50G optics (Optical transceivers) options
Posted by Admin on 2022 Dec 16th
- 50G transceiver modules are available in the SFP56 and QSFP28 form factors. The differences are the electrical signal and size.
- A 50G QSFP28 uses 2 of the 4 available electrical lanes (Electrical I/O) on a QSFP connector, with each lane running at 25Gbs NRZ. A 50G SFP56 uses 1 x 50Gbs PAM-4 lane (26.5625Gbaud/s). Both use PAM4 modulation for the optical signal.
- The SFP56 module is slightly smaller in size than a QSFP28 and allows for higher port density. So, it's not compatible with the QSFP slot.
- SFP56 50G modules are forward compatible with 100G Single lambda and 400G and future 800G PAM4 modules.
- QSFP56 is 200G based on 4x50G PAM4 Optical modulation.
- QSFP-DD SR8/LR8 (initially used to be called QSFP56-DD) is 400G based on 8x50G PAM4 Optical modulation.
- QSFP-DD DR4, XDR4, FR4, and LR4 are 400G based on 100G PAM4 Optical Modulation.