64B66B encoding

64B66B coding is a very efficient coding method used in 10 Gigabit Ethernet, 40 Gig abit Ethernet and 100 Gigabit Ethernet. With this method, only two additional bits are required for the transmission of a 64-bit data block. Pure data (D0 - D7) are coded with "01" in this method, control bytes (C0 - C7) and a mixture of control and data bytes are given the coding "10". Unused bits are transmitted as "0".