The value of tmnxDhcpServerCfgItfIdMapping specifies
whether the DHCPv6 server uses a unique /64 prefix per interface-ID
options combination.
If the value of this object is set to 'true(1)'
and the client requests a non-temporary address,
the DHCPv6 server leases a /128 address from the unique /64 prefix
belonging to the interface-ID option from the relay-forward message
and, if present, the interface-ID option from the encapsulated LDRA
relay forward message.
If the value of this object is set to 'false(2)'
each client requesting a non-temporary address,
gets a /128 lease from a different /64 prefix.
The value of this object is only meaningful when the value of
tmnxDhcpServerCfgAddrType is set to 'ipv6(2)' and the value of
iesIfIPv6IpoeBridgedModeEnabled is set to 'true(1)' for all group
interfaces relaying to this server.