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Encyclopedia > Ethernet
The five-layer TCP/IP model
5. Application layer

DHCPDNSFTPGopherHTTPIMAP4IRCNNTPXMPPPOP3SIPSMTPSNMPSSHTELNETRPC • RTP • RTCPRTSPTLS/SSLSDPSOAPBGP • PPTP • L2TPGTPSTUNNTP • ... 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. ... It has been suggested that this article be split into multiple articles. ... “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 operating on port 143 that allows a local client to access e-mail on... “IRC” redirects here. ... 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. ... 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. ... This article or section includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... 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). ... The Real Time Streaming Protocol (RTSP), developed by the IETF and created in 1998 as RFC 2326, is a protocol for use in streaming media systems which allows a client to remotely control a streaming media server, issuing VCR-like commands such as play and pause, and allowing time-based... Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL), are cryptographic protocols that provide secure communications on the Internet for such things as web browsing, e-mail, Internet faxing, instant messaging and other data transfers. ... Session Description Protocol (SDP), is a format for describing streaming media initialization parameters. ... This article is about the computer protocol. ... The Border Gateway Protocol (BGP) is the core routing protocol of the Internet. ... The Point-to-Point Tunneling Protocol (PPTP) is a method for implementing virtual private networks. ... In computer networking, the Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks (VPNs). ... GPRS Tunneling Protocol (or GTP) is an IP based protocol used within GSM and UMTS networks. ... This article is about the Internet protocol. ... The Network Time Protocol (NTP) is a protocol for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. ...

4. Transport layer

TCPUDPDCCPSCTPRSVP • ... In computing and telecommunications, the transport layer is the second highest layer in the four and five layer TCP/IP reference models, where it responds to service requests from the application layer and issues service requests to the Internet layer. ... The 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. ... 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. ... 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. ...

3. Network/Internet Layer

IP (IPv4IPv6) • IGMPICMPOSPFISISIPsecARPRARPRIP • ... The network layer is third layer out of seven in OSI model and it is the third layer out of five in TCP/IP model. ... The 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. ... It has been suggested that IPv6 internet be merged into this article or section. ... The Internet Group Management Protocol is a communications protocol used to manage the membership of Internet Protocol multicast groups. ... The (ICMP) is one of the core protocols of the Internet protocol suite. ... The Open Shortest Path First (OSPF) protocol is a hierarchical interior gateway protocol (IGP) for routing in Internet Protocol, using a link-state in the individual areas that make up the hierarchy. ... 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 standard method for finding a hosts hardware address when only its network layer address is known. ... Reverse Address Resolution Protocol (RARP) is a network layer protocol used to obtain an IP address for a given hardware address (such as an Ethernet address). ... This article is chiefly about the Routing Information Protocol for IPv4 and IPv6. ...

2. Data link layer

802.11WiFiWiMAXATMDTMToken RingEthernetFDDIFrame RelayGPRS • EVDO • HSPA • HDLC • PPP • ... This article does not cite any references or sources. ... IEEE 802. ... Wi-Fi (or Wi-fi, WiFi, Wifi, wifi), short for Wireless Fidelity, is a set of standards for wireless local area networks (WLAN) currently based on the IEEE 802. ... WiMAX, the Worldwide Interoperability for Microwave Access, is a telecommunications technology aimed at providing wireless data over long distances in a variety of ways, from point-to-point links to full mobile cellular type access. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... Dynamic synchronous Transfer Mode , or DTM for short, is a network protocol. ... Token-Ring local area network (LAN) technology was developed and promoted by IBM in the early 1980s and standardised as IEEE 802. ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ... In the context of computer networking, frame relay consists of an efficient data transmission technique used to send digital information quickly and cheaply in a relay of frames to one or many destinations from one or many end-points. ... General Packet Radio Service (GPRS) is a Mobile Data Service available to users of Global System for Mobile Communications (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. ...

1. Physical layer

Ethernet physical layerISDNModemsPLCSONET/SDHG.709OFDMOptical FiberCoaxial CableTwisted Pair • ... This article does not cite any references or sources. ... 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 Synchronous digital hierarchy. ... There are very few or no other articles that link to this one. ... Orthogonal frequency division modulation (OFDM, also called orthogonal frequency division multiplexing) is a technique for the modulation of digital information onto an analog carrier electromagnetic (e. ... 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. ... Coaxial Cable For the weapon, see coaxial weapon. ... 25 Pair Color Code Chart 10BASE-T UTP Cable Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of cancelling out electromagnetic interference known as crosstalk. ...

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Ethernet is a large, diverse family of frame-based computer networking technologies that operate at many speeds for local area networks (LANs). The name comes from the physical concept of the ether. It defines a number of wiring and signaling standards for the physical layer, through means of network access at the Media Access Control (MAC)/Data Link Layer, and a common addressing format. In telecommunications, a frame is a packet which has been encoded for transmission over a particular link. ... For the scientific and engineering discipline studying computer networks, see Computer networking. ... Local area network scheme A local area network (LAN) is a computer network covering a small geographic area, like a home, office, or group of buildings. ... The luminiferous aether: it was hypothesised that the Earth moves through a medium of aether that carries light In the late 19th century luminiferous aether (light-bearing aether) was the term used to describe a medium for the propagation of light. ... This article does not cite any references or sources. ... The Media Access Control (MAC) data communication protocol sub-layer, also known as the Medium Access Control, is a part of the data link layer specified in the seven-layer OSI model (layer 2). ... This article does not cite any references or sources. ...


Ethernet has been standardized as IEEE 802.3. The combination of the twisted pair versions of Ethernet for connecting end systems to the network, along with the fiber optic versions for site backbones, has become the most widespread wired LAN technology. It has been in use from the 1990s to the present, largely replacing competing LAN standards such as coaxial cable Ethernet, token ring, FDDI, and ARCNET. In recent years, Wi-Fi, the wireless LAN standardized by IEEE 802.11, has been used instead of Ethernet for many home and small office networks and in addition to Ethernet in larger installations. IEEE 802. ... Twisted-pair cable used with 10BASE-T 8P8C (not RJ-45) plug used with 10BASE-T There are several standards for Ethernet over twisted pair cable. ... 2007 is a common year starting on Monday of the Gregorian calendar. ... Coaxial Cable For the weapon, see coaxial weapon. ... Token-Ring local area network (LAN) technology was developed and promoted by IBM in the early 1980s and standardised as IEEE 802. ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ... ARCNET (also CamelCased as ARCnet, an acronym from Attached Resource Computer NETwork) is a local area network (LAN) protocol, similar in purpose to Ethernet or Token Ring. ... Official Wi-Fi logo Wi-Fi is a wireless technology brand owned by the Wi-Fi Alliance intended to improve the interoperability of wireless local area network products based on the IEEE 802. ... IEEE 802. ...

