3 Switching Technologies of Industrial Switch

Industrial Switches can withstand harsh working environments, with a wide variety of products and flexible port configurations, which can meet the selection needs of various industrial fields. The industrial switch is designed with wide temperature, the protection level is not lower than IP30, applicable standards and private ring network redundancy protocols. Now, industrial switches are used more and more widely, especially in cities with bad temperature and environment. Professional technicians and security construction teams must understand various performances of industrial switches because they want to participate in the design scheme or system integration. Understanding the switching technology of the industrial switch can help us understand how the industrial switch operates, and can help us to design special programs and customize products.

There are three kinds of switching technologies of industrial switches:

1. Port Switching

Port switching technology first appeared in slot type hubs. The backplane of such hubs is usually divided into multiple Ethernet segments (each segment is a broadcast domain). Networks are not interconnected without bridges or routing connections. After the Ethernet main module is inserted, it is usually allocated to the network segment of a backplane. Port switching is used to allocate and balance the ports of the Ethernet module among multiple network segments of the backplane. Depending on the degree of support, port switching can also be subdivided into:

Module switching: migrate the entire module to the network segment.

Port group switching: Generally, ports on the module are divided into several groups, and each group of ports allows network segment migration.

Port level switching: supports migration of each port between different network segments. This switching technology is based on the first layer of OSI and has the advantages of flexibility and load balancing. If properly configured, fault tolerance can be achieved to a certain extent, but the characteristics of shared transmission media are not changed, so it cannot be called a real switching.

2. Frame Switching

Frame switching is the most widely used LAN switching technology at present. It provides a parallel transmission mechanism by subdividing traditional transmission media to reduce the conflict domain and obtain high bandwidth. Generally speaking, each company's product implementation technology will be different, but the network frame processing methods generally include the following:

Pass through switching: the Ethernet switch in the pass through mode can be understood as a line matrix telephone switch with crisscross lines between ports. When the input port detects a data packet, it checks the packet header, obtains the destination address of the packet, starts the internal dynamic lookup table to convert it to the corresponding output port, connects at the intersection of input and output, and directly connects the data packet to the corresponding port to achieve the switching function. Because no storage is required, the delay is very small and the exchange is very fast, which are its advantages. Its disadvantage is that, because the content of the data packet has not been saved by the Ethernet switch, it cannot check whether the transmitted data packet is wrong, and it cannot provide error detection capability. Since there is no cache, I/O ports with different rates cannot be connected directly, and packets are easily lost.

Store and forward: Store and forward mode is the most widely used mode in computer network field. It stores the data packet of the input port first, and then checks the CRC (Cyclic Redundancy Code Check). After processing the error packet, it takes out the destination address of the data packet, and converts it to the output port through the lookup table to send the packet. Because of this, the store and forward mode has a large delay in data processing, which is its disadvantage. However, it can detect errors in packets entering the switch and effectively improve network performance. In particular, it can support the conversion between ports with different speeds, and maintain the cooperation between high-speed ports and low-speed ports.

Fragment isolation: This is a solution between the first two. It checks whether the length of the data packet is 64 bytes. If it is less than 64 bytes, it indicates that it is a false packet, and the packet is discarded; If it is greater than 64 bytes, the packet is sent. This method also does not provide data verification. Its data processing speed is faster than store and forward mode, but slower than pass through mode.

3. Cell Switching

ATM technology represents the future direction of network and communication technology development, and is also a 'good medicine' to solve many problems in current network communication. ATM adopts cell switching with a fixed length of 53 bytes. Because the length is fixed, it is easy to implement with hardware. ATM adopts special non differential connection and runs in parallel. It can establish multiple nodes simultaneously through a switch, but it will not affect the communication ability between each node. ATM also allows multiple virtual links to be established between the source node and the target node to ensure sufficient bandwidth and fault tolerance. ATM uses a statistical time division circuit for multiplexing, which can greatly improve the utilization of channels. The bandwidth of ATM can reach 25M, 155M, 622M or even several gigabytes.