IEEE 802.3 40GBase-LR4
Under 40 Gigabit Ethernet, there are several interfaces for fiber optics, one of which is 40GBase-LR4, which can be used to bridge long distances of up to 40 km.
The name 40GBase indicates that the interface supports a data rate of 40 Gbit/s (40G) and operates in baseband technology (base). The specific characteristics can be seen from the LR4 extension. LR stands for Long Reach and indicates that the interface works with long wavelengths. The coding is a 64B66B coding and the number 4 states that the transmission is carried out by means of Coarse Wavelength Division Multiplexing( CWDM) over four CWDM paths of a single mode fiber. The wavelengths used are 1,270 nm, 1,290 nm, 1,310 nm and 1,330 nm as specified by ITU specification G.694.2. The effective data rate per CWDM path is 10 Gbit/s and results in a baud rate of 10.3125 GBaud for 64B66B coding.
The 40GbE optical interface for long distances uses the QSFP module as the transceivermodule.