Re: [Roll] Opinion please

[Richard Kelsey <richard.kelsey at ember.com>]

   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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