Preferred and valid address lifetimes

Autoconfigured IPv6 global unicast addresses acquire their valid and preferred lifetime assignments from RAs. A valid lifetime is the time period during which an address is allowed to remain available and usable on an interface. A preferred lifetime is the length of time an address is intended for full use on an interface, and must be less than or equal to the address's valid lifetime.

Figure 1: Preferred and valid address lifetimes