Direct answer
CWDM pairing requires the transmitter wavelength range, multiplexer passband and endpoint path map. The G.694.2 20 nm grid supplies nominal centers, not an interoperability guarantee. For labels such as 1470 and 1471, review exact parts rather than deciding from the 1 nm difference alone.
What the CWDM grid defines
CWDM uses different wavelengths over a shared optical path. At this review, ITU lists G.694.2 (2003) as in force. Its table provides nominal centers spaced by 20 nm, from 1271 through 1611 nm. ITU status G.694.2 text
The recommendation relates wavelength bounds to application requirements. Grid spacing is not a filter's passband width or a universal permitted laser drift.
Use this review for wavelength-system procurement, legacy expansion and module replacement. A CWDM label does not make every optical module, passive filter or jumper interchangeable.
Review actual parts when labels differ
Cisco's 2011 ONS 15216 installation document lists 1470, 1490 through 1610 nm labels for a specific eight-channel module and separately documents bandwidth, loss and isolation. Cisco historical module documentation
This illustrates why a field label may differ from a grid name. It does not establish compatibility between arbitrary 1470 and 1471 nm products or present-day availability of the historical module. Review the endpoints' wavelength ranges and actual filter specifications.
| Field | Meaning | Source to request |
|---|---|---|
| Nominal grid | Reference channel center | Adopted standard |
| Transmitter range | Output wavelengths under specified conditions | Exact module specification |
| Filter passband | Usable range under stated loss conditions | Actual multiplexer specification |
| Port label | Faceplate channel identifier | Model manual and port diagram |
| Path metrics | Input-to-output loss and isolation | Corresponding path evidence |
Record both ends of each channel
For each service, identify the near-end module, channel port, common fiber, far-end channel port and far-end module. Record directions, single- or dual-fiber architecture, monitoring ports and expansion ports in the approved drawing; a wavelength list alone is incomplete.
| Review step | Check | Deliverable |
|---|---|---|
| Identify parts | Full references and hardware revisions | Traceable component list |
| Compare ranges | Transmitter range and each filter passband | Supported range comparison |
| Trace paths | Channel/common ports and directions | Endpoint path diagram |
| Review loss | Mux, demux, connections and cable | Per-path budget |
| Validate system | Platform support and agreed service tests | Configuration and acceptance record |
These are procurement recommendations. Responsible system engineering should assess wavelength coverage with actual temperature conditions and specifications. Ordinary fiber fan-outs organize fibers; they do not select CWDM wavelengths. Specify filtering components when wavelength separation is required.
Procurement FAQ
- Is 20 nm the filter passband? It is nominal grid spacing; obtain the device passband.
- Are 1470 and 1471 labels necessarily incompatible? Labels alone are insufficient; compare actual ranges.
- Do LC connectors establish interoperability? Connector shape does not establish wavelength, power or platform compatibility.
- Can an ordinary MPO fan-out separate CWDM wavelengths? Fiber routing does not perform wavelength selection.
- What should a channel replacement review cover? Endpoint parts, complete filter path, directions, loss budget and approved configuration.
Related guides and configurations
Splitters and MPO fan-outs · Single-fiber BiDi pairing · Optical path loss budget · Multi-fiber harness configuration · Telecom and FTTA review
Contact an engineer. Share actual part references, drawings and measurement or acceptance needs for configuration review. These links do not establish unverified supply, performance or qualification.
Sources and review date
- ITU-T G.694.2 in-force status
- ITU-T G.694.2 (2003) text
- Cisco ONS 15216 historical channel and specification guide
Sources reviewed on 2026-10-11. Manufacturer examples apply only to the cited parts. Tables and review steps are procurement recommendations, not ARRANEX performance, qualification or test-result claims.
Sources checked: 2026-10-11