How it Works

Geographic Redundancy

This section describes how this feature works.

When you configure the CDL in PCF through the PCF Ops Center, PCF gets enabled to support multiple CDL datastore endpoints. You can configure the endpoints by specifying the IP addresses, port numbers, and assigning ratings to each endpoint. By default, PCF considers the local endpoint as the primary endpoint, which has the highest rating. PCF performs CDL API operations on the primary endpoint. If this endpoint is unavailable, then PCF routes the operations to the next highest rated endpoint. PCF keeps failing over to the accessible secondary endpoint or until all the configured endpoints are exhausted. It does not reattempt a query on the next rated endpoint if the endpoint is reachable but responds with error or timeout.

If PCF is unable to access any of the endpoints in the cluster, then CDL operation fails with the "Datastore Unavailable" error.

When Rx STR or N5 Delete messages are received on two different sites (site A and site B) for the same subscriber session, a conflict occurs while each PCF site tries to update and replicate the session data. In this situation:

  • PCF receives notification from CDL with session record from both the sites.

  • After receiving the notification from CDL based on the session creation state only one site must processes the notification to resolve the conflict and save the session.