Question: What is the primary purpose of the Accounting-Request ON message sent from GGSN/P-GW to AAA server in a PLMN supporting packet-based services?
Option 1: To request authentication credentials for a specific user.
Option 2: To provide usage information for billing and accounting purposes.
Option 3: To establish a secure tunnel for data transmission.
Option 4: To notify the AAA server of a change in network configuration.
Explanation: The Accounting-Request ON message is used to provide usage information, such as volume of data transmitted or received, to the AAA server for billing and accounting purposes. This allows the operator to track and charge for services provided to users.