The XG2G module allows a 10 Gigabit Ethernet MAC to operate at 10, 100 and 1000Mb/s data rates in addition to 10 Gb/s. The XG2G can operate in either GMII mode or MII mode. Using the XG2G in GMII mode a 10G Ethernet MAC, clocked at 15.625MHz, can be connected to a 1G Ethernet Physical Layer using GMII clocked at 125MHz. In MII mode connection can be made to a 10/100 PHY using MII. The XG2G performs all the conversions required to map XGMII signalling into GMII/MII signalling and vice versa. The XG2G performs error handling to ensure errors are detected and handled correctly.