Ethernet Weili Encyclopedia, Free Encyclopedia JUMP to:, Search SSH, Telnet, ... DCCP, SCTP, TCP, RTP, UDP, IL, RUDP, ... network layer IPv4, IPv6 ... Data link layer Ethernet, Wi-Fi, token Ring, MPLS, PPP ... N Ethernet is a computer local area network group technology. The IEEE 802.3 standard set by IEEE gives the technical standards of Ethernet. It stipulates the content of the connection, electrical signal and medium access layer protocol of the physical layer. Ethernet is the most common LAN technology at present. It has largely replaced other LAN standards, such as token ring, FDDI and Arcnet. The standard topology structure of Ethernet is the bus-type topology, but the current fast Ethernet (100Base-T, 1000BASE-T standard) in order to minimize conflicts and improve network speed and use efficiency to the greatest extent. The network connection and organization are performed. In this way, the topology structure of Ethernet has become a star type, but logically, Ethernet still uses a bus -type topology and CSMA/CD (Carrier Sense Multiple Access/COLLISION Derect Multi -road access) bus competition technology. Directory 1]
* 1 History * 2 Overview * 3 CSMA/CD shared medium The internet relay and hub * 5 bridge and exchange * 6 Ethernet type o 6.1 Ethernet o 6.2 10Mbps Ethernet o 6.3 Express Ethernet (100Mbps ) o 6.4 Gigabit Ethernet o 65,000 mega Ethernet * 7 reference * 8 [Edit]
History
The initial progress of Ethernet technology comes from one of many pioneering technology projects of the Xerox PARC. It is often considered that Ethernet was invented in 1973. At that time, Robert Metcalfe wrote a memo of Ethernet potential for Parc's boss. However, Metcafe himself thought that Ethernet appeared in the next few years. In 1976, Metkaf and his assistant David Boggs published an article entitled "Ethernet: Distributed Package Exchange Technology of LAN: LAN: LAN:".
In 1979, Metkaf left Schola in order to develop a personal computer and LANS (Lans) and set up 3COM. 3COM lobby DEC, Intel, and Xiele, hoping to standardize and standardize the Ethernet with them. This universal Ethernet standard was issued on September 30, 1980. At that time, the industry had two popular non -public network standard token and ARCNET, which was quickly shrinking and replaced by the impact of Ethernet tide. In the process, 3COM also became a large international company.
Matcoff once joked that Jerry Saltzer contributed the success of 3COM. Saltzer pointed out in a very influential paper that coincides with others that theoretically token ring network is superior to Ethernet. Affected by this conclusion, many computer manufacturers are hesitant or decided not to use the Ethernet interface as a standard configuration of the machine, so that 3COM has the opportunity to make a lot of money from the sales Ethernet network card. This situation also led to another saying that "Ethernet is not suitable for research in theory and is only suitable for application in actual situation." Perhaps it is just a joke, but this illustrates such a technical point: Under normal circumstances, the actual data flow characteristics in the network are different from people's estimates before the popularization of LAN. Essence Metkov and Saltzer worked in the same floor of the MAC project of Massachusetts Institute of Technology. At that time, he was doing his graduation thesis of Harvard University. During this period, he laid the theoretical foundation of Ethernet technology. [Edit]
Overview 1990 is an Tai network card or NIC, Ethernet adapter. This card can support 10BASE2 (BNC connectors, left) based on coaxial cables and 10Base-T (RJ-45, right) based on twisted pair. amplified 1990 is an Tai network card or NIC, Ethernet adapter. This card can support 10BASE2 (BNC connectors, left) based on coaxial cables and 10Base-T (RJ-45, right) based on twisted pair.
It Ethernet is based on the idea of sending information on multiple nodes on the network radio system. Each node must obtain cables or channels to transmit information, and sometimes it is also called Ether. (This name comes from the electromagnetic radiation media hypothetical of the physicist of the 19th century-Light Ether. Later research proves that Light Ether does not exist.) Each node has the only 48-bit address in the world, that is, the MAC address assigned by the manufacturer to the network card To ensure that all systems on Ethernet can identify each other. Because Ethernet is very common, many manufacturers integrate the Ethernet card directly into the computer motherboard.
have found that Ethernet communication has its own similarity, which is very important for telecommunications and communication engineering. [Edit]
CSMA/CD sharing medium Ethernet n n carrier listening multi -road visit (CSMA/CD) technology specifies multiple computers Share a channel method. This technology first appeared in Alohanet developed by the University of Hawaii in the 1960s. It uses radio waves as a carrier. This method is simpler than token ring or the main control network. When a computer wants to send information, you must follow the following rules:
1. Start-if the line is idle, then start transmission, otherwise transfer to the fourth step 2. Send-if the detection By the conflict, continue to send data until the minimum message time (ensure that all other forwarders and terminals detect the conflict), then turn to Step 4. 3. Success transmission-successfully send to a higher-level network protocol report successfully. , Exit the transmission mode. . The line is busy-wait until the line is free 5. The line enters the idle state-wait for a random time to go to step 1 Try to transmit the number of transmission-the sending of the higher-level network protocol failed, exit the transmission mode
It is like a symposium without a host, all participants come through a common medium (air) (air)) Talk with each other. Before each participant speaking, they waited politely for others to finish their words. If two guests start speaking at the same time, they stop and wait for a while to start speaking. At this time, the conflict will not appear if the two participants wait for different time. If the transmission fails for more than once, it will use the method of growth for the retreat index (the retreat time is achieved by truncating the Truncated Binary Backoff).
