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Encyclopedia > Physical layer
OSI Model
7 Application layer
6 Presentation layer
5 Session layer
4 Transport layer
3 Network layer
2 Data link layer
1 Physical layer
The five-layer TCP/IP model
5. Application layer

DHCPDNSFTPGopherHTTPIMAP4IRCNNTPXMPPMIMEPOP3SIPSMTPSNMPSSHTELNETRPC • RTP • RTCPTLS/SSLSDPSOAP • … The Open Systems Interconnection Basic Reference Model (OSI Reference Model or OSI Model for short) is a layered, abstract description for communications and computer network protocol design, developed as part of Open Systems Interconnection (OSI) initiative. ... The application layer is the seventh level of the seven-layer OSI model. ... The presentation layer is the sixth level of the seven layer OSI model. ... The session layer is level five of the seven level OSI model. ... In computing and telecommunications, the transport layer is layer four of the seven layer OSI model. ... The network layer is level three of the seven level OSI model. ... The data link layer is layer two of the seven-layer OSI model as well as of the five-layer TCP/IP reference model. ... According to the IEEE 802 family of standards, Logical Link Control (LLC) is the upper sublayer of the OSI data link layer. ... The Medium Access Control (MAC) data communication protocol sub-layer, also known as the Media Access Control, is a part of the data link layer specified in the seven-layer OSI model (layer 2). ... The TCP/IP model or Internet reference model, sometimes called the DoD model (DoD, Department of Defense), ARPANET reference model, is a layered abstract description for communications and computer network protocol design. ... The application layer is the seventh level of the seven-layer OSI model. ... (DHCP) is a set of rules used by a communications device such as a computer, router or network adapter to allow the device to request and obtain an IP address from a server which has a list of addresses available for assignment. ... On the Internet, the Domain Name System (DNS) stores and associates many types of information with domain names; most importantly, it serves as the phone book for the internet, translating human-friendly domain names and computer hostnames, e. ... “FTP” redirects here. ... Gopher is a distributed document search and retrieval network protocol designed for the Internet. ... Hypertext Transfer Protocol (HTTP) is a communications protocol used to transfer or convey information on the World Wide Web. ... The Internet Message Access Protocol (commonly known as IMAP or IMAP4, and previously called Internet Mail Access Protocol, Interactive Mail Access Protocol (RFC 1064), and Interim Mail Access Protocol [1] ) is an application layer Internet protocol that allows a local client to access e-mail on a remote server. ... Internet Relay Chat (IRC) is a form of real-time Internet chat or synchronous conferencing. ... The Network News Transfer Protocol or NNTP is an Internet application protocol used primarily for reading and posting Usenet articles, as well as transferring news among news servers. ... Extensible Messaging and Presence Protocol, or XMPP, is an open, XML-based protocol for near real-time extensible messaging and presence events. ... Multipurpose Internet Mail Extensions (MIME) is an Internet Standard that extends the format of e-mail to support: text in character sets other than US-ASCII; non-text attachments; multi-part message bodies; and header information in non-ASCII character sets. ... In computing, local e-mail clients use the Post Office Protocol version 3 (POP3), an application-layer Internet standard protocol, to retrieve e-mail from a remote server over a TCP/IP connection. ... The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. ... Simple Mail Transfer Protocol (SMTP) is the de facto standard for e-mail transmissions across the Internet. ... The simple network management protocol (SNMP) forms part of the internet protocol suite as defined by the Internet Engineering Task Force (IETF). ... Secure Shell or SSH is a network protocol that allows data to be exchanged over a secure channel between two computers. ... For the packet switched network, see Telenet. ... Remote procedure call (RPC) is a protocol that allows a computer program running on one computer to cause a subroutine on another computer to be executed without the programmer explicitly coding the details for this interaction. ... The Real-time Transport Protocol (or RTP) defines a standardized packet format for delivering audio and video over the Internet. ... RTP Control Protocol (RTCP) is a sister protocol of the Real-time Transport Protocol (RTP). ... This article or section does not adequately cite its references or sources. ... Session Description Protocol (SDP), is a format for describing streaming media initialization parameters. ... This article is about the computer protocol. ...

