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In wide area network computing, Link Access Procedure for Frame Relay (or LAPF) is part of the network's communications protocol which ensures that frames are error free and executed in the right sequence.
LAPF is formally defined in the International Telecommunication Union standard Q.922. It was derived from IBM's Synchronous Data Link Control protocol, which is the layer 2 protocol for IBM's Systems Network Architecture developed around 1975. ITU used SDLC as a basis to develop LAPF for the Frame Relay environment, along with other equivalents: LAPB for the X.25 protocol stack, LAPM for the V.42 protocol, and LAPD for the ISDN protocol stack.
In Frame Relay Local Management Interface (LMI) messages are carried in a variant of LAPF frames.
LAPF corresponds to the OSI model Data Link layer.
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The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP). In the development of this networking model, early versions of it were known as the Department of Defense (DoD) model because the research and development were funded by the United States Department of Defense through DARPA.
Multiprotocol Label Switching (MPLS) is a routing technique in telecommunications networks that directs data from one node to the next based on labels rather than network addresses. Whereas network addresses identify endpoints the labels identify established paths between endpoints. MPLS can encapsulate packets of various network protocols, hence the multiprotocol component of the name. MPLS supports a range of access technologies, including T1/E1, ATM, Frame Relay, and DSL.
The Open Systems Interconnection model is a conceptual model that 'provides a common basis for the coordination of [ISO] standards development for the purpose of systems interconnection'. In the OSI reference model, the communications between a computing system are split into seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.
In computer networking, Point-to-Point Protocol (PPP) is a data link layer communication protocol between two routers directly without any host or any other networking in between. It can provide loop connection authentication, transmission encryption, and data compression.
Frame Relay is a standardized wide area network (WAN) technology that specifies the physical and data link layers of digital telecommunications channels using a packet switching methodology. Originally designed for transport across Integrated Services Digital Network (ISDN) infrastructure, it may be used today in the context of many other network interfaces.
In telecommunications, a protocol data unit (PDU) is a single unit of information transmitted among peer entities of a computer network. It is composed of protocol-specific control information and user data. In the layered architectures of communication protocol stacks, each layer implements protocols tailored to the specific type or mode of data exchange.
High-Level Data Link Control (HDLC) is a bit-oriented code-transparent synchronous data link layer protocol developed by the International Organization for Standardization (ISO). The standard for HDLC is ISO/IEC 13239:2002.
Systems Network Architecture (SNA) is IBM's proprietary networking architecture, created in 1974. It is a complete protocol stack for interconnecting computers and their resources. SNA describes formats and protocols but, in itself, is not a piece of software. The implementation of SNA takes the form of various communications packages, most notably Virtual Telecommunications Access Method (VTAM), the mainframe software package for SNA communications.
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 of the seven-layer OSI model. The LLC sublayer acts as an interface between the media access control (MAC) sublayer and the network layer.
The data link 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 nodes on a network segment across the physical layer. The data link layer provides the functional and procedural means to transfer data between network entities and may also provide the means to detect and possibly correct errors that can occur in the physical layer.
In IEEE 802 LAN/MAN standards, the medium access control sublayer is the layer that controls the hardware responsible for interaction with the wired, optical or wireless transmission medium. The MAC sublayer and the logical link control (LLC) sublayer together make up the data link layer. The LLC provides flow control and multiplexing for the logical link, while the MAC provides flow control and multiplexing for the transmission medium.
AX.25 is a data link layer protocol originally derived from layer 2 of the X.25 protocol suite and designed for use by amateur radio operators. It is used extensively on amateur packet radio networks.
Synchronous Data Link Control (SDLC) is a computer communications protocol. It is the layer 2 protocol for IBM's Systems Network Architecture (SNA). SDLC supports multipoint links as well as error correction. It also runs under the assumption that an SNA header is present after the SDLC header. SDLC was mainly used by IBM mainframe and midrange systems; however, implementations exist on many platforms from many vendors. In the United States and Canada, SDLC can be found in traffic control cabinets.
Link Access Procedure, Balanced (LAPB) implements the data link layer as defined in the X.25 protocol suite. LAPB is a bit-oriented protocol derived from HDLC that ensures that frames are error free and in the correct sequence. LAPB is specified in ITU-T Recommendation X.25 and ISO/IEC 7776. It implements the connection-mode data link service in the OSI Reference Model as defined by ITU-T Recommendation X.222.
Throughput of a network can be measured using various tools available on different platforms. This page explains the theory behind what these tools set out to measure and the issues regarding these measurements.
Connection-oriented communication is a network communication mode in telecommunications and computer networking, where a communication session or a semi-permanent connection is established before any useful data can be transferred. The established connection ensures that data is delivered in the correct order to the upper communication layer. The alternative to connection-oriented transmission is connectionless communication, for example the datagram mode communication used by Internet Protocol (IP) and User Datagram Protocol, where data may be delivered out of order, since different network packets are routed independently and may be delivered over different paths.
Token Ring is a computer networking technology used to build local area networks. It was introduced by IBM in 1984, and standardized in 1989 as IEEE 802.5.
In mobile-telephone technology, the UniPro protocol stack follows the architecture of the classical OSI Reference Model. In UniPro, the OSI Physical Layer is split into two sublayers: Layer 1 and Layer 1.5 which abstracts from differences between alternative Layer 1 technologies. The actual physical layer is a separate specification as the various PHY options are reused in other MIPI Alliance specifications.
Distributed Overlay Virtual Ethernet (DOVE) is a tunneling and virtualization technology for computer networks, created and backed by IBM. DOVE allows creation of network virtualization layers for deploying, controlling, and managing multiple independent and isolated network applications over a shared physical network infrastructure.