Question: In a 5G System (5GS) utilizing Wireless and Wireline Convergence Access Support, how does the Session Management Function (SMF) allocate an IPv6 address to a Residential Gateway (RG) when using DHCPv6 for a PDU Session, based on subscription data and local configuration?
Option 1: The SMF always allocates a /64 prefix from which a single /128 address is selected for the RG.
Option 2: The SMF allocates multiple /128 addresses without assigning a prefix to the PDU Session, providing them directly to the Policy Control Function (PCF).
Option 3: The allocation method is determined by the RG's capabilities, which are signaled during PDU Session Establishment.
Option 4: The SMF may either allocate a prefix (e.g., /64) for the PDU Session from which /128 addresses are selected or allocate individual /128 addresses without a prefix, based on subscription data and local configuration for a specific DNN and S-NSSAI.
Explanation: This option correctly reflects the flexibility in IPv6 address allocation methods as per the 3GPP specification. The SMF can adapt its allocation approach (prefix allocation with subsequent /128 address selection or direct /128 address allocation) based on specific criteria such as subscription data, local configuration, and the identifiers for the Data Network Name (DNN) and Single Network Slice Selection Assistance Information (S-NSSAI). This flexibility supports varied deployment scenarios and user needs in a 5GS environment.