The original Ethernet uses coaxial cables to connect each device. The computer is connected to the cable through a transcendator called the Unit Interface (AUI). A simple network cable is still very reliable for a small network. For large networks, the failure of a line or a fault of a connector will cause the Ethernet to be unstable.
The communication signals are transmitted on the shared line. Even if the information is only sent to one of the terminals (), the message sent by a computer will be accepted by all other computers. Under normal circumstances, the network interface card will filter out the information that is not sent to your own. When receiving the target address is your own information, it will send an interrupt request to the CPU unless the network card is in the mixed mode. The characteristics of this "one say, everyone listen" is the weakness of the shared medium Ethernet, because a node on the Ethernet can choose to listen to all the information transmitted on the line. Sharing cables also means sharing bandwidth, so the speed of the Ethernet may be very slow in some cases. For example, after the power failure, when all the network terminals are restarted. [Edit]
The Ethernet relay and hub
In the development of Ethernet technology, the emergence of Ethernet Hub makes the network even more Reliable and more convenient wiring.
The due to the attenuation and delay of the signal, there is a distance limit according to the different media. For example, the longest distance of 10Base5 coaxial cable is 500 meters (1,640 feet). The maximum distance can be implemented by Ethernet relay, and the relay can be enlarged and transmitted to the next paragraph. The relatives are connected to up to 5 network segments, but only 3 have equipment. This can reduce the problem caused by cable breaks: when a section of coaxial cable is disconnected, all the equipment on this section cannot communicate, and the relay can ensure that other network segments work properly.
S is similar to other high -speed bus. The Ethernet segment must be used as a terminal on both ends. For coaxial cables, the terminals on both ends of the cable must be connected to the 50 ohm resistance and radiator of 50 ohms called "Terminator", and AFFIXED to a Male M or BNC Connector. Situation: When the AC signal on the bus reaches the terminal, it will be reflected and cannot dissipate. The reflected signal will be considered a conflict, so that the communication cannot continue. The relay can be charged with two network segments on it, enhanced and synchronized signals. Most relatives have the function of "automatic isolation", which can be isolated from the web segments with too many conflicts or durations of conflict, so that other network segments will not be affected by the damage part. After the conflict disappears, the relay can restore the connection of the network segment.
With the expansion of the application, people gradually discovered that the star -type network topology structure is the most effective, so equipment manufacturers have begun to develop multiple porters. Multi -port relay is a well -known hub (HUB). The hub can be connected to other hub or coaxial network.
The first hub is considered a "multi -end oral transceiver" or "FANOUTS". The most famous example is DEC's Delni, which allows many hosts with AUI connectors to share a transceiver. The hub also leads to the emergence of small independent Ethernet sections that do not use coaxial cables.
The network device manufacturers like DEC and Synoptics have sold hubs for connecting many 10Base-2 thin-homogeneous network segments.
The non-shielding-Pair Cables (UTP) was first applied to a star network, which was also applied in 10Base-T, and finally replaced the coaxial cable to become Ethernet. Standards. After this improvement, the RJ45 telephone interface replaced AUI to become the standard boundary of the computer and hub, and the non -shielding 3 types of twisted lines/5 twisted twisted lines became standard carriers. The application of the hub makes the failure of a cable or a device that does not affect the entire network and improves the reliability of Ethernet. The twisted pair Ethernet connects each network point, so that the terminal can make a standard hardware to solve the terminal problem of Ethernet.
The Ethernet using the hub group network Although it is a star structure, it is logically a bus type. The hub's effect on reducing package conflict is small. Each packet is sent to each port of the hub, so the bandwidth and security problems have not been resolved. The total throughput of the hub is limited by a single connection speed (10 or 100 mbit/s), which is considered as the minimum of the previous synchronization code, frame interval, head, tail, and packaging. When the network load is too heavy, conflicts often reduce the total throughput. The worst case is that when many hosts with long cables network transmit many very short frames, the load of the network will reduce the throughput of the hub for only 50%. In order to increase the load of the network as much as possible before the conflict is severely reduced through throughput, some settings are usually carried out. [Edit]
bridge and exchange
Although the relay is isolated in some aspects of the Ethernet network segment, the failure of the cable disconnection will not affect the failure of the cable. The entire network, but it forwarded all the data to all the and network devices. This seriously limits the number of machines that can communicate with each other on the same Ethernet network. To reduce this problem, the bridge method is adopted. On the basis of working on the relay of the physical layer, the bridge work on the data link layer. When the network bridge, only the format of theatrical packet can enter another network segment from one network segment; conflict and data packet errors are isolated. By recording and analyzing the MAC address of the devices on the network, the network bridge can determine where they are, so that it will not pass the data packet to the network segment where the non -target device is located. Control mechanisms such as generating tree protocols can coordinate multiple switches to work together.
