI model
3238203
Transport Layer Interface In computer networking, the Transport Layer Interface (TLI) was the networking API provided by AT&T UNIX System V Release 3 (SVR3) in 1987 and continued into Release 4 (SVR4). TLI was the System V counterpart to the BSD sockets programming interface, which was also provided in UNIX System V Release 4 (SVR4). TLI was later standardized as XTI, the X/Open Transport Interface. It was originally expected that the OSI protocols would supersede TCP/IP, thus TLI is designed from an OSI model-oriented viewpoint, corresponding to the OSI transport layer. Otherwise, TLI looks similar, API-wise, to sockets. TLI and
Transport Layer Interface
7966146
application. Layer 3 audio over Ethernet protocols encapsulate audio data in OSI model layer 3 (network layer) packets. By definition it does not limit the choice of protocol to be the most popular layer 3 protocol, the Internet Protocol (IP). In some implementations, the layer 3 audio data packets are further packaged inside OSI model layer 4 (transport layer) packets, most commonly User Datagram Protocol (UDP) or Real-time Transport Protocol (RTP). Use of UDP or RTP to carry audio data enables them to be distributed through standard computer routers, thus a large distribution audio network can be built economically using
Audio over Ethernet
13554230
(TCP), Xerox Network Systems (XNS), Systems Network Architecture (SNA), X.25, Asynchronous Transfer Mode (ATM) or any other transport layer provider that function at Layer 4 of the OSI Model. XTI provides similar functionality as the Berkeley sockets interface, however it is protocol independent in contrast to the socket interface which is heavily biased toward the Internet Protocols. It is based on the UNIX System V Transport Layer Interface (TLI)., which is a transport service definition adhering to the Open Systems Interconnection (OSI) model. XTI consists of a cooperating STREAMS module, link library application programming interface (API), header files, and the
X/Open Transport Interface
206796
the File Transfer Protocol (FTP), the Simple Mail Transfer Protocol (SMTP), and the Dynamic Host Configuration Protocol (DHCP). Data coded according to application layer protocols are encapsulated into transport layer protocol units (such as TCP or UDP messages), which in turn use lower layer protocols to effect actual data transfer. The TCP/IP model does not consider the specifics of formatting and presenting data, and does not define additional layers between the application and transport layers as in the OSI model (presentation and session layers). Such functions are the realm of libraries and application programming interfaces. Application layer protocols generally treat
Internet protocol suite
8031240
example, an address might be codice_1 instead of codice_2. For more information, see JANET NRS. The Yellow Book Transport Service was somewhat misnamed, as it does not fulfill the Transport role in the OSI 7-layer model. It really occupies the top of the Network layer, making up for X.25's lack of NSAP addressing at the time (which didn't appear until the X.25(1980) revision, and wasn't available in implementations for some years afterwards). YBTS used Source routing addressing between YBTS nodes—there was no global addressing scheme at that time. Coloured Book protocols The Coloured Book protocols were a set of computer
Coloured Book protocols
3994222
presentation layer formats shared by different applications. This keeps track of how each application talks to another application. Destination and source addresses are linked to specific applications. OSI protocols The Open Systems Interconnection protocols are a family of information exchange standards developed jointly by the ISO and the ITU-T. The standardization process began in 1977. While the seven-layer OSI model is often used as a reference for teaching and documentation, the protocols originally conceived for the model did not gain popularity, and only X.400, X.500, and IS-IS have achieved lasting impact. The goal of an open-standard protocol suite instead has
OSI protocols
1271417
the person displayed on screen is the current speaker. Another application is in live TV programs, where streams of audio and video need to be seamlessly merged and transitioned from one to the other to avoid silent airtime or excessive overlap. The TCP/IP reference model does not concern itself with the OSI model's details of application or transport protocol semantics and therefore does not consider a session layer. OSI's session management in connection with the typical transport protocols (TCP, SCTP), is contained in the transport-layer protocols, or otherwise considered the realm of the application layer protocols. TCP/IP's layers are "descriptions"
Session layer
1298248
preservation of record boundaries. Detailed characteristics of the classes are shown in the following table: There is also a connectionless transport protocol, specified by ISO/IEC 8602/ITU-T Recommendation X.234. Transport layer In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet Protocol Suite and the Open Systems Interconnection (OSI) reference model. The protocols of this layer provide host-to-host communication services for applications. It provides services such as connection-oriented communication, reliability, flow control, and multiplexing. The details of implementation and semantics of the transport layer of the
Transport layer
206783
own addressing systems (e.g. Ethernet) an address mapping protocol is needed. Such protocols can be considered to be below IP but above the existing link system. While the IETF does not use the terminology, this is a subnetwork dependent convergence facility according to an extension to the OSI model, the internal organization of the network layer (IONL). ICMP & IGMP operate on top of IP but do not transport data like UDP or TCP. Again, this functionality exists as layer management extensions to the OSI model, in its "Management Framework" (OSIRM MF) The SSL/TLS library operates above the transport layer
Internet protocol suite
1298242
Internet all originated in the development of TCP/IP. In the OSI model the transport layer is often referred to as Layer 4, or L4, while numbered layers are not used in TCP/IP. The best-known transport protocol of TCP/IP is the Transmission Control Protocol (TCP), and lent its name to the title of the entire suite. It is used for connection-oriented transmissions, whereas the connectionless User Datagram Protocol (UDP) is used for simpler messaging transmissions. TCP is the more complex protocol, due to its stateful design incorporating reliable transmission and data stream services. Other protocols in this group are the Datagram
Transport layer
1471215
upon the underlying transport layer protocols to establish host-to-host data transfer channels and manage the data exchange in a client-server or peer-to-peer networking model. Though the TCP/IP application layer does not describe specific rules or data formats that applications must consider when communicating, the original specification (in ) does rely on and recommend the robustness principle for application design. In the OSI model, the definition of the application layer is narrower in scope. The OSI model defines the application layer as the user interface responsible for displaying received information to the user. In contrast, the Internet Protocol Suite does not
Application layer
5101459
