From: Nigel Taylor (nigel_taylor@hotmail.com)
Date: Wed Sep 04 2002 - 01:19:12 GMT-3
Chris,
I think you're missing what Peter is trying to say. As you've
noted(and Peter as well) in normal conditions the only time the P-bit is
cleared is to eliminate the translation of type 7's from being translated by
other NSSA ABR's. However, as Peter point's out the problem here would be
why is the ASBR clearing the P-bit. I looked around and came back to (as
Howard pointed out) one of the best books on IP routing (next to Doyle's)
Alex Zinin's - Cisco IP Routing.
This is just a thought but if anyone cares to comment of the validity of my
understanding and or the possibility if these mechanisms applying across the
board with reference to NSSA LSA processing, please do so. Page 497,
9.2.5.3, Alex notes the use of the redistribute command on Cisco OSPF router
and the use of a special process called the OSPF scanner, which is started.
Reason for the scanner is to ensure synchronization of the routing table -
specifically the redistributed routes - and self-originated
AS-external-LSAs. I noted the redistribute command being used on R1 which
caught my attention.
He further notes that it's not enough that the ASBR to originate LSAs. The
remote router(s) must have corresponding entry in their RIBs to install
external routes derived from AS-external-LSAs announced by a particular
router. The most important thing her noted was as follows, "To ensure that
routers residing in the same area as the ASBR install such entries and that
ABR's properly announce the ASBR location in the ASBR-summary-LSAs, the ASBR
sets the E-bit in it's router LSA.
Can you confirm the setting of the E-bit in the router LSAs? Also, the
final paragraph provide some insight as to a number of thing we could look
at in trying to identify the reasoning behind what you're observing.
Thoughts...
Nigel
P.S. Folks add this books to your Intra-domain Routing Library. It
provides an level of insight into so many other aspects of Cisco's protocol
implementation.
(Disclaimer: I was not paid to make that comment... It's all Howard's
fault. He mentioned the book in the list - I just was just crazy enough to
buy it :-) )
----- Original Message -----
From: "Chris Larson" <clarson52@comcast.net>
To: "Peter van Oene" <pvo@usermail.com>; "Khalid Siddiq"
<khalid@sys.net.pk>; <ccielab@groupstudy.com>
Sent: Tuesday, September 03, 2002 9:42 PM
Subject: Re: NSSA and type 7 LSA's -same problem. Configs incl.
> The only reason that I know that this would happen is if the router were
> both ASBR and ABR and R2 is not. Also, an earlier post had mentioned
> reacability. I have taken the config off for now, but I remeber that
subnet
> being an O route.
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