OSPF Understanding LSA Aging and Refreshing
In OSPF networking, each LSA is assigned an aging timer, indicated by the link-state age field. The maximum age for an LSA is 60 minutes, after which it is marked as stale and removed from the link-state database if it remains unrefreshed.
To prevent this, OSPF routers automatically refresh LSAs every 30 minutes by the originating router, ensuring the LSAs remain valid. This refresh involves increasing the LSA's sequence number to denote the latest version, thus avoiding confusion with previous versions. The age of an LSA begins counting from the moment a router receives it, and if not updated within 60 minutes, it is removed from the database without any notification or request for an update.
OSPF routers refresh LSAs every 30 minutes to prevent them from expiring; otherwise, they expire after 60 minutes.
Links
https://forum.networklessons.com/t/ospf-lsas-and-lsdb-flooding-tutorial/915/90?u=lagapidis
https://networklessons.com/ospf/ospf-lsas-and-lsdb-flooding-tutorial/