Section: 6.2.4.3 Additional RG related requirements for IP address allocation
Content: If IPv6 PDU session type or IPv4v6 PDU session type is selected, an IPv6 address, one or more IPv6 prefixes or both are allocated to the 5G-RG or the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device). If the 5G-RG or the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device) receives a Router Advertisement Message as specified in IETF RFC 4861 [38B] with the "Managed address configuration" flag set to zero, the 5G-RG and the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device): a) shall obtain /64 IPv6 prefix via IPv6 stateless address autoconfiguration as specified in 3GPP TS 23.501[ System architecture for the 5G System (5GS) ]  [8] and IETF RFC 4862 [39]; b) may obtain IPv6 configuration parameters via stateless DHCPv6 as specified in IETF RFC 8415 [33D]; and c) may request additional IPv6 prefixes using DHCPv6. If the 5G-RG and the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device) request IPv6 prefixes using DHCPv6, the 5G-RG and the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device) shall act as a "Requesting Router" as described in IETF RFC 8415 [33D], shall perform procedures described in subclause 6.2.4.2a. Additionally, the 5G-RG or the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device) may include DHCPv6 OPTION_ORO option with the OPTION_PD_EXCLUDE option code as specified in IETF RFC 6603 [40A] in the DHCP. If the 5G-RG or the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device) receives a Router Advertisement Message as specified in IETF RFC 4861 [38B] with the "Managed address configuration" flag set to one, the 5G-RG and the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device): a) shall obtain an IPv6 address via DHCPv6 and the DHCPv6 Identity association for non-temporary addresses option as specified in IETF RFC 8415 [33D]; b) may obtain IPv6 configuration parameters via DHCPv6 as specified in IETF RFC 8415 [33D]; and c) may request IPv6 prefixes using DHCPv6. If the 5G-RG and the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device) requests IPv6 prefixes using DHCPv6, the 5G-RG and the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device) shall act as a "Requesting Router" as described in IETF RFC 8415 [33D], shall perform procedures described in subclause 6.2.4.2a. Additionally, the 5G-RG or the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device) may include DHCPv6 OPTION_ORO option with the OPTION_PD_EXCLUDE option code as specified in IETF RFC 6603 [40A] in the DHCP message. The 5G-RG or the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device) may include both IA_PD option and IA_NA option to request the delegated prefix together with the IPv6 address in the same DHCPv6 message. NOTE: The 5G-RG and the W-AGF acting on behalf of the FN-RG (or on behalf of the N5GC device) can send multiple DHCPv6 requests with different DHCPv6 Identity association for non-temporary addresses options when the 5G-RG or the FN-RG acts as a DHCP relay for devices behind the 5G-RG or the FN-RG. The 5G-RG may obtain ACS information via DHCP as specified in subclause 3.1 of BBF TR-069 [49] or in BBF TR-369 [50] R-DIS.1 and R-DIS.2.