Why is a ring network used for the control system’s network?
Thread Content
Does anyone know which company’s control system uses a ring network? Isn’t it said that ring topologies can cause network storms and lead to network paralysis? Then why use a ring network?
Ring networks also have advantages: data at any point on the circumference of a ring network can travel in two directions, and if the optical cable at that point is damaged, data transmission will automatically continue from the other direction.
The issue of network storms you mentioned can now be handled by fiber optic switches themselves. This is no longer a technical issue.
In a ring network, there is usually a switch that acts as a redundancy manager. Under normal conditions, by blocking one of the ring network ports of this redundancy management switch, the entire ring network architecture can be transformed into a linear network. When a break or failure is detected in the network, the redundant management switch will open the blocked ring port and re-establish a linear network in another direction to continue communication.
Hello, I would like to ask how this is achieved? (I know it is achieved by configuring switches; I want to know what the principle is?) ), thank you!
Hello, is this also achieved through the settings of the switch?
Taking Siemens PCS7 control ring networks as an example, there are two methods for implementing redundant ring networks: HSR (Adjusted Redundant Ring) and MRP (Media Redundancy Protocol). The former is a Siemens-specific protocol that is implemented through configuration in the switches; one of the switches is set as the redundancy manager while the other switches act as clients； The latter is a generic protocol that complies with IEC61158, and it is configured using Siemens’ configuration software STEP7.
HSR — High-Speed Redundant Ring. I made a typing mistake in the previous post and wrote “adjusted redundant ring”; my apologies
The advantage of ring networks, especially single-ring networks, is that they enable redundant communication using a single network medium; when a problem occurs at one point, the system can continue to operate using the other path. In the commonly used system topologies today, there are essentially four types for achieving network redundancy: dual-star, dual-bus, single-ring, and dual-ring. The other three types, apart from the single-ring network, require twice as many network cables or even more, as well as twice as many interfaces (only star redundancy requires 2 interfaces). Based on practical experience, a single-ring network is already sufficient in terms of reliability; it can be used in all scenarios except those that require 1:1 redundant communication modules. For specific details, you can refer to the cases of various companies
Many switches these days come equipped with broadcast storm suppression and RSTP functions. . . Try to create a smaller ring network; even if a storm occurs, it will affect only a small area