Ethernet makes it easier for readers to understand and refer to it when reading.

Ethernet was first founded by Xerox. 1980, DEC, lntel and Xerox jointly developed into a standard. Ethernet is the most widely used LAN, including standard Ethernet (10Mbit/s), fast Ethernet (10mb it/s) and 10G Ethernet (10Gbit/s). CSMA/ CD access control method is adopted, all of which conform to IEEE 802. The contents specified in IEEE802.3 standard include physical layer wiring, electrical signals and media access layer protocols. Ethernet is the most widely used LAN technology at present. It has largely replaced other LAN standards, such as token ring network, FDDI and ARCNET. Following the rapid development of 100M Ethernet at the end of last century, with the promotion of international organizations and leading enterprises, the application scope of Gigabit Ethernet and even 10G Ethernet is constantly expanding. Common applications of 802.3 are: 10M: 10base-T (copper UTP mode) 100M: 100base-TX (copper UTP mode) 100base-FX (optical fiber line)/

Edit this paragraph history

The initial development of Ethernet technology came from one of many pioneering technical projects of Xerox Palo Alto Research Center. People usually think that Ethernet was invented in 1973, when robert metcalf wrote a memo to his PARC boss about the potential of Ethernet. But Metcalfe himself thinks that Ethernet didn't appear until several years later. 1976, Metcalfe and his assistant David Boggs published an article entitled "Ethernet: Distributed Packet Switching Technology in Local Computer Networks". At the end of 1977, Metcalfe and his collaborators obtained the patent of "Multipoint Data Communication System with Collision Detection", which is called CSMA/CD (Carrier Sense Multiple Access with Collision Detection). From then on, it marked the birth of Ethernet. From 65438 to 0979, Metcalfe left Xerox Company and founded 3Com Company to develop personal computers and local area networks. 3com plug for Digido, Intel and Ethernet.

[1] Xerox lobbied them to standardize and standardize Ethernet. This universal Ethernet standard was released on September 30th, 1980 in/kloc-0. At that time, there were two popular non-public network standards, token ring network and ARCNET, which quickly shrank and were replaced under the impact of Ethernet tide. In the process, 3Com also became an international company. Metcalfe once joked that Jerry Salz contributed to the success of 3Com. In an influential paper co-authored with others, Saltzer pointed out that token ring network is superior to Ethernet in theory. Influenced by this conclusion, many computer manufacturers either hesitate or decide not to use Ethernet interface as the standard configuration of their machines, so 3Com has the opportunity to make a fortune by selling Ethernet cards. This situation has also led to another saying that "Ethernet is not suitable for theoretical research, but only suitable for practical application". Maybe this is just a joke, but it illustrates a technical point: usually, the actual data flow characteristics in the network are different from those estimated before the popularization of LAN, and it is precisely because of the simple structure of Ethernet that LAN is popularized. Metcalfe and Saltzer used to work on the same floor of the Massachusetts Institute of Technology (MIT) MAC project, when he was doing his graduation thesis at Harvard University, during which he laid the theoretical foundation of Ethernet technology. It is not a specific network, but a technical specification. This standard defines the cable types and signal processing methods used in local area network (LAN). Ethernet transmits data packets between interconnected devices at the rate of 10~ 100Mbps. Twisted-pair 10 Base T Ethernet has become the most widely used Ethernet technology because of its low cost, high reliability and 10Mbps. Direct spread spectrum wireless Ethernet can reach 1 1Mbps, and the products provided by many manufacturers can communicate with each other using common software protocols, which has the best openness.

Edit the classification and development of Ethernet in this section.

