#ip ospf flood-reduction

[dangal.43]

How ip ospf flood-reduction command works? on what basis it reduce the LSA flood?

as well as how ospf database-filter all out command will block all LSA flooding? if yes then how updates are going to be exchange? and how LSA refreshment will work?

[bvsnarayana03]

OSPF database ages out every 30min, so even if your toplogy is stable, unnecessary flooding of SLAs can block the link. "ip ospf flood-reduction" suppress the unnecessary flooding of (LSAs) in stable topologies.

refer thi link:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t2/dt_ospff.htm

By default, OSPF floods new LSAs over all interfaces in the same area, except the interface on which the LSA arrives. Some redundancy is desirable, because it ensures robust flooding. However, too much redundancy can waste bandwidth and might destabilize the network due to excessive link and CPU usage in certain topologies. Database filter out command filter out the LSAs to specific neighbor or interface.