Question: What action may a PCEF take when it needs to send an IP-CAN session modification request to a PCRF known to have restarted since the IP-CAN session establishment, based on operator policy?
Option 1: Tear down the associated PDN connection by initiating a PDN connection deactivation procedure, excluding Emergency, RLOS, and eMPS sessions.
Option 2: Send the IP-CAN session modification request to an alternative PCRF without notifying the original PCRF.
Option 3: Buffer the modification request until the restarted PCRF signals readiness to receive updates.
Option 4: Automatically downgrade the PDN connection to a lower QoS level until the PCRF is fully restored.
Explanation: This action allows for the cleanup of affected PDN connections due to PCRF failure, prompting the UE to reinitiate connectivity for the same APN, while ensuring continuity of critical services (Emergency, RLOS, and eMPS sessions). This approach balances network resource management with service continuity, aligning with practical telecom network operational considerations.