Question: In 3GPP SAE Security Architecture, what is the requirement for activating User Plane (UP) Integrity Protection in a normal UE versus a Relay Node (RN)?
Option 1: Normal UE: during RRC Connection Reconfiguration; RN: at the same time as RRC Ciphering
Option 2: Both Normal UE and RN: at the same time as RRC Ciphering
Option 3: Normal UE: at the same time as RRC Ciphering; RN: during RRC Connection Reconfiguration
Option 4: Both Normal UE and RN: during initial security setup
Explanation: According to specified requirements, for a normal User Equipment (UE), User Plane integrity is activated during the RRC Connection Reconfiguration procedure. For a Relay Node (RN), user plane integrity is activated at the same time as RRC ciphering, highlighting different security protocol activation timelines based on the network entity type.