Question: When updating UE IP address usage information in PFCP Association Update Request/Response messages, what action must the UP function take regarding the UE IP Address Usage Sequence Number?
Option 1: Only increment the UE IP Address Usage Sequence Number if the IP address usage has changed.
Option 2: Increment the UE IP Address Usage Sequence Number for every new message, regardless of changes in IP address usage.
Option 3: Decrement the UE IP Address Usage Sequence Number when renewing the validity timer without changes in IP address usage.
Option 4: Keep the UE IP Address Usage Sequence Number unchanged unless a new network instance is added.
Explanation: The UP function must increment the UE IP Address Usage Sequence Number for updates due to IP address usage changes or when renewing the validity timer without changes, ensuring the CP function identifies the latest valid information.