Usage Scenario
A passive interface does not trace or advertise time information. If a device has multiple master PTP interfaces in the same clock domain, the device selects the interface with the highest priority as the master clock. The interface connected to the master clock is the slave clock. The unselected master interfaces enter the Passive state and function as backups for the slave clock. Passive interfaces can send Delay_Req, Pdelay_Resp, Delay_Resp_Follow_Up, signaling, and management response messages.
A passive interface can be selected as a slave clock or a master clock to participate in time synchronization after a clock source changes. Monitoring the passive interface before a clock source changes helps keep stable time signals on a synchronous PTP network.
When the
display ptp all command output displays "yes" in the "Time lock success" field. The PTP network is time synchronous. To monitor time synchronization performance on the network, run the
ptp passive-measure enable command.
The passive interface checks the offset between the master and slave clocks. If the offset is greater than a configured alarm threshold, the device sends an alarm named hwPtpPassiveFiberLengthChange to a network management system (NMS). To set the alarm threshold, run the
ptp passive-measure alarm-threshold command.
Prerequisites
A passive interface is determined. The display ptp all command output contains "passive" in the State field of the Port Info part.
Precautions
In VS mode, this command is supported only by the admin VS.