Question: When a UE transitions from ECM-IDLE to ECM-CONNECTED, how does the SGW-C handle buffered downlink data packets that have not expired, in terms of forwarding them towards the UE?
Option 1: The SGW-C forwards these packets directly to another network element for relaying to the UE.
Option 2: The SGW-C sends a request to the MME to page the UE before forwarding any buffered packets.
Option 3: The SGW-C discards all buffered packets upon UE's state transition, as per buffering duration policies.
Option 4: The SGW-C forwards those packets to the eNodeB without updating the F-TEIDu.
Explanation: According to the context, when the UE transitions to ECM-CONNECTED, the SGW-C updates the SGW-U with the F-TEIDu of the eNodeB and then forwards buffered packets (that haven't expired) to the SGW-U outside of control plane signalling. The SGW-U then relays these packets to the eNodeB for delivery to the UE. Thus, the correct action involves forwarding to another network element (SGW-U) for relaying to the UE.