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How to prevent black-hole in NSSA
Hi, guys

could you pls explain How to prevent black-hole in NSSA.

Let say there are four routers in area 10 which is NSSA, two ABR
connected to the backbone. one router redistribute external route
to the NSSA area.

as i know we should do something in two ABR JUNIPER router, in order to
prevent blackhole.

from other area, to trace the external route, we would find that the
route is not gone through the shortest path, it means have blackhole in
the NSSA area.



--
Michael <wsf@vodatelsys.com>
How to prevent black-hole in NSSA [ In reply to ]
Hi Michael

If I understand it correct your problem is due to the
OSPF behaviour in case of more than one ABR in an NSSA
... by nature of ospf only one router will do the type
7 to type 5 translation. That might result in
suboptimal routing sometimes as routers in other areas
will know to reach the nssa externals only via the
advertising ABR.

Here the ABR with higher router will perform the
translation.

If you know which path would be optimal, then I guess
you will have to manually make the preferred ABR to
have higher router-id.

Hope this helps.

Cheers,
AMS
--- Michael <wsf@vodatelsys.com> wrote:
> Hi, guys
>
> could you pls explain How to prevent black-hole in
> NSSA.
>
> Let say there are four routers in area 10 which is
> NSSA, two ABR
> connected to the backbone. one router redistribute
> external route
> to the NSSA area.
>
> as i know we should do something in two ABR JUNIPER
> router, in order to
> prevent blackhole.
>
> from other area, to trace the external route, we
> would find that the
> route is not gone through the shortest path, it
> means have blackhole in
> the NSSA area.
>
>
>
> --
> Michael <wsf@vodatelsys.com>
>
> _______________________________________________
> juniper-nsp mailing list juniper-nsp@puck.nether.net
> http://puck.nether.net/mailman/listinfo/juniper-nsp


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