Epoch Guard

Enhanced PTP User Guide (UG1602)

Document ID
UG1602
Release Date
2022-10-18
Revision
1.0 English

This feature is a guard against a NIC clock that resets to the UTC epoch (01 Jan 1970). This can occur, for example, if the NIC is reset or if an external master clock malfunctions directing the downstream slaves to show a current time at or near the UTC epoch.

This option is enabled by default, where the default action is to raise an alarm and prevent the system clock from being synchronized to the affected NIC clock.

alarm-only
Raise an alarm when the NIC clock is near epoch. Does not prevent system clock from being synchronized to the affected NIC clock.
prevent-sync (default)
Raise an alarm and prevent the system clock from being synchronized to the NIC clock when the NIC clock is near the epoch.
correct-clock
Raise an alarm and set the affected NIC clock to the system clock time.

Usage

Enable the option in the sfptpd configuration file.

epoch_guard [alarm-only | prevent-sync | correct-clock]
Note: This option does not consider the clock_control options.