QSFP-DD vs. QSFP28
Comparing 2 standards across 13 specifications. 13 key differences identified.
Quad Small Form-Factor Pluggable Double Density (QSFP-DD) is a high-speed transceiver form factor defined by the QSFP-DD MSA and SFF-TA-1002. It incorporates an 8-lane electrical interface via an extra row of electrical contacts, delivering 400 Gbps (8x50G PAM4) and 800 Gbps (8x100G PAM4) while maintaining mechanical backward compatibility with QSFP28 and QSFP+.
QSFP28 (Quad Small Form-Factor Pluggable 28) is a 100 Gbps transceiver standard defined by SFF-8665 and IEEE 802.3bm. Integrating four 25 Gbps electrical lanes within the exact QSFP mechanical dimensions, it is the primary high-density interconnect for 100 Gigabit Ethernet and EDR InfiniBand.
Specification Comparison Table
13 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standard / MSA
|
QSFP-DD MSA / SFF-TA-1002 | SFF-8665 / SFF-8636 / IEEE 802.3bm |
|
Physical Form Factor
|
QSFP-DD (Double Density) | QSFP28 |
|
Electrical Channels
|
8 lanes (via dual-row contact pins) | 4 lanes @ 25.78125 Gbps NRZ |
|
Optical Connectors
|
MPO/MTP-16, Dual MPO-12, Duplex LC, CS, SN, MDC | MPO/MTP-12 (SR4, PSM4) or Duplex LC (CWDM4, LR4) |
|
Max Data Rate (400G Generation)
|
400 Gbps (8x50G PAM4) | — |
|
Max Data Rate (800G Generation)
|
800 Gbps (8x100G PAM4) | — |
|
Electrical Modulation
|
PAM4 (4-level Pulse Amplitude Modulation) | — |
|
Thermal Power Dissipation
|
Up to 12–25 W | — |
|
Backward Compatibility
|
Accepts QSFP+, QSFP28, and QSFP56 modules | — |
|
Max Data Rate (Ethernet)
|
— | 103.125 Gbps |
|
Max Data Rate (InfiniBand)
|
— | 100 Gbps (EDR) |
|
4x25G Breakout Mode
|
— | Supported (to 4x SFP28 ports) |
|
Typical Power Consumption
|
— | 3.5–5.0 W |