Contents

History

Ethernet was originally developed as one of the many pioneering projects at Xerox PARC. Ethernet was invented in the period of 1973–1975.[1] Robert Metcalfe and David Boggs wrote and presented their "Draft Ethernet Overview" some time before March 1974. In March 1974, R.Z. Bachrach wrote a memo to Metcalfe and Boggs, and their management, stating that "technically or conceptually there is nothing new in your proposal" and that "analysis would show that your system would be a failure."This analysis was flawed, however, in that it ignored the "channel capture effect", though this was not understood until 1994. In 1975, Xerox filed a patent application listing Metcalfe and Boggs, plus Chuck Thacker and Butler Lampson, as inventors (U.S. Patent 4,063,220 : Multipoint data communication system with collision detection). In 1976, after the system was deployed at PARC, Metcalfe and Boggs published a paper titled Ethernet: Distributed Packet-Switching For Local Computer Networks. Bold text // Headline text Link title This article is about the computer research center. ... Robert Melancton Metcalfe (born 1946 in Brooklyn, New York) is an American technology pioneer who co-invented Ethernet with David Boggs, founded 3Com and formulated Metcalfes Law. ... Charles P. (Chuck) Thacker is a technical fellow and computer pioneer. ... Butler W. Lampson is a computer scientist, considered to be one of the most significant in the history of the field. ...


The experimental Ethernet described in that paper ran at 3 Mbit/s, and had 8-bit destination and source address fields, so Ethernet addresses were not the global addresses they are today. By software convention, the 16 bits after the destination and source address fields were a packet type field, but, as the paper says, "different protocols use disjoint sets of packet types", so those were packet types within a given protocol, rather than the packet type in current Ethernet, which specifies the protocol being used. A megabit per second (mbps or mbit/s) is a unit of data transmission equal to 1,000 kilobits per second or 1,000,000 bits per second. ...


Metcalfe left Xerox in 1979 to promote the use of personal computers and local area networks (LANs), forming 3Com. He convinced DEC, Intel, and Xerox to work together to promote Ethernet as a standard, the so-called "DIX" standard, for "Digital/Intel/Xerox"; it standardized the 10 megabits/second Ethernet, with 48-bit destination and source addresses and a global 16-bit type field. The standard was first published on September 30, 1980. It competed with two largely proprietary systems, token ring and ARCNET, but those soon found themselves buried under a tidal wave of Ethernet products. In the process, 3Com became a major company. 3Com (NASDAQ: COMS) is a manufacturer best known for its computer network infrastructure products. ... The DEC logo Digital Equipment Corporation was a pioneering American company in the computer industry. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... Xerox Corporation (NYSE: XRX) (name pronounced ) is a global document management company, which manufactures and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies. ... is the 273rd day of the year (274th in leap years) in the Gregorian calendar. ... Year 1980 (MCMLXXX) was a leap year starting on Tuesday (link displays the 1980 Gregorian calendar). ... Token-Ring local area network (LAN) technology was developed and promoted by IBM in the early 1980s and standardised as IEEE 802. ... ARCNET (also CamelCased as ARCnet, an acronym from Attached Resource Computer NETwork) is a local area network (LAN) protocol, similar in purpose to Ethernet or Token Ring. ... 3Com (NASDAQ: COMS) is a manufacturer best known for its computer network infrastructure products. ...


Twisted-pair Ethernet systems have been developed since the mid-80s, beginning with StarLAN (but becoming widely known with 10BASE-T). These systems replaced the coaxial cable on which early Ethernets were deployed with a system of hubs linked with unshielded twisted pair and later replaced the CSMA/CD scheme in favor of a switched full duplex system offering higher performance. Twisted-pair cable used with 10BASE-T 8P8C (not RJ-45) plug used with 10BASE-T There are several standards for Ethernet over twisted pair cable. ... StarLAN was the first implementation of Ethernet computer networking on twisted pair wiring. ... 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...


General description

A 1990s Ethernet network interface card. This is a combination card that supports both coaxial-based 10BASE2 (BNC connector, left) and twisted pair-based 10BASE-T, aka RJ45 (8P8C modular connector, right).
A 1990s Ethernet network interface card. This is a combination card that supports both coaxial-based 10BASE2 (BNC connector, left) and twisted pair-based 10BASE-T, aka RJ45 (8P8C modular connector, right).

Ethernet was originally based on the idea of computers communicating over a shared coaxial cable acting as a broadcast transmission medium. The methods used show some similarities to radio systems, although there are major differences, such as the fact that it is much easier to detect collisions in a cable broadcast system than a radio broadcast. The common cable providing the communication channel was likened to the ether and it was from this reference that the name "Ethernet" was derived. Download high resolution version (1444x1071, 99 KB)Image depicting a network card. ... Download high resolution version (1444x1071, 99 KB)Image depicting a network card. ... A network card, network adapter or NIC (network interface controller) is a piece of computer hardware designed to allow computers to communicate over a computer network. ... Coaxial Cable For the weapon, see coaxial weapon. ... 10BASE2 cable showing BNC Connector end. ... Male BNC connector Cables with BNC connectors Adapter between a female BNC connector and banana plugs Picture to show the similarity between 50 Ω and 75 Ω BNC connectors Pulse generators with BNC connectors and cables. ... 25 Pair Color Code Chart 10BASE-T UTP Cable Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of cancelling out electromagnetic interference known as crosstalk. ... 10BASE-T cable 10BASE-T plug 10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. ... Cat5 cables with RJ45 connectors, wired to EIA/TIA-568B An RJ45 connector that has yet to be crimped onto a cable RJ45 (Registered Jack 45) is a physical interface often used for terminating twisted pair type cables. ... This article does not cite any references or sources. ... Ether is the general name for a class of chemical compounds which contain an ether group — an oxygen atom connected to two (substituted) alkyl or aryl groups — of general formula R – O–R.[1] A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as ether...


From this early and comparatively simple concept, Ethernet evolved into the complex networking technology that today powers the vast majority of local computer networks. The coaxial cable was later replaced with point-to-point links connected together by hubs and/or switches in order to reduce installation costs, increase reliability, and enable point-to-point management and troubleshooting. StarLAN was the first step in the evolution of Ethernet from a coaxial cable bus to a hub-managed, twisted-pair network. The advent of twisted-pair wiring enabled Ethernet to become a commercial success.


Above the physical layer, Ethernet stations communicate by sending each other data packets, small blocks of data that are individually sent and delivered. As with other IEEE 802 LANs, each Ethernet station is given a single 48-bit MAC address, which is used both to specify the destination and the source of each data packet. Network interface cards (NICs) or chips normally do not accept packets addressed to other Ethernet stations. Adapters generally come programmed with a globally unique address, but this can be overridden, either to avoid an address change when an adapter is replaced, or to use locally administered addresses. IEEE 802 refers to a family of IEEE standards about local area networks and metropolitan area networks. ... In computer networking a Media Access Control address (MAC address) or hardware address or adapter address is a quasi-unique identifier attached to most network adapters (NICs). ...


Despite the very significant changes in Ethernet from a thick coaxial cable bus running at 10 Mbit/s to point-to-point links running at 1 Gbit/s and beyond, all generations of Ethernet (excluding very early experimental versions) share the same frame formats (and hence the same interface for higher layers), and can be readily (and in most cases, cheaply) interconnected. 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. ... A megabit per second (mbps or mbit/s) is a unit of data transmission equal to 1,000 kilobits per second or 1,000,000 bits per second. ... Gigabit Ethernet (GbE) is a term describing various technologies for transmitting Ethernet packets at a rate of a gigabit per second, as defined by the IEEE 802. ... 10 gigabit Ethernet or 10GbE or 10 GigE is the most recent (as of 2006) and fastest of the Ethernet standards. ...


