What is traditional Ethernet?

What is traditional Ethernet? What are the two main standards of Ethernet?

Ethernet refers to the baseband LAN specification created by Xerox, which was jointly developed by Xerox, Intel and DEC. It is the most common communication protocol standard adopted by local area networks. Ethernet uses CSMA/CD (Carrier Sense Multiple Access and Collision Detection) technology and runs at the rate of 10m/s on various types of cables. Ethernet is similar to IEEE802.3 series standards.

Include standard Ethernet (10Mbit/s), fast Ethernet (10mb it/s) and 10G Ethernet. They all conform to IEEE802.3.

Common 802.3 applications are:

10M: 10base-T (copper UTP mode)

100 m: 100base-TX (copper UTP mode)

100base-FX (optical fiber line)

1000m: 1000base-T (copper UTP mode)

What is traditional Ethernet?

Compared with modern Ethernet, traditional Ethernet uses CSMA/CD to transmit data, that is, only one client in a LAN can send data at the same time, and other clients have to wait for a while to send data. The typical model is: hub+N computers.

What does "Ethernet" mean?

Ethernet. Refers to the baseband LAN specification created by Xerox and jointly developed by Xerox, Intel and DEC. Ethernet adopts CSMA/CD (Carrier Sense Multiple Access and Collision Detection) technology and runs on various types of cables at the rate of10m/s. Ethernet is similar to IEEE802 3 series standards.

It is not a specific network, but a technical specification.

Ethernet is the most common communication protocol standard adopted by LAN. 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 throughput of 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.

What are the two MAC frames of traditional Ethernet?

Two kinds of MAC frames are divided into source address and destination address, both of which are hardware addresses, that is, MAC addresses. The source address is the hardware address of the sending node of the frame, and the destination address is the hardware address of the receiving node of the frame.

What is Ethernet?

Ethernet refers to the baseband LAN specification created by Xerox and jointly developed by Xerox, Intel and DEC. It is the most common communication protocol standard adopted by the existing LAN. Ethernet uses CSMA/CD (Carrier Sense Multiple Access and Collision Detection) technology and runs at the rate of 10m/s on various types of cables. Ethernet is similar to IEEE802 3 series standards.

What is Ethernet? Scope of application? I need an easy explanation ~ thank you.

It is not a specific network, but a technical specification.

Ethernet is the most common communication protocol standard adopted by LAN. 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.

△ Ethernet connection

Topological structure:

Bus type: Less cables are needed, the price is cheap, the management cost is high, it is difficult to isolate the fault point, and the access mechanism of * * * is adopted, which is easy to cause network congestion. The early Ethernet mostly used bus topology, using coaxial cable as transmission medium, and the connection was simple. Usually, there is no need for special network equipment in small-scale networks, but because of its inherent defects, it is gradually replaced by star networks with hubs and switches as the core.

Star: It is easy to manage and expand. It needs special network equipment as the core node of the network, needs more network cables, and requires high reliability of the core equipment. Dedicated network devices (such as hubs or switches) are used as the core nodes, and the hosts in the local area network are connected with the core nodes through twisted pairs to form a star structure. Although star networks need more cables than bus networks, wiring and connectors are cheaper than bus networks. In addition, star topology can easily expand the network to a large scale through cascading, so it is widely used and adopted by most Ethernet networks.

Transmission medium:

Ethernet can use various connection media, including coaxial cable, twisted pair and optical fiber. Among them, twisted pair is mostly used to connect the host to the hub or switch, and optical fiber is mainly used for cascading between switches and point-to-point links between switches and routers. Coaxial cable, as an early main connecting medium, has been gradually eliminated.

Working mode of the interface:

Ethernet cards can work in two modes: half-duplex and full-duplex.

Half-duplex: Half-duplex transmission mode realizes Ethernet carrier monitoring multiple access collision detection. Traditional LAN works at half duplex, and can only transmit data in one direction at the same time. When data in two directions are transmitted at the same time, there will be conflicts, which will reduce the efficiency of Ethernet.

Full duplex: Full duplex transmission adopts point-to-point connection. This arrangement does not conflict, because they use two independent lines in twisted pair, which is equivalent to increasing bandwidth without installing new media. For example, in the previous example, a parallel track was added between stations, and two trains can pass in two directions at the same time. In duplex mode, the collision detection circuit is not available, so each duplex connection only uses one port for point-to-point connection. The transmission efficiency of standard Ethernet can reach 50% ~ 60% of the bandwidth, and the efficiency of duplex bidirectional provision 100%.

△ Working principle of Ethernet

Ethernet adopts CSMA/CD mechanism with collision detection. All nodes in Ethernet can see all the information sent in the network, so we say that Ethernet is a broadcast network. The working process of Ethernet is as follows:

When a host in an Ethernet wants to transmit data, it will follow the following steps:

1, whether there is a signal in the frame monitoring channel. If so, it indicates that the channel is busy and frame listening will continue until the channel is idle.

