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ERPS is a redundancy protocol for ring-shaped industrial Ethernet networks. Instead of a linear chain where one cable break cuts off everything downstream, a ring connects back to itself. ERPS manages the ring so one link is always blocked to prevent loops, and opens it in under 50ms if a failure is detected elsewhere.
The 50ms recovery time is the key number. Spanning Tree Protocol (STP) – the alternative – takes 30-50 seconds to converge. In SCADA networks and factory automation, a 30-second communication gap can trigger safety shutdowns or process faults. ERPS was designed specifically to prevent this.
- Standardised as ITU-T G.8032
- One link in the ring is kept blocked to prevent loops (the Ring Protection Link)
- On failure detection, the blocked link opens within 50 milliseconds
- Required for substation, transportation, and automation ring networks
- Supported alongside STP/RSTP/MSTP on industrial managed switches