IBM AIX 7.3 – Common Problem 67 – 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

Application gets ‘EADDRNOTAVAIL’ bursts; netstat shows many TIME_WAIT sockets.

Environment & Reproduction

High-rate outbound connections from app server LPAR on AIX 7.3.

Root Cause Analysis

Default tcp_timewait and ephemeral port range too small for connection rate.

Quick Triage

Run netstat -an | awk ‘{print $6}’ | sort | uniq -c for state counts.

Step-by-Step Diagnosis

Use no -a | grep -E ‘tcp_timewait|ephemeral’ to inspect no tunables.

Solution – Primary Fix

Apply no -p -o tcp_timewait=1 -o tcp_ephemeral_low=1024.

Solution – Alternative Approaches

Add a second source IP and shard outbound connections.

Verification & Acceptance Criteria

TIME_WAIT count drops <10k and no fresh EADDRNOTAVAIL in app log.

Rollback Plan

Restore previous no values with no -d .

Prevention & Hardening

Use connection pooling and tune no values in /etc/tunables/nextboot.

Related Errors & Cross-Refs

EADDRNOTAVAIL, slow connection rate, TCP retransmits.

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

AIX Network Tuning (no command) reference.