If the DPL is statically provisioned under the sub-if>ipv6 hierarchy, all hosts under this subscriber interface inherits this fixed DPL. In case that the DPL is provided by LUDB or RADIUS in addition to static configuration under the subscriber interface then the LUDB or the RADIUS one not match the DPL that is statically provisioned under the subscriber-interface. Otherwise, the prefix instantiation in 7450 ESS and 7750 SR fails.
Note that the no delegated-prefix-length command under the sub-if>ipv6 hierarchy means that the DPL is set to a default-value of 64.
When the delegated-prefix-length commands under the sub-if>ipv6 hierarchy is set to variable, prefixes under such subscriber interface can have different lengths and the DPL can be configured by one of the following:
LUDB
RADIUS
DHCP Server