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Re: [Roll] Border router failure detection

Michael Richardson <mcr+ietf@sandelman.ca> Thu, 13 October 2022 16:05 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: Thu, 13 Oct 2022 12:05:40 -0400
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Archived-At: <https://mailarchive.ietf.org/arch/msg/roll/Noq_RNqGne8DVrY9OyNkKzVyquY>
Subject: Re: [Roll] Border router failure detection
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Konrad Iwanicki <iwanicki@mimuw.edu.pl> wrote:
    > 3. Is rebuilding the DODAG in such a case desirable?

    > If the majority of links to the root that have once formed a DODAG are
    > currently down, then the DODAG should probably look different than for
    > the network with those links up. Rebuilding the DODAG, at least in my
    > opinion, makes a lot of sense in such a case. Furthermore, the threshold
    > describing how large the majority is is configurable. Depending on whether
    > one wants to prioritize speeding up root failure detection or slowing down
    > DODAG rebuilding, different values can be chosen.

Do the sentinels need to agree on this threshold?

    > 4. Why can't Sentinels ask the root whether it is dead?

    > In fact they do. If a Sentinel observes that an increasing number of other
    > Sentinels considers the root as dead, it may perform verification by trying
    > to contact the root via a direct link.

    > I hope to have covered all the questions.

I think so.


--
Michael Richardson <mcr+IETF@sandelman.ca>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide

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