MMS using Internet protocols instead of the bottom four layers of the original stack plus RFC 1006 ("ISO Transport over TCP") in the transport layer. The top three layers use the same OSI protocols as before. In terms of the seven-layer OSI model, the new MMS stack looks like this: With the new stack, MMS has become a globally accepted standard. Manufacturing Message Specification Manufacturing Message Specification (MMS) is an international standard (ISO 9506) dealing with messaging systems for transferring real time process data and supervisory control information between networked devices or computer applications. The standard is developed and maintained
Manufacturing Message Specification
3515721
communication consists of independent requests with responses. An established session is the basic requirement to perform a connection-oriented communication. A session also is the basic step to transmit in connectionless communication modes. However any unidirectional transmission does not define a session. Communication Transport may be implemented as part of protocols and services at the application layer, at the session layer or at the transport layer in the OSI model. In the case of transport protocols that do not implement a formal session layer (e.g., UDP) or where sessions at the application layer are generally very short-lived (e.g., HTTP), sessions are
Session (computer science)
3994216
OSI protocols The Open Systems Interconnection protocols are a family of information exchange standards developed jointly by the ISO and the ITU-T. The standardization process began in 1977. While the seven-layer OSI model is often used as a reference for teaching and documentation, the protocols originally conceived for the model did not gain popularity, and only X.400, X.500, and IS-IS have achieved lasting impact. The goal of an open-standard protocol suite instead has been met by the Internet protocol suite, maintained by the Internet Engineering Task Force (IETF). The OSI protocol stack is structured into seven conceptual layers. The layers
OSI protocols
6996403
CANopen CANopen is a communication protocol and device profile specification for embedded systems used in automation. In terms of the OSI model, CANopen implements the layers above and including the network layer. The CANopen standard consists of an addressing scheme, several small communication protocols and an application layer defined by a device profile. The communication protocols have support for network management, device monitoring and communication between nodes, including a simple transport layer for message segmentation/desegmentation. The lower level protocol implementing the data link and physical layers is usually Controller Area Network (CAN), although devices using some other means of communication
CANopen
206803
in protocols like HTTP and SMTP and is more evident in protocols like Telnet and the Session Initiation Protocol (SIP). Session layer functionality is also realized with the port numbering of the TCP and UDP protocols, which cover the transport layer in the TCP/IP suite. Functions of the presentation layer are realized in the TCP/IP applications with the MIME standard in data exchange. Conflicts are apparent also in the original OSI model, ISO 7498, when not considering the annexes to this model, e.g., the ISO 7498/4 Management Framework, or the ISO 8648 Internal Organization of the Network layer (IONL). When
Internet protocol suite
17920019
Wire data Wire data is the information that passes over computer and telecommunication networks defining communications between client and server devices. It is the result of decoding wire and transport protocols containing the bi-directional data payload. More precisely, wire data is the information that is communicated in each layer of the OSI model (Layer 1 not being included because those protocols are used to establish connections and do not communicate information). Wire data is the observed behavior and communication between networked elements which is an important source of information used by IT operations staff to troubleshoot performance issues, create activity
Wire data
1298244
address of the process-to-process communication. In the OSI model, this function is supported by the session layer. Some transport layer protocols, for example TCP, but not UDP, support virtual circuits, i.e. provide connection-oriented communication over an underlying packet oriented datagram network. A byte-stream is delivered while hiding the packet mode communication for the application processes. This involves connection establishment, dividing of the data stream into packets called segments, segment numbering and reordering of out-of order data. Finally, some transport layer protocols, for example TCP, but not UDP, provide end-to-end reliable communication, i.e. error recovery by means of error detecting code
Transport layer
304513
"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. The transport layer provides the functional and procedural means of transferring variable-length data sequences from a source to a destination host, while maintaining the quality of service functions. 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
OSI model
8640681
Layer 8 Layer 8 is used to refer to "user" or "political" layer on top of the OSI model of computer networking. The OSI model is a 7-layer abstract model that describes an architecture of data communications for networked computers. The layers build upon each other, allowing for abstraction of specific functions in each one. The top (7th) layer is the Application Layer describing methods and protocols of software applications. It is then held that the user is the 8th layer. Network appliances vendor like Cyberoam claim that Layer 8 allows IT administrators to identify users, control Internet activity of
Layer 8
304516
mail to determine its delivery. 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 the endpoint, GRE becomes closer to a transport protocol that uses IP headers but contains complete Layer 2 frames or Layer
OSI model
6100774
port, AT&T developed protocol-independent STREAMS message passing guidelines for the link, network, and transport layers of the OSI model (layers 2-4). Due to the typically close implementation coupling of the network and transport protocols in a given protocol stack, and the typical practice of implementing layers 5-7 outside of the kernel, only the link and transport layer STREAMS service interfaces were later standardized by X/Open. In conjunction with the transport message passing model, the Transport Layer Interface (later adopted as the X/Open Transport Interface) was defined to provide a transport protocol-independent API for application development. Also, a library supporting the
STREAMS
984026
layer and request services from the session layer. It provides support for common application services, such as: The specific application service element sublayer provides application specific services (protocols), such as Other protocols sometimes considered at this level (though perhaps not strictly adhering to the OSI model) include: Presentation layer In the seven-layer OSI model of computer networking, the presentation layer is layer 6 and serves as the data translator for the network. It is sometimes called the syntax layer. The presentation layer is responsible for the delivery and formatting of information to the application layer for further processing or display.
