What is a CFP module and how is it different from QSFP?
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✓ Best Answer
CFP (C Form-factor Pluggable) is an older, larger optical module standard for 100G, largely superseded by QSFP28.
CFP Evolution
- CFP: Original, large, 24W power budget, 12x125mm
- CFP2: Half size, 12W, still relatively large
- CFP4: Quarter size, 6W
- QSFP28: Smaller still, 3.5-5W (won the market)
Physical Comparison
| Form Factor | Size (W×H×L mm) | Speed | Power |
|---|---|---|---|
| CFP | 82×14×145 | 100G, 400G | Up to 32W |
| CFP2 | 41.5×14×108 | 100G, 400G | Up to 12W |
| CFP4 | 21×14×92 | 100G | Up to 6W |
| QSFP28 | 18×8.5×72 | 100G | 3.5-5W |
| QSFP-DD | 18×8.5×89.4 | 400G | 7-14W |
Where CFP is Still Used
- Coherent optics (long-distance 100G+)
- Legacy 100G equipment
- DWDM transponder shelves
- Applications needing more power/space
Coherent Optics
CFP2-ACO and CFP2-DCO enable coherent transmission:
- 100G/200G/400G over 1000+ km
- No external DSP required (DCO version)
- Direct plug into router/switch line cards
Migration Path
- New deployments: QSFP28 for standard 100G
- Long-haul/coherent: CFP2-DCO or specialized modules
- 400G: QSFP-DD or CFP2/CFP8 for coherent
Cost and Availability
- QSFP28 has largest ecosystem and lowest cost
- CFP modules more expensive per port
- CFP still preferred for coherent long-haul
Density Impact
QSFP28 offers 32 ports of 100G in 1U — impossible with older CFP. This density advantage drove QSFP28 adoption.
2 Other Answers
13
CFP still king for coherent long-haul. QSFP28 dominates data center.
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Coherent QSFP-DD is starting to compete in long-haul too. Watch this space.
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