DIRECT ANSWER / 01
Budget the complete optical path, not just patch-cord loss
A link-loss budget compares attenuation across the actual optical path with equipment requirements. Confirm both optics, wavelength, topology and connection points, then record allowances for fibre segments, mated connections, splices and other passive devices. A patch cord’s typical insertion loss is not the complete-link budget.
Use this for added patching, inter-rack trunks and 400G/800G migration reviews. This is a purchasing review method, not a universal module loss limit. A budget is a design input; installed measurements are acceptance evidence. Align their measurement boundaries.
SELECTION MATRIX / 02
Purchasing decision matrix
| Item | Identify | Correct action | Avoid |
|---|---|---|---|
| Equipment limits | Full module references, wavelength and platform support | Use matching data sheets and project requirements | Assigning a fixed budget by rate |
| Fibre segments | Type, length and wavelength | Calculate each segment from approved data with units | Ignoring installed trunks |
| Connection points | Actual mated interfaces and cassette paths | List path contributions without omissions or double counting | Counting housings rather than the optical path |
| Reserved margin | Project requirements, future connections and maintenance | Record approval and purpose of each reserve | Using an unexplained universal margin |
| Acceptance boundary | Endpoints, reference method, wavelengths and lane results | Align the budget and test plan to the same path | Treating estimates as measurements |
RFQ INPUTS / 03
Minimum inputs a supplier can verify
| Category | Required input or confirmation |
|---|---|
| Path inventory | A/B equipment, segment lengths, all connections/splices/passives and lane map |
| Budget worksheet | Each allowed contribution, source, units, total, reserves and approval |
| Test plan | Scope, referencing, wavelengths, limits, lane IDs and report format |
BUYER FAQ / 04
Purchasing FAQ
Can another patch panel always be added?
Do not assume so. Review added path contributions against module/project requirements, then validate installation.
Can typical losses be summed for acceptance?
Typicals can support a labelled estimate, not guaranteed acceptance. An approved budget needs limits, evidence and risks.
Does one result cover every MPO position?
Check active lanes individually. One fibre result does not cover unmeasured lanes.
Does a passing budget remove the need to test?
No. A design budget does not prove assembly, cleanliness, mapping or installation acceptance.
What should be sent first?
Provide both module references, topology, distance and connection inventory, then agree measurement boundaries.
SOURCES / 05
Sources and applicability
Sources checked: 2026-10-02. This guide clarifies purchasing fields; it does not replace current equipment data sheets, full standards or the approved project drawing.