The early bridge to detect each data packet. In this way, especially when processing multiple ports at the same time, the data forwarding is slower than HUB (relay). In 1989, the Internet company Kalpana invented, the first Ethernet switch. The Ethernet switch can be implemented with hardware, so that the rate of reposting data can reach the line speed.
The Modern Ethernet use Ethernet switch instead of HUB. Although the wiring is the same as the HUB Ethernet, the exchanging Ethernet has many obvious advantages than the Ethernet, such as a larger bandwidth and better ending isolation. Exchange network typical use of star topology, although the equipment work in the semi -dual -work mode is still a multi -nodder network for sharing media. The 10Base-T and the future standards are all dual-workers Ethernet, which is no longer a shared medium system.
Plash when the switch is charged, first work like hub to forward all data to all ports. Next, when it learned the address of each port, he only sent non -wide broadcast data to a specific destination port. In this way, the line speed Ethernet exchange can be implemented between any port pair, and the communication between all port pairs does not interfere with each other.
Because the data packet is generally only sent to his destination port, the traffic on the Ether Ethernet is slightly smaller than the shared medium Ethernet. Nevertheless, the switching Ethernet is still an unsafe network technology, because it can easily be paralyzed by ARP deception or MAC overflowing. At the same time, the network administrator can also use the monitoring function to capture the network data packet.
Is to access the switch port when only simple devices (except HUB) are connected to the switch port, then the entire network may work in a full -duplex method. If there are only 2 devices in a network segment, conflict detection is not needed, and the two devices can send and receive data at any time. The total bandwidth is twice the link (although the bandwidth is the same in each direction), but no conflict occurs means allowing almost 100%of the link bandwidth.
This ports and connected devices must use the same dual -work settings. Most 100BASE-TX and 1000Base-T device support the automatic negotiation characteristics, that is, these devices coordinate the rate and dual-time settings through signals to coordinate. However, if the automatic negotiation is disabled or the device is not supported, the dual -work settings must be set up by automatic detection or manually setting on the switch port and device to avoid dual -work errors -this is a common type of Ethernet problem. The reason (the device is set to the semi -dual -union report to report the conflict, and the device is set to a full dual -worker to report RUNT). Many low -end switches do not have the ability to perform speed and dual -time settings, so the ports always try to conduct automatic negotiation. When the automatic negotiation is enabled but unsuccessful (for example, other devices are not supported), the automatic negotiation will set the port to semi -dual workers. The rate can be automatically sensitive, so connecting a 10Base-T device to a 10/100 exchange port that enables automatic negotiation can successfully build a half-dual-work 10Base-T connection. However, when connecting a device configured to a full dual -worker 100MB work to an exchange port that is configured to automatically negotiate, it will lead to dual -work mismatch.
as, even if both ends of the cable are set to automatic rate and dual -work mode negotiation, the error guess is to retreat to 10Mbps mode. Therefore, if the performance is poor than expected, you should check whether there is a computer setting to 10Mbps mode. If the other end is known to be 100Mbit, you can manually set it to the correct mode. .
Is when two nodes are trying to communicate with maximum support data rates exceeding the cable (for example, using 100Mbps or 3/5 lines on the 3 -line line to communicate with 1000Mbps). Unlike ADSL or traditional dial -up modem, the maximum support data rate of the link is detected by detailed methods. Therefore, if a high rate causes the cable to be unreliable, the link will fail. The solution only reduces the rate of compulsory communication to the cable support. [Edit]
The Ethernet type
In addition to the different frame types mentioned above, the difference between the various types of Ethernet is only the rate and wiring. Therefore, in general, the same network protocol stack software can run on most Ethernet.
The chapters below briefly summarize different formal Ethernet types. In addition to these formal standards, many manufacturers have formulated some special standards for some special reasons, such as to support longer -distance optical fiber transmission.
This Ethernet cards and switching devices support multi -speed. The best connection speed and dual -work method are set up by automatic negotiation. If the negotiation fails, the multi -rate device will detect the rate used by the other party but the default is the semi -dual -work method. 10/100 Ethernet port supports 10Base-T and 100Base-TX. 10/100/1000 supports 10Base-T, 100BASE-TX, and 1000Base-T. [Edit]
The early Ethernet
* Schola Ethernet-the original 3-mbit/s Ethernet, there are two versions: version one and harmony Version 2. The frame format of version two is still commonly used. * 10Broad36 - Over time. A early support for long -distance Ethernet. It runs on the coaxial cable and uses a broadband modulation technology similar to a cable modem system. * 1base5 -also called a star network with a rate of 1Mbit/s. It failed in business. The first use of the twin line is used here.
