[j-nsp] OSPF NSSA Type 4 LSA generation behavior

Adam adam.tajer at gmail.com
Tue Apr 19 10:34:32 EDT 2011


If I recall correctly, the ABR that translates Type7 into Type5
(highest RID) shows up in the backbone and other non-backbone areas as
ASBR, because it changes the Advertising router to itself while
performing translation from Type 7 and generating Type5 into Area 0.
So in areas other than the NSSA (where prefix was injected), you
should not see the "real" ASBR as Advertising Router, you should see
the ABR that performed the 7-to-5 translation listed in that field.

Regards,
Adam

On Tue, Apr 19, 2011 at 4:08 PM, Muruganandham M <sedhuanand at gmail.com> wrote:
> Dear Experts,
>
>        As per RFC 3101, *The OSPF Not-So-Stubby Area (NSSA) Option*, listed
> in the Juniper supported standards,
>
> Since Type-5 AS-external-LSAs are not flooded
>   into NSSAs, NSSA border routers should not originate Type-4 summary-
>   LSAs into their NSSAs.  Also an NSSA's border routers never originate
>   Type-4 summary-LSAs for the NSSA's AS boundary routers, since Type-7
>   AS-external-LSAs are never flooded beyond the NSSA's border.
>
> This looks to be the same behavior in CISCO also.
>
> But JUNIPER router (ABR) does generate the ASBR summary (type 4) for
> the NSSA ASBR.  Is there any specific  reason for doing this
> implementation? Or Juniper follows any other RFC for this behavior?
>
> --
> Thanks
> Muruganandham M
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