Subject: What is real ABR?

From: Igor Miroshnik <[email-masked]>
Date: Tue, 4 Mar 2003 05:24:45 -0500

Ladies and Gentlemen,

I have failed to find the answer in the archives. The question is what the
behavior of ABR should be when it is neither physically connected to the
backbone, nor having any configured virtual link. RFC2328 says such a
router (having active interfaces to multiple areas) marks its router LSA
with the bit B. Furthermore, as an ABR, the router originates summary LSAs
and injects them into the attached non-stub areas.

1. Are the routes built by internal routers on the basis of those summary
LSAs valid? Such inter-area routes pass between areas without the backbone
mediation.

2. ABR should only process the backbone summary LSAs. The database of the
router described has no backbone summary LSAs. Does it mean that this
router cannot build inter-area routes?

Thank you,
Igor

---

From: "Manral, Vishwas" <[email-masked]>
Date: Tue, 4 Mar 2003 05:42:58 -0500

Hi Igor,

To answer your questions: -

1. Yes they are. The leaking of summary LSA's is given in section 12.4.3
RFC2328.
"           Note that only intra-area routes are advertised into
            the backbone, while both intra-area and inter-area routes
            are advertised into the other areas.
"

2. Yes in case a router has active attachments to multiple areas, only the
backbone summary LSA's are to be processed for routing table calculations.
In this case no summary LSA's will be processed.

Going through the document
http://www.ietf.org/internet-drafts/draft-ietf-ospf-abr-alt-05.txt would be
helpful to clear any doubts you have.

Thanks,
Vishwas

-----Original Message-----
From: Igor Miroshnik [mailto:[email-masked]]
Sent: Tuesday, March 04, 2003 3:55 PM
To: [email-masked]
Subject: What is real ABR?

Ladies and Gentlemen,

Thank you,
Igor