📖 ~1 min read
Table of contents
Symptom & Impact
Network throughput drops with rising adapter error counts.
Environment & Reproduction
Seen on Virtual I/O backed ent adapters under EtherChannel load.
Root Cause Analysis
MTU mismatch, flow control, or SEA failover is dropping frames.
Quick Triage
Run entstat -d entX and look at Transmit/Receive Errors counters.
Step-by-Step Diagnosis
Check no -a output for tcp_sendspace and large_send settings.

Solution – Primary Fix
Reset SEA failover with chdev -l entX -a ha_mode=auto on VIOS.
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Solution – Alternative Approaches
Alternative: rebalance EtherChannel adapters with smit etherchannel.
Verification & Acceptance Criteria
Verify with netstat -v entX and entstat -d that errors stop rising.
Rollback Plan
Roll back chdev with the prior -a values if connectivity degrades.
Prevention & Hardening
Pin MTU and flow_ctrl across SEA, switch, and client LPAR profiles.
Related Errors & Cross-Refs
Related: 0514-040 errors in errpt and EC_LINK_DOWN entries.
Related tutorial: View the step-by-step tutorial for aix-7.3.
View all aix-7.3 tutorials on the Tutorials Hub →
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
IBM Docs: Shared Ethernet Adapter and EtherChannel diagnostics.
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