The IEC 62439 series is applicable to high-availability automation networks based on the ISO/IEC 8802-3 (IEEE 802.3) (Ethernet) technology. This part of the IEC 62439 series specifies two redundancy protocols based on the duplication of the LAN, resp. 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.