[nsp] OSPF NSSA

[Oliver Boehmer (oboehmer)]

> 
> I am currently trying out OSPF on the following lab
> network:
> 
> R - R2 - R
> 1 - R3 - 4
> 
> * R1 is connected to both R2 and R3 via router FE
> ports
> * R4 is connected to both R2 and R3 via router FE
> ports
> 
> R1, R2 & R3 are in Area 0 while R2, R3 & R4 are in
> Area 1.
> 
> In default configuration, R1 is able to see two paths
> to R4 via either R2 or R3.
> 
> However, after I configured Area 1 as a NSSA, R1 only
> saw 1 path to R4 via R3.
> 
> Does anyone know why R1 only saw 1 path to R4 when
> Area 1 is in NSSA mode? Is it possible for R1 to see
> the same two paths to R4 when Area 1 is in NSSA mode?

This is expected behavior. There is only one Type7-Type5 translator with
OSPF-NSSAs, so only one of the two NSSA-ABRs will announce the path to
R4 into area 0. 

There is a "new" RFC 3101 which allows multiple translators, but support
for this is still on our roadmap.

	oli