Question: Upon detecting an SMF restart, what action does the UPF take with stored session contexts affected by the restarted PFCP entity?
Option 1: The UPF updates all stored session contexts with the new SMF-C Recovery Time Stamp.
Option 2: The UPF deletes all stored session contexts affected by the PFCP entity restart.
Option 3: The UPF temporarily suspends all stored session contexts until further instruction from the SMF.
Option 4: The UPF sends a confirmation request to the SMF for each stored session context.
Explanation: When a UPF detects an SMF restart, it must ensure data consistency and prevent potential conflicts by removing outdated session information. Deleting all affected session contexts aligns with this requirement, as part of restoration procedures to maintain network integrity after an SMF restart, preventing the use of stale session data which could lead to errors or security vulnerabilities.