Auto-syntonization and time-of-day synchronization for master-slave physical layer devices

A network device comprising:

• a master physical layer device configured to communicate with a plurality of network devices, the master physical layer device including
• a signal generator module configured to generate a first clock that is syntonized to a grandmaster clock having a fixed frequency, and
• a frequency adjusting module configured to, at a predetermined time interval, adjust a frequency of the first clock to the fixed frequency of the grandmaster clock;
• and
• a slave physical layer device configured to communicate with the plurality of network devices, the slave physical layer device including
• a time of day calculating module configured to calculate a first time of day of the slave physical layer device based on a second clock that is asynchronous to the first clock, and
• a period adjusting module configured to synchronize the first time of day to a second time of day of the master physical layer device based on the predetermined time interval,
• wherein the frequency adjusting module is further configured to
• output N control signals to the slave physical layer device when the first clock is updated N times, respectively, where N is an integer greater than 1, and
• output to the slave physical layer device a reference value corresponding to the predetermined time interval;
• and
• wherein the period adjusting module is further configured to
• capture a first value of the first time of day when a first of the N control signals is received,
• capture a second value of the first time of day when a second of the N control signals is received,
• calculate a first difference between the first value and the second value,
• calculate a second difference between the first difference and the reference value, and
• synchronize the first time of day to the second time of day based on the second difference.