4. Transport layer

TCPUDPDCCPSCTPGTP • … In computing and telecommunications, the transport layer is layer four of the seven layer OSI model. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite, often simply referred to as TCP/IP. Using TCP, applications on networked hosts can create connections to one another, over which they can exchange streams of data using Stream Sockets. ... The User Datagram Protocol (UDP) is one of the core protocols of the Internet protocol suite. ... The Datagram Congestion Control Protocol (DCCP) is a message-oriented transport layer protocol that is currently under development in the IETF. Applications that might make use of DCCP include those with timingconstraints on the delivery of data such that reliable in-order delivery, when combined with congestion control, is likely... In the field of computer networking, the IETF Signaling Transport (SIGTRAN) working group defined the Stream Control Transmission Protocol (SCTP) as a transport layer protocol in 2000. ... GPRS Tunneling Protocol (or GTP) is an IP based protocol used within GSM and UMTS networks. ...

3. Internet layer

IP (IPv4IPv6) • IGMPICMPRSVPBGPRIPOSPFISISIPsecARPRARP • … The network layer is level three of the seven level OSI model. ... The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... Internet Protocol version 4 is the fourth iteration of the Internet Protocol (IP) and it is the first version of the protocol to be widely deployed. ... Internet Protocol version 6 (IPv6) is a network layer protocol for packet-switched internetworks. ... The Internet Group Management Protocol is a communications protocol used to manage the membership of Internet Protocol multicast groups. ... The Internet Control Message Protocol (ICMP) is one of the core protocols of the Internet protocol suite. ... The Resource ReSerVation Protocol (RSVP), described in RFC 2205, is a transport layer protocol designed to reserve resources across a network for an integrated services Internet. ... The Border Gateway Protocol (BGP) is the core routing protocol of the Internet. ... This article is chiefly about the Routing Information Protocol for IPv4 and IPv6. ... The Open Shortest Path First (OSPF) protocol is a link-state, hierarchical interior gateway protocol (IGP) for network routing. ... Intermediate system to intermediate system (IS-IS), is an IGP routing protocol originally designed for CLNS as part of the OSI protocol stack and described in ISO 10589 . ... IPsec (IP security) is a suite of protocols for securing Internet Protocol (IP) communications by authenticating and/or encrypting each IP packet in a data stream. ... In computer networking, the Address Resolution Protocol (ARP) is the method for finding a hosts hardware address when only its network layer address is known. ... Reverse address resolution protocol (RARP) is a protocol used to resolve an IP address from a given hardware address (such as an Ethernet address). ...

2. Data link layer

802.11ATMDTMEthernetFDDIFrame RelayGPRS • EVDO • HSPA • HDLC • PPPL2TP • PPTP • … The data link layer is layer two of the seven-layer OSI model as well as of the five-layer TCP/IP reference model. ... IEEE 802. ... Asynchronous Transfer Mode (ATM) is a cell relay, Circuit switching network and data link layer protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header information) fixed-sized cells. ... Dynamic synchronous Transfer Mode , or DTM for short, is a network protocol. ... Ethernet is a large, diverse family of frame-based computer networking technologies that operates at many speeds for local area networks (LANs). ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ... In the context of computer networking, frame relay (also found written as frame-relay) consists of an efficient data transmission technique used to send digital information quickly and cheaply in a relay of frames to one or many destinations from one or many end-points. ... General Packet Radio Service (GPRS) is a mobile data service available to users of GSM and IS-136 mobile phones. ... Evolution-Data Optimized or Evolution-Data only, abbreviated as EV-DO or EVDO and often EV, is one telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access. ... High-Speed Packet Access (HSPA) is a collection of mobile telephony protocols that extend and improve the performance of existing UMTS protocols. ... High-Level Data Link Control (HDLC) is a bit-oriented synchronous data link layer protocol developed by the International Organization for Standardization (ISO). ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ... In computer networking, the Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks (VPNs). ... The Point-to-Point Tunneling Protocol (PPTP) is a method for implementing virtual private networks. ...

