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Re: [Roll] draft-rahul-roll-rpl-observations-00 Section 2.1: Wear leveling

Michael Richardson <mcr+ietf@sandelman.ca> Sun, 13 May 2018 16:55 UTC

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From: Michael Richardson <mcr+ietf@sandelman.ca>
To: Routing Over Low power and Lossy networks <roll@ietf.org>
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Date: Sun, 13 May 2018 12:55:02 -0400
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Subject: Re: [Roll] draft-rahul-roll-rpl-observations-00 Section 2.1: Wear leveling
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Pascal Thubert (pthubert) <pthubert@cisco.com> wrote:
    > The default of 16 points in the straight line is there to cover
    > multiple losses in a row; 16 may be too large for a reliable Mac like
    > TSCH in which case a node may start at another value, e.g.,
    > 250. Starting at 255 looks optimistic though. In case of a loss numbers
    > will move to the circular part and will be uncomparable.

okay, so with TSCH it would make sense to start a higher number?

    > It is not really that the node is stable that counts but that all other
    > nodes got a chance to see that this node as rebooted so they can reset
    > their reference value and keep numbers comparable.

Yes, agreed.
The goal is to have a way for children to see that the node is freshly
rebooted and to reset their threshold.

    > I’m happy to pursue this discussion to see more clearly than I do now;
    > at this point I still do not see what change we could make - and why -
    > to the sequence counter behavior... 

Maybe there is no change, but you claim the DTSN does need to be written to
flash, and Rahul says that it must be.   (Correct me if my understanding is wrong).
A protocol which does not require flash writes is clearly better.

-- 
]               Never tell me the odds!                 | ipv6 mesh networks [ 
]   Michael Richardson, Sandelman Software Works        | network architect  [ 
]     mcr@sandelman.ca  http://www.sandelman.ca/        |   ruby on rails    [

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