[Edit]
10Mbps Ethernet
* 10base5 (also known as coarse cable or yellow cable) -the earliest realization of 10 mbit/s Ethernet network Essence Early IEEE standard, using a single 50 ohm impedist RG-8 coaxial cable with a maximum distance of 500 meters. The receiving end is inserted into the core and shielding layer of the cable through the so -called "insertion segmentation". Use the N -type connector at the end of the cable. An AUI Cable then Connected the to the Ethernet Device. Although there are still some systems in the early days, this standard has been discarded. The endor is required at both ends of the cable. * 10base2 (also known as fine cable or simulation network)-50 ohm RG-58 coaxial cable, 200 meters, connect all the computer, each computer uses a adapter to connect to a network card with a BNC connector Essence Two ends of the line need to be an ender. It has always been the mainstream of 10M nets for a long time. * Starlan-The Ethernet standard 10 mbit/s. After the first twisted cylinder, the Ethernet standard 10 Mbit/s. The 4 lines of the twisted pair (2 pairs of twisted lines) 100 meters. Ethernet hub or Ethernet switch is located in the middle to connect all nodes. * Foill -Fiber Fiber Constifier Link. The original version of the optical fiber Ethernet. * 10Base-F-10Mbps Ethernet Fiber Standard NTC, 2 kilometers. Only 10base-fl applications are widely wide o 10base-fl-Foirl standard 1 upgrade. o 10base-fb-the backbone network technology for connecting multiple HUBs or switches, it has been abandoned O n o 10base-fp-no relay passive star network, never obtained
[Edit]
Quick Ethernet (100Mbps)
* 100Base-T-The standard of the three 100 mbit/s twisted lines below is generally called, up to 100 meters. o 100Base-TX-10Base-T. Similar to the star structure, use 2 pairs of cables, but require 5 types of cables to reach 100Mbit/s. o 100base-t4-use 3 cables use All 4 pairs of lines have been abandoned due to the popularity of 5 lines, half a two -time work. o 100base-T2-products. Use 3 types of cables. Support the full dual-working 2-pair line, functional equivalent 100Base-TX, but supports old cables. * 100base-fx-Use multi-mode fiber, with the farthest support of 400 meters, half a dual-work connection (guarantee conflict test), 2km full dual-work. * 100base-vg-only Hewlett-Packard support, VG first appeared in the market. Three -to -three cables are needed. Some people suspect that VG is not Ethernet.
[Edit]
Gigabit Ethernet
* 1000base-t-1 gbit/s medium super five types of twisted lines or 6 Dive twisted lines. * 1000Base-SX-1 gbit/s multi-mode fiber (less than 550 m). * 1000base-lx-1 gbit/s multi-mode fiber (less than 550 m). Need to use long -distance single -mode (optical fiber 10 kilometers). * 1000base-lh-1 gbit/s single-mode fiber (less than 100 kilometers). Long distance scheme * 1000Base-CX-a short distance (less than 25 m) scheme on the copper cable reaches 1Gbps. As early as 1000Base-T, it was abandoned.
[Edit]
The vigital Ethernet
The new 10 -dimensional Ethernet standard contains 7 different types of restraint types suitable for local area networks, cities Domain network and wide area network. Currently using additional standard IEEE 802.3AE to explain that in the future, IEEE 802.3 standards will be merged in the future.
* 10GBase-CX4-a short-distance copper cable solution is used for 4X connectors and CX4 cables, with a maximum length of 15 meters. * 10GBASE-SR-For short-distance multimodular fiber, it can reach 26-82 meters according to the cable type, and the new 2GHz multi-mode fiber can reach 300 meters. * 10GBASE-LX4-Use waves to reuse the multi-mode fiber 240-300 meters, and the single-mode fiber exceeds 10 kilometers. * 10GBASE-LR and 10GBase-EE-support 10 km and 40 km through single-mode fiber * 10GBase-SW, 10GBase-LW, 10GBase-EW. Used for wide-area network PHY, OC-192 / STM-64 synchronous optical fiber network / SDH device. The physical layer corresponds to 10GBase-SR, 10GBASE-LR and 10GBase-ER, so the same optical fiber support distance is also consistent. (No wide area network PHY standard) * 10GBase-T-use non-shielding twisted lines, it is planned to be released in August 2006.
Thousands of trillion Ethernet is a new standard. It takes time to test those more suitable for commercial use. [Edit]
The reference
* Ethernet protocol details
[Edit]
See
* chaosnet * Unit interface * Virtual LAN * generation tree protocol n * communication * Internet n * n * 5 types of twisted lines * RJ45 and Extension Cable * Cross -cable * Ethernet exchange mode * Power over ethernet * mii and phy n * Network wake -up
[Edit]
external link
* Ethernet protocol * ieee 802.3 Standard * Wanzo Ethernet * Ethernet frame format * 10,000 -Dibolia IP Ethernet White Paper * Gigabit Ethernet (1000Baset) n from "/wiki /以太网 "
Popular explanations are: 1 Land, wide area, urban area, and geographical range. 2, ADSL accessing broadband is a service company. For example, telecommunications, it is a kind of Internet service (in writing, it is called dedicated digital services)
3. Ethernet is just a kind of local area network. The network is to connect the host with some cables, and then everyone determines how to communicate with each other. The host is connected to the network, and the rules are called the network. 4, the Internet on our Internet is a wide area network, which is to connect the local area networks in various places, and go to Baidu to search for details (this will start with the past of the US Department of Defense DOD ...)
