OSFP - Conditional default injection with NSSA Area

[Map23]

Hi all, 

I have a configuration with default route injection on NSSA area: 

area 31 nssa default-information-originate no-summary

This announce seems is always active. It is not related to default route presence on route table. 

So seems that "always" option is active by default, and isn't possible disable it. 

Can someone confirm me that with nssa area isn't possibile create a conditional default route injection ? 

Thanks!

[Georg Pauwen]

Hello,

I don't think you can keep the LSA type 7 for the default route to be generated and put into the OSPF database. To keep it out of the routing tables of the other NSSA routers, you could block the forward address, which is 0.0.0.0:

access-list 1 deny 0.0.0.0

access-list 1 permit any

!

router ospf 1

area 1 nssa

distribute-list 1 in

This keeps the default route out of the routing table...

[Map23]

Hello Georg, 

sorry, probably I described bad my situation. 

RTR01 -- area NSSA -- RTR02 -- area NO NSSA -- RTR03

I did configuration for default route injection to NSSA on RTR02. This device announce default route on NSSA area. 

RTR02 receive also default route from RTR03 with separated OSPF process with area NO NSSA. 

My expectation is that RTR02 inject default route to NSSA only when it receive default route from RTR03. 

So, RTR02 announce default to RTR01 under condition of default reception from RTR03

With normal area this is the difference between case with "default-information originate" with and without "always".

But with NSSA area, seems that it announce default route always by default, and isn't possibile disable it. 

So, I want default route on NSSA router (RTR01) but only if RTR02 receive default from RTR03

Thanks!

[Georg Pauwen · Accepted solution]

Hello,

the command 'area x nssa default-information originate' will create the default route (LSA type 7) no matter what. It doesn't depend on the existence of a route in the routing table, as is the case with 'normal' OSPF areas. There is no way you can conditionally create (or not) that route...

[Map23]

OK Georg,

thank you for confirmation, unfortunately I didn't find documentation about it.

Thanks!