The value of tmnxMobPdnApnDhcpRelayV6GiAddr specifies the subnet in
which the DHCP server should return addresses for DHCP requests for
the User Equipments (UEs) entering a particular Packet Data Network
(PDN) access point. A corresponding IP loopback interface must be
configured in the Packet Data Network Gateway (PGW), in the same sub
network as the DHCP gateway address.