Due to the ubiquity of Ethernet, the ever-decreasing cost of the hardware needed to support it, and the reduced panel space needed by twisted pair Ethernet, most manufacturers now build the functionality of an Ethernet card directly into PC motherboards, obviating the need for installation of a separate network card. 25 Pair Color Code Chart 10BASE-T UTP Cable Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of cancelling out electromagnetic interference known as crosstalk. ... The ABIT KT7, an ATX format motherboard A motherboard is a printed circuit board used in a personal computer. ...


Dealing with multiple users

CSMA/CD shared medium Ethernet

Ethernet originally used a shared coaxial cable (the shared medium) winding around a building or campus to every attached machine. A scheme known as carrier sense multiple access with collision detection (CSMA/CD) governed the way the computers shared the channel. This scheme was simpler than the competing token ring or token bus technologies. When a computer wanted to send some information, it used the following algorithm: Coaxial Cable For the weapon, see coaxial weapon. ... In computer networking, Carrier Sense Multiple Access With Collision Detection (CSMA/CD) is a network control protocol in which a carrier sensing scheme is used and a transmitting data station that detects another signal while transmitting a frame, stops transmitting that frame, transmits a jam signal, and then waits for... Token-Ring local area network (LAN) technology was developed and promoted by IBM in the early 1980s and standardised as IEEE 802. ... Token bus is token ring over a virtual ring on a coaxial cable. ... In mathematics, computing, linguistics, and related disciplines, an algorithm is a finite list of well-defined instructions for accomplishing some task that, given an initial state, will terminate in a defined end-state. ...


Main procedure

  1. Frame ready for transmission
  2. Is medium idle? If not, wait until it becomes ready and wait the interframe gap period (9.6 µs in 10 Mbit/s Ethernet).
  3. Start transmitting
  4. Does a collision occur? If so, go to collision detected procedure.
  5. Reset retransmission counters and end frame transmission
  6. Collision detected procedure – Continue transmission until minimum packet time is reached (jam signal) to ensure that all receivers detect the collision
  7. Increment retransmission counter
  8. Is maximum number of transmission attempts reached? If so, abort transmission.
  9. Calculate and wait random backoff period based on number of collisions
  10. Re-enter main procedure at stage 1

This can be likened to what happens at a dinner party, where all the guests talk to each other through a common medium (the air). Before speaking, each guest politely waits for the current speaker to finish. If two guests start speaking at the same time, both stop and wait for short, random periods of time (in Ethernet, this time is generally measured in microseconds). The hope is that by each choosing a random period of time, both guests will not choose the same time to try to speak again, thus avoiding another collision. Exponentially increasing back-off times (determined using the truncated binary exponential backoff algorithm) are used when there is more than one failed attempt to transmit. Ethernet devices must allow a minimum idle period between transmission of Ethernet frames known as the interframe gap (IFG) or interpacket gap (IPG). ... To help compare orders of magnitude of different times this page lists times between 10-6 seconds and 10-5 seconds (1. ... In mathematics, exponential growth (or geometric growth) occurs when the growth rate of a function is always proportional to the functions current size. ... In a variety of computer networks, binary exponential backoff or truncated binary exponential backoff refers to an algorithm used to space out repeated retransmissions of the same block of data. ...


Computers were connected to an Attachment Unit Interface (AUI) transceiver, which was in turn connected to the cable (later with thin Ethernet the transceiver was integrated into the network adaptor). While a simple passive wire was highly reliable for small Ethernets, it was not reliable for large extended networks, where damage to the wire in a single place, or a single bad connector, could make the whole Ethernet segment unusable. Multipoint systems are also prone to very strange failure modes when an electrical discontinuity reflects the signal in such a manner that some nodes would work properly while others work slowly because of excessive retries or not at all (see standing wave for an explanation of why); these could be much more painful to diagnose than a complete failure of the segment. Debugging such failures often involved several people crawling around wiggling connectors while others watched the displays of computers running a ping command and shouted out reports as performance changed. AUI Connectors. ... A standing wave, also known as a stationary wave, is a wave that remains in a constant position. ... For other uses, see Ping (disambiguation). ...


Since all communications happen on the same wire, any information sent by one computer is received by all, even if that information is intended for just one destination. The network interface card interrupts the CPU only when applicable packets are received: the card ignores information not addressed to it unless it is put into "promiscuous mode". This "one speaks, all listen" property is a security weakness of shared-medium Ethernet, since a node on an Ethernet network can eavesdrop on all traffic on the wire if it so chooses. Use of a single cable also means that the bandwidth is shared, so that network traffic can slow to a crawl when, for example, the network and nodes restart after a power failure. Die of an Intel 80486DX2 microprocessor (actual size: 12×6. ... Promiscuous mode, in computing, refers to a configuration of a network card wherein a setting is enabled so that the card passes all traffic it receives to the CPU rather than just packets addressed to it, a feature normally used for packet sniffing. ...


Ethernet repeaters and hubs

For signal degradation and timing reasons, coaxial Ethernet segments had a restricted size which depended on the medium used. For example, 10BASE5 coax cables had a maximum length of 500 metres (1,640 feet). Also, as was the case with most other high-speed buses, Ethernet segments had to be terminated with a resistor at each end. For coaxial-cable-based Ethernet, each end of the cable had a 50-ohm resistor attached. Typically this resistor was built into a male BNC or N connector and attached to the last device on the bus, or, if vampire taps were in use, to the end of the cable just past the last device. If termination was not done, or if there was a break in the cable, the AC signal on the bus was reflected, rather than dissipated, when it reached the end. This reflected signal was indistinguishable from a collision, and so no communication could take place. A network segment is a portion of a computer network in which computers can access each others using a network device. ... ‹ The template below (Unit of length) is being considered for deletion. ... This article is about a foot as a unit of length. ... Resistor symbols (non-European) Resistor symbols (Europe, IEC) Axial-lead resistors on tape. ... The ohm (symbol: Ω) is the SI unit of electric resistance. ... Male BNC connector Cables with BNC connectors Adapter between a female BNC connector and banana plugs Picture to show the similarity between 50 Ω and 75 Ω BNC connectors Pulse generators with BNC connectors and cables. ... Type N connector (male) Type N connector (female) Picture to show the similarity between 50ohm and 75ohm N connectors The N connector (in full, Type N connector) is a threaded RF connector used to join coaxial cables. ... CentreCOM AUI Vampire Tap A vampire tap is a device for physically connecting a station (i. ... City lights viewed in a motion blurred exposure. ...


A greater length could be obtained by an Ethernet repeater, which took the signal from one Ethernet cable and repeated it onto another cable. If a collision was detected, the repeater transmitted a jam signal onto all ports to ensure collision detection. Repeaters could be used to connect segments such that there were up to five Ethernet segments between any two hosts, three of which could have attached devices. Repeaters could detect an improperly terminated link from the continuous collisions and stop forwarding data from it. Hence they alleviated the problem of cable breakages: when an Ethernet coax segment broke, while all devices on that segment were unable to communicate, repeaters allowed the other segments to continue working, although depending on which segment was broken and the layout of the network the partitioning that resulted may have made other segments unable to reach important servers and thus effectively useless. A repeater is an electronic device that receives a weak or low-level signal and retransmits it at a higher level or higher power, so that the signal can cover longer distances without degradation. ... In telecommunication, a jam signal is a signal that carries a bit pattern sent by a data station to inform the other stations that they must not transmit. ...


