Redundancy - ethernet single, dual or ring or combination?
If building a new control network, would you choose single ethernet in ring (ie.Moxa Turbo Ring/Turbo Chain) or dual ethernet or dual ethernet both in ring?
Would a single ethernet ring replace a dual ethernet? pros/cons?
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Ring networks makes troubleshooting wire breaks harder. Also there is the danger when replacing the ring manager switch that someone makes a mistakes and installs a switch without ring manager functionality and then causing a broadcast storm which can upset the controllers.
I would go for a redundant network instead of a ring network and only would go for a redundant ring network only if necessary by customer or application.
I agree with WvanWees comment. I would in addition highlight that rings and redundant networks provides different levels of redundancy. A ring will provide a second path if a link/cable is "cut". Dual networks would in addition provide a secondary network if a network storm occur on one network, or if e.g. a network switch breaks altogether. I.e. a redundant network provides full redundancy, a ring does not. Having dual networks configured as rings provide little additional redundancy, but includes risk of misconfiguration, like WvanWees pointed out.
Also, ABB now launched an own portfolio of network equipment, and is therefore able to provide even more detailed guidance.
I had in incident earlier this year where I lost power in my main server room.
Having a second server room I thought this would not be a problem, but all my network run through the main server room so my network was practically cut in the middle. Having dual network in this case would not have done any difference because both network would be cut in the middle. Therefore I was thinking that a network ring must be a more safe solution, maybe with a combination of dual networking like two switches for each PLS like the drawing I have attached.
Reading the answers below I sense that a network ring is problem when you need to troubleshoot, do anyone have experience here or is it a general assumption?
Replacing the master ring switch is not something you do every 5 years, maybe not ever.