A physical-layer device includes a first sublayer to receive a first continuous bitstream from a media-independent interface and to provide a second continuous bitstream to the media-independent interface. The physical-layer device also includes a second sublayer to transmit first signals corresponding to the first continuous bitstream onto an external link during a first plurality of time windows and to receive second signals corresponding to the second continuous bitstream from the external link during a second plurality of time windows. The second plurality of time windows is distinct from the first plurality of time windows.