PTP Notifications Overview

StarlingX supports applications that rely on PTP for synchronization. These applications are able to receive PTP status notifications from StarlingX hosting the application.

StarlingX provides a Sidecar, which runs with the hosted application in the same pod and communicates with the application via a REST API.

StarlingX supports the following features:

  • Provides the capability to enable application(s) subscribe to PTP status notifications and pull for the PTP state on demand.

  • Uses a REST API to communicate PTP notifications to the application.

  • Enables operators to install the ptp-notification-armada-app, Sidecar container, and the application supporting the REST API. For more information, see, https://docs.starlingx.io/api-ref/ptp-notification-armada-app/index.html.

  • Supports the ptp4l module and PTP port that is configured in Subordinate mode (Slave mode).

  • The PTP status notifications are derived based on the following conditions:

Clock Status

Status

Description

Freerun

Clock is out of sync state

  • If portState is not “SLAVE” or ClockClass value is NOT “6, 7 or 135” or timeTraceable flag is FALSE.

  • If holdover time exceeds its provided value.

  • If PMC, ptp4l.conf, ptp4l or phc2sys are not accessible.

Locked

Clock is in sync state

If portState is “SLAVE” and ClockClass value is “6, 7 or 135” and timeTraceable flag is TRUE and PMC, ptp4l.conf, ptp4l or phc2sys are accessible.

Holdover

Clock is in holdover state

If the state is transitioned from “Locked” to “Freerun” AND phc2sys is accessible, and holdover time does not expire.

Integrated Containerized Applications

  • Applications that rely on PTP for synchronization have the ability to retrieve the relevant data that indicates the status of the PHC clock related to the worker node that the application is running on.

  • Once an application subscribes to PTP notifications it receives the initial data that shows the PHC synchronization state, and receives notifications when there is a state change to the sync status and/or per request for notification (pull).

The figure below describes the subscription framework for PTP notifications.

../../_images/gvf1614702096862.png

For more information on PTP notifications, see: