valid-lifetime preferred-lifetime


[valid-lifetime preferred-lifetime|at|valid-date preferred-date|infinite|at|no-advertise]


VLAN or tunnel context command for specifying prefixes for the routing switch to include in RAs transmitted on the VLAN or tunnel. IPv6 hosts use the prefixes in RAs to autoconfigure themselves with global unicast addresses. A host’s autoconfigured address is composed of the advertised prefix and the interface identifier in the host’s current link-local address.



The total time the prefix remains available before becoming unusable. After preferred-lifetime expiration, any autoconfigured address is deprecated and used only for transactions that began before the preferred-lifetime expired. If the valid lifetime also expires, the address becomes unusable.

Default: 2,592,000 seconds - 30 days; Range: 0 - 4294967295 seconds


The span of time during which the address can be freely used as a source and destination for traffic. This setting must be less than or equal to the corresponding valid-lifetime setting.

Default: 604,000 second – 7 days; Range: 0 - 4294967295 seconds


Applied to all on-link prefixes that are not individually set by theipv6 ra prefix ipv6-prefix/prefix-len command. It applies the same valid and preferred lifetimes, link state, autoconfiguration state, and advertise options to the advertisements sent for all on-link prefixes that are not individually configured with a unique lifetime. This also applies to the prefixes for any global unicast addresses configured later on the same VLAN or tunnel.

Using default once, and then using it again with any new values results in the new values replacing the former values in advertisements.

If default is used without the no-advertise, no-autoconfig, or the off-link keyword, the advertisement setting for the absent keyword is returned to its default setting.


To configure a prefix as off-link or no-autoconfig , you must enter unique valid and preferred lifetimes with the prefix command (instead of the default command).


Specifies that the prefix lifetime will not expire. This option sets the valid and preferred lifetimes to infinity. (All bits set to 1; ffffffff.)


Specifies no advertisement for the prefix.

For example, if the routing-switches VLAN or tunnel interface is configured with any prefixes that you do not want advertised on the VLAN, use this command to specify the prefixes to withhold from advertisements on the subject VLAN or tunnel.

Default: Advertising enabled.