Question: In a 3GPP SAE (System Architecture Evolution) security architecture, how does an eNB (Evolved Node B) initiate an update of the LWIP-PSK (Lightweight IP Security Protocol Suite Pre-Shared Key) for a UE (User Equipment)?
Option 1: By directly sending the new LWIP-PSK to the UE over the user plane.
Option 2: Through a series of DNS (Domain Name System) queries that indirectly inform the UE.
Option 3: By releasing the current IPSec tunnel, providing a new LWIP-PSK, and instructing the UE via RRC (Radio Resource Control) signaling to re-initiate IKEv2 (Internet Key Exchange version 2).
Option 4: Via SMS (Short Message Service) containing the updated security key.
Explanation: This option correctly outlines the process for updating the LWIP-PSK. Releasing the current IPSec tunnel ensures a clean slate, providing a new LWIP-PSK supports establishing a secure new IPsec tunnel. Utilizing RRC signaling to instruct the UE to re-initiate IKEv2 with the new key ensures a secure and controlled update process.