I. Standard Ethernet

Ethernet

At first, the throughput of Ethernet was only 10Mbps, and CSMA/CD (Carrier Sense Multiple Access/Collision Detection) access control mode with collision detection was adopted. This early 10Mbps Ethernet is called standard Ethernet. Ethernet can be connected through a variety of transmission media, such as thick coaxial cable, thin coaxial cable, unshielded twisted pair, shielded twisted pair and optical fiber. In IEEE 802.3 standard, different physical layer standards are formulated for different transmission media. In these standards, the first number represents the transmission speed in Mbps, the last number represents the length of a single network cable (reference unit is 100m), and Base stands for baseband. 10BASE-5 adopts thick coaxial cable with a diameter of 0.4 inch and an impedance of 50 Ω, also known as thick cable Ethernet, with a maximum length of 500m, baseband transmission mode and bus topology; The main hardware devices of 10BASE-5 networking are: thick coaxial cable, Ethernet card with AUI socket, repeater, transceiver, transceiver cable, terminator, etc. 10BASE-2 adopts a thin coaxial cable with a diameter of 0.2 inch and an impedance of 50 Ω, also known as thin cable Ethernet, with a maximum length of 185m, baseband transmission mode and bus topology; The main hardware devices of 10BASE-2 networking include: thin coaxial cable, Ethernet card with BNC socket, repeater, T-connector, terminator, etc. 10BASE-T adopts twisted pair, with maximum segment length of 100m and star topology; The main hardware devices of 10BASE-T networking include: unshielded twisted-pair cables of class 3 or 5, Ethernet cards with RJ-45 sockets, hubs, switches, RJ-45 plugs, etc. 1base-5 adopts twisted pair, with the maximum segment length of 500m and the transmission speed of1Mbps; ; 10bbroad-36 adopts coaxial cable (RG-59/U CATV), with the maximum network span of 3600m and the maximum segment length of 1800m, which is a broadband transmission mode; 10BASE-F adopts optical fiber transmission medium, and the transmission rate is 10Mbps.

Second, fast Ethernet.

Ethernet protocol

With the development of network, the traditional standard Ethernet technology has been difficult to meet the increasing demand of network data transmission speed. Before 1993, in 10, for LAN applications requiring data traffic above 10Mbps, only fiber distributed data interface (FDDI) was available, but this is a very expensive LAN based on 100 Mbps optical cable. 1993 10, Grand Junction introduced the world's first fast Ethernet hub fastch10100 and network interface card FastNIC 100, and the fast Ethernet technology was formally applied. Subsequently, Intel, SynOptics, 3COM, BayNetworks and other companies also launched their own fast Ethernet devices. At the same time, the IEEE802 engineering team also studied various standards of 100Mbps Ethernet, such as 100 base-TX, 100 base-T4, MII, repeater, full duplex and so on. 1in March, 1995, IEEE published the IEEE 802.3U 100BASE-T fast Ethernet standard, which started the era of fast Ethernet. Compared with FDDI which used to work in 100Mbps bandwidth, Fast Ethernet has many advantages. Most importantly, the fast Ethernet technology can effectively ensure the user's investment in the basic realization of wiring. Support the connection of 3, 4 and 5 twisted pairs and optical fibers, which can effectively use the existing facilities. The shortage of fast Ethernet is actually the shortage of Ethernet technology, that is, fast Ethernet is still based on CSMA/CD technology. When the network load is heavy, it will reduce efficiency. Of course, this can be compensated by switching technology. 100Mbps fast Ethernet standard is divided into three subclasses: 100base-TX, 100base-FX and 100base-T4. 100BASE-TX: It is a fast Ethernet technology that uses unshielded twisted pair or shielded twisted pair for class 5 data. It uses two pairs of twisted pairs, one for sending data and the other for receiving data. The transmission adopts 4b/5b coding mode, and the signal frequency is 125MHz. It conforms to Class 5 wiring standard of EIA586 and Class 0 wiring standard of SPT 1 of IBM. Use the same rj-45 connector as10base-t. The maximum segment length is100m. It supports full duplex data transmission. 100base-FX: It is a fast Ethernet technology using optical cables, which can use single-mode and multimode optical fibers (62.5 and 125um). The maximum distance of multimode fiber connection is 550 meters. The maximum distance of single-mode fiber connection is 3000 meters. The transmission adopts 4b/5b coding mode, and the signal frequency is 125MHz. It uses MIC/FDDI connector, ST connector or SC connector. The maximum segment length is 150m, 4 12m, 2000m or longer to 10 km, which is related to the type of optical fiber used and the working mode. It supports full duplex data transmission. 100base-FX is especially suitable for environments with electrical interference, long-distance connection or high security. 100base-T4: It is a fast Ethernet technology, which can use unshielded twisted pair or shielded twisted pair of Category 3, 4 and 5. 100Base-T4 uses 4 pairs of twisted pairs, of which 3 pairs are used to transmit data at the frequency of 33MHz, and each pair works in half-duplex mode. The fourth pair is used for CSMA/CD collision detection. The transmission adopts 8B/6T coding mode, and the signal frequency is 25MHz, which conforms to the EIA586 structured wiring standard. It uses the same RJ-45 connector as 10BASE-T, and the maximum segment length is100m.

