An me1200PtpNotifsClockSlaveStateChange notification is sent when the clock slave state changes. Clock Slave Sate is an enumerated integer value. Description of various possible Port States is: Freerun - Applies to a slave device that is not locked to a master. This is the initial state a slave starts out with when it is not getting any PTP packets from the master or because of some other input error (erroneous packets, etc). FreqLocking - The slave device is receiving packets from a master and is trying to acquire a frequency lock. PhaseLocking - The slave device is receiving packets from a master and is trying to acquire a phase lock. Locked - Locked to the master with respect to frequency and phase. Holdover - In this state the slave device is locked to a master but communication with the master is lost or the timestamps in the ptp packets are incorrect. But since the slave was locked to the master, it can run with the same accuracy for sometime. The slave can continue to operate in this state for some time. If communication with the master is not restored for a while, the device is moved to the FREERUN state. Invalid - The slave is in Invalid state.