Subject: [Roll] [roll] routing-metrics #82 (new): Comment received during WG Last Call on draft-ietf-roll-routing-metrics-09.txt --- Clarification on Node Fanout Ratio Object

From: "roll issue tracker" <[email-masked]>
Date: Tue, 05 Oct 2010 14:55:12 -0000

#82: Comment received during WG Last Call on draft-ietf-roll-routing-
metrics-09.txt --- Clarification on Node Fanout Ratio Object
-----------------------------+----------------------------------------------
 Reporter:  jpv@…            |       Owner:  nicolas.dejean@…          
     Type:  defect           |      Status:  new                       
 Priority:  major            |   Milestone:                            
Component:  routing-metrics  |     Version:                            
 Severity:  In WG Last Call  |    Keywords:                            
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 Original Email below (refer to the archives for the full discussion)

 Email sent on September 23, by Phoebus Chen:

 "I'm a little confused about the Node Fanout Ratio (NFR) Object in Section
 3.4 .  Does fanout refer to outgoing links (upward, to a parents), or
 incoming links (downward, from children) of a node?

 The text says:
 "The Node Fanout Ratio (NFR) object is used to provide information on
 the nodes current forwarding load."

 From this, I would read fanout to mean the number of incoming links, if
 you are concerned with upward routing.  The amount of traffic you have to
 forward depends on the amount of traffic coming in, which might be roughly
 related to the number of children.  But as far as I know, RPL nodes only
 keep track of parents, not of children, so it cannot keep track of the
 number of incoming links.

 Or is the NFR object is used for optimizing the topology for downward
 routing (related to DAO fanout), to get path diversity / reliability? If
 this is the case, perhaps this should be explained in the metrics
 document."

-- 
Ticket URL: <https://svn.tools.ietf.org/wg/roll/trac/ticket/82>
roll <http://tools.ietf.org/wg/roll/>

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From: "roll issue tracker" <[email-masked]>
Date: Tue, 12 Oct 2010 17:34:52 -0000

Comment(by jpv@…):

 Email from Nicolas Dejean - October 12

 Response below.

 --
 Phoebus Chen
 Postdoctoral Researcher
 Automatic Control Lab, KTH (Royal Institute of Technology)
 http://www.ee.kth.se/~phoebus

 On 10/12/10 9:18 AM, Nicolas DEJEAN wrote:
 Hello Phoebus,

 2010/9/23 Phoebus Chen<[email-masked]>:
 I'm a little confused about the Node Fanout Ratio (NFR) Object in Section
 3.4 .  Does fanout refer to outgoing links (upward, to a parents), or
 incoming links (downward, from children) of a node?

 The idea is that this metric refers to the incoming links.

 The text says:

 From this, I would read fanout to mean the number of incoming links, if
 you
 are concerned with upward routing.  The amount of traffic you have to
 forward depends on the amount of traffic coming in, which might be roughly
 related to the number of children.

 You are right.

  But as far as I know, RPL nodes only
 keep track of parents, not of children, so it cannot keep track of the
 number of incoming links.

 Unfortunately, you are right again. Good point.

 document.

 This is absolutely not the idea.
 As a conclusion, maybe we could find some specific cases (based on
 storing/non storing mode and DAO usage for instance) that could allow
 using this metric but in all cases, this is much more complicated than
 expected at start.

 My proposal is to remove this metric from the draft. It might be
 reintroduced later in a separate ID.

 That's fine by me.

 Nicolas.

 --
 Phoebus Chen
 Postdoctoral Researcher
 Automatic Control Lab, KTH (Royal Institute of Technology)
 http://www.ee.kth.se/~phoebus

Ticket URL: <https://svn.tools.ietf.org/wg/roll/trac/ticket/82#comment:1>
roll <http://tools.ietf.org/wg/roll/>

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From: "roll issue tracker" <[email-masked]>
Date: Wed, 13 Oct 2010 08:35:07 -0000

Changes (by jpv@…):

  * status:  new => closed
  * resolution:  => fixed

-- 
-----------------------------+----------------------------------------------
 Reporter:  jpv@…            |        Owner:  nicolas.dejean@…          
     Type:  defect           |       Status:  closed                    
 Priority:  major            |    Milestone:                            
Component:  routing-metrics  |      Version:                            
 Severity:  In WG Last Call  |   Resolution:  fixed                     
 Keywords:                   |  
-----------------------------+----------------------------------------------

Ticket URL: <https://svn.tools.ietf.org/wg/roll/trac/ticket/82#comment:2>
roll <http://tools.ietf.org/wg/roll/>