IEC 62439-4:2010

Overview

IEC 62439-4:2010 - Industrial communication networks - High availability automation networks - Part 4: Cross-network Redundancy Protocol (CRP) - defines a redundancy protocol for Ethernet (ISO/IEC 8802-3 / IEEE 802.3) based automation networks. CRP implements redundancy by duplicating networks and running the redundancy logic in the end nodes rather than in switches. Each node makes its own switchover decision and singly attached devices can connect to either of the two networks (cross-network capability). IEC 62439-4 is part of the IEC 62439 high‑availability family and is intended to be read together with IEC 62439-1 (general concepts and calculation methods).

Key topics and technical requirements

• Scope: High-availability automation networks using Ethernet; node-based redundancy (end-node protocol).
• Topology support: Single and double LAN topologies; support for doubly-attached nodes (DANCs) and singly-attached nodes.
• Protocol elements:
  • DiagnosticFrame and AnnunciationFrame messaging for status and fault detection.
  • Network_Status_Table to track link and node status across networks.
  • Multicast and unicast handling, path selection and reception adapter selection rules.
  • Redundancy statistics, services and a Management Information Base (MIB).
• Availability and recovery:
  • Methods for calculating CRP recovery time and maximum repair time in network configurations.
  • Failure detection mechanisms based on diagnostic message arrival and redundancy information exchange.
• Integration: Node configuration and repair procedures; LRE (LAN Redundancy Entity) attributes and their operational impact.
• Standards evolution: This edition replaces IEC 62439 (2008) and aligns with additions across the series (e.g., RSTP calculation, HSR, DRP).

Practical applications and users

• Where used: Industrial automation, process control, manufacturing systems, power substations, critical infrastructure where deterministic, low-latency network recovery is required.
• Who uses it:
  • Network architects and automation engineers designing redundant Ethernet topologies.
  • Device and equipment manufacturers implementing node-based redundancy features.
  • System integrators and consultants specifying high-availability solutions.
  • Test labs and certification bodies verifying compliance and recovery performance.
• Benefits: Maintains standard Ethernet compatibility while providing deterministic failover, supports single-attached endpoints via cross-network connectivity, and enables distributed failure decisions at nodes.

Related standards

• IEC 62439-1:2010 - General concepts and calculation methods (mandatory companion).
• IEC 62439-2 - MRP (Media Redundancy Protocol).
• IEC 62439-3 - PRP (Parallel Redundancy Protocol) and HSR (High-availability Seamless Redundancy).
• IEC 62439-5 - BRP (Bridge Redundancy Protocol).
• IEC 62439-6 - DRP (Distributed Redundancy Protocol).

Keywords: IEC 62439-4, Cross-network Redundancy Protocol, CRP, high availability, industrial communication networks, Ethernet redundancy, PRP, HSR, DRP, recovery time, RSTP.