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

[Federico Consoli <[e-mail]>]

Hi,
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:

Example:
------
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 
worse.

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.

-- 
Regards
Consoli Federico