OSPF LSAs and LSDB flooding Tutorial

Hi there,
I could not get the idea of the age field in the LSA!!
I know that: Once the LSA has aged out, this means it’s become too old and it should be updated.
So, what happened exactly after this step???
Please, correct me if I’m wrong.

Hello Abdel

OSPF routers keep track of how “old” an LSA is within the OSPF database. They have an Age counter that counts up every second and is reset to zero when a newer LSA arrives. Any LSAs that exceed an age of 1 hour (3600 seconds) will be flushed or removed from the database. This maximum age value is called MaxAge and cannot be changed. Once that takes place, nothing specific happens. The LSA is simply removed.

An OSPF router that actively has an LSA in its database will periodically send out an updated LSA at the very least every 30 minutes to ensure that the MaxAge time is not reached.

Now how is the age field used in all of this? The age field within the LSA contains an age value that the sending router wants to impose on the database of the neighboring OSPF routers. A sending router can choose to send an age equal to MaxAge (3600 seconds), making all receiving routers flush out the LSA from their databases. This kind of update is used to refresh the LSDB, and is sometimes called a paranoid update.

I hope this has been helpful!

Laz