Presentation layer
10229903
Systems Interconnection (OSI) protocol stack. Although they have some overlap, these two models represent different classification methods. In particular, the allowed characteristics of protocols (e.g., whether they are connection-oriented or connection-less) placed in these layers are different between the models. OSI's network layer is a "catch-all" layer for all protocols that facilitate network functionality. The internet layer, on the other hand, is specifically a suite of protocols that facilitate internetworking using the Internet Protocol. Internet layer The internet layer is a group of internetworking methods, protocols, and specifications in the Internet protocol suite that are used to transport network packets
Internet layer
538759
protocols used). Although X.25 predates the OSI Reference Model (OSIRM), the physical Layer of the OSI model corresponds to the X.25 "physical layer", the data link layer to the X.25 "data link layer", and the network layer to the X.25 "packet layer". The X.25 "data link layer", LAPB, provides a reliable data path across a data link (or multiple parallel data links, multilink) which may not be reliable itself. The X.25 "packet layer" provides the virtual call mechanisms, running over X.25 LAPB. The "packet layer" includes mechanisms to maintain virtual calls and to signal data errors in the event that
X.25
3994221
manages and terminates the connections between the local and remote application. It provides for full-duplex, and 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. This layer defines and encrypts/decrypts data types from the application layer. Protocols such as MIDI, MPEG, and GIF are
OSI protocols
200113
or voice chat. Two architectural models are commonly used to describe the protocols and methods used in internetworking. The Open System Interconnection (OSI) reference model was developed under the auspices of the International Organization for Standardization (ISO) and provides a rigorous description for layering protocol functions from the underlying hardware to the software interface concepts in user applications. Internetworking is implemented in the Network Layer (Layer 3) of the model. The Internet Protocol Suite, also called the TCP/IP model of the Internet was not designed to conform to the OSI model and does not refer to it in any of
Internetworking
304505
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
OSI model
304525
its own right. OSI model The Open Systems Interconnection model (OSI model) is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technology. Its goal is the interoperability of diverse communication systems with standard protocols. The model partitions a communication system into abstraction layers. The original version of the model defined seven layers. A layer serves the layer above it and is served by the layer below it. For example, a layer that provides error-free communications across a network provides the path needed by applications
OSI model
304502
OSI model The Open Systems Interconnection model (OSI model) is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technology. Its goal is the interoperability of diverse communication systems with standard protocols. The model partitions a communication system into abstraction layers. The original version of the model defined seven layers. A layer serves the layer above it and is served by 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
OSI model
7282723
while at the same time each layer communicates with its corresponding layer on the receiving node. These are known as adjacent-layer interaction and same-layer interaction, respectively. In discussions of encapsulation, the more abstract layer is often called the upper layer protocol while the more specific layer is called the lower layer protocol. Sometimes, however, the terms upper layer protocols and lower layer protocols are used to describe the layers above and below IP, respectively. Encapsulation is a characteristic feature of most networking models, including both the OSI model and TCP/IP suite of protocols. Encapsulation (networking) In computer networking, encapsulation is
Encapsulation (networking)
206765
into four abstraction layers, which classify all related protocols according to the scope of networking involved. From lowest to highest, the layers are the link layer, containing communication methods for data that remains within a single network segment (link); the internet layer, providing internetworking between independent networks; the transport layer, handling host-to-host communication; and the application layer, providing process-to-process data exchange for applications. Technical standards specifying the Internet protocol suite and many of its constituent protocols are maintained by the Internet Engineering Task Force (IETF). The Internet protocol suite predates the OSI model, a more comprehensive reference framework for general
Internet protocol suite
1471214
Application layer An application layer is an abstraction layer that specifies the shared communications protocols and interface methods used by hosts in a communications network. The application layer abstraction is used in both of the standard models of computer networking: the Internet Protocol Suite (TCP/IP) and the OSI model. Although both models use the same term for their respective highest level layer, the detailed definitions and purposes are different. In TCP/IP, the application layer contains the communications protocols and interface methods used in process-to-process communications across an Internet Protocol (IP) computer network. The application layer only standardizes communication and depends
Application layer
1471216
concern itself with such detail. OSI also explicitly distinguishes additional functionality below the application layer, but above the transport layer at two additional levels: the session layer, and the presentation layer. OSI specifies a strict modular separation of functionality at these layers and provides protocol implementations for each layer. The IETF definition document for the application layer in the Internet Protocol Suite is RFC 1123. It provided an initial set of protocols that covered the major aspects of functionality of the early Internet. There are commonly reoccurring problems that occur in the design and implementation of communication protocols that can
Application layer
3788054
and integrated into ISODE by Robbins. ISODE has a full implementation of a CMIP/TMN built on top of it by the OSIMIS project. The following people or groups were listed in the ISODE 8.0 manual as the significant contributors Several companies used the ISODE software to build successful commercial products and services including (alphabetical order): ISO Development Environment The ISODE software (pronounced eye-soo-dee-eee), more formally the "ISO Development Environment", was an implementation of the OSI upper layer protocols, from transport layer to application layer, which was used in the Internet research community to experiment with implementation and deployment of OSI
ISO Development Environment
984024
