Router Advertisement Prefixes

Router advertisements contain a list of prefixes that is used for on-link determination. The list of prefixes is also used for autonomous address configuration. Flags that are associated with the prefixes specify the intended uses of a particular prefix. Hosts use the advertised on-link prefixes to build and maintain a list. The list is used to decide when a packet's destination is on-link or beyond a router. A destination can be on-link even though the destination is not covered by any advertised on-link prefix. In such instances, a router can send a redirect that informs the sender that the destination is a neighbor.

Router advertisements (and per-prefix flags) allow routers to inform hosts how to perform address autoconfiguration. For example, routers can specify whether hosts should use stateful (DHCPv6) or autonomous (stateless) address configuration.