An Ethernet physical layer (PHY) module is provided with a method for transceiving between a 10GBASE-R client interface and a 100G attachment interface. On each of ten client interface logical lanes a 10GBASE-R signal is accepted. Each 10GBASE-R logical lane is demultiplexed into two 5 gigabit per second (Gbps) pseudo 100GBASE-R logical lanes, creating a total of twenty pseudo 100GBASE-R logical lanes. The pseudo 100GBASE-R logical lanes are arranged into n groups of 20/n pseudo 100GBASE-R logical lanes. Further, the pseudo 100GBASE-R logical lanes from each group are arranged into a 100G attachment logical lane. Finally, a 100G attachment logical lane is transmitted at an attachment interface on each of n physical lanes. In the reverse direction, each of n physical lanes accepts a 100G attachment logical lane at the attachment interface, and a de-aggregation process supplies a 10GBASE-R signal on each of ten client interface logical lanes.