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discard routes internal and external on NSSA ABR ?

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link between r1 and r2 is in area 0.(10.1.1.0/30)

link between r2 and r3 is in area1.(10.1.1.5/30)

link between r3 and switch(i.e f0/1) is running rip.(20.1.1.1)

area 1 is nssa.

all routers have a loopback of x.x.x.x/32,
'x' is the router numbers.

r1's loopback is in area 0,
r2 and r3's loopback in area 1.

redistribute rip subnets is configured under r3's ospf process.


case 1:


1)i configured this command on NSSA ABR.(i.e r2)


area 1 range 3.0.0.0 255.0.0.0


and i checked on r1's routing table i found classful
route for 3.0.0.0/8


again i configured this command on NSSA ABR.


2)area 1 range 3.0.0.0 255.0.0.0 not-advertise


i checked r1's routing table no route for 3.0.0.0 network.


fine.


again i configured this command on NSSA ABR.


3)no discard route-internal


but i didn't find the 3.0.0.0/8 in r1's routing table and in r2's routing table.








question:


1)did this command "no discard-route internal" prevents the installation of summary route in the
routing table or just remove the summary route pointing to null0,so that we can route with
less matching routes such as default routes ?




case 2:


1)i configured this command on NSSA ABR.(i.e r2)


summary-address 20.0.0.0 255.0.0.0 not-advertise




and i checked on r1's routing table i found classful
route for 20.0.0.0/8


2)again i configured this command on NSSA ABR.




summary-address 20.0.0.0 255.0.0.0 not-advertise


and i checked on r1's routing table i didn't found any routes for 20.0.0.0/8 on r1.


3) again i configured this command on NSSA ABR.


no discard route-external


but i didn't find the 20.0.0.0/8 in r1's routing table and in r2's routing table.


again my question is same as the first case,


questions:
1)did this command "no discard-route external" prevents the installation of summary route in the
routing table or just remove the summary route pointing to null0,so that we can route with
less matching routes such as default routes ?




2)shouldn't i use both discard routes external and internal on this NSSA ABR(i.e r2) ?


what i tought regarding these question is when i enter not-advertise in both the cases,
i discarded the routes from routing table using discard route external and internal command.


i expected both the prefixes 3.0.0.0/8 and 20.0.0.0/8 will be in r1's routing table,but it doesn't ..

 

 

here is the configs i used

 

r1:
Router#sh running-config
Building configuration...

Current configuration : 818 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
archive
 log config
  hidekeys
!
!
!
!
!
!
!
!
interface Loopback0
 ip address 1.1.1.1 255.255.255.0
 ip ospf 1 area 0
!
interface FastEthernet0/0
 ip address 10.1.1.1 255.255.255.252
 ip ospf 1 area 0
 duplex auto
 speed auto
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
router ospf 1
 log-adjacency-changes
!
ip forward-protocol nd
!
!
ip http server
no ip http secure-server
!
!
!
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
!
!
end




r2:

Router#sh running-config
Building configuration...

Current configuration : 975 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
archive
 log config
  hidekeys
!
!
!
!
!
!
!
!
interface Loopback0
 ip address 2.2.2.2 255.255.255.0
 ip ospf 1 area 1
!
interface FastEthernet0/0
 ip address 10.1.1.2 255.255.255.252
 ip ospf 1 area 0
 duplex auto
 speed auto
!
interface FastEthernet0/1
 ip address 10.1.1.5 255.255.255.252
 ip ospf 1 area 1
 duplex auto
 speed auto
!
router ospf 1
 log-adjacency-changes
 no discard-route
 area 1 nssa
 area 1 range 3.0.0.0 255.0.0.0 not-advertise
 summary-address 20.0.0.0 255.0.0.0 not-advertise
!
ip forward-protocol nd
!
!
ip http server
no ip http secure-server
!
!
!
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
!
!
end

Router#




r3:


Router#sh running-config
Building configuration...

Current configuration : 926 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
archive
 log config
  hidekeys
!
!
!
!
!
!
!
!
interface Loopback0
 ip address 3.3.3.3 255.255.255.0
 ip ospf 1 area 1
!
interface FastEthernet0/0
 ip address 10.1.1.6 255.255.255.252
 ip ospf 1 area 1
 duplex auto
 speed auto
!
interface FastEthernet0/1
 ip address 20.1.1.1 255.255.255.0
 duplex auto
 speed auto
!
router ospf 1
 log-adjacency-changes
 area 1 nssa
 redistribute rip subnets
!
router rip
 version 2
 network 20.0.0.0
 no auto-summary
!
ip forward-protocol nd
!
!
ip http server
no ip http secure-server
!
!
!
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
!
!
end

Router#

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