Duplicate and circulating frames discard methods for PRP and HSR (IEC62439-3)

Parallel Redundancy Protocol (PRP) and High-availability Seamless Redundancy (HSR), defined in the IEC62439-3 about high availability automation networks and proposed as reference network topologies for substation communication networks by IEC61850, assure the upkeep of the communication when an error in a network occurs. Those methods consist in sending information duplicated through different and independent paths; so that nodes must be capable to eliminate the duplicated information circulating in the network. This paper analyzes ways to do the discard of those frames, which is crucial for a good implementation of the standard.