3. Gigabit Ethernet

Gigabit Ethernet technology, as the latest high-speed Ethernet technology, brings users an effective solution to improve the core network. The biggest advantage of this scheme is that it inherits the advantage of low price of traditional Ethernet technology. Gigabit technology is still Ethernet technology, which adopts the same frame format, frame structure, network protocol, full/half-duplex working mode, flow control mode and wiring system as 10M Ethernet. Because this technology does not change the desktop application and operating system of traditional Ethernet, it can be used well with 10M or 100M Ethernet. Upgrading to Gigabit Ethernet does not need to change network applications, network management components and network operating systems, which can protect investment to the greatest extent. In addition, the IEEE standard will support multimode optical fiber with a maximum distance of 550 meters, single-mode optical fiber with a maximum distance of 70 kilometers and copper shaft cable with a maximum distance of 100 meters. Gigabit Ethernet fills the gap of 802.3 Ethernet/Fast Ethernet standard. In order to detect the collision of 64-byte frames, Gigabit Ethernet supports shorter distances. The network types supported by Gigabit Ethernet are as follows: transmission medium distance 1000base-CX copper STP 25m 1000base-T copper cat5UTP100m1000base-SX multimode fiber 500m 10. 00Base-LX single-mode fiber 3000m Gigabit Ethernet technology has two standards: IEEE802.3z and IEEE802.3ab IEEE802.3z establishes the standard of optical fiber and short-distance copper wire connection scheme. IEEE802.3ab establishes the standard of long-distance connection scheme on five types of twisted pair. 1.ieee802.3z the ieee802.3z working group is responsible for formulating the full duplex link standard for optical fiber (single mode or multimode) and coaxial cable. IEEE802.3z defines 100ba se-X based on optical fiber and short-distance copper cable, adopts 8B/ 10B coding technology, and the channel transmission speed is 1.25Gbit/s, After decoupling, the transmission speed is1000 bit/s ... IEEE 802.3z has the following gigabit Ethernet standards: 1000BASE-SX only supports multimode optical fibers, with a diameter of 62.5um or 50um, working wavelength of 770-860nm and transmission distance of 220-550m m. 1000base-LX single-mode fiber: It can support single-mode fiber with a diameter of 9um or 10um, with the working wavelength range of 1270- 1355nm and the transmission distance of about 5km. 1000base-CX adopts 150 ohm shielded twisted pair (STP) with a transmission distance of 25m. 2. IEEE 802.3 ab The IEEE 802.3ab working group is responsible for formulating gigabit Ethernet standards for UTP-based half-duplex links and generating IEEE 802.3ab standards and protocols. IEEE802.3ab defines 1000Base-T standard based on five UTP, and its purpose is to transmit 1000Mbit/s on five UTP. The significance of IEEE802.3ab standard has two main points: (1) to protect users' investment in five types of UTP wiring systems. (2) 1000Base-T is a natural extension of 100Base-T, which is completely compatible with 100Base-T and 100base-t ... However,1000bit should be implemented on five types of UTP.

Fourth, 10 Gigabit Ethernet

10 Gigabit Ethernet specification is included in IEEE 802.3ae, which is a supplementary standard of IEEE 802.3, extends the IEEE 802.3 protocol and MAC specification, and supports the transmission rate of10Gb/s. In addition, through WAN interface sublayer (WIS), 10 gigabit Ethernet can also be adjusted to a lower transmission rate, such as 9.584640 Gb/s (OC- 192), which allows 10 gigabit Ethernet devices to communicate with the synchronous optical network STS-662. 10Gbase-SR and 10GBASE-SW mainly support short-wave (850 nm) multimode optical fiber (MMF), and the optical fiber distance is 2m to 300 m. 10GBASE-SR mainly supports "dark optical fiber", which refers to optical fiber that has no light propagation and is not connected to any equipment. 10GBASE-SW is mainly used to connect SONET devices and is applied to remote data communication. 10Gbase-LR and 10GBASE-LW mainly support long-wave (13 10nm) single-mode fiber (SMF), and the fiber distance is 2m to 10km (about 32,808 feet). When 10GBASE-LW is mainly used to connect SONET devices, 10GBASE-LR is used to support "dark fiber". 10Gbase-ER and 10GBASE-EW mainly support ultra-long wave (1550nm) single-mode fiber (SMF), and the fiber distance is 2m to 40km (about 13 1233 feet). 10GBASE-EW is mainly used to connect SONET devices, and 10GBASE-ER is used to support "dark fiber". 10Gbase-LX4 uses wavelength division multiplexing technology to transmit signals at four times the wavelength of light on a pair of optical cables. The system runs in 13 10nm multimode or single-mode dark fiber mode. The design goal of the system is aimed at multimode fiber mode from 2 meters to 300 meters or single-mode fiber mode from 2 meters to 10 kilometers.