OSPF IP unnumbered issue

[tarnhundal]

Hi All,

I am facing a issue in my network. I have point 2 point connectivity between two routers running OSPF. Now the thing is I am using ip unnumber command on serial int pointing towards fast eth int , which has IP address assigned to it. now i have one more fast eth int , I want to run different IP address on this second interface. but i am unable to ping the second int IP add from remote site, only the IP unnumbered int IP add is reachable. I am doubtful that in this scenario only one IP add is reachable not the second IP add.

Thanks

Taran

[lgijssel]

Try to add a network statement for the second interface under router ospf:

example:

router ospf 1

network x.x.x.0 0.0.0.255 area y

regards,

Leo

[tarnhundal]

Hi ,

I have already done this but no results.

Thanks

Taran

[spremkumar]

hi taran

can you paste the configs here?

regds

[thomasanthony]

it got to do something related to your OSPF advertisement , check if OSPF advertise your Ethernet 2 subnets out of the router also on the remote site also try for testing - redistributing connected

[tarnhundal]

Hi ,

Following is the conf :

R1 :

interface Serial2/3:0
ip address 10.88.102.81 255.255.255.240
encapsulation ppp

R2 :

interface FastEthernet0/0
ip address 10.88.102.82 255.255.255.240
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 10.88.97.17 255.255.255.240
duplex auto
speed auto
!
interface Serial0/0/0
ip unnumbered FastEthernet0/0
encapsulation ppp
!
router ospf 1
network 10.88.97.17 0.0.0.0 area 30
  network 10.88.102.82 0.0.0.0 area 30

[lgijssel]

Please change your config as follows:

R1 :

interface Serial2/3:0
ip address 10.88.102.81 255.255.255.240
encapsulation ppp

!

router ospf 1
network 10.88.102.82 0.0.0.15 area 0

R2 :

interface FastEthernet0/0
ip address 10.88.102.82 255.255.255.240
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 10.88.97.17 255.255.255.240
duplex auto
speed auto
!
interface Serial0/0/0
ip unnumbered FastEthernet0/0
encapsulation ppp
!
router ospf 1
network 10.88.102.82 0.0.0.15 area 0
network 10.88.97.17 0.0.0.0 area 0

regards,

Leo

[tarnhundal]

Hi Leo,

According to u , I have to put same route on both routers in OSPF. Am I right ? how this will work ? I am bit doubtful that will this situation work or not ?

Thanks

taran

[Yasir Ashfaque]

what is the output of following commands ?

R1:

show ip ospf int brief

show ip ospf nei

show ip route ospf

show ip route 10.88.97.17

[Yasir Ashfaque]

Whenever you will configure one interface as unnumbered  and other as numbered it can create discrepancy in the Ospf Database, the only solution here is to configure either both interface numbered or unnumbered.

for more details you can read the following document:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009481a.shtml#r4