OSPF FILTERING

OSPF Filtering Using Distribute List with Prefix-List

ip prefix-list BLOCK_L0 deny x.x.x.x/xx
ip prefix-list BLOCK_L0 permit x.x.x.x/x

router ospf 1

distribute-list prefix BLOCK_L0 in or out

OSPF Filtering Using Distribute List with ACL

ip access-list standard BLOCK_L0
deny x.x.x.x
permit any

router ospf 1

distribute-list BLOCK_L0 in or out

OSPF Filtering Using Distribute-List with Route-Map

!
access-list 1 deny x.x.x.x
access-list 1 permit any
!
route-map BLOCK permit 10
match ip address 1
!
router ospf 1
distribute-list route-map BLOCK in
!

OSPF Filtering Using Administrative Distance

!
access-list 1 permit x.x.x.x
!
router ospf 1
distance 255 0.0.0.0 255.255.255.255 1 ( distance of 255 = NULL )
!

OSPF Inter-Area Filtering Using Area Range

!
router ospf 1
area 0 range x.x.x.x x.x.x.x not-advertise
!

OSPF Inter-Area Filtering using Area Filter-List

!
ip prefix-list BLOCK deny x.x.x.x /xx
ip prefix-list BLOCK permit x.x.x.x /0 le xx
!
router ospf 1
area 0 filter-list prefix BLOCK in or out
!

OSPF LSA Database Filtering

interface X

ip ospf database-filter all out

#Config:

ip route x.x.x.x x.x.x.x int X

OSPF Demand Circuit

!
interface X
ip address x.x.x.x x.x.x.x
ip ospf demand-circuit ( disable hello packets on the interface )

OSPF Flooding Reductiond

! to be configure on both interfacefacing each other .

interface X

ip address x.x.x.x x.x.x.x

ip ospf flood-reduction