People recognized the advantages of cabling in a star topology, primarily that only faults at the star point will result in a badly partitioned network, and network vendors started creating repeaters having multiple ports, thus reducing the number of repeaters required at the star point. Multiport Ethernet repeaters became known as "hubs". Network vendors such as DEC and SynOptics sold hubs that connected many 10BASE2 thin coaxial segments. There were also "multi-port transceivers" or "fan-outs". These could be connected to each other and/or a coax backbone. The best-known early example was DEC's DELNI. These devices allowed multiple hosts with AUI connections to share a single transceiver. They also allowed creation of a small standalone Ethernet segment without using a coaxial cable. A computer network with a star network topology, in its simplest form, consists of one central, or hub computer which acts as a router to transmit messages Comparing star networks to other types of network Advantages Easy to implement and extend, even in large networks Well suited for temporary networks... Multiport repeater: In digital networking, an active device, having multiple input/output (I/O) ports, in which a signal introduced at the input of any port appears at the output of every port. ... 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. ... SynOptics Communications SynOptics Communications was a Santa Clara, California based important early Ethernet vendor. ... 10BASE2 cable showing BNC Connector end. ... The DEC logo Digital Equipment Corporation was a pioneering American company in the computer industry. ... DELNI (Digital Ethernet Local Network Interconnect) is an Ethernet communications product manufactured by Digital Equipment Corporation (DEC) in the 1980s. ...

A twisted pair CAT-3 or CAT-5 cable is used to connect 10BASE-T Ethernet
A twisted pair CAT-3 or CAT-5 cable is used to connect 10BASE-T Ethernet

Ethernet on unshielded twisted-pair cables (UTP), beginning with StarLAN and continuing with 10BASE-T, was designed for point-to-point links only and all termination was built into the device. This changed hubs from a specialist device used at the center of large networks to a device that every twisted pair-based network with more than two machines had to use. The tree structure that resulted from this made Ethernet networks more reliable by preventing faults with (but not deliberate misbehavior of) one peer or its associated cable from affecting other devices on the network, although a failure of a hub or an inter-hub link could still affect lots of users. Also, since twisted pair Ethernet is point-to-point and terminated inside the hardware, the total empty panel space required around a port is much reduced, making it easier to design hubs with lots of ports and to integrate Ethernet onto computer motherboards. 10BASE-T Cable. ... 10BASE-T Cable. ... 25 Pair Color Code Chart 10BASE-T UTP Cable Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of cancelling out electromagnetic interference known as crosstalk. ... Twisted-pair cable used with 10BASE-T 8P8C (not RJ-45) plug used with 10BASE-T There are several standards for Ethernet over twisted pair cable. ... StarLAN was the first implementation of Ethernet computer networking on twisted pair wiring. ... 10BASE-T cable 10BASE-T plug 10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. ...


Despite the physical star topology, hubbed Ethernet networks still use half-duplex and CSMA/CD, with only minimal activity by the hub, primarily the Collision Enforcement signal, in dealing with packet collisions. Every packet is sent to every port on the hub, so bandwidth and security problems aren't addressed. The total throughput of the hub is limited to that of a single link and all links must operate at the same speed.


Collisions reduce throughput by their very nature. In the worst case, when there are lots of hosts with long cables that attempt to transmit many short frames, excessive collisions can reduce throughput dramatically. However, a Xerox report in 1980 summarized the results of having 20 fast nodes attempting to transmit packets of various sizes as quickly as possible on the same Ethernet segment.[2] The results showed that, even for minimal Ethernet frames (64B), 90% throughput on the LAN was the norm. This is in comparison with token passing LANs (token ring, token bus), all of which suffer throughput degradation as each new node comes into the LAN, due to token waits. Xerox Corporation (NYSE: XRX) (name pronounced ) is a global document management company, which manufactures and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies. ... Token Passing is a technique in which only that system can communicate that has token. ...


This report was wildly controversial, as modeling showed that collision-based networks became unstable under loads as low as 40% of nominal capacity. Many early researchers failed to understand the subtleties of the CSMA/CD protocol and how important it was to get the details right, and were really modeling somewhat different networks (usually not as good as real Ethernet).[3]


Bridging and switching

While repeaters could isolate some aspects of Ethernet segments, such as cable breakages, they still forwarded all traffic to all Ethernet devices. This created practical limits on how many machines could communicate on an Ethernet network. Also as the entire network was one collision domain and all hosts had to be able to detect collisions anywhere on the network the number of repeaters between the furthest nodes was limited. Finally segments joined by repeaters had to all operate at the same speed, making phased in upgrades impossible A network segment is a portion of a computer network in which computers can access each others using a network device. ...


To alleviate these problems, bridging was created to communicate at the data link layer while isolating the physical layer. With bridging, only well-formed packets are forwarded from one Ethernet segment to another; collisions and packet errors are isolated. Bridges learn where devices are, by watching MAC addresses, and do not forward packets across segments when they know the destination address is not located in that direction. In computer networking a Media Access Control address (MAC address) or hardware address or adapter address is a quasi-unique identifier attached to most network adapters (NICs). ...


Prior to discovery of network devices on the different segments, Ethernet bridges and switches work somewhat like Ethernet hubs, passing all traffic between segments. However, as the switch discovers the addresses associated with each port, it only forwards network traffic to the necessary segments improving overall performance. Broadcast traffic is still forwarded to all network segments. Bridges also overcame the limits on total segments between two hosts and allowed the mixing of speeds, both of which became very important with the introduction of Fast Ethernet. Broadcasting in a computer network refers to transmiting a packet that will be received (conceptionally) by every device on the network. ... In computer networking, Fast Ethernet is a collective term for a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s, against the original Ethernet speed of 10 Mbit/s. ...


Early bridges examined each packet one by one using software on a CPU, and some of them were significantly slower than hubs (multi-port repeaters) at forwarding traffic, especially when handling many ports at the same time. In 1989 the networking company Kalpana introduced their EtherSwitch, the first Ethernet switch. An Ethernet switch does bridging in hardware, allowing it to forward packets at full wire speed. It is important to remember that the term switch was invented by device manufacturers and does not appear in the 802.3 standard. Functionally, the two terms are interchangeable. Kalpana was a Silicon Valley computer networking equipment manufacturer in the 1980s and 1990s, who invented the Ethernet switch. ...


Since packets are typically only delivered to the port they are intended for, traffic on a switched Ethernet is slightly less public than on shared-medium Ethernet. Despite this, switched Ethernet should still be regarded as an insecure network technology, because it is easy to subvert switched Ethernet systems by means such as ARP spoofing and MAC flooding. The bandwidth advantages, the slightly better isolation of devices from each other, the ability to easily mix different speeds of device and the elimination of the chaining limits inherent in non-switched Ethernet have made switched Ethernet the dominant network technology. A typical Ethernet frame. ... In computer networking, MAC flooding is a technique employed to compromise the security of network switches. ...


