Brief Summary Of Industrial Switch Technology

Industrial Switch is also called industrial Ethernet switch, that is, Ethernet communication equipment applied to industrial Internet and industrial digital intelligent control field. Because of the standard TCP/IP network, it has good openness, wide application, high performance and high reliability, Ethernet communication technology has become the main communication standard in industrial control field.

Brief summary of industrial switch technology:

(1) Direct forwarding technology of industrial switch and storage and forwarding technology of Ethernet switch:

Once the ethernet switch interprets the destination address of the packet, it starts to send the packet to the destination port. Generally, the ethernet switch knows the destination address when it receives the first six bytes of a packet, so it can decide which port to forward the packet to. The advantages of pass through forwarding technology are fast forwarding rate, reduced delay and improved overall throughput. Its disadvantage is that the ethernet switch has started data forwarding before it has completely received and checked the correctness of the data packets. In this way, in the environment of low communication quality, the ethernet switch will forward all the complete packets and wrong packets, which actually brings a lot of garbage packets to the entire switch network, and the ethernet switch will be misunderstood as a broadcast storm. In a word, the direct forwarding technology is applicable to the network environment with better network link quality and fewer error packets.

Ethernet Switch storage and forwarding technology:

The store and forward technology requires the ethernet switch to decide how to forward after receiving all data packets. This allows the ethernet switch to check packet integrity and correctness before forwarding. Its advantage is that there is no incomplete packet forwarding, reducing the potential unnecessary data forwarding. Its disadvantage is that the forwarding rate is slower than the direct forwarding technology. Therefore, store and forward technology is more suitable for the network environment with ordinary link quality.

(2) Delay:

Switch delay refers to the time interval from the time when the industrial switch receives the data packet to the time when it starts to copy the data packet to the destination port. There are many factors that affect the delay, such as forwarding technology. The switch using the direct forwarding technology has a fixed delay. Because the direct switch only determines the forwarding direction according to the destination address, regardless of the overall size of the packet. Therefore, its delay is fixed, depending on the reading rate of the destination address in the first six bytes of the packet read by the switch. The switch using store and forward technology must receive complete data packets before forwarding them, so its delay is related to the size of the data packets. If the data packet is large, the delay is large; If the data packet is small, the delay is small.

(3) Management function:

The management function of an industrial switch refers to how the ethernet switch controls user access to the switch and how users can see the ethernet switch. Generally, ethernet switch manufacturers provide management software or third-party management software to remotely manage ethernet switches. General ethernet switches meet the SNMP MIB I/MIB II statistical management function. For more complex switches, the built-in RMON group (mini RMON) is added to support the RMON active monitoring function. Some ethernet switches also allow external RMON probes to monitor the network status of optional ports.

(4) Single/multiple MAC address type:

Each port of a single MAC switch has only one MAC hardware address. Each port of a multi MAC switch is bundled with multiple MAC hardware addresses. Single MAC switch is mainly designed to connect end users, network shared resources or non bridged routers. They cannot be used to connect hubs or segments that contain multiple network devices. The multi MAC switch has enough memory on each port to remember multiple hardware addresses. Each port of a multi MAC switch can be regarded as a hub, and a multi MAC switch can be regarded as a hub of a hub. The storage buffer capacity of each manufacturer's ethernet switch is different. The size of the buffer capacity limits the exchange address capacity that the switch can provide. Once the address capacity is exceeded, some ethernet switches will discard other address packets, and some switches will copy the packets to each port for no exchange.

(5) External monitoring support:

Some ethernet switch manufacturers provide "monitoring ports" to allow external network analyzers to directly connect to industrial switches to monitor network conditions.

(6) Extension tree:

As industrial switches are actually multi port transparent bridging devices, they also have the inherent problem of bridging devices - topology loops. When the data packet of a network segment is transmitted to another network segment through a bridge device, the returned data packet returns the source address through another bridge device. This phenomenon is called "topological ring". In general, the switch uses the extended tree protocol algorithm to let each bridge device in the network know each other and automatically prevent topology ring phenomenon. By disconnecting a port in the detected "topology ring", the switch can eliminate the "topology ring" and maintain the integrity of the topology tree in the network. In network design, "topology ring" is often recommended for redundant backup link selection of key data links. Therefore, switches with the extended tree protocol support can be used to connect switch redundancy of the key resources in network.

(7) Full duplex and half duplex:

The full duplex port can send and receive data at the same time, but the ethernet switch and connected devices must support the full duplex working mode. Half duplex data transmission means that data can be transmitted in both directions of a signal carrier, but not simultaneously.

The above introduction is very general and easy to understand, but this is just the tip of the iceberg. In fact, ethernet switches have many professional knowledge and technologies, such as vlan technology. With the development of communication network technology, 5G technology, and industrial Internet of Things, the requirements for industrial switches are becoming higher and higher. Because of its high performance, relatively simple, easy to implement, flexible networking, etc, Industrial switches will also be rapidly popularized and applied to all walks of life.