IBM AIX 7.1 – Common Problem 005 – Diagnosis and Fix

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

EtherChannel fails over and primary adapter reports LINK_DOWN in errpt.

Environment & Reproduction

IBM AIX 7.2 LPAR exhibiting network interface down / EtherChannel issues under standard PowerVM workloads.

entstat -d en0
netstat -in

Root Cause Analysis

SEA or physical adapter loses link due to switch port misconfiguration.

Quick Triage

Confirm scope with errpt, recent changes, and subsystem state via lssrc.

lsdev -Cc adapter
lssrc -s inetd

Step-by-Step Diagnosis

Inspect entstat counters and trace MAC negotiation on the failing adapter.

entstat -d ent0 | grep -i error
netstat -v ent0

Solution – Primary Fix

Reset the adapter and rebuild EtherChannel with correct primary.

smit etherchannel  # change primary
chdev -l ent4 -a adapter_names=ent0,ent1

Solution – Alternative Approaches

Move VIO Server SEA failover to backup VIOS while replacing NIC.

Verification & Acceptance Criteria

Confirm subsystem returns to RUNNING state and errpt shows no new entries.

entstat -d en0 | grep Up
ping -c3 gateway

Rollback Plan

Restore prior configuration from mksysb or alt_disk_install clone if the fix regresses.

chdev -l ent4 -a adapter_names=ent1,ent0  # revert primary

Prevention & Hardening

Encode the fix in NIM customisation scripts and monitor via topas/nmon.

no -p -o tcp_sendspace=262144  # baseline tunables

Related Errors & Cross-Refs

errpt LABEL=GOENT_LINK_ERR; LACP timeouts

Related tutorial: View the step-by-step tutorial for aix-7.1.

View all aix-7.1 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

AIX Virtual I/O Server networking