Subject: summary LSA

From: Alok Dube <[email-masked]>
Date: Sat, 12 Jul 2003 01:21:44 +0530

Hi,

I have a  question regarding the following topology,

Router A connects to 2 ABRs, ABR-1 and ABR 2 and is in Area 1.

Router B also connects to ABR-1 and ABR-2 and is in Area 2.

my questions:

1. is there a problem with the above?

2. if the ABR is shared between multiple areas 1 & 2, can one send summary
LSAs of routes in Area 1 into Area 2? I assume the "summarizartion
configuration" is per area.
3. In general, is the summary LSA generated by the ABR of the area into
which it is flooded and or by the ABR of the area which originates the
LSA? If the former, isnt it better from a aggregation view point to do the
former?
-thanks
Alok

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From: Acee Lindem <[email-masked]>
Date: Fri, 11 Jul 2003 15:48:17 -0400

> 1. is there a problem with the above?

No.

> LSAs of routes in Area 1 into Area 2?

Yes but replace "can" with "must".

> I assume the "summarizartion

Yes.

> LSA?

The summary for intra-area routes (or a range of routes) is always
originated by the ABR connecting the area corresponding to the
intra-area routes. For inter-area routes from the backbone areas,
ABRs will originate a summary into non-backbone areas.

This is all covered in RFC 2328 (although it is articulated much better).

> If the former, isnt it better from a aggregation view point to do the
> former?
> -thanks
> Alok
>

--
Acee