OSPF Default route

Routing & Switching OSPF
1

Hello guys,

i do labs for ospf and i need your advice.
I’m propagating default route through several ospf areas.
I’m clear with stub and totally stub areas - they make default route themself.
My question is about nssa and totally nssa areas - there are not allowed LSAs type 5 (3) so the default route is not propagated to nssa (tnssa) - if i am right and default route uses type 5 :slight_smile:
Is the best practice to add the default route to nssa manually?

Thanks a lot for your advice and i’m sorry for my english :wink:
Standa

2

Standa,
Actually, default routes into a NSSA and TNSSA are of type 3. This is the only exception to the rule that Type 3 LSAs are not allowed in NSSA or TNSSA areas.

As far as your best practice question … you have no choice but to configure a default route manually via the ABR. The default behavior of an ABR for an NSSA/TNSSA area is NOT to inject a default route.

3

Hello Andrew,

thanks for your answer.
I configured area 1 nssa default-information originate and that works.
Type 3 is not allowed also in NSSA? I thought NSSA areas allow type 3.
Thanks
S.

4

Sims,
You are correct. I was thinking Totally Stubby Area and NSSA Totally Stubby. So many crazy stub names in OSPF!

5

Yea, it is a bit confusing. But your topic about OSPF Area types is great to understand.