There are three main packaging forms for 400G optical modules, namely QSFP-DD, OSFP, and QSFP112. So what are the differences between these three packaging forms?
Electric Port Modulation
From the electrical port side, QSFP-DD‘s electrical port uses 8-channel 50G PAM4 modulation, while QSFP112’s electrical port uses 4-channel 100G PAM4 modulation. The single channel rate of the electrical port is twice that of QSFP-DD. The optical module packaged in OSFP can adopt either 8-channel 50G PAM4 or 4-channel 100G PAM4 modulation schemes on the electrical port side.
Size Compatibility
The QSFP-DD package and QSFP28 package are fully compatible, resulting in the same size as QSFP28. With the support of existing devices, module accessories can be directly replaced to complete the upgrade iteration of transmission rate. Due to its heat dissipation device, the OSFP package is slightly larger in size than QSFP-DD and is not compatible with the 100G QSFP28 package.
The meaning of 112 encapsulated in QSFP112 is that the single channel rate is 112Gbps, and both 400G QSFP112 SR4 and 400G QSFP112 DR4 are 4-channel. Therefore, the transmission rate of the entire optical module can reach 400G, and the module is also compatible with 100G QSFP28 encapsulation, which facilitates the update and iteration of the transmission rate of existing devices.
Power Consumption
The OSFP package integrates a heat sink, which provides better heat dissipation performance compared to the QSFP-DD and QSFP112 packages, resulting in lower power consumption characteristics. The power consumption index of optical modules is so important that it not only affects the performance and service life of optical modules, but also affects the energy consumption and heat dissipation of the entire data center. So OSFP integrates heat dissipation devices, which consume less energy at the same transmission rate and distance, which is particularly important for large-scale data centers and high-performance supercomputer systems. The energy consumption factor has even become a key factor in whether the supercomputing center can be profitable.
