There are 40GBASE-SR4 QSFP+ transceivers and 40GBASE-LR4 QSFP+ transceivers. It is recognized that 40GBASE-SR4 makes use of a parallel multimode fiber (MMF) hyperlink to realize forty G. It gives four unbiased transmit and obtain channels, every able to 10 G operation for an combination knowledge price of 40G over one hundred meters of OM3 MMF or one hundred fifty meters of OM4 MMF. Whereas for 40GBASE-LR4 QSFP+ transceivers, there are two sorts of hyperlinks. One is coarse wavelength division multiplexing and the opposite is parallel single-mode fiber. What is the distinction?