Question: A UE (User Equipment) sends an S1AP message to an eNodeB (evolved Node B) initiating a procedure with a missing IE (Information Element) marked as 'Ignore IE and Notify Sender'. How should the eNodeB handle this situation?
Option 1: Reject the procedure, terminate it, and initiate the Error Indication procedure.
Option 2: Ignore the missing IE, continue with the procedure based on present IEs, and report the missing IE in the response message.
Option 3: Suspend the procedure until the missing IE is provided by the UE.
Option 4: Execute only the functional requests related to the present IEs, ignoring those dependent on the missing IE.
Explanation: According to the specified criticality handling rules for 'Ignore IE and Notify Sender', if a received message initiating a procedure is missing one or more IEs/IE groups with this criticality, the receiving node (in this case, the eNodeB) shall ignore that those IEs are missing and continue with the procedure based on the other IEs/IE groups present in the message. Additionally, it should report in the response message of the procedure that one or more IEs/IE groups were missing, which aligns with Option 2.