Subject: [Roll] Parent selection for leaf nodes

From: "JeongGil Ko (John)" <[email-masked]>
Date: Wed, 22 Sep 2010 15:01:21 -0400

Hi.

Let's say we have a case where a node 'wants' to join the network as a leaf node (for various reasons). In this case, I guess the assumption behind this happening would be that this node cannot (or will not) understand the OFs in the DODAG. Then among the multiple DIOs it hears from multiple routers how should the leaf node determine the most preferred parent node? Since it does not understand the OFs in the DIOs, it would not be able to compute 'its' rank and thus, will just go for the node in its reach with the lowest rank (despite that the one hop link quality to this node can be bad)? 

Thanks.

-John

------
JeongGil Ko (John)
Ph.D. Student
Department of Computer Science
Johns Hopkins University
http://www.cs.jhu.edu/~jgko

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From: Michael Richardson <[email-masked]>
Date: Wed, 22 Sep 2010 22:20:06 -0400

>>>>> "JeongGil" == JeongGil Ko <(John)" <[email-masked]>> writes:
    JeongGil> Let's say we have a case where a node 'wants' to join the
    JeongGil> network as a leaf node (for various reasons). In this
    JeongGil> case, I guess the assumption behind this happening would
    JeongGil> be that this node cannot (or will not) understand the OFs
    JeongGil> in the DODAG. Then among the multiple DIOs it hears from

Not understanding the OFs forces a node to join as a leaf.
It is not necessarily a "want".  There are other reasons to join as a leaf.

    JeongGil> multiple routers how should the leaf node determine the
    JeongGil> most preferred parent node? Since it does not understand
    JeongGil> the OFs in the DIOs, it would not be able to compute 'its'
    JeongGil> rank and thus, will just go for the node in its reach with
    JeongGil> the lowest rank (despite that the one hop link quality to
    JeongGil> this node can be bad)?

I think so.  If it can locally compute single hop qualities, then it can
make a more informed decision, even if it does not understand the OFs to
be able to pass that information on.

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