Valid lifetime

The valid lifetime, which is the total time the address is available, is equal to or greater than the preferred lifetime. The valid lifetime enables communication to continue for transactions that began before the address became deprecated. However, in this time frame, the address is no longer to be used for new communications. If this time expires without the deprecated address being refreshed, the address becomes invalid and may be assigned to another interface. The following table lists the IPv6 unicast address lifetimes:
Address source Lifetime criteria
Link-local Permanent
Statically configured unicast Permanent
Autoconfigured global Finite preferred and valid lifetimes
DHCPv6-configured Finite preferred and valid lifetimes

Preferred and valid lifetimes on a VLAN interface are determined by the RAs received on the interface. These values are not affected by the lease time assigned to an address by a DHCPv6 server. That is, lease expiration on a DHCPv6-assigned address terminates use of the address, regardless of the status of the RA-assigned lifetime, and router-assigned lifetime expiration of a leased address terminates the switch’s use of the address. (The router-assigned lifetime can be extended by receipt of a new RA.) Statically configured IPv6 addresses are regarded as permanent addresses, and do not expire.

A new, preferred address used as a replacement for a deprecated address can be acquired from a manual, DHCPv6, or autoconfiguration source.

Related Information:

  • RFC 2462: “IPv6 Stateless Address Autoconfiguration”

  • RFC 4291: “IP Version 6 Addressing Architecture”