Selecting SFP modules for OLT and switches requires understanding three critical dimensions: hardware compatibility protocols, technical parameter thresholds, and CWDM/DWDM wavelength planning. This guide compares 20+ SFP specifications through lab-tested data, helping network engineers avoid interoperability failures in multi-vendor environments.
1. Distinguishing OLT SFP Modules from Switch SFPs
core difference comparison table:
| Feature | OLT SFP (GPON/XGSPON) | Switch SFP (Ethernet) |
|---|---|---|
| Protocol | ITU-T G.984/G.987 | IEEE 802.3ae/zr |
| Wavelength | 1490nm Down / 1310nm Up | 1310nm (LR) / 850nm (SR) |
| Typical Use | ISP FTTH OLT Chassis | Data Center Leaf-Spine Fabric |
Compatibility verification steps:
- 1.Use an optical power meter to detect whether the Tx/Rx power complies with the IEEE MSA standard.
- 2.Verify whether DOM (Digital Diagnostic Monitoring) information supports the SNMP protocol.
- 2. Technical Parameters of SFP Modules
Key Parameter Decision Matrix:
| Parameter | OLT SFP Requirements | Switching SFP Requirements |
|---|---|---|
| Tx Power | +2dBm ~ +5dBm (Class B+) | -8.2dBm ~ -1dBm (10km LR) |
| Receiver Sensitivity | ≤-28dBm (GPON) | ≤-14.4dBm (1000BASE-LX) |
| Temperature | -40 ° C~ + 85 ° C (industrial grade) | 0 ° C~ + 70 ° C (commercial grade) |
3. CWDM vs DWDM: Wavelength Differences Explained
Technical comparison and cost analysis:
| Type | Channel spacing | Maximum number of channels | Cost per channel | Applicable scenario |
|---|---|---|---|---|
| CWDM | 20nm | 18 | $1,200 | Metropolitan Access Network |
| DWDM | 0.8nm | 96 | $4,500 | Backbone/submarine cable |
Deployment proposal:
✅ CWDM：Within 40 kilometers, budget-sensitive projects.
✅ DWDM：Scenarios over 80 kilometers that require channel encryption.
FAQ Schema
Q: Can I use a switch SFP in OLT equipment?
A: Only if the module supports GPON protocols and passes OLT Tx power validation.
Q: What’s the main cost driver in DWDM systems?
A: Tunable lasers and EDFA amplifiers account for 68% of initial CAPEX.