[Roll] I-D Action: draft-ietf-roll-minrank-hysteresis-of-10 Comments

Federico Consoli <admin@ipv6it.org> Sun, 13 May 2012 14:02 UTC

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Date: Sun, 13 May 2012 16:01:59 +0200
From: Federico Consoli <admin@ipv6it.org>
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Subject: [Roll] I-D Action: draft-ietf-roll-minrank-hysteresis-of-10 Comments
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I have a doubt concerning the selection of parent set.
Draft Section 3.3 says:
"The exact selection of a parent set is an implementation decision."

The document does not specify what to do in a situation like this:

The node A has 1 parent with rank 700 and path cost 300 => A has a rank 
= 1000.
B has A as Preferred parent and the path cost A-B is 300, soB has rank 1300.

Later A receives from node C a DIO. Node C has rank 900 andpath cost A-C 
is 500 => A puts C in its parent set and announce a rank 1400.
But, A receives a DIO from node B before to send a DIO =>A puts B in its 
parent set.

When B receives the DD it will increase its rank. When Node A receives 
the DIO from the node B, it has 2 options:
1) Increase its rank
2) Delete the node from the parent set

If A chooses option 1 there will be an infinite loop.

In general, a node does not know the reason why a parent increase its 
rank. In fact, a node can also increase his rank because its link is got 

IMHO I think that if a parent announces a rank higher than the rank of 
the the nodethen the node MUST remove the parent from its Parent set.

Consoli Federico