IEC 62439-5:2016 is applicable to high-availability automation networks based on the ISO/IEC/IEEE 8802-3 (IEEE 802.3) Ethernet technology. This part of the IEC 62439 series specifies a redundancy protocol that is based on the duplication of the network, the redundancy protocol being executed within the end nodes, as opposed to a redundancy protocol built in the switches. Fast error detection is provided by two beacon nodes, the switchover decision is taken in every node individually. The cross-network connection capability enables singly attached end nodes to be connected on either of the two networks. This second edition cancels and replaces the first edition published in 2010. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- The protocol is now independent of application (Path_Check_Request is sent periodically);
- Failure_Notify message has been removed;
- Frame format had been changed;
- New MAC address had been added.

This publication is to be read in conjunction with IEC 62439-1:2010.