Question: When a Traffic Detection Function (TDF) detects an application for an IPv6 address for which a TDF session already exists, what type of CC-Request is sent to the Policy and Charging Rules Function (PCRF), and what additional AVP is included under Application-Detection-Information?
Option 1: INITIAL-REQUEST with Framed-Ipv6-Prefix AVP
Option 2: UPDATE_REQUEST with TDF-Application-Identifier AVP
Option 3: INITIAL-REQUEST with Flow-Information AVP
Option 4: UPDATE_REQUEST with PDN Identifier AVP
Explanation: According to the specified behavior for existing TDF sessions, when an application is detected for an IPv6 address (or prefix) for which a TDF session already exists, the TDF sends a CC-Request with the CC-Request-Type set to 'UPDATE_REQUEST'. Additionally, the corresponding TDF-Application-Identifier AVP must be included under the Application-Detection-Information AVP to identify the detected application. This ensures the PCRF can update its records accurately for the ongoing session.