NSSA & default route

Unanswered Question
Aug 2nd, 2009

Hi experts,

When working with OSPF NSSA lab, I was trying to originate a default-route to Area 0 from NSSA

R1 ------------- R2-----------------R3

area 1 NSSA AREA 0

1. In R1 When i use command "(config-router)#default-information originate always" I am seeing a route (EXT E2) in R3

2. In R1 when i use command "(config-router)#area 1 nssa default-information-originate I am seeing a route (N2) in R1

perfect right?

But I am not able to generate "default route" from R1

Is there is any way to generate default route from NSSA Router (R1 in this example)

Hope the explanation is clear. Please clear this doubt


I have this problem too.
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Edison Ortiz Sun, 08/02/2009 - 11:59


R3 is not part of the NSSA hence it will never receive a NSSA generated default route.




snarayanaraju Sun, 08/02/2009 - 22:18

Hi Edison,

Thanks for reponse.

I will try to explain with the scenario.

If R1 is connected to INTERNET, then a default route is required to send the traffic to INTERNET.

In this case for the routers to send the traffic to INTERNET I can configure "default-information originate" in R2, so that R3 will have Default route of EXTERNAL type.

Instead of configuring "default-information originate" in R2, Is it posssible to send a default route to R3 from R1? It is like sending redistributed prefix to R3 (AREA 0)

Hope i explained the requiremen better


Edison Ortiz Mon, 08/03/2009 - 05:41

If R1 is connected to the internet and you've decided to have that section of the network as NSSA, then it's just a bad design all around.

NSSA are designed for sections of the network where there is not transit path, for instance a remote location internal LAN that connects to corporate.

The only way R1 would be able to send a default route to other routers outside the NSSA is to use the 'default-information originate' command. Only NSSA participating routers will receiving 'N' routes.




snarayanaraju Mon, 08/03/2009 - 21:43

Hi Edison,

I tried this with "default-information originate" command in R1. As you mentioned it is sending default route only with in NSSA.

If I am trying to send the default route from R1 using "redistribute static" (after configuring static default route in R1), I am seeing a default routes in R3.

Is this the actual behaviour



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