Over the past years, the discussion of 200G and 400G Ethernet speeds started heating up among data centers. Though 400G Ethernet is not mainstream now, it will finally be the next major Ethernet speed for data centers. In fact, many cloud providers have proposed 400G QSFP-DD, OSFP, CFP8, and COBO transceivers for 400G data transmission. Here will mainly focus on 400G QSFP-DD vs OSFP transceivers. For more information on 400G transceiver types, please click: How Many 400G Transceiver Types Are in the Market?
QSFP-DD vs OSFP: Basic Information
What Is 400G QSFP-DD Transeiver?
400G QSFP-DD (Quad Small Form Factor Pluggable Double Density) transceiver is designed with eight lanes that operate at up to 25 Gbps via NRZ modulation or 50 Gbps via PAM4 modulation, which would support optical transmission of 200 Gbps or 400 Gbps aggregate, thus doubling the density. The transmission rate of QSFP-DD form factor could enable up to 14.4 Tbps aggregate bandwidth in a single switch slot so as to cope with rapid data center traffic growth, suitable for 400GBASE Ethernet and data centers.
What Is OSFP Transceiver?
The first iteration of 400G OSFP (Octal Small Formfactor Pluggable) is an 8-lane 50G PAM4 physical link with a possible future 4x 100G PAM4 and 8x 100G PAM4 variants. The OSFP transceiver module or cable plug is a dual paddleboard direct-attachment type connection. This form factor allows 32 400 Gb/s ports per 1U to enable 12.8 Tb/s per switch slot. OSFP transceiver is a very new interconnect system in development that is targeted to support 400G optical data links inside data centers, campuses and external metro long reach. For more detailed information, please click: 400G OSFP Transceiver Types Overview.
QSFP-DD vs OSFP: What Are the Differences?
400G QSFP-DD vs OSFP: Size
The width, length and thickness of QSFP-DD are 18.35mm, 89.4mm and 8.5mm, while those of OSFP are 22.58mm, 100.4mm and 13.0mm. The OSFP is substantially larger in all three dimensions resulting in a package consuming a bit over three times the total volume of the QSFP-DD.
400G QSFP-DD vs OSFP: Bandwidth
QSFP-DD currently only supports up to 400Gb/s, but OSFP can support up to 800Gb/s. Considering scalability, OSFP is slightly better than QSFP-DD.
400G QSFP-DD vs OSFP: Thermal Capacity and Power Consumption
The QSFP-DD is smaller in size, so its thermal capacity is only 7 to 12w. While the OSFP is larger in size, its thermal capacity can reach 12 to 15w. The larger the thermal capacity, the greater the power consumption that the optical module can withstand. Consistent with the thermal capacity, OSFP’s power consumption is generally higher than QSFP-DD.
400G QSFP-DD vs OSFP: Backwards Compatibility
400G QSFP-DD is also more flexible with regard to backward compatibility. The QSFP-DD is identical dimensionally with the 40G QSFP+ and 100G QSFP28 transceivers. While OSFP transceiver will need an adapter to support backward compatibility between form factors.
QSFP-DD vs OSFP: Who Will Win?
The wave of 400G optical transceivers is already on the way. As mentioned above, it seems that the future for 400G QSFP-DD transceiver is brighter. But now it is still too early to draw the conclusion. For the question: 400G QSFP-DD vs OSFP transceivers: Who Will Win? Let’s wait and see!