Question: In a Policy and Charging Control (PCC) architecture, when the Traffic Detection Function (TDF) detects an application and marks it with a specific DSCP value for downlink packets, what action can the Policy and Charging Rules Function (PCRF) take to support policy and charging control?
Option 1: The PCRF must deactivate all pre-defined PCC rules to prevent conflicts with the TDF's marking.
Option 2: The PCRF can only install a new static PCC rule that ignores the DSCP value for downlink traffic management.
Option 3: The PCRF is required to send an error message to the TDF, indicating it cannot support DSCP-based policy control.
Option 4: The PCRF may either install a corresponding dynamic PCC Rule or activate a pre-defined PCC rule based on the DSCP value provided by the ToS-Traffic Class AVP.
Explanation: This is the correct answer because, when the TDF marks downlink packets with a specific DSCP value for a detected application, the PCRF can effectively manage policy and charging control by either creating a new dynamic rule tailored to that DSCP value or by activating a predefined rule that matches the DSCP marking, enabling efficient QoS enforcement in the downlink direction.