The SR OS OSPF implementation supports a configuration option to filter outgoing OSPF LSAs on selected OSPFv2 or OSPFv3 interfaces. This feature should be used with some caution because it goes against the principle that all OSPF routers in an area should have a synchronized Link State Database (LSDB), but it can be a useful resource saving in specific hub and spoke topologies where learning routes through OSPF is only needed in one direction (for example, from spoke to hub).
Three filtering options are available (configurable per interface).
Do not flood any LSAs out the interface. This option is suitable if the neighbor is simply-connected and has a statically configured default route with the address of this interface as next hop.
Flood a minimum set of self-generated LSAs out the interface (for example, router-LSA, intra-area-prefix-LSA, and link-LSA and network-LSA corresponding to the connected interface); suppress all non-self-originated LSAs. This option is suitable if the neighbor is simply connected and has a statically configured default route with a loopback or system interface address as next hop.
Flood a minimum set of self-generated LSAs (for example, router-LSA, intra-area-prefix-LSA, and link-LSA and network-LSA corresponding to the connected interface) and all self-generated type-3, type-5 and type-7 LSAs advertising a default route (0/0) out the interface; suppress all other flooded LSAs. This option is suitable if the neighbor is simply-connected and does not have a statically configured default route.