If the IPv4 addressing assignment is facilitated by the DHCPv4 relay and an internal DHCPv4 server, the DHCPv4 server itself can query the LUDB for IPv4 address information. LUDB can provide a v4 pool name and IPv4 DHCP options to the DHCPv4 server or it can instruct it to use the gi-address as the IPv4 address selection mechanism.
ESM strings can also be provided by LUDB queried by the DHCPv4 server.
If LUDB access by DHCPv4 server is provided in addition to other authentication means (another LUDB under the group-interface, or RADIUS server), the ESM strings from the LUDB under the grp-interface or from the RADIUS server has priority over the ESM strings configured under the LUDB accessed by the DHCPv4 server. On the other hand, the IPv4 addressing information has the highest priority from the LUDB accessed directly by the DHCPv4 server.
Accessing LUDB directly by DHCPv4 server should be used in rare and exceptional cases.
LUDB access under the group-interface, possibly complemented by the RADIUS server provides necessary means for subscriber-host instantiation in majority of use cases.