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OSPF IP unnumbered issue

tarnhundal
Level 1
Level 1

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

9 Replies 9

lgijssel
Level 9
Level 9

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

Hi ,

I have already done this but no results.

Thanks

Taran

hi taran

can you paste the configs here?

regds

thomasanthony
Level 1
Level 1

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
Level 1
Level 1

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

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

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

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

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

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