00:00 / 00: 5170% shortcut keys to describe space: Play / suspend ESC: exit full screen ↑: increase volume 10% ↓: reduced volume decrease by 10% →: single fast forward 5 seconds ←: single fast retreat 5 seconds Press hold up and hold it up. Here you can drag no longer appear in the player settings to reopen the small window shortcut key description
00:00 / 08: 0570% shortcut keys to describe space: Play / pause ESC: Exit full screen ↑: increase volume 10% ↓: decreases by 10% →: Single fast forward 5 seconds studio Here you can drag no longer appear in the player settings to reopen the small window shortcut key description
Ethernet
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Ethernet is a computer local area network group technology. The IEEE 802.3 standard set by IEEE gives the technical standards of Ethernet. It stipulates the content of the connection, electrical signal and medium access layer protocol of the physical layer. Ethernet is the most common LAN technology at present. It has largely replaced other LAN standards, such as token ring, FDDI and Arcnet. The standard topology structure of Ethernet is the bus-type topology, but the current fast Ethernet (100Base-T, 1000BASE-T standard) in order to minimize conflicts and improve network speed and use efficiency to the greatest extent. The network connection and organization are performed. In this way, the topology structure of Ethernet has become a star type, but logically, Ethernet still uses a bus -type topology and CSMA/CD (Carrier Sense Multiple Access/COLLISION Derect Multi -road access) bus competition technology.
Directory
1]
* 1 History
* 2 Overview
* 3 CSMA/CD shared medium The internet relay and hub
* 5 bridge and exchange
* 6 Ethernet type
o 6.1 Ethernet
o 6.2 10Mbps Ethernet
o 6.3 Express Ethernet (100Mbps )
o 6.4 Gigabit Ethernet
o 65,000 mega Ethernet
* 7 reference
* 8 [Edit]
History
The initial progress of Ethernet technology comes from one of many pioneering technology projects of the Xerox PARC. It is often considered that Ethernet was invented in 1973. At that time, Robert Metcalfe wrote a memo of Ethernet potential for Parc's boss. However, Metcafe himself thought that Ethernet appeared in the next few years. In 1976, Metkaf and his assistant David Boggs published an article entitled "Ethernet: Distributed Package Exchange Technology of LAN: LAN: LAN:".
In 1979, Metkaf left Schola in order to develop a personal computer and LANS (Lans) and set up 3COM. 3COM lobby DEC, Intel, and Xiele, hoping to standardize and standardize the Ethernet with them. This universal Ethernet standard was issued on September 30, 1980. At that time, the industry had two popular non -public network standard token and ARCNET, which was quickly shrinking and replaced by the impact of Ethernet tide. In the process, 3COM also became a large international company.
Matcoff once joked that Jerry Saltzer contributed the success of 3COM. Saltzer pointed out in a very influential paper that coincides with others that theoretically token ring network is superior to Ethernet. Affected by this conclusion, many computer manufacturers are hesitant or decided not to use the Ethernet interface as a standard configuration of the machine, so that 3COM has the opportunity to make a lot of money from the sales Ethernet network card. This situation also led to another saying that "Ethernet is not suitable for research in theory and is only suitable for application in actual situation." Perhaps it is just a joke, but this illustrates such a technical point: Under normal circumstances, the actual data flow characteristics in the network are different from people's estimates before the popularization of LAN. Essence Metkov and Saltzer worked in the same floor of the MAC project of Massachusetts Institute of Technology. At that time, he was doing his graduation thesis of Harvard University. During this period, he laid the theoretical foundation of Ethernet technology.
[Edit]
Overview
1990 is an Tai network card or NIC, Ethernet adapter. This card can support 10BASE2 (BNC connectors, left) based on coaxial cables and 10Base-T (RJ-45, right) based on twisted pair.
amplified
1990 is an Tai network card or NIC, Ethernet adapter. This card can support 10BASE2 (BNC connectors, left) based on coaxial cables and 10Base-T (RJ-45, right) based on twisted pair.
It Ethernet is based on the idea of sending information on multiple nodes on the network radio system. Each node must obtain cables or channels to transmit information, and sometimes it is also called Ether. (This name comes from the electromagnetic radiation media hypothetical of the physicist of the 19th century-Light Ether. Later research proves that Light Ether does not exist.) Each node has the only 48-bit address in the world, that is, the MAC address assigned by the manufacturer to the network card To ensure that all systems on Ethernet can identify each other. Because Ethernet is very common, many manufacturers integrate the Ethernet card directly into the computer motherboard.
have found that Ethernet communication has its own similarity, which is very important for telecommunications and communication engineering.
[Edit]
CSMA/CD sharing medium Ethernet
n n carrier listening multi -road visit (CSMA/CD) technology specifies multiple computers Share a channel method. This technology first appeared in Alohanet developed by the University of Hawaii in the 1960s. It uses radio waves as a carrier. This method is simpler than token ring or the main control network. When a computer wants to send information, you must follow the following rules:
1. Start-if the line is idle, then start transmission, otherwise transfer to the fourth step
2. Send-if the detection By the conflict, continue to send data until the minimum message time (ensure that all other forwarders and terminals detect the conflict), then turn to Step 4.
3. Success transmission-successfully send to a higher-level network protocol report successfully. , Exit the transmission mode.
