Subject: LDP-09 - Receive Label Mapping

From: "James R. Leu" <[email-masked]>
Date: Thu, 10 Aug 2000 12:03:17 -0400

Forgive me if this has already been discussed, just point me to the thread in
the archive.

I have a question about the loop from LMp.17 to LMp.31
Here is my interpretation of what should happen:

When processing a incoming label map message the LSR needs to figure out
what other peers this mapping needs to be propagated to.  While processing
the list of all peers:

-if the LSR has previously sent a mapping, and the attributes of the new
 mapping are different then the attributes of the old mapping then send an
 updated mapping (LMp.22-LMp.27).
-if a peer is operating in DU then the LSR should propagate the mapping
 (LMp.20,LMp.21)
-if a peer is operating in DOD AND the LSR has a record of an outstanding label
 request from that peer, propagate the mapping and delete the record of the
 outstanding request (LMp.29-DOD).

If this is a reasonable interpretation then what is LMp.29-DU for?
Didn't the LSR already do that work in LMp.20,LMp.21?

Jim
-- 
James R. Leu
Software Engineer
Laurel Networks, Inc
[email-masked]

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From: Bob Thomas <[email-masked]>
Date: Thu, 10 Aug 2000 13:47:07 -0400

Jim,

> Didn't the LSR already do that work in LMp.20,LMp.21?

LMp.20+LMp.21 handles (only) the situation where a label mapping
has not previously been sent to the upstream peer AND the mode is
DU Ordered.

LMp.29-DU handles the situation where there are outstanding label
requests from the peer (which won't be the case if LMp.20+LMp,21
is executed since in the unlikely event that the peer had
requested a label in DU Ordered mode LMp.20+LMp.21 would have satisfied
the request).  In addition, LMp.29-DU handles the situation where
DU Independent is being used, which LMp.20+LMp.21 does not.

This procedure is complex because the number of combinations of modes
that must be handled (DU/DoD advertisment, liberal/conservative retention,
ordered/independent control).  There are no doubt ways to re-arrange
it to achieve the desired effect.

Bob

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From: "James R. Leu" <[email-masked]>
Date: Thu, 10 Aug 2000 15:01:14 -0400

Bob,

Thanks for the clarification.  I have one additional question.

On Thu, Aug 10, 2000 at 01:47:07PM -0400, Bob Thomas wrote:
<snip>
> requests from the peer (which won't be the case if LMp.20+LMp,21

Shouldn't the record of these requests be deleted then in LMp.29-DU?
LMp.29-DoD has the line "4.  Delete record of pending request."

> that must be handled (DU/DoD advertisement, liberal/conservative retention,

Jim
-- 
James R. Leu
Software Engineer
Laurel Networks, Inc
[email-masked]

---

From: Bob Thomas <[email-masked]>
Date: Thu, 10 Aug 2000 15:29:14 -0400

Jim,

> LMp.29-DoD has the line "4.  Delete record of pending request."

Yes.

A difficulty in generating these procedures (in addition to trying to
get them right) was keeping them short enough so that they could be
read/understood yet detailed enough to cover the important actions.

Doing this involved numerous judgements as to what could be omitted.
In this case (and probably others), we were inconsistent.

Bob