IEC 62439-2:2010(E) is applicable to high-availability automation networks based on the ISO/IEC 8802-3 (IEEE 802.3) (Ethernet) technology. It specifies a recovery protocol based on a ring topology, designed to react deterministically on a single failure of an inter-switch link or switch in the network, under the control of a dedicated media redundancy manager node. 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 proto