1. Physical layer

Ethernet physical layerISDNModemsPLCSONET/SDHG.709WiMAX • … IEEE photograph of a diagram with the original terms for describing Ethernet drawn by Robert M. Metcalfe around 1976. ... // Integrated Services Digital Network (ISDN) is a circuit-switched telephone network system, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in better quality and higher speeds than that is available with the PSTN system. ... A modem (from modulate and demodulate) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. ... For other uses, see Power band. ... It has been suggested that this article be split into articles entitled synchronous optical networking, SONET and SDH. (Discuss) Synchronous optical networking, is a method for communicating digital information using lasers or light-emitting diodes (LEDs) over optical fiber. ... There are very few or no other articles that link to this one. ... WiMAX is defined as Worldwide Interoperability for Microwave Access by the WiMAX Forum, formed in June 2001 to promote conformance and interoperability of the IEEE 802. ...

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The physical layer is level one in the seven level OSI model of computer networking as well as in the five layer TCP/IP reference model. It performs services requested by the data link layer. The Open Systems Interconnection Basic Reference Model (OSI Reference Model or OSI Model for short) is a layered, abstract description for communications and computer network protocol design, developed as part of Open Systems Interconnection (OSI) initiative. ... “Computer Networks” redirects here. ... The TCP/IP reference model or TCP/IP model, sometimes called the DoD model (DoD, Department of Defense), ARPANET reference model or the Internet reference model, is a layered abstract description for communications and computer network protocol design. ... The data link layer is layer two of the seven-layer OSI model as well as of the five-layer TCP/IP reference model. ...


The physical layer is the most basic network layer, providing only the means of transmitting raw bits rather than packets over a physical data link connecting network nodes. No packet headers nor trailers are consequently added to the data by the physical layer. The bit stream may be grouped into code words or symbols, and converted to a physical signal, which is transmitted over a physical transmission medium. The physical layer provides an electrical, mechanical, and procedural interface to the transmission medium. The shapes of the electrical connectors, which frequencies to broadcast on, what modulation scheme to use and similar low-level parameters are specified here. An analogy of this layer in a physical mail network would be the roads along which the vans carrying the mail drive. In telecommunication, the term data link has the following meanings: The means of connecting one location to another for the purpose of transmitting and receiving data. ... A node is a device that is connected as part of a computer network. ... A bitstream or bit stream is a time series of bits. ... Look up signal, signaling in Wiktionary, the free dictionary. ... A transmission medium is any material substance, such as fiber-optic cable, twisted-wire pair, coaxial cable, dielectric-slab waveguide, water, or air, that can be used for the propagation of signals, usually in the form of modulated radio, light, or acoustic waves, from one point to another. ... An electrical connector is a device for joining electrical circuits together. ... In telecommunications, modulation is the process of varying a periodic waveform, i. ...


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

The physical layer is also concerned with A transmission medium is any material substance which can propagate waves or energy. ... An electrical connector is a device for joining electrical circuits together. ... 6 or 15cm outside diameter, oil-cooled cables, traversing the Grand Coulee Dam throughout. ... A transmission line is the material medium or structure that forms all or part of a path from one place to another for directing the transmission of energy, such as electromagnetic waves or acoustic waves, as well as electric power transmission. ... In a communications system, the signal level is the signal power or intensity at a specified point and with respect to a specified reference level, e. ... Electrical impedance, or simply impedance, is a measure of opposition to a sinusoidal alternating electric current. ... Legend γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High... The electromagnetic spectrum is an aspect of the physical world, like land, water, and air. ... In telecommunications, and particularly in radio, signal strength is the measure of how strongly a transmitted signal is being received, measured, or predicted, at a reference point that is a significant distance from the transmitting antenna. ... This article does not cite any references or sources. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... Optical fibers An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length by confining as much light as possible in a propagating form. ... In telecommunications, modulation is the process of varying a periodic waveform, i. ... In telecommunication, a line code is a code chosen for use within a communications system for transmission purposes. ... In telecommunications, a self-synchronizing code is a line code in which the symbol stream formed by a portion of one code word, or by the overlapped portion of any two adjacent code words, is not a valid code word. ... In telecommunications and computer science, serial communications is the process of sending data one bit at one time, sequentially, over a communications channel or computer bus. ... Asynchronous serial communication describes an asynchronous transmission protocol in which a start signal is sent prior to each byte, character or code word and a stop signal is sent after each code word. ... The flow control mechanism is used for controlling the flow of data in a network under well-defined conditions, while congestion control is used for controlling the flow of data when congestion has actually occurred . ... Asynchronous serial communication describes an asynchronous transmission protocol in which a start signal is sent prior to each byte, character or code word and a stop signal is sent after each code word. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In telecommunications, multiplexing (also muxing or MUXing) is the combining of two or more information channels onto a common transmission medium using hardware called a multiplexer or (MUX). ... Carrier Sense Multiple Access (CSMA) is a probabilistic Media Access Control (MAC) protocol in which a node verifies the absence of other traffic before transmitting on a shared physical medium, such as an electrical bus, or a band of electromagnetic spectrum. ... In computer networking, Carrier Sense Multiple Access With Collision Detection (CSMA/CD) is a network control protocol in which (a) a carrier sensing scheme is used and (b) a transmitting data station that detects another signal while transmitting a frame, stops transmitting that frame, transmits a jam signal, and then... In communications, a channel access method or multiple access method allows several terminals connected to the same physical medium to transmit over it and to share its capacity. ... For information about computer bandwidth management, see Equalization (computing). ... In optics, Femtosecond pulse shaping refers to various techniques to modify the time profile of an ultrashort pulse from a laser. ... Signal processing is the processing, amplification and interpretation of signals, and deals with the analysis and manipulation of signals. ...

