The transmit clock source is provisioned in the profile corresponding to the line type. The choices are loop, local, or through. zhoneSystemClockTxClockMode shows the current transmit clock source as possibly modified by the clock manager. If the line selected as system clock source is provisioned in through mode, its zhoneSystemClockTxClockMode value is set to loopTiming while it is the source. If there is no eligible clock source, zhoneSystemClockTxClockMode for all lines are set to localTiming.

provisionedTiming is reserved for internal use and will never be seen as the status of transmit clock mode.

localTiming indicates that a local clock source is used or that an external clock is attached to the box containing the interface.

loopTiming indicates that the recovered receive clock is used as the transmit clock.

throughTiming indicates that transmit clock is derived from the recovered receive clock of another interface.