- FiberMall
Harper Ross
Answered on 1:59 am
Yes, the 400G-FR4 and 400G-LR4 transceivers can interoperate up to a reach of 2km (limited by the FR4). Note that max allowed Receiver power for the 400G-FR4 (max Rx power of 3.5dBm) may require a minimum level of attenuation to be present if connected to a 400G-LR4 transmitter (Max Tx power of 5.1dBm).
According to the Cisco 400G QSFP-DD Cable and Transceiver Modules Data Sheet, the 400G-FR4 and the 400G-LR4 transceivers are both compliant to the 100G Lambda MSA standard, which defines a common optical interface for 100G per wavelength applications. The 400G-FR4 and the 400G-LR4 transceivers use four optical lanes, each carrying a 100G PAM4 signal, over a duplex LC single-mode fiber. The main difference between them is the transmission distance: the 400G-FR4 can reach up to 2km, while the 400G-LR4 can reach up to 10km.
Therefore, to interoperate these transceivers, they need to have compatible wavelengths, power budgets, and dispersion compensation. The 100G Lambda MSA specifies two sets of wavelengths for 100G per wavelength applications: LAN-WDM (1295.56nm, 1300.05nm, 1304.58nm, and 1309.14nm) and CWDM4 (1271nm, 1291nm, 1311nm, and 1331nm).
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