When a twisted pair or fiber link segment is used and neither end is connected to a hub, full-duplex Ethernet becomes possible over that segment. In full duplex mode both devices can transmit and receive to/from each other at the same time, and there is no collision domain. This doubles the aggregate bandwidth of the link and is sometimes advertised as double the link speed (e.g. 200 Mbit/s) to account for this. However, this is misleading as performance will only double if traffic patterns are symmetrical (which in reality they rarely are). The elimination of the collision domain also means that all the link's bandwidth can be used and that segment length is not limited by the need for correct collision detection (this is most significant with some of the fiber variants of Ethernet). In telecommunications, duplex means two-way when referring to communications channels. ...


Dual speed hubs

In the early days of Fast Ethernet, Ethernet switches were relatively expensive devices. However, hubs suffered from the problem that if there were any 10BASE-T devices connected then the whole system would have to run at 10 Mbit. Therefore a compromise between a hub and a switch appeared known as a dual speed hub. These devices consisted of an internal two-port switch, dividing the 10BASE-T (10 Mbit) and 100BASE-T (100 Mbit) segments. The device would typically consist of more than two physical ports. When a network device becomes active on any of the physical ports, the device attaches it to either the 10BASE-T segment or the 100BASE-T segment, as appropriate. This prevented the need for an all-or-nothing migration from 10BASE-T to 100BASE-T networks. These devices are often known as dual-speed hubs, since the traffic between devices connected at the same speed is not switched. In computer networking, Fast Ethernet is a collective term for a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s, against the original Ethernet speed of 10 Mbit/s. ... 10BASE-T cable 10BASE-T plug 10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. ... 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. ... 10BASE-T cable 10BASE-T plug 10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. ... The megabit is a unit of information storage, abbreviated Mbit or sometimes Mb. ... 100BASE-T is any of several Fast Ethernet 100 Mbit/s (12. ... The megabit is a unit of information storage, abbreviated Mbit or sometimes Mb. ...


More advanced networks

Simple switched Ethernet networks, while an improvement over hub based Ethernet, suffer from a number of issues:

  • They suffer from single points of failure. If any link fails some devices will be unable to communicate with other devices and if the link that fails is in a central location lots of users can be cut off from the resources they require.
  • It is possible to trick switches or hosts into sending data to your machine even if it's not intended for it, as indicated above.
  • Large amounts of broadcast traffic whether malicious, accidental or simply a side effect of network size can flood slower links and/or systems.
    • It is possible for any host to flood the network with broadcast traffic forming a denial of service attack against any hosts that run at the same or lower speed as the attacking device.
    • As the network grows normal broadcast traffic takes up an ever greater amount of bandwidth.
    • If switches are not multicast aware multicast traffic will end up treated like broadcast traffic due to being directed at a MAC with no associated port.
    • If switches discover more MAC addresses than they can store (either through network size or through an attack) some addresses must inevitably be dropped and traffic to those addresses will be treated the same way as traffic to unknown addresses, that is essentially the same as broadcast traffic (this issue is known as failopen).
  • They suffer from bandwidth choke points where a lot of traffic is forced down a single link.

Some switches offer a variety of tools to combat these issues including: Routing Schemes anycast broadcast multicast unicast Multicast is sometimes also used to refer to a multiplexed broadcast, although that is a very different thing and should not be confused. ...

  • Spanning-tree protocol to maintain the active links of the network as a tree while allowing physical loops for redundancy.
  • Various port protection features, as it is far more likely an attacker will be on an end system port than on a switch-switch link.
  • VLANs to keep different classes of users separate while using the same physical infrastructure.
  • fast routing at higher levels to route between those VLANs.
  • Link aggregation to add bandwidth to overloaded links and to provide some measure of redundancy, although the links won't protect against switch failure because they connect the same pair of switches.

The Spanning-Tree Protocol is used to interconnect network switches, based on an algorithm invented by Radia Perlman. ... A virtual LAN, commonly known as a VLAN, is a logically segmented network mapped over physical hardware. ... It has been suggested that layer 4 router be merged into this article or section. ... Link aggregation is a computer networking term which describes using multiple Ethernet network cables/ports in parallel to increase the link speed beyond the limits of any one single cable or port. ...

Autonegotiation and duplex mismatch

Main articles: Autonegotiation and Duplex mismatch

The autonegotiation standard does not allow autodetection to detect duplex setting if the other computer is not also set to Autonegotation. When two interfaces are connected and set to different "duplex" modes, the effect of the duplex mismatch is a network that works, but much slower than at its nominal speed. The primary rule for avoiding this is that you must not set one end of a connection to a forced full duplex setting and the other end to autonegotiation. Autonegotiation (formerly NWay) is an Ethernet procedure for the automatic handshaking of two directly networked interfaces connected by identical parameters. ... In Ethernet, a duplex mismatch is a condition where two connected devices operate in different duplex modes, that is, one operates in half duplex while the other one operates in full duplex. ...


Many different modes of operations (10BASE-T half duplex, 10BASE-T full duplex, 100BASE-TX half duplex, …) exist for Ethernet over twisted pair cable using 8P8C modular connectors (not to be confused with FCC's RJ45), and most devices are capable of different modes of operations. In 1995, a standard was released for allowing two network interfaces connected to each other to autonegotiate the best possible shared mode of operation. This works well for the case of every device being set to autonegotiate. The autonegotiation standard contained a mechanism for detecting the speed but not the duplex setting of Ethernet peers that did not use autonegotiation. Twisted-pair cable used with 10BASE-T 8P8C (not RJ-45) plug used with 10BASE-T There are several standards for Ethernet over twisted pair cable. ... This article does not cite any references or sources. ... A registered jack (RJ) is a standardized physical interface for connecting telecommunications equipment (commonly, a telephone jack) or computer networking equipment. ...


Interoperability problems lead network administrators to manually set the mode of operation of interfaces on network devices. What would happen is that some device would fail to autonegotiate and therefore had to be set into one setting or another. This often led to duplex setting mismatches: in particular, when two interfaces are connected to each other with one set to autonegotiation and one set to full duplex mode, a duplex mismatch results because the autonegotiation process fails and half duplex is assumed – the interface in full duplex mode then transmits at the same time as receiving, and the interface in half duplex mode then gives up on transmitting a packet. The interface in half duplex mode is not ready to receive a packet, so it signals a clash, and tranmissions are halted, for amounts of time based on backoff (random wait times) algorithms. When both packets start trying to transmit again, they interfere again and the backoff strategy may result in a longer and longer wait time before attempting to transmit again; eventually a transmission succeeds but this then causes the flood and collisions to resume. This article or section does not cite its references or sources. ...


Because of the wait times, the effect of a duplex mismatch is a network that is not completely 'broken' but is incredibly slow.


Ethernet frame types and the EtherType field

Main article: Ethernet II framing

Frames are the format of data packets on the wire. Note that a frame viewed on the actual physical hardware would show start bits, sometimes called the preamble, and the trailing Frame Check Sequence. These are required by all physical hardware and is seen in all four following frame types. They are not displayed by packet sniffing software because these bits are removed by the Ethernet adapter before being passed on to the network protocol stack software. Ethernet v2 framing, also known as DIX Ethernet (named after the major participants in the framing of the protocol: Digital Equipment Corporation, Intel, Xerox) differs from IEEE 802. ... A frame check sequence (FCS) refers to the extra checksum characters added to a Frame in a communication protocol for error detection and correction. ... Packet sniffers (also known as Network Analyzers or Ethernet Sniffers) are usually software programs (but sometimes implemented in hardware) which can intercept and log traffic passing over a network or part of a network. ... A network card, network adapter or NIC (network interface controller) is a piece of computer hardware designed to allow computers to communicate over a computer network. ... It has been suggested that this article or section be merged with communications protocol. ...

