Question: During an authenticated re-registration in a 3GPP IP-based service, what happens to the protected client ports at the User Equipment (UE) and the P-CSCF when security associations are changed?
Option 1: Both UE's port_uc and P-CSCF's port_pc remain unchanged.
Option 2: Only the UE's port_uc changes, while the P-CSCF's port_pc remains the same.
Option 3: The protected client ports at both the UE (port_uc) and the P-CSCF (port_pc) change.
Option 4: Neither the UE's port_uc nor the P-CSCF's port_pc changes, but server ports are updated.
Explanation: According to the principles of authenticated re-registration in 3GPP IP-based services, when security associations are updated, the protected client ports at both the User Equipment (UE) and the P-CSCF must change to reflect the new security context, enhancing network security. In contrast, server ports remain unchanged for service continuity.