GPU cluster networks fail in subtle ways. A fabric can appear healthy under light traffic yet degrade under collective communication patterns used during distributed training. Validation must reflect real workload behavior, not just link-up checks.
Start with design assumptions
- Document expected east-west bandwidth and congestion tolerance.
- Identify failure domains and maintenance impact on training jobs.
- Align buffer, ECN, and QoS settings with the vendor reference for RoCE.
Validate before cutover
- Baseline latency and loss under representative traffic patterns.
- Test failover behavior for spine, leaf, and uplink failures.
- Confirm telemetry exposes congestion before job-level timeouts.
- Document rollback triggers if post-check thresholds fail.
Production acceptance should connect test results to operational alerts. If NOC cannot distinguish healthy training congestion from a fabric fault, the validation is incomplete.