Ubuntu 20.04 LTS Throughput Drops on High Bandwidth Links

📖 ~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

Transfer rates fall below expected levels, extending backup windows and replication lag.

Environment & Reproduction

Often appears with jumbo frame mismatch, offload conflicts, or constrained virtual NIC drivers.

Root Cause Analysis

Packet retransmits and suboptimal NIC settings reduce effective throughput on high-speed paths.

Quick Triage

Check interface errors, MTU consistency, and offload configuration across both endpoints.

Step-by-Step Diagnosis

Run controlled iperf tests and inspect counters to isolate bottlenecks at host or network layer.

Solution – Primary Fix

Align MTU, tune ring buffers and offloads, and update drivers or firmware where required.

Solution – Alternative Approaches

Use multiple flows, bonding strategies, or dedicated replication networks for heavy data paths.

Verification & Acceptance Criteria

Throughput stabilizes near target and packet error counters remain low under sustained load.

Rollback Plan

Revert NIC tuning parameters if packet loss or latency worsens after adjustments.

Prevention & Hardening

Standardize host network profiles and validate link tuning in provisioning workflows.

Related Errors & Cross-Refs

Correlates with TCP retransmission spikes and intermittent stream resets.

Related tutorial: View the step-by-step tutorial for Ubuntu 20.04 LTS.

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Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

See Ubuntu NIC tuning and Linux network performance troubleshooting references.