Subject: Re: [OSPF] Database Exchange Summary List Optimization

From: Paul Jakma <[email-masked]>
Date: Wed, 2 Aug 2006 07:39:07 +0100 (IST)

Hi Richard,

On Wed, 12 Jul 2006, Richard Ogier wrote:

> http://www.ietf.org/internet-drafts/draft-ogier-ospf-dbex-opt-00.txt

> Comments?

Excellent idea :).

One comment though, with repsect to the suggested modifying text to 
2328:

" If it does not, or if the database copy is less recent (see Section
   13.1), the LSA is put on the Link state request list so that it can
   be requested (immediately or at some later time) in Link State
   Request Packets.  The router also looks up the LSA in the Database
   summary list for the neighbor.  If the Database summary list
   contains an instance of the LSA that is the same or less recent
   than the one listed in the received packet, the LSA is removed from
   the Database summary list."

The second recency comparison with the LSA on the DB-summary list 
seems superfluous. Additionally, it makes for mildly confusing 
reading to have "less recent" for one case, and "same or less recent" 
for the other.

It could, perhaps, be better expressed in terms of just that single 
recency test of the database copy against the received LSA:

" If it does not, or if the database copy is less recent (see Section
   13.1), the LSA is put on the Link state request list so that it can
   be requested (immediately or at some later time) in Link State
   Request Packets. Additionaly, if it does and the dabase copy is
   the same as or less recent than the received copy, the LSA is
   also removed from the Database summary list, if a copy still
   exists on it."

Which seems slightly clearer to my mind anyway.

regards,
-- 
Paul Jakma	[email-masked]	[email-masked]	Key ID: 64A2FF6A
Fortune:
Computer programs expand so as to fill the core available.

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From: Richard Ogier <[email-masked]>
Date: Thu, 03 Aug 2006 15:49:22 -0700

Hi Paul,

Thanks for your comment. Yes, I agree that we can do the comparison
based on the database copy and avoid looking up the LSA on the
summary list (unless it must be removed from the list).
(But we still have "less recent" for the first comparison and
"same or less recent" for the second comparison.)

Richard

Paul Jakma wrote:

> One comment though, with repsect to the suggested modifying text to 2328:
>
> seems superfluous. Additionally, it makes for mildly confusing reading 
> to have "less recent" for one case, and "same or less recent" for the 
> other.
>

---

From: Paul Jakma <[email-masked]>
Date: Fri, 4 Aug 2006 06:01:47 +0100 (IST)

> summary list (unless it must be removed from the list).

Potentially anyway.

> "same or less recent" for the second comparison.)

Yes indeed. :) Sorry, badly worded. I think I meant that it was 
mildly confusing to have two tests, of two different LSA instances 
(potentially) against the received LSA, and to figure out exactly how 
they related to each other.

If its the same test of the same two LSA instances, it's more clear, 
regardless that < and <= remain (to me anyway).

regards,
-- 
Paul Jakma	[email-masked]	[email-masked]	Key ID: 64A2FF6A
Fortune:
How much net work could a network work, if a network could net work?