Point-to-Point telecommunications is most recently (2003) referenced regarding wireless data communications for Internet or Voice over IP via radio frequencies in the multi-gigahertz range. ... Multipoint may refer to: Multi-point fuel injection Multipoint ground Multipoint videoconferencing Category: ... Point-to-multipoint (PT2MP) telecommunications is most typically (2003) used in wireless Internet and IP Telephony via gigahertz radio frequencies. ... A Möbius strip, an object with only one surface and one edge; such shapes are an object of study in topology. ... Image showing bus network layout A bus network Topology is a network architecture in which a set of clients are connected via a shared communications line, called a bus. ... Image showing ring network layout A ring network is a network topology in which each node connects to exactly two other nodes, forming a circular pathway for signals: a ring. ... Mesh networking is a way to route data, voice and instructions between nodes. ... Star network layout Star networks are one of the most common computer network topologies. ... In telecommunications and computer science, serial communications is the process of sending data one bit at one time, sequentially, over a communications channel or computer bus. ... It has been suggested that this article or section be merged with Parallel communications. ... A simplex communication system is one where all signals flow in one direction. ... This article or section does not cite its references or sources. ... This article or section does not cite its references or sources. ... Autonegotiation (formerly NWay) is an Ethernet procedure for the automatic handshaking of two directly networked interfaces connected by identical parameters. ...

Physical signaling sublayer

In a local area network (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: Local area network scheme A local area network is a computer network covering a small geographic area, like a home, office, or group of buildings. ... Metropolitan area networks, or MANs, are large computer networks usually spanning a city. ... This article or section does not adequately cite its references or sources. ...

Source: from Federal Standard 1037C According to the IEEE 802 family of standards Media Access Control (MAC) is the lower sublayer of the OSI data link layer, the interface between a nodes Logical Link Control and the networks physical layer. ... In telecommunications, transmission is the act of transmitting electrical messages (and the associated phenomena of radiant energy that passes through media). ... Federal Standard 1037C, entitled Telecommunications: Glossary of Telecommunication Terms is a United States Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. ...