are 'objects' in object-oriented programming, and the exact way that streaming video is transmitted. In many widely used applications and protocols, no distinction is made between the presentation and application layers. For example, HyperText Transfer Protocol (HTTP), generally regarded as an application-layer protocol, has presentation-layer aspects such as the ability to identify character encoding for proper conversion, which is then done in the application layer. Within the service layering semantics of the OSI network architecture, the presentation layer responds to service requests from the application layer and issues service requests to the session layer. In the OSI model: the presentation
Presentation layer
13170105
Packet segmentation In data communications networks, packet segmentation is the process of dividing a data packet into smaller units for transmission over the network. Packet segmentation happens at layer four of the OSI model or the transport layer. Segmentation may be required when: Protocols that perform packet segmentation at the source usually include a mechanism at the destination to reverse the process and reassemble the original packet from individual segments. This process may include automatic repeat-request (ARQ) mechanisms to detect missing segments and to request the source to re-transmit specific segments. In a communication system based on a layered OSI
Packet segmentation
14733898
monolithic communication protocol, into the first two layers of the communication suite. This model was expanded to four layers by additional protocols. However, the Internet protocol development has not focussed on the principle of layering as mandatory recipe for communication, rather it evolved as a convenient description of modularity and protocol cooperation. A different model is the OSI seven layer model, which was developed internationally as a rigorous reference model for general communication, with much stricter rules of protocol interaction and a rigorous layering concept of functionality. Typically, application software is built upon a robust data transport layer. Underlying this
Communication protocol
15334706
wide area network connection. Despite the different semantics of layering in TCP/IP and OSI, the link layer is sometimes described as a combination of the data link layer (layer 2) and the physical layer (layer 1) in the OSI model. However, the layers of TCP/IP are descriptions of operating scopes (application, host-to-host, network, link) and not detailed "prescriptions" of operating procedures, data semantics, or networking technologies. RFC 1122 exemplifies that local area network protocols such as Ethernet and IEEE 802, and framing protocols such as Point-to-Point Protocol (PPP) belong to the link layer. Local area networking standards such as Ethernet
Link layer
15334711
however it was developed within the OSI reference stack, where it is a Layer 2 protocol. It is not an Internet standard. The link layer of the TCP/IP model is often compared directly with the combination of the data link layer and the physical layer in the Open Systems Interconnection (OSI) protocol stack. Although they are congruent to some degree in technical coverage of protocols, they are not identical. The link layer in TCP/IP is still wider in scope and in principle a different concept and terminology of classification. This may be observed when certain protocols, such as the Address
Link layer
14733931
of standardization and an overview of protocols using this scheme is given in the article on OSI protocols. In networking equipment configuration, a term-of-art distinction is often drawn: The term "protocol" strictly refers to the transport layer, and the term "service" refers to protocols utilizing a "protocol" for transport. In the common case of the TCP and UDP "protocols", "services" are distinguished by their port numbers. Conformance to these port numbers is voluntary, so in content inspection systems the term "service" strictly refers to port numbers, and the term "application" is often used to refer to protocols identified through inspection
Communication protocol
304521
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 are services that are not tied to a given layer, but may affect more than one layer. Examples include the following: Neither the OSI Reference Model nor OSI
OSI model
5980654
The DNP3 protocol has significant features that make it more robust, efficient, and interoperable than older protocols such as Modbus, at the cost of higher complexity. In terms of the OSI model for networks, DNP3 specifies a layer 2 protocol. It provides multiplexing, data fragmentation, error checking, link control, prioritization, and layer 2 addressing services for user data. It also defines a Transport function (somewhat similar to the function of layer 4) and an Application Layer (layer 7) that defines functions and generic data types suitable for common SCADA applications. The DNP3 frame strongly resembles, but is not identical to
DNP3
3788050
ISO Development Environment The ISODE software (pronounced eye-soo-dee-eee), more formally the "ISO Development Environment", was an implementation of the OSI upper layer protocols, from transport layer to application layer, which was used in the Internet research community to experiment with implementation and deployment of OSI during the late 1980s and early 1990s. The ISODE software was initially a public domain / open source implementation, led by Marshall Rose. Following version 6.0, Marshall handed the lead over to Colin Robbins and Julian Onions, who coordinated the 7.0 and 8.0 releases. Version 8.0 was the final public domain release, made on June
ISO Development Environment
538938
Protocol (IP) networks. IPsec supports network-level peer authentication, data-origin authentication, data integrity, data confidentiality (encryption), and replay protection. The initial IPv4 suite was developed with few security provisions. As a part of the IPv4 enhancement, IPsec is a layer 3 OSI model or Internet Layer end-to-end security scheme, while some other Internet security systems in widespread use operate above layer 3, such as Transport Layer Security (TLS) and Secure Shell (SSH), both of which operate at the Application layer. IPsec can automatically secure applications at the IP layer. From 1986 to 1991, the NSA sponsored the development of security protocols
IPsec
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host to interact with a corresponding entity at the same layer in another host. Service definitions abstractly describe 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. 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. The recommendation X.200 describes seven layers, labeled 1
OSI model
206784
(uses TCP) but below application protocols. Again, there was no intention, on the part of the designers of these protocols, to comply with OSI architecture. The link is treated as a black box. The IETF explicitly does not intend to discuss transmission systems, which is a less academic but practical alternative to the OSI model. The following is a description of each layer in the TCP/IP networking model starting from the lowest level. The link layer has the networking scope of the local network connection to which a host is attached. This regime is called the "link" in TCP/IP literature.
