Re: [Roll] Opinion please

[Emmanuel Baccelli <Emmanuel.Baccelli at inria.fr>]

Hi JP,

I also root for option 1. It will indeed make the draft simpler. Actually I already mentionned this subject in my previous email to the list, giving feedback on the overview section (section 3).

Emmanuel

On Thu, Nov 5, 2009 at 2:56 PM, Richard Kelsey <richard.kelsey at ember.com> wrote:

  Date: Thu, 5 Nov 2009 10:21:19 +0100
  From: "Julien Abeille (jabeille)" <jabeille at cisco.com>

  Hi JP,

  I am for option 1. As you say OF mismatch is a configuration problem,
  joining as a leaf works fine. I am also not too keen having extra code
  on a sensor just because the admin did not do a rather simple task
  properly.

+1
                -Richard Kelsey

-----Original Message-----
From: roll-bounces at ietf.org [mailto:roll-bounces at ietf.org] On
Behalf Of JP Vasseur (jvasseur)
Sent: jeudi 5 novembre 2009 08:25
To: roll WG
Subject: [Roll] Opinion please

Dear all,

/co-chair hat off/

We would welcome your opinion on the following issue:

Suppose that a DAG is formed that support OFx. A new node
willing to join the DAG does not support OFx but OFy. Note
that by OF we actually mean the Objective function and the metric.

We have two options here.

Option 1: The node simply joins the DAG as a leaf. In order
words, the node has connectivity since it joins the DAG but
will not act as a router for others since it does not
understand the OF. Parent selection could be a simply a "random".

Option 2: The node joins the DAG and falls back to the
"default" OCP.
 From there is prolongs the DAG but with OF0 (of course
inconsistent metrics are not added). This also means that
everynode MUST implement OF0 and that the network may
compromise nodes with different OF at some point. Several
options even more complex have been discussed where one could
use common denominator to get as close as possible to the
desired OF, allow a node not to be so "altruistic", ...

My personal view is that OF management can quick get fairly
complex and hard to manage. Option 1 is extremely simple and
easy to manage.
If a node is mis-configured (does not support the OF of the
DAG) it can join it as a leaf in order to have connectivity
and send an alarm to fix its configuration. We now just need
to specify OF in some document and this is it.

Several of you mentioned that they were leaning toward option
1, but could you please express your opinion, we would like
to have it solved for the next revision next week.

Thanks.

JP.

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