100 gigabit media independent interface (CGMII)
CGMII is the media-independent interface of 100 Gigabit Ethernet( 100GbE), equivalent to XLGMII for 40 Gig abit Ethernet and to XGMII for 10 Gigabit Ethernet. CGMII is the interface between the MAC layer and the Physical Coding Sublayer( PCS) of 100 Gigabit Ethernet.
XLGMII connects ports to each other and to other electronic boards in full duplex. Receive, transmit and control signals are transmitted via XLGMII. XGMII can only bridge small distances in the centimeter range and is therefore mainly used at board level for intra- chip connections. Extension is achieved via the CAUI.
The transmission paths of CGMII for the transmit and receive data each comprise 64 bits, which are grouped into eight lanes with eight bits each. An additional transmitted control bit on each lane indicates whether it is data or control information. The transmit and receive paths have their own clock signals. The clock frequency of 1.5625 MHz is derived from these clock signals via a frequency divider (1/64).