DHCPv6 IA_NA assignment

If UE requests DHCPv6 IA_NA, a /128 address can be provided from a unique /64 prefix per UE from a local-pool. The pool name can be provided from LUDB or from RADIUS (in Framed-IPv6-Pool attribute). The address could also be provided via LUDB or RADIUS (in Alc-IPv6-Address VSA). DHCPv6 can also be linked with DHCPv4 by enabling ipoe-linking command. The M-bit in RA message is configurable. DHCPv6 IA_NA is allowed if it is received after a SLAAC host exists, if allow-multiple-wan-addresses is enabled under group-interface ipv6 configuration. In previous releases, this is precluded. This however consumes two hosts (one each for IA_NA and SLAAC) per UE. Based on a configuration command override-slaac, SLAAC host can be deleted if DHCPv6 IA_NA host is successfully created. Prefix-delegation is not supported with DHCPv6 on WLAN-GW interfaces.