An Ethernet frame, including the FCS terminating the frame.
An Ethernet frame, including the FCS terminating the frame.

There are several types of Ethernet frames: Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ...

In addition, Ethernet frames may optionally contain a IEEE 802.1Q tag to identify what VLAN it belongs to and its IEEE 802.1p priority (quality of service). This doubles the potential number of frame types. Ethernet v2 framing, also known as DIX Ethernet (named after the major participants in the framing of the protocol: Digital Equipment Corporation, Intel, Xerox) differs from IEEE 802. ... The DEC logo Digital Equipment Corporation was a pioneering American company in the computer industry. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... Xerox Corporation (NYSE: XRX) (name pronounced ) is a global document management company, which manufactures and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies. ... The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... IEEE 802. ... IEEE 802. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... IEEE 802. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The SubNetwork Access Protocol (SNAP) is a standard for the transmission of IP datagrams over IEEE 802 networks. ... IEEE 802. ... A virtual LAN, commonly known as a vLAN or as a VLAN, is a method of creating independent logical networks within a physical network. ... IEEE 802. ... In the fields of packet-switched networks and computer networking, the traffic engineering term Quality of Service (QoS) refers to control mechanisms that can provide different priority to different users or data flows, or guarantee a certain level of performance to a data flow in accordance with requests from the...


The different frame types have different formats and MTU values, but can coexist on the same physical medium. In computer networking, the term Maximum Transmission Unit (MTU) refers to the size (in bytes) of the largest datagram that a given layer of a communications protocol can pass onwards. ...

The most common Ethernet Frame format, type II
The most common Ethernet Frame format, type II

Versions 1.0 and 2.0 of the Digital/Intel/Xerox (DIX) Ethernet specification have a 16-bit sub-protocol label field called the EtherType. The original IEEE 802.3 Ethernet specification replaced that with a 16-bit length field, with the MAC header followed by an IEEE 802.2 logical link control (LLC) header; the maximum length of a packet was 1500 bytes. The two formats were eventually unified by the convention that values of that field between 0 and 1500 indicated the use of the original 802.3 Ethernet format with a length field, while values of 1536 decimal (0600 hexadecimal) and greater indicated the use of the DIX frame format with an EtherType sub-protocol identifier.[4] This convention allows software to determine whether a frame is an Ethernet II frame or an IEEE 802.3 frame, allowing the coexistence of both standards on the same physical medium. See also Jumbo Frames. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The DEC logo Digital Equipment Corporation was a pioneering American company in the computer industry. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... Xerox Corporation (NYSE: XRX) (name pronounced ) is a global document management company, which manufactures and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies. ... EtherType is a field in the Ethernet networking standard. ... IEEE 802. ... IEEE 802. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... It has been suggested that this article or section be merged into Jumbogram. ...


By examining the 802.2 LLC header, it is possible to determine whether it is followed by a SNAP (subnetwork access protocol) header. Some protocols, particularly those designed for the OSI networking stack, operate directly on top of 802.2 LLC, which provides both datagram and connection-oriented network services. The LLC header includes two additional eight-bit address fields, called service access points or SAPs in OSI terminology; when both source and destination SAP are set to the value 0xAA, the SNAP service is requested. The SNAP header allows EtherType values to be used with all IEEE 802 protocols, as well as supporting private protocol ID spaces. In IEEE 802.3x-1997, the IEEE Ethernet standard was changed to explicitly allow the use of the 16-bit field after the MAC addresses to be used as a length field or a type field. The SubNetwork Access Protocol (SNAP) is a standard for the transmission of IP datagrams over IEEE 802 networks. ... This article or section does not adequately cite its references or sources. ... It has been suggested that this article or section be merged with communications protocol. ... IEEE 802 refers to a family of IEEE standards about local area networks and metropolitan area networks. ...


Novell's "raw" 802.3 frame format was based on early IEEE 802.3 work. Novell used this as a starting point to create the first implementation of its own IPX Network Protocol over Ethernet. They did not use any LLC header but started the IPX packet directly after the length field. This does not conform to the IEEE 802.3 standard, but since IPX has always FF at the first two bytes (while in IEEE 802.2 LLC that pattern is theoretically possible but extremely unlikely), in practice this mostly coexists on the wire with other Ethernet implementations, with the notable exception of some early forms of DECnet which got confused by this. Novell Inc. ... See also Ericsson IPX Internetwork Packet Exchange (IPX) is the OSI-model Network layer protocol in the IPX/SPX protocol stack. ... DECnet is a proprietary suite of network protocols created by Digital Equipment Corporation, originally released in 1975 in order to connect two PDP-11 minicomputers. ...


Novell NetWare used this frame type by default until the mid nineties, and since Netware was very widespread back then, while IP was not, at some point in time most of the world's Ethernet traffic ran over "raw" 802.3 carrying IPX. Since Netware 4.10 Netware now defaults to IEEE 802.2 with LLC (Netware Frame Type Ethernet_802.2) when using IPX. (See "Ethernet Framing" in References for details.) NetWare is a network operating system developed by Novell, Inc. ...


Mac OS uses 802.2/SNAP framing for the AppleTalk V2 protocol suite on Ethernet ("EtherTalk") and Ethernet II framing for TCP/IP. This article or section does not adequately cite its references or sources. ... AppleTalk is a proprietary suite of protocols developed by Apple Computer for computer networking. ...


The 802.2 variants of Ethernet are not in widespread use on common networks currently, with the exception of large corporate Netware installations that have not yet migrated to Netware over IP. In the past, many corporate networks supported 802.2 Ethernet to support transparent translating bridges between Ethernet and IEEE 802.5 Token Ring or FDDI networks. The most common framing type used today is Ethernet Version 2, as it is used by most Internet Protocol-based networks, with its EtherType set to 0x0800 for IPv4 and 0x86DD for IPv6. The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... EtherType is a field in the Ethernet networking standard. ... 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. ... It has been suggested that IPv6 internet be merged into this article or section. ...


There exists an Internet standard for encapsulating IP version 4 traffic in IEEE 802.2 frames with LLC/SNAP headers.[5] It is almost never implemented on Ethernet (although it is used on FDDI and on token ring, IEEE 802.11, and other IEEE 802 networks). IP traffic can not be encapsulated in IEEE 802.2 LLC frames without SNAP because, although there is an LLC protocol type for IP, there is no LLC protocol type for ARP. IP Version 6 can also be transmitted over Ethernet using IEEE 802.2 with LLC/SNAP, but, again, that's almost never used (although LLC/SNAP encapsulation of IPv6 is used on IEEE 802 networks). An Internet standard is a specification for an innovative internetworking technology or methodology, which the Internet Engineering Task Force (IETF) ratified as an open standard after the innovation underwent peer review. ... IEEE 802. ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ... Token-Ring local area network (LAN) technology was developed and promoted by IBM in the early 1980s and standardised as IEEE 802. ... IEEE 802. ... IEEE 802 refers to a family of IEEE standards about local area networks and metropolitan area networks. ... In computer networking, the Address Resolution Protocol (ARP) is the standard method for finding a hosts hardware address when only its network layer address is known. ...