. The line is busy-wait until the line is free
5. The line enters the idle state-wait for a random time to go to step 1 Try to transmit the number of transmission-the sending of the higher-level network protocol failed, exit the transmission mode
It is like a symposium without a host, all participants come through a common medium (air) (air)) Talk with each other. Before each participant speaking, they waited politely for others to finish their words. If two guests start speaking at the same time, they stop and wait for a while to start speaking. At this time, the conflict will not appear if the two participants wait for different time. If the transmission fails for more than once, it will use the method of growth for the retreat index (the retreat time is achieved by truncating the Truncated Binary Backoff).
The original Ethernet uses coaxial cables to connect each device. The computer is connected to the cable through a transcendator called the Unit Interface (AUI). A simple network cable is still very reliable for a small network. For large networks, the failure of a line or a fault of a connector will cause the Ethernet to be unstable.
The communication signals are transmitted on the shared line. Even if the information is only sent to one of the terminals (), the message sent by a computer will be accepted by all other computers. Under normal circumstances, the network interface card will filter out the information that is not sent to your own. When receiving the target address is your own information, it will send an interrupt request to the CPU unless the network card is in the mixed mode. The characteristics of this "one say, everyone listen" is the weakness of the shared medium Ethernet, because a node on the Ethernet can choose to listen to all the information transmitted on the line. Sharing cables also means sharing bandwidth, so the speed of the Ethernet may be very slow in some cases. For example, after the power failure, when all the network terminals are restarted.
[Edit]
The Ethernet relay and hub
In the development of Ethernet technology, the emergence of Ethernet Hub makes the network even more Reliable and more convenient wiring.
The due to the attenuation and delay of the signal, there is a distance limit according to the different media. For example, the longest distance of 10Base5 coaxial cable is 500 meters (1,640 feet). The maximum distance can be implemented by Ethernet relay, and the relay can be enlarged and transmitted to the next paragraph. The relatives are connected to up to 5 network segments, but only 3 have equipment. This can reduce the problem caused by cable breaks: when a section of coaxial cable is disconnected, all the equipment on this section cannot communicate, and the relay can ensure that other network segments work properly.
S is similar to other high -speed bus. The Ethernet segment must be used as a terminal on both ends. For coaxial cables, the terminals on both ends of the cable must be connected to the 50 ohm resistance and radiator of 50 ohms called "Terminator", and AFFIXED to a Male M or BNC Connector. Situation: When the AC signal on the bus reaches the terminal, it will be reflected and cannot dissipate. The reflected signal will be considered a conflict, so that the communication cannot continue. The relay can be charged with two network segments on it, enhanced and synchronized signals. Most relatives have the function of "automatic isolation", which can be isolated from the web segments with too many conflicts or durations of conflict, so that other network segments will not be affected by the damage part. After the conflict disappears, the relay can restore the connection of the network segment.
With the expansion of the application, people gradually discovered that the star -type network topology structure is the most effective, so equipment manufacturers have begun to develop multiple porters. Multi -port relay is a well -known hub (HUB). The hub can be connected to other hub or coaxial network.
The first hub is considered a "multi -end oral transceiver" or "FANOUTS". The most famous example is DEC's Delni, which allows many hosts with AUI connectors to share a transceiver. The hub also leads to the emergence of small independent Ethernet sections that do not use coaxial cables.
The network device manufacturers like DEC and Synoptics have sold hubs for connecting many 10Base-2 thin-homogeneous network segments.
The non-shielding-Pair Cables (UTP) was first applied to a star network, which was also applied in 10Base-T, and finally replaced the coaxial cable to become Ethernet. Standards. After this improvement, the RJ45 telephone interface replaced AUI to become the standard boundary of the computer and hub, and the non -shielding 3 types of twisted lines/5 twisted twisted lines became standard carriers. The application of the hub makes the failure of a cable or a device that does not affect the entire network and improves the reliability of Ethernet. The twisted pair Ethernet connects each network point, so that the terminal can make a standard hardware to solve the terminal problem of Ethernet.
The Ethernet using the hub group network Although it is a star structure, it is logically a bus type. The hub's effect on reducing package conflict is small. Each packet is sent to each port of the hub, so the bandwidth and security problems have not been resolved. The total throughput of the hub is limited by a single connection speed (10 or 100 mbit/s), which is considered as the minimum of the previous synchronization code, frame interval, head, tail, and packaging. When the network load is too heavy, conflicts often reduce the total throughput. The worst case is that when many hosts with long cables network transmit many very short frames, the load of the network will reduce the throughput of the hub for only 50%. In order to increase the load of the network as much as possible before the conflict is severely reduced through throughput, some settings are usually carried out.
[Edit]
bridge and exchange
Although the relay is isolated in some aspects of the Ethernet network segment, the failure of the cable disconnection will not affect the failure of the cable. The entire network, but it forwarded all the data to all the and network devices. This seriously limits the number of machines that can communicate with each other on the same Ethernet network. To reduce this problem, the bridge method is adopted. On the basis of working on the relay of the physical layer, the bridge work on the data link layer. When the network bridge, only the format of theatrical packet can enter another network segment from one network segment; conflict and data packet errors are isolated. By recording and analyzing the MAC address of the devices on the network, the network bridge can determine where they are, so that it will not pass the data packet to the network segment where the non -target device is located. Control mechanisms such as generating tree protocols can coordinate multiple switches to work together.
