IEC 62439-3:2010(E) is applicable to high-availability automation networks based on the ISO/IEC 8802-3 (IEEE 802.3) (Ethernet) technology. It specifies two redundancy protocols based on the duplication of the LAN, respectively duplication of the transmitted information, designed to provide seamless recovery in case of single failure of an inter-switch link or switch in the network. It cancels and replaces IEC 62439 published in 2008 and constitutes a technical revision. It includes the following significant technical changes with respect to IEC 62439 (2008): -adding a calculation method for RSTP (rapid spanning tree protocol, IEEE 802.1Q), - adding two new redundancy protocols: HSR (High-availability Seamless Redundancy) and DRP (Distributed Redundancy Protocol), - moving former Clauses 1 to 4 (introduction, definitions, general aspects) and the Annexes (taxonomy, availability calculation) to IEC 62439-1, which serves now as a base for the other documents, - moving Clause 5 (MRP) to IEC 62439-2 with minor editorial changes, -