What is the difference between SFP, SFP+, QSFP+, and QSFP28 modules?
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✓ Best Answer
These are all hot-pluggable optical transceiver form factors defined by MSA (Multi-Source Agreement) standards.
Form Factor Comparison
| Form Factor | Max Speed | Channels | Typical Use |
|---|---|---|---|
| SFP | 1.25 Gbps | 1 | Gigabit Ethernet |
| SFP+ | 10 Gbps | 1 | 10GbE, 8G/16G FC |
| SFP28 | 25 Gbps | 1 | 25GbE, InfiniBand EDR |
| QSFP+ | 40 Gbps | 4 x 10G | 40GbE, 4x10G breakout |
| QSFP28 | 100 Gbps | 4 x 25G | 100GbE, 4x25G breakout |
| QSFP-DD | 400 Gbps | 8 x 50G | 400GbE data centers |
Key Physical Differences
- SFP/SFP+/SFP28 share the same cage dimensions — often backward compatible
- QSFP+ and QSFP28 share cage but QSFP28 requires higher-speed SerDes
- QSFP+ modules can operate in QSFP28 slots (at 40G)
Wavelength & Distance Variants
- SR (Short Reach): 850nm multi-mode, up to 300-400m
- LR (Long Reach): 1310nm single-mode, up to 10km
- ER (Extended Reach): 1550nm single-mode, up to 40km
- ZR: Up to 80km
- BiDi: Single-fiber bidirectional
DDM/DOM Diagnostics
Modern modules include Digital Diagnostic Monitoring (per SFF-8472) reporting real-time optical power, temperature, voltage, and bias current.
2 Other Answers
24
Bookmark-worthy. I reference this table every week when spec'ing modules.
11
Add CWDM/DWDM variants for the full picture!
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