Internet protocol suite
206801
use the best-effort UDP transport. Different authors have interpreted the TCP/IP model differently, and disagree whether the link layer, or the entire TCP/IP model, covers OSI layer 1 (physical layer) issues, or whether a hardware layer is assumed below the link layer. Several authors have attempted to incorporate the OSI model's layers 1 and 2 into the TCP/IP model, since these are commonly referred to in modern standards (for example, by IEEE and ITU). This often results in a model with five layers, where the link layer or network access layer is split into the OSI model's layers 1 and
Internet protocol suite
3799145
Service Access Point A Service Access Point (SAP) is an identifying label for network endpoints used in Open Systems Interconnection (OSI) networking. The SAP is a conceptual location at which one OSI layer can request the services of another OSI layer. As an example, PD-SAP or PLME-SAP in IEEE 802.15.4 can be mentioned, where the Media Access Control (MAC) layer requests certain services from the Physical Layer. Service access points are also used in IEEE 802.2 Logical Link Control in Ethernet and similar Data Link Layer protocols. When using the OSI Network Layer (CONS or CLNS), the base for constructing
Service Access Point
1909827
Data Link Control In the OSI networking model, Data Link Control (DLC) is the service provided by the data link layer. Network interface cards have a DLC address that identifies each card; for instance, Ethernet and other types of cards have a 48-bit MAC address built into the cards' firmware when they are manufactured. There is also a network protocol with the name Data Link Control. It is comparable to better-known protocols such as TCP/IP or AppleTalk. DLC is a transport protocol used by IBM SNA mainframe computers and peripherals and compatible equipment. In computer networking, it is typically used
Data Link Control
206789
information, and IGMP which is used to manage IP Multicast data, are layered on top of IP but perform internetworking functions. This illustrates the differences in the architecture of the TCP/IP stack of the Internet and the OSI model. The TCP/IP model's internet layer corresponds to layer three of the Open Systems Interconnection (OSI) model, where it is referred to as the network layer. The internet layer provides an unreliable datagram transmission facility between hosts located on potentially different IP networks by forwarding the transport layer datagrams to an appropriate next-hop router for further relaying to its destination. With this
Internet protocol suite
514132
Although the OSI model is often still referred to, the Internet's TCP/IP protocol suite is used in lieu of the OSI protocols. TCP/IP's pragmatic approach to computer networking and two independent implementations of simplified protocols made it a practical standard. Some protocols and specifications in the OSI stack remain in use, one example being IS-IS, which was specified for OSI as ISO/IEC 10589:2002 and adapted for Internet use (with TCP/IP) as . The standard ISO/IEC 7498 consists of the following parts: Open Systems Interconnection The Open Systems Interconnection model (OSI model) is a conceptual model that characterizes and standardizes the
Open Systems Interconnection
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order to allow the receiving node to pass each received frame to an appropriate device driver which understands given protocol. The Open Systems Interconnect (OSI) model uses a SAP to define the communication between layers (like Network, Transport, Session, and the other layers of the Seven-Layered Model), that is to identify which protocol should process an incoming message. Within a given layer, programs can exchange data by a mutually agreed upon protocol mechanism. A pair of programs that do not support a common protocol cannot communicate with each other. Thus for multiple protocols to coexist within a layer, it is
Subnetwork Access Protocol
206802
2. The IETF protocol development effort is not concerned with strict layering. Some of its protocols may not fit cleanly into the OSI model, although RFCs sometimes refer to it and often use the old OSI layer numbers. The IETF has repeatedly stated that Internet protocol and architecture development is not intended to be OSI-compliant. RFC 3439, addressing Internet architecture, contains a section entitled: "Layering Considered Harmful". For example, the session and presentation layers of the OSI suite are considered to be included to the application layer of the TCP/IP suite. The functionality of the session layer can be found
Internet protocol suite
9909182
about hop costs, the time they require to reach routing convergence, their scalability, and other factors. Although there are many types of routing protocols, three major classes are in widespread use on IP networks: Many routing protocols are defined in documents called RFCs. Routing protocols, according to the OSI routing framework, are layer management protocols for the network layer, regardless of their transport mechanism: Interior gateway protocols (IGPs) exchange routing information within a single routing domain. Examples of IGPs include: Exterior gateway protocols exchange routing information between autonomous systems. Examples include: Many software implementations exist for most of the common
Routing protocol
19406600
VARAN VARAN (Versatile Automation Random Access Network) is a Fieldbus Ethernet-based industrial communication system. VARAN is a wired data network technology for local data networks (LAN) with the main application in the field of automation technology. It enables the exchange of data in the form of data frames between all LAN connected devices (controllers, input/output devices, drives, etc.). VARAN includes the definitions for types of cables and connectors, describes the physical signalling and specifies packet formats and protocols. From the perspective of the OSI model, VARAN specifies both the physical layer (OSI Layer 1) and the data link layer (OSI
VARAN
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a strict hierarchical sequence of encapsulation requirements, as is attributed to OSI protocols. Data link layer The data layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between adjacent network nodes in a wide area network (WAN) or between nodes on the same local area network (LAN) segment. The data link layer provides the functional and procedural means to transfer data between network entities and might provide the means to detect and possibly correct errors that may occur in the physical layer. The data
Data link layer
3596524
