Integrated physical coding sublayer and forward error correction in networking applications

Techniques are provided for receiving data at a physical coding sublayer (PCS) transmit structure from a media access control (MAC) sublayer. Data is received at a PCS transmit structure from a MAC sublayer, and one or more alignment markers are inserted in the data. FEC encoding is performed, in a first clock domain, on the one or more alignment markers and the data in the PCS transmit structure to generate FEC encoded data. The FEC encoded data is transmitted from the first clock domain with a first clock cycle to a second clock domain with a second clock cycle, and the FEC encoded data is transmitted on one or more physical medium attachment (PMA) lanes to a PCS receive structure. FEC decoding is performed, in the second clock domain, on the FEC encoded data in the PCS receive structure to generate FEC decoded data.