Reduced Gigabit Media Independent Interface
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Reduced Gigabit Media Independent Interface (RGMII) specifies a particular interface between an Ethernet MAC and PHY.
RGMII uses half the number of pins as used in the GMII interface. This reduction is achieved by clocking data on both the rising and falling edges of the clock, and by eliminating non-essential signals (carrier-sense and collision-indication). Thus RGMII consists only of: RXC, RD[3:0], RX_CTL, TXC, TXD[3:0], and TX_CTL (12 pins, as opposed to GMII's 24).
Unlike GMII, the transmit clock signal is always provided by the MAC on the TXC line, rather than being provided by the PHY for 10/100 Mbps operation and by the MAC at 1000 Mbs.
RGMII supports Ethernet speeds of 10 Mbit/s, 100 Mb/s and 1000 Mbit/s.
