SDX 6.4.x Application Library Guide > Overview of Controlling Volume Usage with the VTA > VTA Operation

VTA Operation

Figure 26 illustrates the VTA operation process.

Figure 26: Operation of the VTA

The VTA operates as follows:

1. When an event that activates a value-added service occurs (for example, a subscriber logs in), the SAE sends a session start event to the VTA through the SAE external plug-in interface.
2. Optionally, the VTA queries a database for the subscriber's current set of sessions and accounts.
3. Depending on the configuration of the VTA, it may activate or deactivate services based on the subscriber's use of resources.
4. The VTA tracks the subscriber's use of resources for a period of time.
5. The VTA updates sessions and account balances in the database.
6. The VTA sends to the SAE changes in the interim accounting interval and takes action to limit excessive bandwidth use or to allow increased bandwidth use.
7. When an event that deactivates a value-added service occurs (for example, the subscriber logs out), the VTA updates the VTA session, closes the VTA session, and may update the account balances.

Events received through the remote interface can also cause the VTA to activate services, deactivate services, or change the accounting interval.