Certified Ring Redundancy Protocol
I would like to know which Ring Rerundacy protocol are homologated to use with 800xA System 5.1 FP4, i.e., MRP, RSTP HyperRing
ABB promotes using two (2) separated LAN with RNRP instead of ring structure.
Ring or rings do work, but are in general more complex to setup and fault trace.
Eg RSTP and STP are too slow to be able to prevent loop detection when a previously open ring is closed. Interfaces will be blocked and reopened by RNRP when so happen.
Most vendors have fast acting ring protocol that may act fast enough (HIPER ring, TurboRing, FRNT, etc.) to prevent loop detection.
Short (<1second) loops are in general no problems to handle.
A sustained loop risk halting a controller unless its Storm Protection kicks in fast enough. Storm Control is often an option in switch firmware (sometimes called Rate Limiter). ABB NE800 equipment uses 2 mbit/second in factory default.
No ring or media redundancy protocol have been tested or certified for use with System 800xA (at least as far as I know).
You are correct in that ABB has "Certified for use with System 800xA" a number of networking products from various vendors (Hirschmann, Cisco, Moxa, Westermo, etc).
However, just because a certain Westermo or Hirschmann switch has been certified for use with System 800xA it does not mean its implementation of public or proprietary media redundancy protocools such as STP, RSTP, FRNT, HIPER Ring, MRP, etc. is certified.
Rings and mesh networks are in general cheaper in hardware (only one physical network).
But rings and meshes are also far more complex in fault tracing.
An improperly made firmware upgrade or hardware replacement/rearrangement may result in shorter or sustained storms. In best case, RNRP Loop Protection and AC 800M Storm Protection act fast enough to prevent malfunction (e.g. a controller halt).
A flooded ring or mesh may prevent communication.
ABB's RNRP concept requires doubled hardware (two of every switch, fiber, copper cable, network adapter, etc) but is (in ABB's view) more fault tolerant and easier to handle. If flood or storm occur on primary network, its ports are disabled and application traffic is transparently (application is unaware) rerouted via the secondary network.