ospf nssa and default-gateway

Unanswered Question
Feb 16th, 2007

Let's say I've got 3 routers

R1 -- R2 -- R3

R1 and R2 are in area 0

R2 and R3 are in area 1 nssa

R3 runs also RIP and redistributes rip into OSPF. So it's an ASBR.

Now, how do I make R1 learn about this default route coming from R3?

I've tried already:

1) create a static route on R3 + redistribute static subnets under OSPF --> no luck

2) Still on R3 under ospf router config: default-information originate always --> no luck

Thanks to read!

I have this problem too.
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sundar.palaniappan Fri, 02/16/2007 - 13:16

To generate a default route in NSSA ASBR, use the command 'area (#) nssa default-information-originate' under the OSPF process. A default route needs to exist in the routing table for this to work.

HTH

Sundar

mohammedmahmoud Fri, 02/16/2007 - 13:32

Hi there,

You need "area nssa default-information-originate" on the ABR (R2 in your case) --> For NSSA a Type 7 default route is injected into the NSSA Area.

As stated by Cisco:

"The ABR originates the 0.0.0.0 type 7 LSA, even though it does not have a default route."

How OSPF Injects a Default Route into a Not So Stubby Area:

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00801ec9fa.shtml

The ABR originates the 0.0.0.0 type 7 LSA, even though it does not have a default route.

r2.2.2.2#show ip route 0.0.0.0

% Network not in table

r1.1.1.1#show ip route ospf

O IA 6.0.0.0/8 [110/65] via 5.0.0.2, 00:00:18, Serial2/1/0

O*N2 0.0.0.0/0 [110/1] via 5.0.0.2, 00:00:18, Serial2/1/0

HTH, Please rate if it does,

Mohammed.

sundar.palaniappan Fri, 02/16/2007 - 13:40

The original poster wants to originate default route on R3, which is an ASBR, for which you need to have to have a default route in the routing table to originate one. What you are saying is true only the if the router originating the default route is an ABR.

From CCO;

Default Type 7

The following configuration generates a type 7 default route. You can configure this command on any NSSA ASBR or NSSA ABR with the following rules:

* NSSA ASBR can generate a default only when it has a default route in its routing table.

* NSSA ABR can generate a default route with or without a default route in its own routing table.

The following command is used to generate an NSSA default route:

router ospf 1

area 1 nssa default-information originate

http://www.cisco.com/warp/public/104/nssa.html

HTH

Sundar

mohammedmahmoud Fri, 02/16/2007 - 13:54

Hi Sundar,

I totally agree with you, and i am sorry for seeing the original poster's request the other way round.

regards,

Mohammed.

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