Prefix delegation allows a delegating router—known as a prefix delegation server—to delegate IPv6 prefixes to requesting routers, known as prefix delegation clients. The clients can then use these prefixes to assign global IPv6 addresses to devices on their internal interfaces. Since it uses DHCPv6 messages to do this (defined in RFC 3633), it is sometimes referred to as DHCPv6 prefix delegation.

In order to utilize prefix delegation, enter the range in the Prefix Delegation Range edit boxes under DHCPv6 Options. You may also specify a size for the prefix in the Prefix Delegation Size drop-down box. Note that the start and end of the Prefix Delegation Range must end on the boundaries of the prefix delegation size.