What causes fault code AB-STRAT-RACK (Stratix Managed Switch — Port Error / Redundancy Fault)?

DLR ring cable broken — single point of failure, ring operates in linear mode. REP ring segment down — switch detects topology change. Port CRC errors from damaged Ethernet cable or bad connector. Port speed/duplex mismatch — auto-negotiate failure with connected device. Switch port went into err-disable from broadcast storm or loop detection

How do I fix fault code AB-STRAT-RACK?

Access Stratix switch web interface — check port status page for error counts and port state. For DLR ring fault, check DLR status LED on switch — identify which ring port lost link. Check Ethernet cables on faulted port — replace if CRC error count is incrementing. If port is err-disabled, identify root cause (loop, broadcast storm) before re-enabling. Verify port speed matches connected device — set both to auto-negotiate or both to fixed 100Mbps full-duplex. For ring redundancy, walk the ring path physically — find the break point using link LEDs at each device

Stratix Managed Switch — Port Error / Redundancy Fault

AB-STRAT-RACK

Allen-Bradley Stratix 5700 or 5400 managed switch detected a port error, ring break, or redundancy protocol fault. Network topology may be degraded.

high allen-bradley plc

allen-bradley stratix switch dlr ring network ethernet

Probable Causes (ranked)

DLR ring cable broken — single point of failure, ring operates in linear mode
REP ring segment down — switch detects topology change
Port CRC errors from damaged Ethernet cable or bad connector
Port speed/duplex mismatch — auto-negotiate failure with connected device
Switch port went into err-disable from broadcast storm or loop detection

Fix Steps

1 Access Stratix switch web interface — check port status page for error counts and port state
2 For DLR ring fault, check DLR status LED on switch — identify which ring port lost link
3 Check Ethernet cables on faulted port — replace if CRC error count is incrementing
4 If port is err-disabled, identify root cause (loop, broadcast storm) before re-enabling
5 Verify port speed matches connected device — set both to auto-negotiate or both to fixed 100Mbps full-duplex
6 For ring redundancy, walk the ring path physically — find the break point using link LEDs at each device

Field Trick

When a DLR ring breaks, all devices still communicate because the ring 'opens' into a linear chain. But you now have zero redundancy. The Stratix ring supervisor LED goes from GREEN to RED. Fix the break ASAP — the next cable failure takes the whole network down.

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