Internal Structure and Working Principle of Industrial Switch

Industrial Switches are composed of small parts, so we need to understand the internal structure and working principle of industrial switches, so that we can have a more comprehensive understanding of industrial switches.

The internal structure of the industrial switch:

1. Mainboard (backplane):

Provide the contact channel of each service interface and data forwarding unit.Backplane throughput, also known as backplane bandwidth, is the maximum amount of data that can be handled between the interface processor or interface card of an industrial switch and the data bus, which is an important indicator of the switching performance of an industrial switch.The higher the backplane bandwidth of an industrial switch, the stronger its ability to process data.

2. Processor (CPU):

The core component of the industrial switch operation; its main frequency directly determines the operation speed of the industrial switch, which is measured by the amount of calculation that can be completed per unit time.

3. Memory (RAM):

Provides dynamic storage space for CPU operations; the size of the memory space and the main frequency of the CPU together determine the maximum amount of operations.

4、Flash：

Provide permanent storage function, mainly save configuration files and system files; Flash can quickly restore services, effectively ensuring the normal operation of industrial switches.At the same time, it also provides a convenient and fast way for the upgrade and maintenance of network equipment.Such as using FTP, TFTP upgrade or configuration and so on.

5. Power system of industrial switch:

Provide power input for industrial switches. The performance of the power system largely determines whether the industrial switch can operate normally. The maximum output current, the maximum number of power supplies, and the variable range of input voltage are all important indicators to measure the power system.Generally, core devices are provided with redundant power supplies. After one power supply fails, other power supplies can continue to supply power without affecting the normal operation of the device.When connecting multiple power sources, pay attention to using multiple relays to supply power, so that when one line fails, other lines can still continue to supply power.

How Industrial Switches Work

Industrial switches work on the second layer of the OSI reference model, the data link layer.The CPU inside the switch will form a MAC table by mapping the MAC address to the port when each port is successfully connected.In future communications, packets sent to this MAC address will only be sent to its corresponding port, not all ports.Therefore, the industrial switch can be used to divide the broadcast of the data link layer, that is, the collision domain; but it cannot divide the broadcast of the network layer, that is, the broadcast domain.

Industrial switches have a high-bandwidth back bus and internal switch fabric.All ports of the industrial switch are connected to this back bus. After the control circuit receives the data packet, the processing port will look up the address comparison table in the memory to determine the NIC (network card) of the destination MAC (hardware address of the network card). On which port is connected, the data packet is quickly transmitted to the destination port through the internal switching matrix. If the destination MAC does not exist, it will be broadcast to all ports. After receiving the response from the port, the switch will "learn" the new MAC address and add it to the port. in the internal MAC address table.The use of industrial switches can also "segment" the network. By comparing the IP address table, the industrial switch only allows the necessary network traffic to pass through the switch.Through the filtering and forwarding of the switch, the collision domain can be effectively reduced.

Industrial switches can transmit data between multiple port pairs at the same time.Each port can be regarded as an independent physical network segment (note: non-IP network segment), and the network devices connected to it can enjoy all the bandwidth alone without competing with other devices.When node A sends data to node D, node B can send data to node C at the same time, and both transmissions enjoy the full bandwidth of the network and have their own virtual connections.If a 10Mbps Ethernet switch is used here, then the total traffic of the switch is equal to 2×10Mbps=20Mbps, and when a 10Mbps shared HUB is used, the total traffic of a HUB will not exceed 10Mbps.In short, an industrial switch is a network device that can be identified based on MAC addresses and can complete the function of encapsulating and forwarding data frames.The switch can "learn" the MAC address and store it in the internal address table. By establishing a temporary exchange path between the originator of the data frame and the target receiver, the data frame can directly reach the destination address from the source address.

Data transfer principle

After any node of the industrial switch receives the data transmission instruction, it will quickly search the address table stored in the memory, so as to confirm the connection position of the network card of the MAC address, and then transmit the data to the node.If the corresponding position is found in the address table, it will be transmitted; if not, the switch will record the address to facilitate the next search and use.The industrial switch generally only needs to send the frame to the corresponding point, instead of sending it to all the nodes like the hub, thus saving resources and time and increasing the rate of data transmission.

Data transfer method

Data transmission by means of exchange is actually the way of data transmission of industrial switches.The previous hubs used more sharing methods to transmit data, and there was no way to request the speed of communication.The sharing method of the hub, also known as the shared network, uses the hub as the connecting device and has only one direction of data flow, so the efficiency of network sharing is very low.Relatively speaking, the industrial switch can identify each computer connected to itself, and use the physical address of each computer's network card, also known as the MAC address, to memorize and identify it.Under this premise, there is no need to perform broadcast search, but can directly find the corresponding location of the memorized MAC address and complete the data between the two nodes without external interference through a temporary dedicated data transmission channel. transmitted communications.Since the industrial switch also has a full-duplex transmission mode, a three-dimensional and crossed data transmission channel structure can also be formed by simultaneously establishing temporary dedicated channels between multiple pairs of nodes.