Question: Upon expiration of the `TRELOCcomplete` timer in UTRAN Iu interface RANAP signalling, how should the Core Network (CN) proceed with regards to Iu connections for both the source and target Radio Network Controllers (RNCs)?
Option 1: The CN should send a RELOCATION DETECT message to both RNCs to re-initiate relocation.
Option 2: The CN should hold all Iu connections temporarily, awaiting further instructions from either RNC.
Option 3: The CN should only release Iu connections for the target RNC, keeping source RNC connections active.
Option 4: The CN should initiate the Iu Release procedure for both source and target RNCs, citing 'TRELOCcomplete expiry' as the cause.
Explanation: Upon `TRELOCcomplete` timer expiration, indicating a potential issue with the relocation process, the Core Network (CN) must take corrective action to manage resources efficiently. Initiating the Iu Release procedure for both source and target RNCs with an appropriate cause ('TRELOCcomplete expiry') allows the CN to gracefully terminate connections that are likely in a stalled state due to the relocation failure, freeing up network resources. This approach aligns with managing abnormal conditions by proactively resolving pending connections.