The XAUI IP module provides the functionality of a physical coding sublayer (PCS) to facilitate full duplex 10G Ethernet communication. The XAUI PCS takes packet data from a 10 Gigabit Ethernet MAC and performs idle conversion and code-group generation before performing 8B/10B encoding. On the receive path, the XAUI PCS takes the unaligned data from the four SerDes modules, re-aligns each lane to the 8B/10B boundary, decodes the data and then aligns all four lanes. The decoded and aligned data is then passed to the MAC. Both the transmit and receive paths provide data buffers to the MAC allowing the MAC to run at 156.25 MHz while the PCS runs at 312.5 MHz. The XAUI PCS can also be configured to operate as four independent 1000BASE-X channels