2. If no frame hears any signal, transmit data.

3. Continue to monitor the frame during transmission. If a conflict is found, a fallback algorithm is executed. After waiting for a period of time at random, execute step 1 again (when a conflict occurs, the computers involved in the conflict will send a congestion sequence to warn all nodes).

4. If no conflict is found, the transmission is successful and the computer will return to the channel state of the frame.

Note: Each computer is only allowed to send one data packet at a time. All computers must wait 9.6 microseconds after the last transmission (running at 10Mbps) before trying to send data again.

△ frame structure

Overview of Ethernet frames:

Ethernet frame is the encapsulation of the data link layer, and the data packet in the network layer is added with a frame header and a frame trailer to become a data frame (framing) that can be recognized by the data link layer. Although the number of bytes used in the frame header and trailer is fixed, it depends on the size of the encapsulated packet. Ethernet >:>

What is an Ethernet interface?

Ethernet interface is just a port for network data connection. Ethernet interface types are divided into traditional Ethernet interface and fast Ethernet interface.

What is the topology of traditional Ethernet?

Bus star ring. . This means connecting to a hub. .

What is the main difference between fast Ethernet and traditional Ethernet?

The difference between fast Ethernet and traditional Ethernet is mainly in speed. They all conform to the IEEE 802.3 standard.

The traditional Ethernet speed is 1000 MB/s, the fast Ethernet speed is1000 MB/s, and the high-speed Ethernet speed can reach1000 MB/s. 。

If you want to make a fine distinction, you should look at it from the physical layer specification.

What is Ethernet?

foreword

Computer networks are divided into two categories: point-to-point networks and broadcast channel networks. In all broadcast networks, the key problem is how to allocate the right to use channels when there is competition in the use of channels. The protocol used to determine the channel allocation in the broadcast channel belongs to the sublayer of the data link layer, which is called the Media Access Control (MAC) sublayer. Because almost all local area networks use multiplexed channels as the basis of communication, and wide area networks use point-to-point connections except satellite networks, the MAC sublayer is particularly important in local area networks.

The central theme of the media access sublayer is how to allocate individual broadcast channels among competing users. There are two distribution methods: static distribution and dynamic distribution. However, all the traditional static channel allocation methods can't effectively deal with burst communication, so dynamic channel allocation must be adopted. Among various multiple access protocols, this paper only introduces several carrier sense protocols closely related to Ethernet.

2. Carrier sense multi-access protocol (carrier sense).

In a local area network, one site can detect what other sites are doing and adjust its actions accordingly. The protocol that a network station listens to whether a carrier exists (that is, whether there is a transmission) and acts accordingly is called carriersenseprotocol. The following are some CSMA/CD (Carrier Sense Multiple Access with Collision Detection) protocols. CSMA/CD protocol is an improvement of ALOHA protocol (a system based on terrestrial wireless broadcast communication, which is suitable for uncoordinated multi-users to compete for the right to use a single channel). It ensures that no new station starts transmitting when the channel is busy. When a station detects a collision, it will cancel the transmission, and Ethernet is a version of it.

2. 1, 1- continuous CSMA

When a station wants to transmit data, it first listens to the channel to see if other stations are transmitting. If the channel is busy, it will wait until it hears that the channel is free, and then send data. If there is a conflict, the site will randomly wait for a long time and then start again. This protocol is called 1 persistent CSMA, because once a station finds that the channel is free, its probability of sending data is 1.

2.2. discontinuous CSMA

Before transmitting, the station will listen to the status of the channel, and if no other station is transmitting, it will start transmitting. However, if the channel is in use, the station will not continue to listen to the channel, but wait for a random time and then repeat the above process.

2.3, p- continuous CSMA

A station listens to the channel before transmission. If the channel is idle, it will transmit with probability p and postpone the transmission to the next time slot with probability q = 1-p ... Repeat this process until the transmission is successful or another station starts to transmit. In the latter case, the action of the site is the same as when the conflict occurs (that is, wait for a random time and then start again). If the station hears that the channel is busy at the beginning, it will wait for the next time slot and then start the above process.

3、IEEE802.3

The IEEE802 standard has been adopted as an international standard by ANSI, NIST and ISO, and is called ISO8802. These standards are different in the physical layer and MAC sublayer, but they are compatible in the data link layer.

These standards are divided into several parts. 802. 1 standard introduces this set of standards and defines interface primitives. The 802.2 standard describes the upper part of the data link layer, which uses the logical link control LLC(logicallinkcontrol) protocol. 802.3 to 802.5 respectively describe three LAN standards, namely CSMA/CD, token bus and token ring standards, and each standard includes physical layer and MAC sublayer protocols. Only 802.3 is introduced below.

3. 1IEEE802.3 standard and Ethernet

IEEE802.3 standard is applicable to 1 persistent CSMA/ optical disk LAN. Its working principle is that when the station wants to transmit, it waits for the line to be idle, otherwise it transmits immediately. If two or more stations start transmitting on idle cables at the same time, they will collide. So everything is in a hurry ... >>