19
edits
Global settings: Difference between revisions
→Hardware packet timestamping
No edit summary |
|||
| Line 270: | Line 270: | ||
When enabled, packets received on supported interfaces will carry a timestamp with nanosecond resolution instead of microsecond resolution. | When enabled, packets received on supported interfaces will carry a timestamp with nanosecond resolution instead of microsecond resolution. | ||
====== Time synchronization for hardware packet timestamping ====== | |||
Except when the network interface supports GNSS/GPS time synchronization and this has been selected as type of time synchronization (see [[Administration]] time settings) the internal clock of the interface is synchronized to the main device system clock. Even when no time synchronization method is chosen ("none") the system clock is free-running and the internal clock of the interface will be regularly synced to the system clock. | |||
The synchronization to the system time happens roughly every 5 seconds. When the interface clock deviates more than 500ms from the system clock (should only happen at startup or when there is a big jump in the system time e.g. when changing the time synchronization method) the interface time is immediately reset to the system time. If there is a smaller deviation from the system clock the frequency of the interface clock is gradually adjusted to make the clock anneal to the system time so to avoid any discontinuous jumps of the packet timestamps. | |||
When "GNSS/GPS" time synchronization has been configured and the interface is receiving a valid GNSS/GPS time signal the interface clock is directly disciplined to the GNSS/GPS time signal and the system clock is synchronized to the GNSS/GPS time. Other interfaces with hardware packet timestamping but without a GNSS/GPS connection will continue to be synchronized to the system time (which is now running much closer to the global GNSS/GPS time). | |||
===External timestamps=== | ===External timestamps=== | ||