The early bridge to detect each data packet. In this way, especially when processing multiple ports at the same time, the data forwarding is slower than HUB (relay). In 1989, the Internet company Kalpana invented, the first Ethernet switch. The Ethernet switch can be implemented with hardware, so that the rate of reposting data can reach the line speed.
The Modern Ethernet use Ethernet switch instead of HUB. Although the wiring is the same as the HUB Ethernet, the exchanging Ethernet has many obvious advantages than the Ethernet, such as a larger bandwidth and better ending isolation. Exchange network typical use of star topology, although the equipment work in the semi -dual -work mode is still a multi -nodder network for sharing media. The 10Base-T and the future standards are all dual-workers Ethernet, which is no longer a shared medium system.
Plash when the switch is charged, first work like hub to forward all data to all ports. Next, when it learned the address of each port, he only sent non -wide broadcast data to a specific destination port. In this way, the line speed Ethernet exchange can be implemented between any port pair, and the communication between all port pairs does not interfere with each other.
Because the data packet is generally only sent to his destination port, the traffic on the Ether Ethernet is slightly smaller than the shared medium Ethernet. Nevertheless, the switching Ethernet is still an unsafe network technology, because it can easily be paralyzed by ARP deception or MAC overflowing. At the same time, the network administrator can also use the monitoring function to capture the network data packet.
Is to access the switch port when only simple devices (except HUB) are connected to the switch port, then the entire network may work in a full -duplex method. If there are only 2 devices in a network segment, conflict detection is not needed, and the two devices can send and receive data at any time. The total bandwidth is twice the link (although the bandwidth is the same in each direction), but no conflict occurs means allowing almost 100%of the link bandwidth.
This ports and connected devices must use the same dual -work settings. Most 100BASE-TX and 1000Base-T device support the automatic negotiation characteristics, that is, these devices coordinate the rate and dual-time settings through signals to coordinate. However, if the automatic negotiation is disabled or the device is not supported, the dual -work settings must be set up by automatic detection or manually setting on the switch port and device to avoid dual -work errors -this is a common type of Ethernet problem. The reason (the device is set to the semi -dual -union report to report the conflict, and the device is set to a full dual -worker to report RUNT). Many low -end switches do not have the ability to perform speed and dual -time settings, so the ports always try to conduct automatic negotiation. When the automatic negotiation is enabled but unsuccessful (for example, other devices are not supported), the automatic negotiation will set the port to semi -dual workers. The rate can be automatically sensitive, so connecting a 10Base-T device to a 10/100 exchange port that enables automatic negotiation can successfully build a half-dual-work 10Base-T connection. However, when connecting a device configured to a full dual -worker 100MB work to an exchange port that is configured to automatically negotiate, it will lead to dual -work mismatch.
as, even if both ends of the cable are set to automatic rate and dual -work mode negotiation, the error guess is to retreat to 10Mbps mode. Therefore, if the performance is poor than expected, you should check whether there is a computer setting to 10Mbps mode. If the other end is known to be 100Mbit, you can manually set it to the correct mode. .
Is when two nodes are trying to communicate with maximum support data rates exceeding the cable (for example, using 100Mbps or 3/5 lines on the 3 -line line to communicate with 1000Mbps). Unlike ADSL or traditional dial -up modem, the maximum support data rate of the link is detected by detailed methods. Therefore, if a high rate causes the cable to be unreliable, the link will fail. The solution only reduces the rate of compulsory communication to the cable support.
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The Ethernet type
In addition to the different frame types mentioned above, the difference between the various types of Ethernet is only the rate and wiring. Therefore, in general, the same network protocol stack software can run on most Ethernet.
The chapters below briefly summarize different formal Ethernet types. In addition to these formal standards, many manufacturers have formulated some special standards for some special reasons, such as to support longer -distance optical fiber transmission.
This Ethernet cards and switching devices support multi -speed. The best connection speed and dual -work method are set up by automatic negotiation. If the negotiation fails, the multi -rate device will detect the rate used by the other party but the default is the semi -dual -work method. 10/100 Ethernet port supports 10Base-T and 100Base-TX. 10/100/1000 supports 10Base-T, 100BASE-TX, and 1000Base-T.
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The early Ethernet
* Schola Ethernet-the original 3-mbit/s Ethernet, there are two versions: version one and harmony Version 2. The frame format of version two is still commonly used.
* 10Broad36 - Over time. A early support for long -distance Ethernet. It runs on the coaxial cable and uses a broadband modulation technology similar to a cable modem system.
* 1base5 -also called a star network with a rate of 1Mbit/s. It failed in business. The first use of the twin line is used here.
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10Mbps Ethernet
* 10base5 (also known as coarse cable or yellow cable) -the earliest realization of 10 mbit/s Ethernet network Essence Early IEEE standard, using a single 50 ohm impedist RG-8 coaxial cable with a maximum distance of 500 meters. The receiving end is inserted into the core and shielding layer of the cable through the so -called "insertion segmentation". Use the N -type connector at the end of the cable. An AUI Cable then Connected the to the Ethernet Device. Although there are still some systems in the early days, this standard has been discarded. The endor is required at both ends of the cable.
