Question: In RANAP signalling (UTRAN Iu interface), when a receiving node encounters an IE or IE group with unspecified Criticality Information, which of the following actions should it take by default?
Option 1: Reject the entire message containing the IE/IE group.
Option 2: Ignore the IE/IE group but notify the sender about the ignored element(s).
Option 3: Completely ignore the IE/IE group without any notification to the sender.
Option 4: Request additional information from the sender before taking any action.
Explanation: According to the principles of handling criticality in RANAP signalling, when an element's criticality is not specified, the most prudent approach is to 'Ignore IE and Notify Sender'. This ensures system continuity while keeping the sender informed about potential compatibility issues. Rejecting the entire message could be too severe, completely ignoring without notice might mask important updates, and requesting additional information isn't a standard default action for handling unspecified criticality in this context.