Patent ID: 7649912

Claim:
A method of synchronizing node clocks within a plurality of nodes on a network including a time master node having a master clock and including at least one time slave node, the method comprising: connecting the plurality of nodes through a full duplex Ethernet network with a daisy-chain connection of the nodes to each other; transmitting a time synchronization message frame from one of the plurality of nodes to a second one of said plurality of nodes, the time synchronization message frame having a timestamp field according to IEEE 1588 standard and a checksum field and a cyclic redundancy checking code; at a given one of the plurality of nodes between the first and second nodes: (i) receiving the time synchronization message frame; (ii) reading a timestamp value of a timestamp field of the time synchronization message frame; (iii) near a time of retransmission of the time synchronization message frame from the given node, adjusting the read timestamp value in the timestamp field by an amount of delay between time of reception and a time of the retransmission to produce a corrected timestamp value; (iv) writing the corrected timestamp value over the timestamp value of the timestamp field of the time synchronization message frame; (v) adjusting a checksum value in the checksum field and adjusting the cyclic redundancy checking code of the time synchronization message frame to account for adjusting the timestamp value; and (vi) transmitting the time synchronization message frame from the given node; and providing a highest priority to process and forward time synchronization message frames and lower priorities to process and forward other types of message frames.