* 10base2 (also known as fine cable or simulation network)-50 ohm RG-58 coaxial cable, 200 meters, connect all the computer, each computer uses a adapter to connect to a network card with a BNC connector Essence Two ends of the line need to be an ender. It has always been the mainstream of 10M nets for a long time.
* Starlan-The Ethernet standard 10 mbit/s. After the first twisted cylinder, the Ethernet standard 10 Mbit/s. The 4 lines of the twisted pair (2 pairs of twisted lines) 100 meters. Ethernet hub or Ethernet switch is located in the middle to connect all nodes.
* Foill -Fiber Fiber Constifier Link. The original version of the optical fiber Ethernet.
* 10Base-F-10Mbps Ethernet Fiber Standard NTC, 2 kilometers. Only 10base-fl applications are widely wide
o 10base-fl-Foirl standard 1 upgrade.
o 10base-fb-the backbone network technology for connecting multiple HUBs or switches, it has been abandoned
O n o 10base-fp-no relay passive star network, never obtained
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Quick Ethernet (100Mbps)
* 100Base-T-The standard of the three 100 mbit/s twisted lines below is generally called, up to 100 meters.
o 100Base-TX-10Base-T. Similar to the star structure, use 2 pairs of cables, but require 5 types of cables to reach 100Mbit/s.
o 100base-t4-use 3 cables use All 4 pairs of lines have been abandoned due to the popularity of 5 lines, half a two -time work.
o 100base-T2-products. Use 3 types of cables. Support the full dual-working 2-pair line, functional equivalent 100Base-TX, but supports old cables.
* 100base-fx-Use multi-mode fiber, with the farthest support of 400 meters, half a dual-work connection (guarantee conflict test), 2km full dual-work.
* 100base-vg-only Hewlett-Packard support, VG first appeared in the market. Three -to -three cables are needed. Some people suspect that VG is not Ethernet.
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Gigabit Ethernet
* 1000base-t-1 gbit/s medium super five types of twisted lines or 6 Dive twisted lines.
* 1000Base-SX-1 gbit/s multi-mode fiber (less than 550 m).
* 1000base-lx-1 gbit/s multi-mode fiber (less than 550 m). Need to use long -distance single -mode (optical fiber 10 kilometers).
* 1000base-lh-1 gbit/s single-mode fiber (less than 100 kilometers). Long distance scheme
* 1000Base-CX-a short distance (less than 25 m) scheme on the copper cable reaches 1Gbps. As early as 1000Base-T, it was abandoned.
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The vigital Ethernet
The new 10 -dimensional Ethernet standard contains 7 different types of restraint types suitable for local area networks, cities Domain network and wide area network. Currently using additional standard IEEE 802.3AE to explain that in the future, IEEE 802.3 standards will be merged in the future.
* 10GBase-CX4-a short-distance copper cable solution is used for 4X connectors and CX4 cables, with a maximum length of 15 meters.
* 10GBASE-SR-For short-distance multimodular fiber, it can reach 26-82 meters according to the cable type, and the new 2GHz multi-mode fiber can reach 300 meters.
* 10GBASE-LX4-Use waves to reuse the multi-mode fiber 240-300 meters, and the single-mode fiber exceeds 10 kilometers.
* 10GBASE-LR and 10GBase-EE-support 10 km and 40 km through single-mode fiber
* 10GBase-SW, 10GBase-LW, 10GBase-EW. Used for wide-area network PHY, OC-192 / STM-64 synchronous optical fiber network / SDH device. The physical layer corresponds to 10GBase-SR, 10GBASE-LR and 10GBase-ER, so the same optical fiber support distance is also consistent. (No wide area network PHY standard)
* 10GBase-T-use non-shielding twisted lines, it is planned to be released in August 2006.
Thousands of trillion Ethernet is a new standard. It takes time to test those more suitable for commercial use.
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The reference
* Ethernet protocol details
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See
* chaosnet
* Unit interface
* Virtual LAN
* generation tree protocol n * communication
* Internet n * n * 5 types of twisted lines
* RJ45 and Extension Cable
* Cross -cable
* Ethernet exchange mode
* Power over ethernet
* mii and phy n * Network wake -up
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external link
* Ethernet protocol
* ieee 802.3 Standard
* Wanzo Ethernet
* Ethernet frame format
* 10,000 -Dibolia IP Ethernet White Paper
* Gigabit Ethernet (1000Baset)
n from "/wiki /以太网 "
Page category: network protocol | LAN
Popular explanations are:
1 Land, wide area, urban area, and geographical range.
2, ADSL accessing broadband is a service company. For example, telecommunications, it is a kind of Internet service (in writing, it is called dedicated digital services)
3. Ethernet is just a kind of local area network. The network is to connect the host with some cables, and then everyone determines how to communicate with each other. The host is connected to the network, and the rules are called the network.
4, the Internet on our Internet is a wide area network, which is to connect the local area networks in various places, and go to Baidu to search for details (this will start with the past of the US Department of Defense DOD ...)
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