About OSPF passive

OSPF sends LSAs to all other routers in the same AS. To limit the flooding of LSAs throughout the AS, you can configure OSPF to be passive. OSPF does not run in the AS, but it does advertise the interface as a stub link into OSPF. Routing updates are accepted by a passive interface, but not sent out.

There is a limit of 512 total active and passive interfaces, but only a total of 128 can be active interfaces.