Subject: [Roll] RE Opinion please

From: [email-masked]
Date: Thu, 5 Nov 2009 23:34:40 +0100

Hi JP,
I vote for option 1 also to avoid complexity and confusion.
Nicolas

JP Vasseur <[email-masked]> 
Envoyé par : [email-masked]
05/11/2009 08:24

A
roll WG <[email-masked]>
cc

Objet
[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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