The IEEE 802.1Q tag, if present, is placed between the Source Address and the EtherType or Length fields. The first two bytes of the tag are the Tag Protocol Identifier (TPID) value of 0x8100. This is located in the same place as the EtherType/Length field in untagged frames, so an EtherType value of 0x8100 means the frame is tagged, and the true EtherType/Length is located after the tag. The TPID is followed by two bytes containing the Tag Control Information (TCI) (the IEEE 802.1p priority (quality of service) and VLAN id). The tag is followed by the rest of the frame, using one of the types described above. IEEE 802. ... In the fields of packet-switched networks and computer networking, the traffic engineering term Quality of Service (QoS) refers to control mechanisms that can provide different priority to different users or data flows, or guarantee a certain level of performance to a data flow in accordance with requests from the... A virtual LAN, commonly known as a vLAN or as a VLAN, is a method of creating independent logical networks within a physical network. ...


Physical layer

The first Ethernet networks, 10BASE5, used thick yellow cable with vampire taps as a shared medium (using CSMA/CD). Later, 10BASE2 Ethernet used thinner coaxial cable (with BNC connectors) as the shared CSMA/CD medium. The later StarLAN 1BASE5 and 10BASE-T used twisted pair connected to Ethernet hubs with 8P8C modular connectors (not to be confused with FCC's RJ45). IEEE photograph of a diagram with the original terms for describing Ethernet drawn by Robert M. Metcalfe around 1976. ... 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. ... CentreCOM AUI Vampire Tap A vampire tap is a device for physically connecting a station (i. ... 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... 10BASE2 cable showing BNC Connector end. ... Coaxial Cable For the weapon, see coaxial weapon. ... Male BNC connector Cables with BNC connectors Adapter between a female BNC connector and banana plugs Picture to show the similarity between 50 Ω and 75 Ω BNC connectors Pulse generators with BNC connectors and cables. ... StarLAN was the first implementation of Ethernet computer networking on twisted pair wiring. ... 10BASE-T cable 10BASE-T plug 10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. ... 25 Pair Color Code Chart 10BASE-T UTP Cable Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of cancelling out electromagnetic interference known as crosstalk. ... 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. ... This article does not cite any references or sources. ... A registered jack (RJ) is a standardized physical interface for connecting telecommunications equipment (commonly, a telephone jack) or computer networking equipment. ...


Currently Ethernet has many varieties that vary both in speed and physical medium used. Perhaps the most common forms used are 10BASE-T, 100BASE-TX, and 1000BASE-T. All three utilize twisted pair cables and 8P8C modular connectors (often called RJ45). They run at 10 Mbit/s, 100 Mbit/s, and 1 Gbit/s, respectively. However each version has become steadily more selective about the cable it runs on and some installers have avoided 1000BASE-T for everything except short connections to servers. Twisted-pair cable used with 10BASE-T 8P8C (not RJ-45) plug used with 10BASE-T There are several standards for Ethernet over twisted pair cable. ... This article does not cite any references or sources. ... A registered jack (RJ) is a standardized physical interface for connecting telecommunications equipment (commonly, a telephone jack) or computer networking equipment. ...


Fiber optic variants of Ethernet are commonly seen connecting buildings or network cabinets in different parts of a building but are rarely seen connected to end systems for cost reasons. Their advantages lie in performance, electrical isolation and distance, up to tens of kilometers with some versions. Fiber versions of a new speed almost invariably come out before copper. 10 gigabit Ethernet is becoming more popular in both enterprise and carrier networks, with development starting on 100G Ethernet. 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. ... 10 gigabit Ethernet or 10GbE or 10 GigE is the most recent (as of 2006) and fastest of the Ethernet standards. ... 100 gigabit Ethernet or 100GbE is an Ethernet standard presently under early development by the IEEE. The fastest existing standard is 10 gigabit Ethernet. ...


Through Ethernet's history there have also been RF versions of Ethernet, both wireline and wireless. The currently recommended RF wireless networking standards, 802.11 and 802.16, are not Ethernet, in that they do not use the Ethernet link-layer header, and use control and management packet types that don't exist in Ethernet – it would not be simply a matter of modulation to transmit Ethernet packets on an 802.11 or 802.16 network, or to transmit 802.11 or 802.16 packets on an Ethernet network. It has been suggested that this article or section be merged with Radio waves. ... 2006 is a common year starting on Sunday of the Gregorian calendar. ... IEEE 802. ... IEEE 802. ...


Related standards

  • Networking standards that are not part of the IEEE 802.3 Ethernet standard, but support the Ethernet frame format, and are capable of interoperating with it.
    • LattisNet — A SynOptics pre-standard twisted-pair 10 Mbit/s variant.
    • 100BaseVG — An early contender for 100 Mbit/s Ethernet. It runs over Category 3 cabling. Uses four pairs. Commercial failure.
    • TIA 100BASE-SX — Promoted by the Telecommunications Industry Association. 100BASE-SX is an alternative implementation of 100 Mbit/s Ethernet over fiber; it is incompatible with the official 100BASE-FX standard. Its main feature is interoperability with 10BASE-FL, supporting autonegotiation between 10 Mbit/s and 100 Mbit/s operation – a feature lacking in the official standards due to the use of differing LED wavelengths. It is targeted at the installed base of 10 Mbit/s fiber network installations.
    • TIA 1000BASE-TX — Promoted by the Telecommunications Industry Association, it was a commercial failure, and no products exist. 1000BASE-TX uses a simpler protocol than the official 1000BASE-T standard so the electronics can be cheaper, but requires Category 6 cabling.
  • Networking standards that do not use the Ethernet frame format but can still be connected to Ethernet using MAC-based bridging.
    • 802.11 — A standard for wireless networking often paired with an Ethernet backbone.
  • 10BaseS — Ethernet over VDSL
  • Long Reach Ethernet
  • Avionics Full-Duplex Switched Ethernet
  • Metro Ethernet

LattisNet the product family LattisNet was a family of computer networking hardware and software products built and sold by SynOptics (also rebranded by Western Digital) during the 80-90s. ... SynOptics Communications SynOptics Communications was a Santa Clara, California based important early Ethernet vendor. ... 100BaseVG is a 100 Mbit/s Ethernet standard specified to run over four pairs of category 3 UTP wires (known as voice grade, hence the VG). It is also called 100VG-AnyLAN because it was defined to carry both Ethernet and token ring frame types. ... 100BASE-SX is a version of fast ethernet over optical fiber. ... The Telecommunications Industry Association (TIA) is the leading trade association for the information and communications technology (ICT) industry, with 600 member companies that manufacture or supply the products and services used in global communications across all technology platforms. ... 1000BASE-TX is one implementation of Gigabit Ethernet - a computer network that transmits data at a nominal speed of 1 gigabit per second. ... The Telecommunications Industry Association (TIA) is the leading trade association for the information and communications technology (ICT) industry, with 600 member companies that manufacture or supply the products and services used in global communications across all technology platforms. ... IEEE 802. ... VDSL or VHDSL (Very High bit rate DSL) is an xDSL technology providing faster data transmission over a single twisted pair of wires. ... Long Reach Ethernet (LRE) is a developing set of networking protocols intended to support multi-megabit (5-15Mbps) performance over telephone-grade Category 1/2/3 wiring over distances up to 5,000 feet. ... Avionics Full-Duplex Switched Ethernet (AFDX) is Part 7 of the ARINC 664 Specification which defines how Commercial Off-the-Shelf (COTS) networking technology will be used for future generation Aircraft Data Networks (ADN). ... A Metro Ethernet is a computer network based on the Ethernet standard covering a metropolitan area. ...

