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cnf-about-ptp-fast-event-notifications-framework.adoc

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About the PTP fast event notifications framework

Use the Precision Time Protocol (PTP) fast event notifications framework to subscribe cluster applications to PTP events that the bare-metal cluster node generates.

Note

The fast events notifications framework uses a REST API for communication. The REST API is based on the O-RAN O-Cloud Notification API Specification for Event Consumers 3.0 that is available from O-RAN ALLIANCE Specifications.

The framework consists of a publisher, subscriber, and an AMQ or HTTP messaging protocol to handle communications between the publisher and subscriber applications. Applications run the cloud-event-proxy container in a sidecar pattern to subscribe to PTP events. The cloud-event-proxy sidecar container can access the same resources as the primary application container without using any of the resources of the primary application and with no significant latency.

Overview of PTP fast events
Figure 1. Overview of PTP fast events
20 Event is generated on the cluster host

linuxptp-daemon in the PTP Operator-managed pod runs as a Kubernetes DaemonSet and manages the various linuxptp processes (ptp4l, phc2sys, and optionally for grandmaster clocks, ts2phc). The linuxptp-daemon passes the event to the UNIX domain socket.

20 Event is passed to the cloud-event-proxy sidecar

The PTP plugin reads the event from the UNIX domain socket and passes it to the cloud-event-proxy sidecar in the PTP Operator-managed pod. cloud-event-proxy delivers the event from the Kubernetes infrastructure to Cloud-Native Network Functions (CNFs) with low latency.

20 Event is persisted

The cloud-event-proxy sidecar in the PTP Operator-managed pod processes the event and publishes the cloud-native event by using a REST API.

20 Message is transported

The message transporter transports the event to the cloud-event-proxy sidecar in the application pod over HTTP or AMQP 1.0 QPID.

20 Event is available from the REST API

The cloud-event-proxy sidecar in the Application pod processes the event and makes it available by using the REST API.

20 Consumer application requests a subscription and receives the subscribed event

The consumer application sends an API request to the cloud-event-proxy sidecar in the application pod to create a PTP events subscription. The cloud-event-proxy sidecar creates an AMQ or HTTP messaging listener protocol for the resource specified in the subscription.

The cloud-event-proxy sidecar in the application pod receives the event from the PTP Operator-managed pod, unwraps the cloud events object to retrieve the data, and posts the event to the consumer application. The consumer application listens to the address specified in the resource qualifier and receives and processes the PTP event.