Examples

V.92 is an ITU-T modem standard allowing near 56 kbit/s download and 48 kbit/s upload rates first presented in August 1999. ... A modem (a portmanteau word constructed from modulator and demodulator) is a device that modulates an analog carrier signal (sound), to encode digital information, and that also demodulates such a carrier signal to decode the transmitted information. ... Digital Subscriber Line, or DSL, is a family of technologies that provide a digital connection over the copper wires of the local telephone network. ... The initials IRDA can refer to various things: In Information Technology and Communications, IrDA refers to Infrared Data Association, a standard for communication between devices (such as computers, PDAs and mobile phones) over short distances using infrared signals. ... Note: USB may also mean upper sideband in radio. ... The 6-pin and 4-pin FireWire Connectors FireWire is Apple Inc. ... The Electronic Industries Alliance (EIA, until 1997 Electronic Industries Association) is a trade organization for electronics manufacturers in the United States. ... RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ... EIA-422 (formerly RS-422), now TIA-422, is a technical standard which specifies the electrical characteristics of the balanced voltage digital interface circuit[1]. It provides for data transmission, using balanced or differential signaling, with unidirectional/non-reversible, terminated or non-terminated transmission lines, point to point, or multi... RS-449 - Wikipedia /**/ @import /skins/monobook/IE50Fixes. ... EIA-485 (formerly RS-485 or RS485) is an electrical specification of a two-wire, half-duplex, multipoint serial connection. ... The International Telecommunication Union (ITU; French: Union internationale des télécommunications, Spanish: Unión Internacional de Telecomunicaciones) is an international organization established to standardize and regulate international radio and telecommunications. ... The ITU Telecommunication Standardization Sector (ITU-T) coordinates standards for telecommunications on behalf of the International Telecommunication Union (ITU) and is based in Geneva, Switzerland. ... A DSL Modem DSL or xDSL, is a family of technologies that provide digital data transmission over the wires of a local telephone network. ... // Integrated Services Digital Network (ISDN) is a circuit-switched telephone network system, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in better quality and higher speeds than that is available with the PSTN system. ... Two Network Interface Units, one with a single card, the other with two In telecommunications, T-carrier is the generic designator for any of several digitally multiplexed telecommunications carrier systems originally developed by Bell Labs and used in North America and Japan. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... 10BASE-T cable 10BASE-T plug 10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. ... 10BASE2 cable showing BNC Connector end. ... 10BASE5 vampire tap Medium Attachment Unit (Transceiver) 10BASE5 (also known as thicknet) is the original full spec variant of Ethernet cable, using RG-8 (Radio Grade - 8) coaxial cable. ... 100BASE-TX is the predominant form of Fast Ethernet, providing 100 Mbit/s Ethernet. ... 100BASE-FX is a version of fast ethernet over optical fiber. ... 100BASE-T is any of several Fast Ethernet 100 Mbit/s (12. ... 1000BASE-T or IEEE 802. ... 1000BASE-SX is a fiber optic gigabit Ethernet standard. ... IEEE photograph of a diagram with the original terms for describing Ethernet drawn by Robert M. Metcalfe around 1976. ... IEEE 802. ... Synchronous Optical Networking, commonly known as SONET, is a standard for communicating digital information over optical fiber. ... Not to be confused with Get Some Mates The Global System for Mobile Communications (GSM) is the most popular standard for mobile phones in the world. ... Bluetooth logo Bluetooth is an industrial specification for wireless personal area networks (PANs). ... IEEE 802. ... Official Wi-Fi logo Wi-Fi, popularly known as an acronym for wireless fidelity (see below for origin), but, in actuality is simply a play on the term Hi-Fi, was originally a brand licensed by the Wi-Fi Alliance to describe the embedded technology of wireless local area networks...

Hardware equipment (network node) examples

Note: Physical layer Associated with transmission of unstructured bit streams over a physical link. Responsible for the mechanical, electrical and procedural characteristics that establish, maintain and deactivate the physical link. A transitional network card with both BNC Thinnet (left) and Twisted pair (right) connectors. ... An Icom Radio Repeater. ... 4 port ethernet hub An Ethernet hub or concentrator is a device for connecting multiple twisted pair or fiber optic Ethernet devices together, making them act as a single segment. ... A modem (from modulate and demodulate) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. ...


See also


  Results from FactBites:
 
Managing the Physical Layer (3538 words)
All things considered, the physical layer is essentially the true “edge” of the network, but unfortunately has the least amount of visibility of all of the critical components making up the network infrastructure.
If a physical layer management system (such as one with the attributes described in the previous sections) is in place, an unauthorized access event would be generated and sent to the NOC.
To make matters worse, for the physical layer it is not the equipment side cabling or the OSP/horizontal cabling that is the item that is the most prone to changes and errors; it is the cross-connects on the patch panels.
Howstuffworks "How OSI Works" (291 words)
Application - This is the layer that actually interacts with the operating system or application whenever the user chooses to transfer files, read messages or perform other network-related activities.
Flow control means that the Transport layer looks to see if data is coming from more than one application and integrates each application's data into a single stream for the physical network.
Data - In this layer, the appropriate physical protocol is assigned to the data.
  More results at FactBites »

 
 

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