alarms to the network management system. CMIP is implemented in association with the ACSE and ROSE protocols. Both are Layer 7 OSI protocols (Application Layer). ACSE is used to manage associations between management applications (i.e. manage connections between CMIP agents). ROSE is employed for all data exchange interactions. Besides the presence of these Layer 7 protocols, CMIP assumes the presence of all OSI layers at lower levels but does not explicitly specify what these should be. There have been some attempts to adapt CMIP to the TCP/IP protocol stack. Most notable is CMOT contained in RFC 1189 (detailing CMIP over
Common Management Information Protocol
193700
was held — February 1980. The services and protocols specified in IEEE 802 map to the lower two layers (Data Link and Physical) of the seven-layer OSI networking reference model. In fact, IEEE 802 splits the OSI Data Link Layer into two sub-layers named logical link control (LLC) and media access control (MAC), so the layers can be listed like this: The IEEE 802 family of standards is maintained by the IEEE 802 LAN/MAN Standards Committee (LMSC). The most widely used standards are for the Ethernet family, Token Ring, Wireless LAN, Bridging and Virtual Bridged LANs. An individual working group
IEEE 802
6614488
Wireless Datagram Protocol Wireless Datagram Protocol (WDP) defines the movement of information from receiver to the sender and resembles the User Datagram Protocol in the Internet protocol suite. The Wireless Datagram Protocol (WDP), a protocol in WAP architecture, covers the Transport Layer Protocols in the Internet model. As a general transport service, WDP offers to the upper layers an invisible interface independent of the underlying network technology used. In consequence of the interface common to transport protocols, the upper layer protocols of the WAP architecture can operate independently of the underlying wireless network. By letting only the transport layer deal
Wireless Datagram Protocol
5714584
and they are Physical layer, Data-Link layer, Network layer, Transport layer, Session layer, Presentation layer, and Application layer. Each packet that a computer sends out to another computer must go through each layer of the OSI Model. Sockets The standard way to communicate on a network with the use of computer operating systems is a socket. A socket is used by a programmer to create a way to send and receive data using the layers of the OSI. There are two types of sockets: a Stream Socket and a Datagram Socket. Stream Sockets use Transmission Control Protocol (TCP). A Datagram
Hacking: The Art of Exploitation
206800
top layers in the OSI model, i.e. the application layer, the presentation layer and the session layer, are not distinguished separately in the TCP/IP model which only has an application layer above the transport layer. While some pure OSI protocol applications, such as X.400, also combined them, there is no requirement that a TCP/IP protocol stack must impose monolithic architecture above the transport layer. For example, the NFS application protocol runs over the eXternal Data Representation (XDR) presentation protocol, which, in turn, runs over a protocol called Remote Procedure Call (RPC). RPC provides reliable record transmission, so it can safely
Internet protocol suite
7966145
systems based on the lowest layer in the OSI model where the protocol exists. Layer 1 protocols use Ethernet wiring and signaling components but do not use the Ethernet frame structure. Layer 1 protocols often use their own media access control (MAC) rather than the one native to Ethernet, which generally creates compatibility issues and thus requires a dedicated network for the protocol. Layer 2 protocols encapsulate audio data in standard Ethernet packets. Most can make use of standard Ethernet hubs and switches though some require that the network (or at least a VLAN) be dedicated to the audio distribution
Audio over Ethernet
19707981
Hybrid Management Sub-Layer The SCTE Hybrid Management Sub-Layer (HMS) refers to a set of specifications intended to support the design and implementation of inter-operable management systems for evolving HFC cable networks. The HMS Physical (PHY) Layer Specification describes the physical layer portion of the protocol stack used for communication between HMS-compliant transponders interfacing to manage outside plant network elements (NE) and a centralized headend element (HE). The HMS Media Access Control (MAC) Layer Specification describes the messaging and protocols implemented at the Data Link Layer (DLL), Layer 2 in the 7-layer ISO-OSI reference model, that support reliable and efficient communications
Hybrid Management Sub-Layer
881016
model has a layer called the Internet layer, located above the link layer. In many textbooks and other secondary references, the TCP/IP Internet layer is equated with the OSI network layer. However, this comparison is misleading, as the allowed characteristics of protocols (e.g., whether they are connection-oriented or connection-less) placed into these layers are different in the two models. The TCP/IP Internet layer is in fact only a subset of functionality of the network layer. It describes only one type of network architecture, the Internet. The following are examples of protocols operating at the network layer. Network layer In the
Network layer
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Reliable Data Protocol The Reliable Data Protocol (RDP) is a network transport protocol defined in RFC 908 and was updated in RFC 1151. It is meant to provide facilities for remote loading, debugging and bulk transfer of images and data. It should not be confused with RUDP. The Reliable Data Protocol is located on the Transport Layer of the OSI Model next to protocols like TCP or UDP. It is number 27 in the list of IP protocol numbers. Similar to TCP, the Reliable Data Protocol is connection oriented, but, contrary to TCP, it does not require sequenced delivery of
Reliable Data Protocol
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segments. The Reliable Data Protocol has not gained popularity, though experimental implementations for BSD exist. Reliable Data Protocol The Reliable Data Protocol (RDP) is a network transport protocol defined in RFC 908 and was updated in RFC 1151. It is meant to provide facilities for remote loading, debugging and bulk transfer of images and data. It should not be confused with RUDP. The Reliable Data Protocol is located on the Transport Layer of the OSI Model next to protocols like TCP or UDP. It is number 27 in the list of IP protocol numbers. Similar to TCP, the Reliable Data
Reliable Data Protocol
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ISDN User Part (ISUP), the User Part provides layer 7. Currently there are no protocol components that provide OSI layers 4 through 6. The Transaction Capabilities Application Part (TCAP) is the primary SCCP User in the Core Network, using SCCP in connectionless mode. SCCP in connection oriented mode provides transport layer for air interface protocols such as BSSAP and RANAP. TCAP provides transaction capabilities to its Users (TC-Users), such as the Mobile Application Part, the Intelligent Network Application Part and the CAMEL Application Part. The Message Transfer Part (MTP) covers a portion of the functions of the OSI network layer
