Wired communication system including asymmetrical physical layer devices

A first physical layer device, comprising:

• a first transmitter configured to send first transmit bursts on a cable at a first line rate during a first transmit period to a second physical layer device, wherein the first transmit bursts include a training header and T frames, where T is an integer greater than zero;
• and
• a first receiver configured to receive second transmit bursts on the cable at a second line rate during a second transmit period from the second physical layer device, wherein the second transmit bursts include a training header and P frames, where P is an integer greater than zero,
• wherein, during a normal operating mode, the first line rate is greater than or equal to the second line rate and the first transmit period is greater than the second transmit period,
• wherein a transmit cycle includes one of the first transmit bursts and one of the second transmit bursts, and
• wherein the first transmitter transmits in-band data including B bytes over two or more of the T frames, where B is an integer greater than one.

A first physical layer device, comprising:

• a first transmitter configured to send first transmit bursts on a cable at a first line rate during a first transmit period to a second physical layer device, wherein the first transmit bursts include a training header and a training frame including a timing field;
• a first receiver configured to receive second transmit bursts on the cable at a second line rate during a second transmit period from the second physical layer device,
• wherein, during a normal operating mode, the first line rate is greater than or equal to the second line rate and the first transmit period is greater than or equal to the second transmit period, and
• wherein the first transmitter and first receiver communicate asymmetrically with the second physical layer device;
• and
• a frequency offset calculator configured to calculate a local frequency adjustment based on a first symbol rate of the first line rate and a grandmaster clock