The OSPF database overflow feature allows you to limit the size of the LSDB and to maintain a consistent LSDB across all the routers in the domain, which ensures that all routers have a consistent view of the network.
number—Specifies the number of external LSAs that the system supports before it goes into overflow state. A limit value of 0 disables the functionality. When the LSDB size limit is reached, OSPF database overflow flushes LSAs from the LSDB. OSPF database overflow flushes the same LSAs from all the routers, which maintains consistency.
timeout—Specifies the timeout, in seconds, after which the system ceases to be in overflow state. A timeout value of 0 leaves the system in overflow state until OSPF is disabled and re-enabled.