Signalling System No. 7
849752
(LAN) or a metropolitan area network (MAN) using Open Systems Interconnection (OSI) architecture, the "physical signaling sublayer" is the portion of the physical layer that The Internet protocol suite, as defined in RFC 1122 and RFC 1123, is a high-level networking description used for the Internet and similar networks. It does not define an equivalent layer that deals exclusively with hardware-level specifications and interfaces, as this model does not concern itself directly with physical interfaces. Several RFCs mention a "physical layer" and "data link layer", but that is in the context of IEEE protocols. RFC 1122 and 1123 do not
Physical layer
2785772
is ANSI T1.111. In Europe, national MTP protocols are based on ETSI EN 300-0088-1. The SS7 stack can be separated into four functional levels: Level 1 through Level 3 comprise the "MTP", and Level 4 the "MTP user". "MTP Level 3" is sometimes abbreviated "MTP3"; "MTP Level 2", "MTP2". MTP and SCCP are together referred to as the "Network Service Part (NSP)". There is no one-to-one mapping of MTP Levels 1 through 3 onto the OSI model. Instead, MTP provides the functionality of layers 1, 2 and part of layer 3 in the OSI model. The part of layer 3
Message Transfer Part
117376
of its history, Ethernet data transfer rates have been increased from the original 2.94 megabits per second (Mbit/s) to the latest 400 gigabits per second (Gbit/s). The comprise several wiring and signaling variants of the OSI physical layer in use with Ethernet. Systems communicating over Ethernet divide a stream of data into shorter pieces called frames. Each frame contains source and destination addresses, and error-checking data so that damaged frames can be detected and discarded; most often, higher-layer protocols trigger retransmission of lost frames. As per the OSI model, Ethernet provides services up to and including the data link layer.
Ethernet
519004
or channel access method, for example, TDM into time-division multiple access (TDMA) and statistical multiplexing into carrier-sense multiple access (CSMA). A multiple access method makes it possible for several transmitters connected to the same physical medium to share its capacity. Multiplexing is provided by the Physical Layer of the OSI model, while multiple access also involves a media access control protocol, which is part of the Data Link Layer. The Transport layer in the OSI model, as well as TCP/IP model, provides statistical multiplexing of several application layer data flows to/from the same computer. Code-division multiplexing (CDM) is a technique
Multiplexing
519060
with media access control methods and protocols. Some networks are able to dynamically change their logical topology through configuration changes to their routers and switches. The transmission media (often referred to in the literature as the "physical media") used to link devices to form a computer network include electrical cable (Ethernet, HomePNA, power line communication, G.hn), optical fiber (fiber-optic communication), and radio waves (wireless networking). In the OSI model, these are defined at layers 1 and 2 — the physical layer and the data link layer. A widely adopted "family" of transmission media used in local area network (LAN) technology
Network topology
6614489
with physical network-dependent issues, global interoperability can be acquired using mediating gateways. Wireless Datagram Protocol Wireless Datagram Protocol (WDP) defines the movement of information from receiver to the sender and resembles the User Datagram Protocol in the Internet protocol suite. The Wireless Datagram Protocol (WDP), a protocol in WAP architecture, covers the Transport Layer Protocols in the Internet model. As a general transport service, WDP offers to the upper layers an invisible interface independent of the underlying network technology used. In consequence of the interface common to transport protocols, the upper layer protocols of the WAP architecture can operate independently
Wireless Datagram Protocol
518979
protocols. Of these, the MAC group addresses in the range of 01-80-C2-00-00-00 to 01-80-C2-00-00-0F are not relayed by MAC bridges conforming to 802.1D. 802.11 wireless networks use the same 01:00:5E:xx:xx:xx and 33:33:xx:xx:xx:xx MAC addresses for multicasting as Ethernet. Multicast address A multicast address is a logical identifier for a group of hosts in a computer network that are available to process datagrams or frames intended to be multicast for a designated network service. Multicast addressing can be used in the link layer (layer 2 in the OSI model), such as Ethernet multicast, and at the internet layer (layer 3 for
Multicast address
10638864
transmitting the MID to ensure that another node has not simultaneously transmitted a MID with a higher priority. SAE J1708, although still widely used, is replaced by SAE J1939 which is a CAN protocol. SAE J1708 SAE J1708 is a standard used for serial communications between ECUs on a heavy duty vehicle and also between a computer and the vehicle. With respect to Open System Interconnection model (OSI), J1708 defines the physical layer. Common higher layer protocols that operate on top of J1708 are SAE J1587 and SAE J1922. The protocol is maintained by SAE International. The standard defines a
SAE J1708
22497
delivery. All application-level protocols, including the infrastructure protocols NBP, RTMP and ZIP, were built on top of DDP. AppleTalk's DDP corresponds closely to the Network layer of the Open Systems Interconnection (OSI) communication model. Name Binding Protocol was a dynamic, distributed system for managing AppleTalk names. When a service started up on a machine, it registered a name for itself as chosen by a human administrator. At this point, NBP provided a system for checking that no other machine had already registered the same name. Later, when a client wanted to access that service, it used NBP to query machines
AppleTalk
538901
of ISDN's layer two protocol, LAPD and LAPB. As such, its integrity operations pertain only between nodes on a link, not end-to-end. Any retransmissions must be carried out by higher layer protocols. The X.25 UNI protocol is part of the X.25 protocol suite, which consists of the lower three layers of the OSI Model. It was widely used at the UNI for packet switching networks during the 1980s and early 1990s, to provide a standardized interface into and out of packet networks. Some implementations used X.25 within the network as well, but its connection-oriented features made this setup cumbersome and
