OSPF is not installing Default route in Database

[Deepak Kumar]

Hi,

I am working on OSPF network and OSPF router is installing default route (SLA 5) in the database. Here, I am sharing the full configuration. 

Please helps me.

:: Internet ---(BGP)----->R1 (OSPF Area 12) ------->R2 (Ospf area 0) ------->R3

R1#sho ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface

2.2.2.2 0 FULL/ - 00:00:36 10.1.1.2 Serial0/0/0.12

R1#

R1#sho ip ospf database

OSPF Router with ID (1.1.1.1) (Process ID 1)

Router Link States (Area 12)

Link ID ADV Router Age Seq# Checksum Link count

2.2.2.2 2.2.2.2 1472 0x8000000e 0x00f597 2

1.1.1.1 1.1.1.1 1472 0x8000000e 0x007804 3

Summary Net Link States (Area 12)

Link ID ADV Router Age Seq# Checksum

2.2.2.2 2.2.2.2 406 0x80000169 0x0027bd

10.1.1.4 2.2.2.2 406 0x8000016a 0x002679

3.3.3.3 2.2.2.2 406 0x8000016b 0x007727

10.1.1.8 2.2.2.2 396 0x8000016e 0x0078de

4.4.4.4 2.2.2.2 396 0x8000016f 0x00c392

Summary ASB Link States (Area 12)

Link ID ADV Router Age Seq# Checksum

1.1.1.1 2.2.2.2 1572 0x8000007d 0x009afa

3.3.3.3 2.2.2.2 2 0x800001be 0x00b892

Type-5 AS External Link States

Link ID ADV Router Age Seq# Checksum Tag

10.2.1.0 3.3.3.3 2217 0x80000004 0x00090c 0

10.2.2.0 3.3.3.3 2217 0x80000005 0x00fb17 0

22.22.22.22 3.3.3.3 2217 0x80000006 0x00b215 0

192.168.1.128 3.3.3.3 2217 0x80000007 0x002c27 0

11.11.11.11 3.3.3.3 2217 0x80000008 0x00aa47 0

10.1.21.128 3.3.3.3 416 0x80000002 0x007c26 0

10.1.4.4 3.3.3.3 416 0x80000003 0x00bb57 0

10.1.4.8 3.3.3.3 416 0x80000003 0x00937b 0

R1#

R1#sho ip ospf interface serial 0/0/0.12

Serial0/0/0.12 is up, line protocol is up

Internet address is 10.1.1.1/30, Area 12

Process ID 1, Router ID 1.1.1.1, Network Type POINT-TO-POINT, Cost: 64

Transmit Delay is 1 sec, State POINT-TO-POINT, Priority 0

No designated router on this network

No backup designated router on this network

Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Hello due in 00:00:04

Index 2/2, flood queue length 0

Next 0x0(0)/0x0(0)

Last flood scan length is 1, maximum is 1

Last flood scan time is 0 msec, maximum is 0 msec

Neighbor Count is 1 , Adjacent neighbor count is 1

Adjacent with neighbor 2.2.2.2

Suppress hello for 0 neighbor(s)

Message digest authentication enabled

Youngest key id is 1

R1#

Regards,

Deepak Kumar

[Georg Pauwen]

Hello,

you need to use the keyword 'always' with the 'default-information originate' on R1, since R1 does not already have a default route configured.

router ospf 1
router-id 1.1.1.1
log-adjacency-changes
area 12 authentication message-digest
network 10.1.1.0 0.0.0.3 area 12
network 1.1.1.1 0.0.0.0 area 12
default-information originate always

[Deepak Kumar]

HI,

I am getting error :

R1(config-router)#default-information originate ?

<cr>

R1(config-router)#default-information originate always

^

% Invalid input detected at '^' marker.

R1(config-router)#

[Georg Pauwen · Accepted solution]

Hello,

are you trying this on a 'real' router or on something like Packet Tracer ?

Either way, try and add a default route on R1:

ip route 0.0.0.0 0.0.0.0 x.x.x.x

where x.x.x.x is the next hop (the ISP in your case).

[Deepak Kumar]

Hi Georg,

Thanks for your quick support but I have one question

I added one default route to null interface as

ip route 0.0.0.0 0.0.0.0 Null0

As per null interface rules, traffic will drop here. But in my case, the problem is resolved and I found default route is added to the database and traffic moving to ISP.

After that, I add default route point to ISP interface.

ip route 0.0.0.0 0.0.0.0 serial 0/0/1

This is also working fine. 

Can you guide to me, Why it is happening?

Regards,

Deepak Kumar

[Georg Pauwen · Accepted solution]

Hello Deepak,

OSPF doesn't care where the default route is pointing to, as long as it is there. It doesn't 'know' that a null route effectively blackholes all default traffic, that is, it doesn't verify the validity of the default route.

Does that make sense ? I hope it does...