Ethernet Switches The Use Of Shared Bus-based Transmission Media LAN

- Nov 03, 2017-

Ethernet switch applications are the most common, the price is cheaper. Grade complete. Therefore, a wide range of applications, in large and small LAN can see their traces. Ethernet switches usually have a few to dozens of ports. Is essentially a multi-port bridge. In addition, its port speed can be different, the way of working can also be different, such as providing 10M, 100M bandwidth, providing half-duplex, full-duplex, adaptive work.

Ethernet switch is based on the Ethernet data transmission switch, Ethernet shared bus-based transmission media LAN. Ethernet switch structure is that each port is directly connected to the host, and generally work in full duplex mode. The switch can simultaneously connect many pairs of ports, allowing each pair of communicating hosts to transmit data in a collision-free manner as monopolized with communications media.

main feature 

1. Each Ethernet switch port directly connected to the host, and generally work in full duplex mode.

2. The switch can simultaneously connect many pairs of ports so that each pair of communicating hosts can transmit data in a collision-free manner as if it were an exclusive communications medium.

3, Share the bandwidth of transmission media, for the common 10 Mb / s shared Ethernet, if there are totally N users in total, each user has average bandwidth only one Nth of the total bandwidth (10 Mb / s).

The Ethernet switch operates on the second layer of the OSI network reference model (ie, the data link layer) and is a network device that performs Ethernet data frame forwarding based on MAC (Media Access Control) address recognition.

The socket on the switch used to link a computer or other device is called a port. Computer with a network card through the network cable connected to the switch port. Each port on the network card, switch, and router has a MAC address that is fixed by the device manufacturer in the device's EPROM. The MAC is assigned by the IEEE and each MAC address is globally unique. The MAC address is a 48-bit binary length with the first 24 digits being the device manufacturer identifier and the last 24 digits being assigned by the manufacturer.

The switch accepts the data frame sent by the computer on the port, searches the MAC address table according to the destination MAC address of the frame header, and then forwards the data frame from the corresponding port, thereby realizing data exchange.

The working process of a switch can be summarized as "Learn, Memory, Receive, Look Up Table, Forwarding" and so on. By learning, you can learn the MAC address of the connected device on each port. Associate the MAC address with the port number The relationship "memory" in memory, the production of MAC address table; from a port "received" to the data frame, the MAC address table "Find" and the header of the destination MAC address corresponding to the port number, and then the data frame From the port to find "forward" out.

Switch split conflict domain, each port independently into a conflict domain. Each port if there is a large amount of data sent, the port will first receive the data to be sent is stored in the register, and then send out the turn to send.

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