Packet switching
206787
stack for transmission or reception over another IP connection. Such a connection, or virtual link, may be established with a transport protocol or even an application scope protocol that serves as a tunnel in the link layer of the protocol stack. Thus, the TCP/IP model does not dictate a strict hierarchical encapsulation sequence. The TCP/IP model's link layer corresponds to the Open Systems Interconnection (OSI) model physical and data link layers, layers one and two of the OSI model. The internet layer has the responsibility of sending packets across potentially multiple networks. Internetworking requires sending data from the source network
Internet protocol suite
15334707
and IEEE 802 specifications use terminology from the seven-layer OSI model rather than the TCP/IP model. The TCP/IP model in general does not consider physical specifications, rather it assumes a working network infrastructure that can deliver media level frames on the link. Therefore, RFC 1122 and RFC 1123, the definition of the TCP/IP model, do not discuss hardware issues and physical data transmission and set no standards for those aspects. Some textbook authors have supported the interpretation that physical data transmission aspects are part of the link layer. Others assumed that physical data transmission standards are not considered communication protocols,
Link layer
2924276
graphical objects. Abstraction layer In computing, an abstraction layer or abstraction level is a way of hiding the working details of a subsystem, allowing the separation of concerns to facilitate interoperability and platform independence. Examples of software models that use layers of abstraction include the OSI model for network protocols, OpenGL and other graphics libraries. In computer science, an abstraction layer is a generalization of a conceptual model or algorithm, away from any specific implementation. These generalizations arise from broad similarities that are best encapsulated by models that express similarities present in various specific implementations. The simplification provided by a
Abstraction layer
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Abstraction layer In computing, an abstraction layer or abstraction level is a way of hiding the working details of a subsystem, allowing the separation of concerns to facilitate interoperability and platform independence. Examples of software models that use layers of abstraction include the OSI model for network protocols, OpenGL and other graphics libraries. In computer science, an abstraction layer is a generalization of a conceptual model or algorithm, away from any specific implementation. These generalizations arise from broad similarities that are best encapsulated by models that express similarities present in various specific implementations. The simplification provided by a good abstraction
Abstraction layer
11706015
cooperation with Texas Instruments Deutschland GmbH and Techem GmbH. The concept was based on the ISO-OSI Reference Model, in order to realize an open system which could use almost any desired protocol. Since the M-Bus is not a network, and therefore does not - among other things - need a transport or session layer, the levels four to six of the OSI model are empty. Therefore, only the physical, the data link, the network and the application layer are provided with functions. Meter-Bus M-Bus (Meter-Bus) is a European standard (EN 13757-2 physical and link layer, EN 13757-3 application layer) for
Meter-Bus
12795448
The specification has been extended multiple times, thereby it became important to the area of voice- and fax-communication. Because pure data transfer over IP-based networks is dominant in modern times, CAPI is being used primarily in the scope of voice applications (voice mail, IVR, call-center, voice conference systems etc.), for fax-servers and combined systems (UMS). The CAPI Interface in its current release (CAPI 2.0) supports a variety of signaling protocols (D channel protocols), e.g. DSS1 and FTZ 1 TR 6. The interface operates in the OSI model between layer 3 and 4 but only controls layers 1 to 3. Besides
Common ISDN Application Programming Interface
17920023
analyzers. Newer approaches receive a copy of network traffic from a port mirror (SPAN) or network tap and reassemble those packets into full per-client sessions and transaction streams, analyzing the entire transaction payload in real time and generating metadata on those transactions without storing the actual packets. Wire data Wire data is the information that passes over computer and telecommunication networks defining communications between client and server devices. It is the result of decoding wire and transport protocols containing the bi-directional data payload. More precisely, wire data is the information that is communicated in each layer of the OSI model
Wire data
1348346
Layer of OSI, and encompasses all methods that affect the local link. The TCP/IP model is not a top-down comprehensive design reference for networks. It was formulated for the purpose of illustrating the logical groups and scopes of functions needed in the design of the suite of internetworking protocols of TCP/IP, as needed for the operation of the Internet. In general, direct or strict comparisons of the OSI and TCP/IP models should be avoided, because the layering in TCP/IP is not a principal design criterion and in general considered to be "harmful" (RFC 3439). In particular, TCP/IP does not dictate
Data link layer
1288912
Logical link control In the IEEE 802 reference model of computer networking, the logical link control (LLC) data communication protocol layer is the upper sublayer of the data link layer (layer 2) of the seven-layer OSI model. The LLC sublayer provides multiplexing mechanisms that make it possible for several network protocols (e.g. IP, IPX, Decnet and Appletalk) to coexist within a multipoint network and to be transported over the same network medium. It can also provide flow control and automatic repeat request (ARQ) error management mechanisms. The LLC sublayer acts as an interface between the media access control (MAC) sublayer
Logical link control
543734
is possible to layer a transport protocol on top of the packet service that can provide such protection; TCP and UDP are the best examples of layer 4, the Transport Layer, of the seven layered OSI model. The Consultative Committee for Space Data Systems (CCSDS) packet telemetry standard defines the protocol used for the transmission of spacecraft instrument data over the deep-space channel. Under this standard, an image or other data sent from a spacecraft instrument is transmitted using one or more packets. A packet is a block of data with length that can vary between successive packets, ranging from
Network packet