Implementations

OpenCores is a loose community of people who are interested in developing open source hardware (digital hardware) through electronic design automation, with a similar ethos to the free software movement. ... Verilog is a hardware description language (HDL) used to model electronic systems. ... GNU logo The GNU Lesser General Public License (formerly the GNU Library General Public License) is an FSF approved Free Software license designed as a compromise between the GNU General Public License and simple permissive licenses such as the BSD license and the MIT License. ...

See also

10 gigabit Ethernet or 10GbE or 10 GigE is the most recent (as of 2006) and fastest of the Ethernet standards. ... 100 gigabit Ethernet or 100GbE is an Ethernet standard presently under early development by the IEEE. The fastest existing standard is 10 gigabit Ethernet. ... An 8P8C modular plug that has yet to be crimped onto a cable Cat5 cables with 8P8C modular plugs, wired to EIA/TIA-568B 8P8C is short for eight positions, eight conductors, and so an 8P8C modular connector (plug or jack) is a modular connector with eight positions, all containing... AUI Connectors. ... Cat5 patch cable Category 5 cable, commonly known as Cat 5, is a twisted pair cable type designed for high signal integrity. ... This is a list of device bandwidths: the channel capacity (or, more informally, bandwidth) of some computer devices employing methods of data transport is listed by bit/s, kilobit/s (kbit/s), megabit/s (Mbit/s), or gigabit/s (Gbit/s) as appropriate and also MB/s or megabytes per... CHAOSnet, developed at MIT by the MIT AI Lab in the late 1970s, refers to two separate, but closely related, technologies. ... Ethernet Automatic Protection System is used to create a fault tolerant topology by configuring a primary and secondary path for each vlan. ... Crossover cable suitable for use with 100BASE-T4 Fast Ethernet 8P8C modular crossover adapter Compare crossover cable pinout with standard pinout. ... Ethernet Flow Control is defined by IEEE 802. ... In computer networking, Fast Ethernet is a collective term for a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s, against the original Ethernet speed of 10 Mbit/s. ... Gigabit Ethernet (GbE) is a term describing various technologies for transmitting Ethernet packets at a rate of a gigabit per second, as defined by the IEEE 802. ... Twisted-pair cable used with 10BASE-T 8P8C (not RJ-45) plug used with 10BASE-T There are several standards for Ethernet over twisted pair cable. ... IEEE photograph of a diagram with the original terms for describing Ethernet drawn by Robert M. Metcalfe around 1976. ... IEEE 802. ... In packet-switching computer networks, a jumbogram is a packet that is larger than the usual size limit for a given technology. ... The Media Independent Interface (MII) is a chip commonly found on Ethernet devices, together with the PHY. The standard MII features a small set of registers: Basic Mode Configuration (#0) Status Word (#1) PHY Identification (#2, #3) Ability Advertisement (#4) Link Partner Ability (#5) Auto Negotiation Expansion (#6) The MII... PHY is a generic electronics term refering to a special electronic integrated circuit or functional block of a circuit that provides physical access to a digital connection cable. ... For other uses, see Power band. ... Wireless LAN Access Point, powered by a PoE-Splitter Power over Ethernet or PoE technology describes a system to transmit electrical power, along with data, to remote devices over standard twisted-pair cable in an Ethernet network. ... The spanning tree network protocol provides a loop free topology for any bridged LAN. The Spanning Tree Protocol, which is also referred to as STP, is defined in the IEEE Standard 802. ... A virtual LAN, commonly known as a vLAN or as a VLAN, is a method of creating independent logical networks within a physical network. ... Wake on LAN (WOL, sometimes WoL) is an Ethernet computer networking standard that allows a shut-down computer to be booted remotely. ...

References

  1. ^ Ethernet Prototype Circuit Board. Smithsonian National Museum of American History. Retrieved on 2007-09-02.
  2. ^ Shoch, John F. and Hupp, Jon A. (December 1980). "Measured performance of an Ethernet local network". Communications of the ACM 23 (12): 711–721. ISSN: 0001-0782. 
  3. ^ Boggs, D.R., Mogul, J.C., and Kent, C.A. (August 1988). "Measured capacity of an Ethernet: myths and reality". ACM SIGCOMM Computer Communication Review 18 (4): 222–234. ISBN 0-89791-279-9. 
  4. ^ LAN MAN Standards Committee of the IEEE Computer Society (20 March 1997). IEEE Std 802.3x-1997 and IEEE Std 802.3y-1997. The Institute of Electrical and Electronics Engineers, Inc., pp. 28–31. 
  5. ^ RFC 1042
  • Metcalfe, Robert M. and Boggs, David R. (July 1976). "Ethernet: Distributed Packet Switching for Local Computer Networks". Communications of the ACM 19 (5): 395–405.  — the original Metcalfe and Boggs paper on Ethernet.
  • Digital Equipment Corporation, Intel Corporation, Xerox Corporation (September, 1980). "The Ethernet: A Local Area Network". — Version 1.0 of the DIX specification.
  • Boggs, David R. and Mogul, Jeffrey C. and Kent, Christopher A. (1988). "Measured capacity of an Ethernet: myths and reality" (PDF). SIGCOMM88 – Symposium proceedings on Communications architectures and protocols: 222–234. DOI:10.1145/52324.52347.  — on the issue of Ethernet bandwidth collapse.
  • IEEE 802.3-2005 standard
  • Don Provan (1993-09-17). "Ethernet Framing". comp.sys.novell. (Google Groups). — a classic series of Usenet postings by Novell's Don Provan that have found their way into numerous FAQs and are widely considered the definitive answer to the Novell Frame Type jungle.

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 245th day of the year (246th in leap years) in the Gregorian calendar. ... is the 79th day of the year (80th in leap years) in the Gregorian calendar. ... For the band, see 1997 (band). ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 1993 (MCMXCIII) was a common year starting on Friday (link will display full 1993 Gregorian calendar). ... is the 260th day of the year (261st in leap years) in the Gregorian calendar. ...

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Ethernet - Wikipedia, the free encyclopedia (4595 words)
Ethernet was originally based on the idea of computers communicating over a shared coaxial cable acting as a broadcast transmission medium.
The Ethernet Version 2 or Ethernet II frame, the so-called DIX frame (named after DEC, Intel, and Xerox); this is the most common today, as it is often used directly by the Internet Protocol.
Ethernet was originally developed as one of the many pioneering projects at Xerox PARC.
Ethernet (3470 words)
Since short Ethernet frames must be padded with zeros to a length of 64 bytes, each of these higher level protocols required either a larger minimum message size or an internal length field that can be used to distinguish data from padding.
Any Ethernet packet with a type/length field less than 1500 is in 802.3 format (with a length) while any packet in which the field value is greater than 1500 must be in DIX format (with a type).
Ethernet is supposed to be a single common medium with multiple connections.
  More results at FactBites »

 
 

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