The lifetime field in router advertisement messages indicates how long a host should consider the advertised address to be valid. If this amount of time passes and the host has not received a router advertisement from the server, the route marks the advertised addresses as invalid. By default, addresses are considered to be valid for 1800 seconds (30 minutes).
To modify the router lifetime timer, include the lifetime statement:
- lifetime seconds;
For a list of hierarchy levels at which you can include this statement, see the statement summary section for this statement.