Patent ID: 8819161

Claim:
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.