Patent ID: 8867400

Claim:
A method for tracking a clock source, the method comprising: classifying each of ports of a device into a slave candidate port, a master candidate port, or a slave and master candidate port, wherein at least one of the ports of the device is only classified as a master candidate port; for each port of the device, calculating a Erbest, wherein the Erbest is a best clock source being tracked by the port of the device; calculating a Ebest of the device only according to Erbests of the slave candidate ports and the slave and master candidate ports; determining a best clock source of the device according the Ebest and a D0, wherein the D0 is the local clock of the device; for each port of the device, determining a current state of the port according to the D0, the Ebest, the Erbest of the port and the classification of the port; distributing the best clock source through a port which is determined as in a BMC_master state.