A system for data transmission includes a physical (PHY) layer which has a rate detection module which determines an adopted clock rate. The rate detection module provides a rate detection signal indicative of the adopted clock rate. The PHY layer includes a reference clock generator which has an input coupled to receive the rate detection signal and an output to provide a reference clock output. The PHY layer includes a PHY interface which has a first input coupled to receive the reference clock output, a data input and a data output. The PHY interface receives data from a MAC interface at the data input and transmits data to the MAC interface through the data output responsive to the reference clock output.