DWDM System Commissioning: The 5-Phase Checklist

A poorly commissioned DWDM span does not fail on day one — it fails months later, after dust, drift and aging push an already-marginal link over the edge. MapYourTech's commissioning checklist structures the entire turn-up as five sequential phases, each with measurable acceptance thresholds: fiber characterization, amplifier setup, channel provisioning, OSNR verification, and protection testing. This article condenses that guide into an actionable reference with the key formulas and thresholds you need in the field, from OTDR discipline to cascaded OSNR budgets.

Phase 1 — Fiber Characterization

Run bidirectional OTDR at 1310/1550 nm on every fiber pair with launch/receive reference fibers (≥500 m) to eliminate dead zones. Key thresholds: span loss ≈ 0.20–0.22 dB/km at 1550 nm (G.652); fusion splice loss ≤ 0.1 dB (re-splice above 0.15 dB); connector return loss ≥ 45 dB (APC). Then verify end-to-end span loss with a power source and meter; a discrepancy over 1 dB warrants investigation.

Span Loss (dB) = α×L + splices + connectors + margin
Example (80 km): 16.80 + 0.64 + 1.40 + 2.00 = 20.84 dB

Phase 2 — Amplifier Setup

For inline EDFAs use AGC mode tied to measured span loss (gain = span loss ± 0.5 dB), confirm noise figure ≤ 6 dB (typical 4–6 dB), and verify per-channel power flatness ≤ ±1 dB. For spans over 25–28 dB loss, consider Raman: confirm the fiber type (G.652/G.655/G.654) is correct in the NMS before enabling pumps — and always verify ALS/APR laser-safety functions first (Raman pumps run 500 mW–2 W).

Single-amp OSNR = 58 + P_in − NF   (0.1 nm RBW @1550 nm)
Cascaded: 1/OSNR_total = Σ 1/OSNR_i

Phase 3 — Channel Provisioning

Provision on the ITU-T G.694.1 grid (12.5/25/50/100 GHz). Verify transponder wavelength with an OSA (±0.01 nm tolerance), start with one mid-band test channel, then edge channels, then the full plan — using ASE noise loading to fill unused spectrum and keep EDFAs stable. Confirm modulation format (QPSK/8QAM/16QAM) and FEC mode match the design.

Phase 4 — OSNR Verification

Measure OSNR at the receiver pre-amplifier input. Typical requirements with 3 dB margin above FEC threshold: 100G DP-QPSK ≥ 12 dB; 200G DP-16QAM ≥ 18 dB; 400G DP-16QAM ≥ 20 dB. Check flatness ≤ 3 dB across the band, record pre-FEC BER below threshold, and post-FEC BER must be error-free over ≥ 15 minutes.

Phase 5 — Protection Testing

Validate protection switching completes within 50 ms: verify protection group configuration, hardware detection thresholds, and control-plane loading. Document every result as the baseline for future troubleshooting.

Common Commissioning Issues

Related: the Infinera DWDM resource guide and the H3C 光模块故障排查手册 for module-level issues.

原文链接：https://mapyourtech.com/dwdm-system-commissioning-interactive-checklist